Mother Nature: A History of Mothers, Infants, and Natural Selection [1 ed.] 0679442650, 9780679442653

Citation preview

Wlother^Slature A History of Mothers, Infants, and

Natural Selection

Sarah Blaffer Hrdy /

^'J

^

Digitized by the Internet Archive in

2010

http://www.archive.org/details/mothernaturehistOOhrdy

Mother Nature yAj--a^ i^^

/ -^

Also by Sarah Blaffer Hrdy:

The

Woman That

Never Evolved

The Langurs ofAbu: Female and Male Strategies of Reproduction The Black-man oj Zinacantan: A Central American Legend

Co-editor with Glenn Hausfater: Infanticide: Comparative

and Evolutionary

Perspectives

Mother Nature A

History of

Mothers, Infants, and

Natural Selection

Sarah Blaffer Hrdy

Pantheon Books

New York

Cop^Tight

©

1

999 by Sarah

Blaffer

Hrdy

All rights reserved

under International and Pan-American Copyright Conventions. Published in the United States by Pantheon Books, a division of Random House, Inc.,

and simultaneously

in

Pantheon Books and colophon are registered trademarks of Random House,

Library of Congress Cataloging-in-Publication Data

Hrdy, Sarah

Mother nature

:

a history

Blaffer,

1

946—

of mothers, infants, and natural

selection / Sarah Blaffer Hrdy. p.

cm.

Includes bibliographical references

(p.

)

and index.

ISBN 0-679-4426^-0 I.

3.

Mother and

New York,

Canada by Random House of Canada Limited, Toronto.

child.

Natural selection.

2.

4.

Motherhood

—

Psychological aspects.

Parental behavior in animals.

mothers.

I.

HQ7?9H784 306. 874*3

5.

Working

Title

—

dc2i

1999

99-13092

Random House Web Address: www.randomhouse.com Book design by Fearn Cutler de Vicq

Printed in the United States of America

24689753

Inc.

For Dan, the wisest choice thisjemale ever

made

Mother Nature

—

who by

the bye

is

an old lady with some bad habits

—

George Eliot,

1

.

.

.

848

9

3

9 8

Contents Preface

xi

PART ONE Look

Animals

to the

1

1

Motherhood

as a

2

A New View

of Mothers

3

Underlying Mysteries of Development

g^

4

Unimaginable Variation

79

^

The Variable Environments of Evolutionary Relevance

96

Minefield

3

27

TWO

PA RT

Mothers and Allomothers

1 1

6

The Milky Way

i2i

7

From Here

146

8

Family Planning Primate-Style

to Maternity

i

Men and a Baby

yg

9

Three

I

o

The Optimal Number of Fathers

23^

I

I

Who

266

12

20^

Cared?

Unnatural Mothers

1

Daughters or Sons?

14

Old Tradeoffs,

New

288 It

All

Depends

Contexts

PA RT

An 15

3

1

35^1

THREE

Infant's-Eye

View

381

Born to Attach

383

I

6

Meeting the Eyes of Love

394

1

7

"Secure from What?" or "Secure from Whom?"

408

I

8

Empowering

the

Embryo

4

IX

1

1

1

CONTENTS

X

19

20

Why Be Adorable? How to Be "An Infant Worth Rearing"

441 45-2

2 2

A Matter of Fat Of Human Bondage

485^

23

Alternate Paths of Development

^11

24

Devising Better Lullabies

^32

Notes

^43

Acknowledgments

^99

Bibliography

603

Index

69

2

^j£

Preface spent

Ihave who is

fluke

I

am

—

entire adult

engaged

in a quest to

me came

to be. That

Out of the seven million or

a miracle.

it is

life

understand not just

humans evolved

at all

My own existence, like that of any other person's, is more than a

a fluke.

born with,

my

but how creatures like

it

was mine

that ripened to

be

so egg cells

fertilized

by

my

my mother was

father.

Against the

And what mean to be

usual odds, that fetus survived the vagaries of gestation to be born.

about

born

this creature, this

a

person

1

would become? What does

mammal, with an emotional

legacy that makes

me

it

capable of caring

for others, breeding with the ovaries of a primate, possessing the

mind of a

human being? What does it mean for a woman to have descended from ances6 million and ten tors who spent the Pleistocene (the time span between i

.

thousand years ago) trying to gather enough food to stay fed and also obtain

enough help from others so

What does To be

a

it

mean

to be

that her offspring

these things

all

would survive and prosper?

embodied

in

one ambitious woman?

semicontinuously sexually receptive, hairless biped,

flicting aspirations

and struggling to maintain her balance

filled

with con-

in a rapidly

chang-

ing world?

For better or for worse, people.

My

depth of

I

see the world through a different lens than

field is millions

most

of years longer, and the subjects in

my

viewfinder have the curious habit of spontaneously taking on the attributes of

other species: chimps, platypuses, australopithecines. This habit of thinking

about mothers in broad evolutionary and comparative cultural

and historical

—

perspectives distinguishes

my

—

as well as cross-

examination of moth-

erhood from those of the psychoanalysts, psychologists, novehsts, poets, and social historians I

am

whose work 1 build on.

trained in anthropology, primatology, and evolutionary theory.

entered graduate school in 1970

male -centered able, as

it

when Harvard was still a very sciences. Nor was it then fashion-

time

at a

institution, especially in the

has since become, to focus

I

on the

tionary processes. During the years of

my

active role of

mothers

in evolu-

education and early career, the

genderscape of the natural sciences was transformed by a broader inclusion of

women. With

their involvement

came new emphases and new

study. Just a century before, the only

women

XI

topics of

writing about evolution were

PREFACE

Xll

novelists or

commentators on the outer edges of the

scientific

community,

with no impact on mainstream theory. Today that situation has changed.

Even more unhkely than being born, the accident of when and to which family

was born meant

I

that

I

ended up among the fraction of human females

ever permitted the kind of education and opportunities to do research traditionally reserved for

observe

men.

I

had

uncommon

opportunities to travel, to

types of primates in the habitats in which they evolved, and to

all

enter previously all-male scientific domains. Because

wanted to be

I

as

well as a scientist, this meant making compromises. But

to

make

the really big compromise, to choose between

I

a

mother

was never forced

my aspirations and the

rewards of marriage, pregnancy, giving birth, and the

satisfaction of watching

my

right.

children

become remarkable people

in their

own

I

owe

this

luxury

to the availability of an unprecedented degree of reproductive choice, especially in the

until after child,

I

realm of birth control.

my

could

I

still

continue to do research, although topics

could postpone

screening and,

could delay the birth of

doctoral thesis was published. After the birth

work and turning to child,

I

if

I

it

my first child of my second

meant giving up

field-

could study closer to home. In the case of my

his birth until after

I

was

necessary, an early abortion

last

forty, confident that genetic

would protect my family from

the liability of aging ovaries.

My

melding of vocation with family has been supported by

a steadfast

partner, resilient children, and the generous hearts of alloparents individuals other than

As

I

would

learn,

me

and

my

husband

mothers have worked for

who as

—

all

the

helped us rear our children.

long as our species has existed,

and they have depended on others to help them rear their children. Like I

many humans

observed

today,

in the field.

own mother had no

I

was reared quite

differently

interest in carrying

me

their

own

infants

my

everywhere she went. Indeed,

the particular tribe of elite Texans into which

mothers nurturing

from the primates

Unlike the mothers in every other ape species,

I

in

was born, the custom of

had been

lost generations before.

My mother delegated the care of her infants to others, just as both my grandmothers had done.

My

mother's idea of good management was that

attached to a nanny,

it

was time to

diminished. This meant that

one ever doubted

that

I

hire a

new

was reared by

my mother

one,

a child

if

lest

became too

maternal control be

a succession

of governesses.

No

loved her five children. She was under the

impression that infants might be born of inferior or superior "stock" (Mke

all

PREFACE southerners, she was fascinated by family Unes), but Hke most college-

women

educated

of her time, she also believed that babies were blank slates,

conditioned to act as they were trained

was born

I

in

1

946.

It

was not

to.

decades later that the writings

until several

of the British medical doctor and psychoanalyst John Bowlby began to change

way educated people thought about the needs of children. Bowlby demonstrated that babies are genetically programmed to seek and form an attachment to a trusted figure. Secure attachment to one or more trusted

the

caretakers

is

an essential aspect of emotional development in humans, just

as

in all other primates.

it is

Along with several recent revisions to "attachment theory," Bowlby 's ideas

among

will stand

psychologists to series of

—

human

made by evolutionary-minded

Bowlby 's

well-being. But

often seemingly irreconcilable

produce

insights also

—dilemmas

for

to rear emotionally healthy, self-confident children, but

want lives

new

the greatest contributions

a

mothers who

who

want

also

or careers of their own.

Both pre- and post-Bowlby,

a

woman's maternal emotions (those con-

cerned with producing and nurturing offspring and keeping them

con-

alive)

tinued to be viewed as separate from and even antithetical to the rest of

her

—

her sexuality and, particularly, her ambition. Yet the compartmental-

ized

wav we have learned

with

how

to think about these emotions has nothing to

do

they evolved.

Such thoughts were

far

from

my

conscious

mind when,

years ago,

I

found

myself in the throes of cyclically experienced sexual feelings. At that time, such restless yearnings were Indeed, in

some

still

a largely

unacknowledged primate

such feelings were assumed not even to exist in

circles

women. Hence I had no framework for interpreting them. attracted to some men more than others for reasons that I

stand. Eventually

1

fell in

in a course, ironically

love (almost

enough, on

from the moment

"fossil

man") with

I

had no idea

how

found myself

first set

my

eyes on

him

conscious thoughts,

he would prove to be a wonderful and very committed I

I

did not under-

a fellow anthropologist.

Even though nothing could have been further from

point,

legacy.

father. Yet, at that

inextricably linked sexual and maternal emotions

have been in the course of primate evolution.

When we dren,

all

1

can

finallv

decided that

it

was

remember was wanting

to be pregnant. Even "doing nothing," I

a

a

"good enough" time to have

how wonderful it was Odd as this may sound to

daughter and

felt creative.

chil-

— PREFACE

XIV

some, birth, too, was

a

euphoric experience, the pain

more

far

nearly fasci-

nating than unbearable. For me, contractions during labor were an opportunity to find out

what

it

biological forces over

my

my

which

be

totally in the grips of all-encompassing

that

comes

mind

to

mind had no say. Thinking back to who emerged head first, luscious is the

conscious

glimpse of the slimy creature

first

word

feels like to

my

to describe the daughter of

stunned by the sensual responses she evoked in me.

I

dreams.

made up

1

was

love songs cel-

ebrating each beautiful feature, her soft skin and silky hair.

After the

weeks of living with

first

nursed through seminars, lived in, caring for a

it

became

baby

a

girl

who

mostly slept or quietly

increasingly apparent that in the world

baby was incompatible with concentrated work.

I

A new

baby's terrifying vulnerability, the magnitude of the responsibility, and the insatiable

demands

that kept

me

came

on-call twenty-four hours a day,

shock.Yet, as a primatologist in the post-Bowlby era, what could

I

as a

do but turn

my life over to her? was overwhelmed by contradictory impulses, trapped

I

I

didn't.

Not the

—

the kind

ment

toward

my

researcher

least

this

did,

most primitive portions of

damned

if

my

brain

daughter's father, by then a medical doctor and infectious -disease

who

could go off and spend long hours in the lab while

eke out of the daily interruptions enough time to write. invest

I

of the emotions that bubbled up was a whirring resent-

identify with the

1

if

more, so

that

1

could be

free. Yet if

mean reverting to the ways

1

1

I

tried to

wanted him to

delegated care to others, wouldn't

of my mother's generation, before

we under-

stood the attachment needs of infants? 1

so desperately

want

to deprive

wanted to succeed

my

in

my

chosen profession; yet

daughter of the emotional security

I

didn't

had become con-

1

vinced she needed. Personal ambition seemed to be on a collision course

with

my

baby's needs. At that time

and professional aspirations actually

From

recent surveys,

I

1

had no idea

how

interrelated maternal

are.

now know

that the kind of ambivalence

experienced to varying degrees by most mothers in the United

felt is

1

States.

Work-

more ambivalence than mothers who stay home with their ing mothers children. Mothers who work by choice feel more conflicted than those who feel

must work to support mothers

Still,

with preschool-age infants are

ongoing changes higher.

their family.'

the

bottom

now working

in the welfare system, that

line

is:

the majority of

outside the home.

proportion

is

With

growing even

— PREFACE Always,

ambivalence

mean

felt

I

my own

hack of

in the

that

the emotional expense of

home

daughter called

belonged there

—

her

mind, lurked nagging questions. Did the

was

I

my

XV

had mother? Would

a

my

week

first

in college to say she

—

come

when my

children? Even years later,

probably not an unusual response

success

at

oldest

wasn't sure she

rcflexively

I

recalled

the miserable, distorted face of a diapcrless toddler standing outside a bunga-

low

in Rajasthan, India.

She was

rash in a far-off land,

must have seemed very

across their faces

mother would not return

week return keeper.

I

to India

1

till

when

evening.

landed in

from

Even more painfully

she stayed

a virulent diaper

their foreheads or veils

strange. Yet the familiar figure of her

home

recall every intonation of

still

phone when

a little girl suffering

where women with dots on

vivid

my

was

six-

with her father and a house-

her voice on the other end of the

New York and called home. "Ma-ma" came the heart-

breaking cry, with no trace of resentment.

But

out to use every perspective tion

I

their mothers,

own three

it

and

means why.

children,

was driven

somebody's

from

at

could locate, to marshal such evidence as

question of what

I

when I could analyze instead. I set my command, and every source of informa-

never been content to agonize

I've

rib.

I

I

failed to learn in

my

past.

are composites of

For

many

we

of years. Even the endorphins that

molecules that humans I

am jumping

occurred to

me

time to help

me rear my

are not ready-made out of

different legacies, put together

been going on for

leftovers in an evolutionary process that has

But

need from

infants

could pass on to others.

to understand

We

what human

to be a mother, and

Even what

could bring to bear on the

I

made my

labor pains tolerable

came from

share with earthworms.

still

ahead of

my

story.

At the outset,

to articulate the nature of

my

would never have

it

quest to understand maternal

ambivalence, female sexuality, and infant needs in these terms. until college that ally

I

learned about evolution. To

my

studied the behavior of other animals to learn

In 1968

1

billions

It

was not

amazement, people actu-

more about human

was taking an undergraduate course

in college

nature.

given by Irven

DeVore, one of the pioneers in the then-fledgling field of primatology. day he mentioned

a

report by Japanese primatologists working in India that

described bizarre behavior

among

their

mothers and

bite

infants safe but, in the end,

them fail.

monkey

adult male langurs, a species of

had never heard of. According to the report, these males

from

One

to death.

On

would grab

Mothers would

rare occasions

—

as

I

fight to

later

I

infants

keep their

confirmed

PREFACE

XVI

Fig.

Ca.

I

The Formation ojEve, by Gustave Dore,

1866.

ffrom

The Dore

Publications, NewYork,

1

Bible Illustrations, Dover

gj4J

they appeared not even to try to

defend them. The bereaved mothers seemingly did not even bear a

grudge. After the male killed her infant,

the langur

mother mated

with him, which struck

me as unac-

countably odd. I

had

just learned that creatures

evolved so

productive success. But

now

was confronted with

1

with more than

killing infants

a hint

I

a description of

of maternal collusion

decreased rather than increased infant survival. After graduating from college,

enhance their re-

as to

went

—

males

behavior that

was more than intrigued.

I

to India to learn why such strange

behavior occurred. Studying infanticide in other primates turned out to be only the beginning of

my

quest to understand female nature and motherhood in particular. This

quest lured

me

to

do research

in seven countries over thirty years,

on extremely unlikely sources of information

documents from foundling homes, books

—

in

my

—

folktales,

last wills

humans can

the sense that

be.

Whatever maternal

most people use

instincts are,

that term.

and testaments,

even the pages of phone

effort to learn about parental attitudes in

Along the way, I have come to understand just how in

drawing

my own

flexible parental

species.

emotions

they are not automatic in

Most important,

I

have learned that

even though the world has undergone immense changes since our ancestors lived by foraging,

many

of the basic outlines of the dilemmas mothers con-

front remain remarkably constant.

For

a billion years,

ever since egg- and sperm -producing organisms

arose, the genetic futures of males (the

first

"sperm -producing" organisms) have

PREFACE

XVll

been affected hv what females (the "ovum-producing" ones) do, and vice

mothers giving of themselves to offspring has

versa. But the selflessness of

always seemed too

included did.

—

Old

examine

to be able to

biases

many

the well-being of too

vital to

for

anyone

—

their behavior dispassionately.

from many sources burrowed

in

and nestled

scientists

And none

at the

heart of

evolutionary theory, the most coherent and all-encompassing theory that entists have ever It

had to explain the living world.

was no accident

looked to nature to

that first moralists and then Victorian evolutionists

justify assigning to

female animals the same qualities that

patriarchal cultures have almost always ascribed to "good"

ing and passive). Women tures

would

sci-

were assumed to be "naturally" what patriarchal

them

socialize

sexually reserved. This,

mothers (nurtur-

1

cul-

to be: modest, compliant, noncompetitive, and

suspect,

been studied separately from

the

is

main reason why

maternity, as if sex has

sexuality has

always

nothing to do with mater-

nity or keeping infants alive.

Inquiring

women

have sensed that there were underlying agendas to the

way female nature was depicted, and they responded male

identified a

bias within science

—

in different ways.

Many

particularly biology. For Virginia

Woolf, the biases were unforgivable. She rejected science outright. "Science, it

would seem,

is

not sexless; she

a

is

man,

a father,

and infected too," Woolf

warned back in 1938. Her diagnosis was accepted and passed on from woman to woman. It is still taught today in university courses. Such charges reinforce the alienation

theory and

many women,

especially feminists, feel

toward evolutionary

fields like sociobiology.

Right from the outset of evolutionary thinking, however, a tiny group of

women were

as

Darwinian

as

who took

a

seriously,

was one of them.

they were feminist. George Eliot, a

man's name because

own

women

Eliot,

woman

writers at that time were not taken

whose

real

name was Mary Ann

Evans,

experiences, frustrations, and desires did not

fit

within the narrow stereotypes scientists then prescribed for her sex.

"1

recognized that her

need not crush myself wo-ote. Eliot's

.

.

.

within a

mould of theory

called Nature!" she

primary interest was always human nature

as

it

could be

revealed through rational study. Thus she was already reading an advance

copy of On

the Origin of Species

was published. For soning faculties,

and arrive

at

the

if

on November

her, "Science has

no sex

24, .

.

i

.

8^9, the day Darwin's the

book

mere knowing and

rea-

they act correctly, must go through the same process

same

result."

1

fall

in Eliot's

camp, aware of the many sources

PREFACE

XVIU

of bias, but nevertheless impressed by the strength of science as a way of

knowing.

UnUke

superstition

or rehgious

faith,

good

a

scientist's

underlying

assumptions are subject to continuous challenge. Sooner or later in science,

wrong assumptions

get revised. Nevertheless,

some

take longer to get cor-

rected than others, as was the case with overly narrow stereotypes about females.

Long ago

me

a

wise friend, evolutionary biologist George Williams, warned

that natural selection

an impersonal "process for the maximization of

is

short-sighted selfishness," something far worse than moral indifference. Dar-

win was of the same mind: "maternal ter fortunately

most

is

rare,

which simply means

others.

that

Once we understand

ues, a concept like

primarily about differential reproduc-

is

some

individuals leave

more

more

offspring than

that natural selection has neither morals

"Mother Nature" ceases to be shorthand

Natural Laws that are

lat-

the same to the inexorable principle of

is all

natural selection." Natural selection tion,

love or maternal hatred, though the

nor

val-

for romanticized

nearly wishful thinking than objective observa-

tion of creatures in the world around us. In the course of revising ideas about

Compared mothers who gradually came received wisdom.

form

—

alien

what

to

a

have had to discard

I

was taught

into focus for

me

much

in graduate school, the

almost seemed a

new

life-

and utterly different from culturally produced expectations.

Mothers were multifaceted creatures,

As

mothers, I

strategists juggling multiple agendas.

consequence, their level of commitment to each offspring born was

highly contingent

on circumstances. Realizing this, have been forced to conI

clusions about our ancestresses that, given the values

I

grew up with and

still

am poorly equipped to comprehend. Among the specific questions address in this book are:

live by,

I

I

1.

What do we mean by

"maternal instincts"?

And

have

women

"lost"

them? 2. If

women

instinctively love their babies,

why

have so

many women

across cultures and through history directly or indirectly contributed to their deaths?

nate

among

a daughter?

Why

their

do so many mothers around the world discrimi-

own

infants

—

for example, feeding a son but starving

— PREFACE

XIX

Unlike other apes, humans have been selected to produce offspring

3.

that are helpless

our Foraging ancestors did could hope to rear

as

a family

have been selection on mothers to produce babies so

means

to rear?

Given

that fathers share the

as

far

beyond

(as

And

if so,

when

are they expressed?

5. So far as babies are concerned, fathers range

men affairs of women?

then do virtually

reproductive

what

infant

Charles Darwin also wondered) "latent instincts"

for nurturing in males?

Why

all

bottom

from caring to

indifferent.

take such an intense interest in the

on infant needs? Just why did these

And,

finally,

little

creatures evolve to be so plump, engaging, and utterly adorable?

is

the

line

Historv and personal experience of course explain a great deal about a

their

same proportion of their genes with babies

mothers do, why didn't fathers evolve to be more attentive to

needs? Are there

6.

by herself .Yet

How could there

paternal assistance was then, as now, far from certain.

4.

woman living

and dependent for so long a time that no

mother

feels

about her baby. But to answer

my

questions

ther back in time, long before a court guaranteed a

over what goes on in her

womb,

I

woman's

must

how

travel fur-

right to privacy

before contraception, before formal laws of

any kind, before regulations about infanticide, even before cradles or walls

back to with

a

a

time

baby

when

just to

it

was

keep

essential for

a wild animal

someone

to be in continuous contact

from eating

it.

Many

of the emotions

informing women's reproductive decisions today were shaped in past,

by processes that by current standards can only be viewed

this distant

as inexorable.

PART ONE

Look Look

to the to the

Animals

animalsJor jour example.

—Jean-Emmanuel

Giliberl, 1770

fp^JS^ATURE'SPATENTFOOJ) ^S USED BY CAIN AND ABEL

GOOD

(Reproduced from Maternity and Child

Welfare

RESULTS

2

[4)

1

9

1

8)

-

I

Motherhood as a Minefield Woman

seems to differ from

Woman owing

to her

man

in her greater tenderness

maternal

and

less selfishness.

instincts, displays these qualities

her injants in an eminent degree; therefore

it is

likely that she

toward

would

often extend them toward herjellow-creatures.

—

Charles Darwin,

1

871

mother has never been simple. Today, modern medicine, Being water, stored food, pasteurized milk, and houses with walls a

safe

cradles,

make

it

easier than ever before to

keep

a

baby

alive.

Rubber-nippled

baby bottles and daycare centers especially designed and licensed for the care of the very young provide working mothers, even those with weeks-old babies, with alternatives to the only

freezers

means

that

two

viable options previously available:

wet nurse. The

pumps and more women can both breast-feed and spend hours sepa-

keep your baby close or

find a

availability of breast

rated from their babies.

Above

all,

there

is

birth control,

which permits

override her ovaries and choose when, or

sound and amniocentesis enable

women to

if,

a

woman

to consciously

she will bear children. Ultra-

spend decades

in a career

and

still

look forward to bearing a healthy infant. Far from simplifying motherhood, these novel choices have exposed tensions just beneath the cheery surface of

our traditional assumptions about what mothers should be. Today, mothers in developed countries, and with

them

fathers

and

chil-

dren, enter uncharted terrain. Without anyone raising their hands to volunteer,

we have become guinea pigs in a vast social experiment that reveals what

women who finding out

who

can control reproduction really want to do. Children, too, are

what

it

means

to be

born to

a

complex and multifaceted creature

has an unprecedented range of options.

with two outcomes already apparent.

First,

It is

an experiment-in-progress,

the decisions that mothers

make

do not always conform to our conventional expectations about innately der, selfless creatures. Second,

whatever today's mother decides

is

ten-

likely to

be

LOOKTOTHEANIMALS

4 controversial in

some

and we are walking through

field,

motherhood has become

quarters. Bluntly put, it

without so

much

as a

map

a

mine-

to guide us.

of Motherhood The politician who naively assumes

that

motherhood,

safe topic quickly learns otherwise.

The

topic was safe only so long as people

Politics

took the centuries-old view of

self-sacrificing

mothers and

Self-sacrificing

that they instinctively

was

that everyone has in

Our sense

is still

designed by nature

their destiny.

and

for,

a

for granted. This

want to rear every baby they

motherhood was what women were

societies have believed this

apple pie,

motherhood

women were

view rested on mankind's assumption that to be

like

women

in

bear.

many

Overlooked was the huge stake

motherhood.

of self, pride, vulnerability, propriety, and job security, our

life-

long preconceptions and anxieties, our peace of mind, not to mention our

toehold on posterity

This

is

why

as well as for

ing

is

that

—

all

of these depend on what our

a politician

mothers, wives,

can lose votes for encouraging mothers to stay home,

suggesting they return to work; for pointing out that breastfeed-

(which

beneficial to infants

it is.

own

and female colleagues do or are expected by others to do.

lovers, daughters,

it is),

mention

as well as for neglecting to

One week, newspaper headlines

ask, "Is day care ruining

our kids?"

or decry "A dangerous experiment in child-rearing." Another week, headlines in the

same paper

bonding

will declare, "Infant

is

a

bogus notion" or

more daycare.^ At the same time, many countries; and on the sidewalks

call for

businesses to provide

birth control

against the law in

outside family plan-

ning clinics in the United States, near

from another planet might well ask

civil

how

war

the

prevails.

A

visitor to

same creatures

is still

Earth

that invented

sophisticated technology to explore the solar system could display such

primitive behavior

No more

topic of

when

mother

politics

irrational debate. In

duced to outlaw

a rare

comes

it

to the female reproductive system?

is

so divisive as abortion, and

Washington, D.C.,

type of abortion

—

in

May

1997, a

the procedure

none

elicits

was

intro-

bill

known

and extraction, christened "partial-birth" by opponents. This

as dilation

is

an over-

whelmingly unpopular, traumatic surgical procedure that no group United States advocates, no

woman

eager to perform. Yet this

marked

lar

bill

in the

world wants, and no doctor

this distressing

is

the fifty-second time that this particu-

Congress had debated an abortion-related

on whether

in the

procedure could

issue.

still

Disagreement centered

be performed even

if

physi-

MO cians

deemed

it

T H H R

M

H O O D AS A

necessary to save the woman's

N

I

lite,

K F

I

K L

1)

^

to ^uard her heahh, or to

preserve her abiHty to have viable children in the future. Those

who

sought

the across-the-board ban were not interested in exploring ways to further

reduce the need for

this rarely

performed procedure (one tenth of

i

percent

of the 1.^ million abortions performed annually in the United States)

more sex

funding

makina

education, birth control, and better prenatal care, or by

easier to get an abortion early on.

it

simply their Hrst step to banning

The abortion "light."

On

by

issue

is

all

Banning late-stage abortion was

abortions.

notorious for generating so

this particular occasion,

much "heat" and

so

little

one of the senators debating the

issue

(Rick Santorum, Republican from Pennsylvania) became "so emotional" that the blood vessels leading to his stomach constricted, while those leading to his heart

and brain dilated. Responding to

tions of his brain, his

mammal

signals

pounding heart caused the

from the most ancient por-

face of this deeply threatened

to flush "crimson" in preparation for a fight. His voice rose to such a

pitch that colleagues had to intervene.^

Chances were vanishingly small that any kind of late-stage abortion would ever be applied to anyone he knew. Yet against such odds, the senator had just

had

a

brush with one.

He and

his

ried suffered a fatal defect. Even

if

wife were informed that the fetus she car-

born

alive,

not be viable. Infections ensued, and with

the baby, they were told,

his wife's life in jeopardy, physi-

cians asked the senator to consider an abortion. in a press

would

The

senator, as he reported

conference afterward, never even came close to accepting that

option. As he saw

it,

his

wife "was in danger of septic shock

.

.

.

but she was

not in imminent danger."

The abortion debate is ultimately about what it means to be a mother; and the senator, like many humans before him, had his own unusually clear notion of w^hat mothers were this

for.

The couple

already had three young children, but

fourth birth was given clear priority over his wife's well-being as well as

that of her other children. Fortunately, the

predicted, the

new baby died

mother survived. But,

as

doctors

shortly after birth.

As the debate unfolded, the rush of blood and pounding heart beneath the senator's coat and tie spoke

than as

is

members

volumes about motivations

of Congress ordinarily consider. Like

all

far

deeper, far older,

humans, and indeed

typical of the entire Primate order, the senator exhibited an intense, even

obsessive, interest in the reproductive condition of other

group members.

Like other high-status male primates before him, he was intent on controlling

LOOK TO THE ANIMALS when, where, and how females belonging

mer member of the House of was more at stake than just the issues they select,"

want to intervene

to his

group reproduced. One

for-

Representatives, however, sensed that there issues

under debate.

"It's

very interesting the

observed Patricia Schroeder of Colorado. "They don't

in the bodily functions of men."^

Schroeder 's quip goes to the heart of the matter. Passionate debates about abortion derive from motivations to control female reproduction that are far older than any particular system of government, older than patriarchy, older

even than recorded female group

history.

Male

fascination with the reproductive affairs of

members predates our

Young women of my

species.

daughters' generation take for granted a historically

unique situation. They regard birth control, precautions against sexually transmitted diseases, women's education and athletic teams, as well as open-

ended professional opportunities for women,

They view the antiabortion movement emergence of powerful

in the

as innovations

United

here to

States, along

stay.

with the

political lobbies seeking to substitute "abstinence

human

only" for practical knowledge about

sexuality and reproduction, as

too irrational to take seriously. Reports from far-off places

like Taliban-

controlled Afghanistan, where Islamic fundamentalists seek to deny

women

personal autonomy (forcing them to stay sequestered in their homes, keep their faces

and bodies veiled, and marry

seem exotic and

as instructed)

remote. It is

hard for

my

daughters and their generation to believe that such forces

could ever intrude upon their

women

is

shown

own

Even when the sequestering of

lives.

to have measurable costs to the health and well-being of

wives and children

(as has recently

been documented for Afghanistan), they

are saddened, but not apprehensive for themselves.

between innate male tudes toward

desires to control

women and

women

see

no connection

times and the

atti-

family that inspire sermons to all-male audiences of

"Promise Keepers," or that motivate elected

who

They

in earlier

has the right to choose whether and

Westerners take seriously the

officials to

when

a

debate endlessly over

woman

possibility that old tensions

gives birth.

Few

between maternal

in their own country and transnearly so confident. If age-old am not form a world they take for granted. pressures are allowed to erode hard- won laws and protections, it is far from

and paternal interests could explode one day I

certain that the unique experiment

we

have embarked upon can persist.

MOTHERHOOD

MINEFIELD

AS A

7

Mothers of Us All With

six billion

people on the planet,

it is

easy to forget that

we

have not

always been so numerous. Every person on earth descends from a population living in Africa roughly

more than

100,000 years ago that probably did not number

ten thousand breeding adults. The Pleistocene epoch, between

million and 10,000 years ago, was also a time

born.

We

when

it

i

.6

was very risky to be

are just beginning to understand the full range of hazards and their

implications for the attributes babies possess.

Almost

all

women who

reached adulthood became pregnant and bore

young. Yet the majority died without a single surviving offspring because so

many

of those born never grew up. Consider the

gatherer a

woman named

Nisa.This plucky

life

history of a hunter-

woman belonged to the !Kung San,

nomadic foraging people who continued

to traverse the Kalahari Desert

long into the twentieth century, confronting challenges similar to those faced

by Pleistocene hunters and gatherers for thousands of years before the invention of agriculture and the domestication of animals for food.

When interviewed for her biography in the early two miscarriages and borne three daughters and family size (3.^ children) for a IKung

a

1

970s, Nisa had suffered

son

—

close to the average

woman. Two of Nisa's

children survived

into adolescence, but both died before adulthood. Thirty-six percent of

IKung Since

women

all

would,

the !Kung

few more might into account

like Nisa, die

women

without

interviewed were postmenopausal

a child

is

the

is

probably higher.

1

the time, a

we

take

estimate that

died childless.

most awful occurrence parents can imagine.

Fortunately for most of those reading this book, childhood death

Unlike Nisa, they

'°

died before they even had a chance to breed,

more of all IKung women born

The death of

at

lose their last child before they themselves died. If

how many women

the true proportion of those dying childless

one-half or

a single surviving offspring.

live in privileged

is

a rarity.

regions of the globe, at least for the time

being, and enjoy an unprecedented standard of living. Nine hundred and

ninety-four of every thousand babies born in the United States survive infancy. Yet even

though the odds of keeping infants

astronomically, the chances that a

woman

alive

have improved

in a postindustrial society will die

without descendants have not changed that much. In the Sacramento Valley of California,

where

1890 and

984

1

I

live, 40 percent of all grown women who died between no surviving offspring. But the reasons so many women '

left

'

LOOK TO THE ANIMALS in the Kalahari

and Cahfornia populations died childless are quite

many

In twentieth-century California,

of the

women

different.

never married. Others

could not, or consciously decided not to, have children, or else decided to give birth to only a few.

Almost

all

number

woman

(1.6)

of children per

infants

born survived, so

that the average

was close to the number

actually born.

The circumstances surrounding motherhood have never been ent. Yet, as

will

I

show

in this

more

book, from contemporary countries

differ-

which

in

women live in a state of ecological release, no longer constrained by having to forage enough food each day to stay alive and with a broad range of reproductive options, to other parts of the world where they are less fortunate,

women

are constantly

making

tradeoffs

between subsistence and reproduc-

tion that are similar in outline.

Quality

vs.

Quantity

Depending on the marriage customs

in the culture she

woman

belongs to, a

may or may not get to choose the father of her children or the time

in

her

life

when she first becomes pregnant. Depending on prevailing values, she may or may not treat her sons and daughters, her firstborn versus her last-born, exactly the same way. Yet, by and large, she will decide how much of herself, her time, energy, and love, she will invest in each child. The father has similar choices, although he

may make

decisions had a direct effect children.

quite different decisions. In the past, such

on both

a

mother's

own

survival and that of her

Throughout most of human existence, to be an

mother, or

a child

vantage. To have

would have had

infant without a

without older kin, was to suffer a life-threatening disad-

become

the ancestress of any one of us today, a

mother

to succeed in rearing at least one offspring to breeding age. In

turn, that offspring

would have had to produce surviving

quantity has rarely been the top priority for a mother.

heirs. This

The well-being

is

why

ot her

children and their quality of life, usually inseparable from her own, were pri-

mary.

When

fidelity to his

mate means

identical to his only wife's, he ity

is

more

over quantity. Otherwise, and

that a man's reproductive success

likely to share

especially

if

is

her preference for qual-

he does not intend to invest in

man may simply seek to breed with as many women, and many offspring, as he can. It is from such ancestors that we

his offspring, a

hence

sire as

inherit our maternal

emotions and decision-making equipment. Underlying

tensions between males striving for quantity and females for quality (a simplification

I

will clarify later) are as old as

humanity. Yet

this tension has risen

MOTHERHOOD to the surface and

become more

AS

MINEFIELD

A

9

consj:)icuous than ever in the ecological cir-

cumstances of a modern world

women

which

in

have unprecedented

choices.

For example,

when young women

dren and improving their

lot in life,

between having

are given a choice

most opt

for the latter.

At

first

chil-

glance,

such a finding seems completely antithetical to predictions from evolutionary theory. In the crass coinage of in

my Darwinian

terms of "fitness," genetic representation

to

more resources should

fewer. Certainly there history, quite a

few

is

men

in

is

measured

succeeding generations. Access

more

translate into people having

children, not

massive documentation that throughout recorded

opted for more.

Kings, emperors, and despots seraglios with fertile

worldview, success

—who had

women. Feudal

the

power

to

do so

—

filled their

on droit de seigneur

lords insisted

with virgins marrying within their domains, while some American presidents have used their office

(literally,

the oval one) to enjoy assignations.'^

How-

ever, the

emphasis on quantity that holds true for male potentates (and surely

we

call

don't

Around

them

that for nothing) does not hold true for mothers.

the world, there

is

a

tendency for people

have a lower birthrate. This tendency India as well as

birthrates in

women

is

evident

who

among

in industrialized societies.

are better off to

modern France and

lished populations in the United States.

Italy

and

is

in

Witness the declining

contemporary Japan, or the below-replacement

long characterized

women

peasant

fertility that has

increasingly true in estab-

Wherever women have both control

over their reproductive opportunities and a chance to better themselves,

women

opt for well-being and economic security over having more

dren.'^ For many, leaving children every day while they survival, the only

way mothers can support

work

is

a

matter of

their families, or the only

they can secure a decent future for offspring. (A big difference between

ern industrial societies and people

who

live

by foraging

is

way

mod-

that children

must not only be fed but clothed and educated become more not

chil-

who

costly with age,

less.)

But survival does not explain

making

a

skimpy

living

on small

all

the choices. Third world peasants just

plots of land will trade the clean air and safer

environment of the countryside

for squalid

urban shantytowns with their

glimmer of economic opportunity, accepting the deaths of some children from respiratory or pect of a "better"

gastrointestinal infections in

life.

Far

more

privileged

exchange for some pros-

women

also

may opt

for self-

LOOK TO THE ANIMALS become

over reproduction, forgoing motherhood to

realization

artists,

pilots, or scientists.

At

first

their choices appear counter to evolutionary expectations, until

we recall that mothers

evolved not to produce as

many

children as they could

and

but to trade off quantity for quality, or to achieve a secure status, w^ay increase the chance that at least a

This

is

why

look

a closer

reveals behavior that

is

at

what

not so

few offspring

late -twentieth- century

much "unnatural" as

with conventional expectations

—

all

and prosper.

women

behavior that

is

are doing in conflict

the myths and superstitions about what

women are supposed to want. So how did people in the Western world come nature and "motherhood" the way

will survive

in that

to conceptualize female

we do?

Maternity and Charity Biologically the

word

maternity refers to conceiving and giving birth, just as

paternity refers to the individual

who

concept of maternity carries with charity

it

sires

an offspring. But in the West, the

was the cause of her maternitie

.

.

."

reads the Oxford English Dictio-

narys illustrative sentence for a word in use from century. in the

How confidently, then, women

for your example.

the seventeenth

could eighteenth-century moralists, steeped

(in a

famous passage from 1770) to "Look to the animals

." .

.

Even though [animal] mothers have Even though care

like all

their offspring have

makes them forget

themselves,

No

at least

Enlightenment's celebration of God, Reason, Nature, and Man,

admonish

first

"Her

a long tradition of self-sacrifice.

is

stomachs torn open.

they have suffered.

under the sway of this

.

—was convinced

.

happiness.

.

.

.They forget .

.

.

that

—French

physician

women should follow nature's

eternal and unchanging precepts by nursing each child they bore.

trying to frighten his patients, only remind

Woman

instinct.

matter what their physical condition, the author

Jean-Emmanuel Gilibert

.

been the cause of all their woes, their

concerned with their own

little

animals

all

their

them of their

He was not

instinctive

and God-

given maternal duty to nurture offspring. Gilibert and others like him looked to the animals not to to confirm their

make unbiased empirical observations but

own and

their society's preconceptions about

to use nature

how humans

MOTHERHOOD

Fig.

1

.

1

AUegorie de

la charite,

AS A

by Pierre Daret, 1636.

should behave. These men,

MINEFIELD

I I

(Counesj of the Bibhotheque Natwnale.

who were more

evangehsts than scientists, im-

posed their moral code on nature rather than allowing creatures ural

Paris)

in the nat-

world to speak for themselves.

Gilibert's passionate insistence

on suckling derived from

his antipathy to

the then-widespread practice of wet-nursing, hiring a lactating, often

poorer,

woman

to breast-feed a mother's baby for her.

A

vast

much

number of

babies during this period were sent away right after birth to a distant rural

wet nurse, consigning them to severe hardships and result, infant mortality soared. Gilibert

was convinced

indifferent care.

more

a

that this "vice" of wet-

nursing was responsible for France's declining population tortion of the real situation, about which

As

(a fascinating dis-

later).

In urban areas such as Paris the majority of infants born (9^ percent, according to a 1780 police report [discussed in chapter 14]) were sent away

to

wet nurses. Yet Gilibert knew

like all

that

humans

female mammals, have breasts

are

mammals, and

that

in order to suckle their young.

women,

To Gilibert,

LOOK TO THE ANIMALS

12

could only

this

young; to shun

mean this

that

women were

intended by

our place in nature derived from the

by the great Swedish taxonomist Carolus Linnaeus. Linnaeus 's Systema Naturae of

humans

to nurture their

duty was unnatural.

Gilibert's grasp of

that links

God

1

new

Among

classification

other things,

73^ called attention to the special relationship

to prosimians,

together in one order, Primates

monkeys, and

—

apes.

They were

all

lumped

Latin for "first ranking."

Underlying Agendas Something

just as primal,

however, also linked Gilibert and Linnaeus. The

two medical men were united and

in their assessment of

in their opposition to wet-nursing. Gilibert

naeus's anti-wet-nursing pamphlets

time) into French so that

it

from Latin

might reach

a

what females were

for

had translated one of Lin-

(the language of science at the

wider audience. The

title

Nutrix

Noverca can be crudely translated as the cruel or unnatural "step-nurse." It

was to highlight the importance of lactation

that Linnaeus identified an

—

—

Mammalia by the odd milk-secreting glands that entire class of animals develop in only half the members of the class. The Latin term mammae derives "mama" spontaneously uttered by young children in widely divergent linguistic groups. The urgent message, "Suckle me," is universal. By calling mammals Mammals, instead of "sucklers" (as in the Ger-

from the

plaintive cry

man term

mammals,

for

Sdugetiere),

Linnaeus was making his point about

both a natural law and the unnaturalness of any

woman who

deviated from

it

by failing to nurse.

Our views ''the

of "motherhood" (including such scientific-sounding phrases as

maternal instinct") derive from these old ideas and even older tensions

between males and females. The

fact that

most of us equate maternity with

charity and self-sacrifice, rather than with the innumerable things a

does to make sure some of her offspring grow up great deal about

how

conflicting interests

played out in our recent history. Sad to

maternity infiltrated

modern

between say,

alive

and well,

fathers

mother

tells

us a

and mothers were

these old conceptions about

evolutionary thinking.

Darwinism, Social Darwinism, and the "Supreme Function" of Mothers God created first heaven, then earth, then each variety species of nonhuman animal, and, on the sixth day, man, and

According to Genesis, of plant, every

MOTHERHOOD

AS A

MINEFIKLD

woman.

I3

Charles Darwin

from one

of his ribs, or perhaps his thigh,

proposed

a revolutionary alternative to the biblical account.

alternative genesis

On

Darwin proposed

In

i

85^9,

He

titled his

the Origin of Species.

that

humans, along with every other kind of animal,

evolved through a gradual, mindless, and unintentional process dubbed natural selection. Morally indifferent, natural selection culls

and biases

life

chances with the unintended result that evolution (defined today as the

change

in

gene frequencies over time) takes place. This mindless and "worse

than morally indifferent" process geared to the maximization of short-sighted

what we mean by natural

selfishness

is

habits, the

"Mother Nature" of my

selection. She

is

the old lady with bad

title.

Everv environment, said Darwin, confronts organisms with challenges to their survival,

whether the problem

is

cold or heat, tropical

damp

or

drought, famine, predators, or limited space. For mothers, these problems

become

obstacles to keeping their infants alive. Individuals that are best

adapted to their current environment survive and reproduce, passing on the attributes they possess to future generations. Losers in the struggle to survive

die before they have a chance to breed, or they

produce few

offspring.

Even-

tually, their line dies out.

The unfortunate and much misused expression paraphrase this lific

"survival of the fittest" to

phenomenon was introduced not by Darwin but by

and widely read contemporary, the

To Spencer, survival of the

fittest

social philosopher

meant

his pro-

Herbert Spencer.

"survival of the best and

most

deserving."

Indeed, Spencer's popularity was due to the simple take -home message delivered to his privileged audience in Victorian England and America: the

advantages you enjoy are well deserved. For him, evolution meant

The

flaw in Spencer's reasoning was to mistakenly assume that environments

stay the

same, unchanging backgrounds against which "superior," optimally

adapted individuals left

rise to the

top and stay there in perpetuity. What Spencer

out were the fluctuating contingencies of an ever-changing world.

Only colored by

that oversight could Spencer's social Darwinism provide a

blanket endorsement of the status quo. By contrast, Darwinism

winian thought, correctly interpreted

No

progress.

—

ascribes

no

—

real

Dar-

special place to anyone.

adaptation continues to be selected for outside the circumstances that

happen to favor

it.

When Darwin

adopted Spencer's phrase "survival of the

fittest,"

he meant

LOOKTOTHEANIMALS

14

the survival of those best suited to their current circumstances, not the sur-

any absolute sense. To Darwin,

vival of the best in

fitness

meant the

ability to

reproduce offspring that would, themselves, mate and reproduce. But no matter. Spencer and his followers were gratified that so celebrated a naturalist

and experimentalist

as

Darwin would

cite his views,

accept his catchy

phrase, and endorse heartfelt convictions about essential differences between

males and females that derived from Spencer's theory of a physiological

divi-

sion of labor by sex.

The supreme function of women, Spencer believed, was toward that great eugenic end species physically

up to

snuff.

women

should be beautiful so as to keep the

Because mammalian females are the ones that

ovulate, gestate, bear young, and lactate (this

assumed

diversion of so

that the

childbearing, and

much

much energy

is

irrefutable),

into reproduction had

inevitably to lead to "an earlier arrest of individual evolution in in

men"

—

a far

more dubious

extension,'^

different, but Spencer's females

For Spencer,

produce, tal

were mired

this physiological division

women

development

women

than

Not only were men and women in maternity.

of labor by sex meant that

men

merely reproduce. Costs of reproduction constrained men-

women

in

and imposed narrow bounds on how much any

one female could vary from another

between

Spencer

individuals

is

in

terms of

intellect. Since variation

(which

essential for natural selection to take place

true), Spencer reasoned (wrongly) that there

was too

little

variation

females for proper selection to occur, precluding the evolution in

is

among

women

of

higher "intellectual and emotional" faculties, which are the "latest products of

human

evolution."

Spencer was aware that a

woman might occasionally possess

a capacity for

The only such female he personally knew, however, was Mary Ann Evans (the novelist George Eliot), whom he regarded as "the most abstract reasoning.

admirable

woman,

mentally,

I

ever met." But Spencer regarded her

gifts as a

freak of nature, attributable to that trace of "masculinity" that characterized

her powerful intellect.

The assumption

that education

would be wasted on women was, of

course, a self-fulfilling prophecy. Denied higher education and opportunities

women not fail to excel in them? Eliot of a minuscule number of women in Europe at that time edu-

to enter fields like science,

herself was one

how

could

cated (in her case, largely self-educated) in languages, literature, philosophy,

MOTHERHOOD

Fig. 1

1

903)

2

.

By the

fell

i

MINEFIELD

AS A

U

86os, Herbert Spencer (1820

completely under the sway of his

own

theory of the physiological division of labor by sex.

He abandoned

his early

cation, an interest he

met

first

in

London

women was to breed, were

less

support for women's edu-

and Eliot shared when they in

if

1

851

.

If

the function of

women's mental

faculties

evolved, he decided, educating

beyond

a certain point

would be

women a

waste.

(iSi^S portrait from Coventrj Citj Library)

and natural science. By regarding her could reconcile

his recognition

evolutionary scale, on which

destined limbo

as a

masculinized exception, Spencer

of this woman's talents with his internalized

women

hovered in

a

fecund, biologically pre-

somewhere between Victorian gentlemen, on

and children and savages, on the other.

the one hand,

'^

Women as Breeding Machines Spencer's validation of the status quo had far broader popular and political

appeal than Darwin's

son

why

social

more

nihilistic

perspective ever could. This

Darwinism would become so

influential

.

is

The second,

one rearelated,

reason was that Spencer's theory of the physiological division of labor by sex

provided

a scientific-sounding rationale for

assuming male intellectual and

were an urgently needed

social superiority. Spencer's "scientific" theories

antidote to the rising tide of feminist sentiment States

—

at a

obtain the rights

Even before Freud declared tionists

—

especially in the United

when women were making real headway in their to vote and to own property in their own name.

time

were constructing

a

that sex

complex

is

destiny,

Spencer and other evolu-

theoretical edifice based

sumption. They took for granted that being female forestalled evolving "the

power of abstract reasoning and

that

efforts to

most

the sentiment of justice." Predestined to be mothers,

on

that as-

women from

abstract of emotions,

women were born to be

LOOK TO THE ANIMALS

i6

•pid^^S^ %

Fig.

3

1

about

.

Progressive and liberal, the French artist

women who

mother

'

is

aspired to be

in the heat of writing.

more

The

Honore Daumicr was nevertheless ambivalent

than mothers.

child

is

The caption

in the bath water!"

to this lithograph read:

"The

While Daumier read books

like

La Physiologic du has bleu (Physiology of the Bluestocking), and produced cruel caricatures of freakish and non-nurturing

women

evolutionist, Herbert Spencer, "girls

for his series entitled Les Bas-hlcu, back in England an early

was struck by the

fact that "upper-class girls"

belonging to the poorer classes," even though the

that the "deficiency of rej^roductive

power among

latter

were

education" would be "incompetent" to breast-feed. Daumier,

London)

less

than

Spencer decided

may be reasonably attributed who survive their high-pressure

[the advantaged]

to the overtaxing of their brains" and that "the flat-chested girls

Alpine l-ineArls Collection,

reproduced

less well fed.

(From Liberated

Women: The

Lithographs of Honore

MOTHHRHOOD

MINEFIELD

AS A

Ij

passive and noncompetitive, intuitive rather than logical. Misinterpretations

of the evidence regarding women's intelligence were cleared up early in the twentieth century.

row

More

basic difficulties having to

and linger to the present Equating ing birth,

known

this overly nar-

"°

complex organism with

a

is

day.

do with

were incorporated into Darwinism proper

definition of female nature

a single defining "essence,"

such as giv-

1949, the French writer

Simone de

as essentialism. In

Beauvoir sarcastically articulated the essentialist view in The Second

"Woman? Very ovary; she

simple, say the fanciers of simple formulas: she

a female

is

—

word

this

is

is

a

Sex:

womb, an

sufficient to define her."

Earlier generations of feminists had also

responded to Spencer and Dar-

win. For the most part, however, their voices went unheard. Eliot was one of the few exceptions, although she

is

far better

remembered for her novels than

for her critiques of early evolutionary thought. Yet even in her fiction Eliot

took every opportunity to

slip in

rejoinders to Spencer's essentialist views

and to demonstrate how multifaceted female nature actually In her first

major novel, Adam Bede (read by Darwin

as

is.

he relaxed after the

exertions of preparing the Origin for publication), Eliot put Spencer's views

concerning the diversion of somatic energy into reproduction in the mouth of a pedantic and blatantly misogynist old schoolmaster, Mr. Bar tie: "That's the

way with

their food

No

all

these

women

runs either to

one of the few people

dogma.

It

or to brats.

life

.""' .

.

Eliot's rebuttals

of Spencer. She had once

with him. Opinionated

as

he was, Spencer was

her circle seeking a rational alternative to religious

in

was Spencer who introduced her to evolutionary thinking, and he

shared her passionate

commitment

to a scientifically based understanding of

nature.

They met sent

fat

they've got no head-pieces to nourish, and so

doubt there was an edge to

dreamed of sharing her

human

—

him an

in

London

in 18^1

and soon

after,

she confessed her love and

extraordinarily direct proposal which

still

his real reasons, Spencer's stated reasons for turning her

survives.^^

Whatever

down were

eugenic.

Eliot lacked, he said, the physical beauty he considered essential for mothers.

As he put

it:

as posterity is

of

little

two."

"Nature's is

.

.

concerned,

.

supreme end,

the welfare of posterity, and as far

a cultivated intelligence

worth, seeing that

Eliot,

is

whose nose was

its

based upon a bad physique

descendants will die out in a generation or

long, her jaw pronounced,

was too masculine-

— LOOK TO THE ANIMALS

i8

Fig.

1

.4 Portrait of

Adolphe Rajon, 18^8.

(From the

S. P.

Division ofArt, Prints Lenox,

looking to be regarded

as pretty,

i

George

Eliot, etching

by Paul

884, from a photograph taken in

Avery Collection; Miriam and

ha

and Photographs; NewYork Public

D. Wallach Library; Astor,

and Tilden Foundations)

and so

far as Spencer's criteria for

mother-

hood were concerned, her robust heahh and obvious inteUigence were not ^''^

relevant, only her looks.

"The One Animal

in All Creation

About Which Man Knows the Least" Spencer was not the only early evolutionist to wear blinders where

were concerned. Guided by

women

theory of unusual scope and power, Charles

a

Darwin exhibited an uncanny knack

for

winnowing out kernels of accurate

observation from the hodgepodge of anecdotes being sent him by a vast array

of hobbyists, pigeon breeders, and sea captains from around the world. Yet he

could not shake the biases of a chal

it

had, after

world where the most important thing

be chosen as

man who

by, a

man

of means.

It

woman

grown up

in a patriar-

ever did was choose, or

did not occur to his Victorian imagination

would immediately have occurred

sourceful and strategic a

a

all,

woman would

to a

!Kung forager

—

^just

how

re-

have to be to keep children alive and

survive herself.

Compared with

his

observations on barnacles, orchids, coral reefs, and

even the expression of emotion

in his

women and other female primates, a passage

few evolutionary

own

children, Darwin's observation of

in particular,

were

at

best cursory. Thus in

biologists like to recall, and

few feminists can

bring themselves to forget, did the ever-careful Darwin deliver himself of

M

Fig.

1

()

T H K R

H

C) C)

I

N

K F

I

F.

L

D

19

used her novel Middlemarch to critique Spencerian notions of eugenic mate choice.

.5 Eliot

Dr. Tertius Lydgate, the rational and positivist

duction, selects his bride,

woman." With her five

AS A M

D

years old,"

Rosamond

of science, seen here in the recent

"perfect blonde loveliness" and "lovely

Rosamond proceeds

tional case study as an (Photo by David Edwards;

man

1

little face," as

to ruin the besotted Lydgate's

admonition against

© BBCWorldwide

BBC

pro-

Vincy, in accordance with a "strictly scientific view of

social

life.

childlike "as

One

if

she was

can read Eliot's

fic-

Darwinist illusions about universal ideal types.

998)

the opinion that: "whether requiring deep thought, reason, or imagination,

or merely the use of the senses and hands, [man will attainl a higher emi-

nence

.

.

.

than can woman."" Like Spencer, Darwin convinced himself that

because females were especially equipped to nurture, males excelled everything

else.

No wonder women turned away from

biology.

at

LOOKTOTHEANIMALS

2o

For

a

handful of nineteenth-century

women intellectuals, however,

evolu-

tionary theory was just too important to ignore. Instead of turning away, they

stepped forward to tap Darwin and Spencer on the shoulder to express their

support for

this

remind them

revolutionary view of

that they

had

left

human

nature, and also to politely

out half the species.

In 187^, four years after Darwin's The Descent of Man and Selection in Relation to Sex

appeared, there came a polite, almost diffident, rejoinder from the

American feminist Antoinette Brown Blackwell. "When, therefore, Mr. Spencer argues that

women

are inferior to

men

because their development

must be earher arrested by reproduction," she wrote Nature, "and Mr.

Darwin claims

in The Sexes Throughout

that males have evolved

muscle and brains

much

superior to females, and entailed their pre-eminent qualities chiefly on

their

male descendants, these conclusions need not be accepted without

question, even by their

own

school of evolutionists.""

Unquestionably, the most brilliantly subversive of these nineteenth-

century distaff Darwinians was Clemence Royer, Darwin's petite, blue-eyed

French

translator. Self-educated like Eliot,

France to be elected to a "oddest and cleverest

had

lost patience

scientific society.

woman

in

Royer was the

Darwin

initially

woman

admired her

Darwin

France" but by the third edition of the Origin It

that she criticized his (erroneous) ideas about

"pangenesis," Darwin's notion of

how

maternal and paternal attributes were

blended in their offspring. Darwin instructed

his publishers to find

translator (a

man, who did not do nearly so good

Ultimately,

what most unnerved Royer 's fellow

women

another

a job), essentially firing her.

evolutionists

been her outspoken views on the "weakening of maternal species and tactics

in

as the

with what he regarded as Royer 's presumptuous manner.

particularly irritated

human

first

would have

instinct" in the

use to subvert patriarchal control of their

28

1-

lives.

In France at this

that

occurred

in

time the decline industrialized

in birthrate,

or "demographic transition,"

countries from the nineteenth century

onward was well under way. Frenchmen were both puzzled and deeply concerned. There were plenty of married

more than

women

sufficient resources for a family,

of breeding age,

some even

many with

wealthy, yet the cen-

suses continued to register a declining population. Plenty of food, yet

the

little in

way of "brats." Not

in the least puzzled,

imagination:

"Woman ...

is

Royer scoffed

at

the one animal in

her male colleagues' lack of all

creation about which

man

M knows

()

H

r

R H

li

() ()

D

AS A M

the least. ... a Foreign species."

1

When

N

K h

men

^uisin^ from

of

women,

in

an exercise in wishful thinking. their conscious desire to have

his

D

2

all fit

I

scientist describes

own

Women

experience

were simply

or,

dis-

few children. Large numbers

she believed, were deliberately curtailing conception

that did not at

—

an idea

current evolutionarv stereotypes about mothers.

Within the French subversive

H L

male

a

women, she cautioned, he either extrapolates From worse, engages

I

scientific

—Darwinian

establishment of that time, Royer was doubly

Lamarck's homeland and a maverick female with

in

No other evolutionist in the world, much less a woman, was writing about women who learn to be "mistresses so iconoclastic ideas about

motherhood.

thev do not have to be mothers," or wrote so enthusiastically about

new tech-

niques emanating from America for aborting unwanted pregnancies, taking

advantage of physicians

out injuring the

who

have learned to "skillfully

off the fruit with-

tree.""

Royer 's own book on the origin of man (Origine appeared

kill

de I'homwe

1870. But her most interesting ideas were set

in

I

875^ edition

la

natalite"

(On

birth),

it

was already

des societes)

down

manuscript explaining why maternal instincts were weakened species. Entitled "Sur

et

in the

in

its

human

proof for an

of the bulletin of the Societe d' Anthropologic de Paris

journal's editors suppressed

in a later

when

the

publication. In that suppressed manuscript

Rover wrote:

Up

until

now, science,

has considered

like law, has

woman

instincts, passions, or

been exclusively made by

men

and

too often an absolutely passive being, without

own

her

interests; a purely plastic material that

without resistance can take whatever form one wishes to give

it;

a liv-

ing creature without personal conscience, without will, without inner

resources to react against her instincts, her hereditary passions, or finally against the

education that she receives and against the discipline

to which she submits following law, customs, and public opinion.

Woman,

however,

not

is

Royer assumed females were hundred vears a

later (in

i

98

i

),

like this.

active strategists with agendas of their

unaware of Royer 's existence,

I

own. A

would publish

made similar points. By then, the had changed. Much more empirical evidence about

book, TheWoman That Never

intellectual climate

made

Evolved, that

females was available, so a stronger case could be made. Evolutionary biology

LOOK TO THE ANIMALS

22

Fig.

1.6

From an i88i

d' Anthropologic

caricature of

Clemence Royer,

de Paris referred to her

supreme compliment

that Eliot

was

as

"almost a

1

830-1 902.

A

colleague at the Societe

man of genius /'echoing Herbert

a "large intellect,

even masculine."^'

Spencer's

(Courtesy of Houghton Library,

Harvard University)

did eventually respond to these criticisms, yet in their lifetimes, the effect that these early

others

Darwinian feminists

—had on mainstream

phrase: the road not taken, The toll

More

—

was

and

and

a

few

summed up with one

a costly one.

than a century would elapse before Darwinians began to incorpo-

rate the full range of selection pressures ses

Eliot, Blackwell, Royer,

evolutionary theory can be

in

on females

into evolutionary analy-

doing so recognize the extent to which males and females had

coevolved, each sex responding to stratagems and attributes of the other.

took

far

longer than

recognize just

it

It

should have to correct old biases, for evolutionists to

how much one mother

could vary from another, and to take

note of the importance of maternal effects and context-specific develop-

ment.

— MOTHKRHOOD An

MINEFIELD

AS A

23

unfortunate hv-product of the delay in correcting long-standing biases

in evolutionary theory

was

that by the last quarter of the twentieth century,

many

when evolutionary paradigms were widened women, especially feminists, had already long

since

abandoned evolutionary

approaches as hopelessly biased. Biology

came

to be viewed by

sow n

as a field

witJi

itself

to include both sexes,

women

mines, best avoided altogether.

The "Invisible Violence of the

Institution of Motherhood"

Today Spencer's ideas are generally out of (mistaking what sometimes

is

favor. Yet the "naturalistic fallacy"

what should

for

be)

never really disappeared.

Spencerian ideas about universal and enduring species-typical standards of physical perfection are alive and well.

"Biology of Beauty" sported a casian

woman

A 1996

Newsweek cover story on the

photo of a perfectly beautiful Barbie-faced Cau-

with the caption, "Would you want your children to carry

model with

person's genes?"'"^ Within, a partially clad male

compares ideal,

this

measuring tape

a

the statistics of his female counterpart against a species-specific

while scientists pronounce that "beauty

genetic quality" which, as far as

1

know,

is

is

of

a signal

a proposition

and

fertility

never tested

among

humans.^' Spencer's ideas on the importance of not just youth and good health but "personal beauty" persist.

ing status quo tial

is still

a given in

some

The notion circles,

women need

just as in the Victorian

choose mates on the

how

according to

test"; thus

some unchang-

quo

to breed so that

is

a

world where

women

England George Eliot described

basis of wealth, while

men

were not of the

large.

.

." .

it:

in

her novels

choose breeding mates

men will choose: men's taste is Eliot character who most epito-

"wives must be what

Lord Grandcourt, the

right shape; nor

men

women

for looks alone (as

a

.

.

and

is

too

women

men

Darwin but not Spencer recognized)

whose

at all

breeding system where

for inherited resources they did not earn,

women but terrible

.

one the lobe of whose ear was

The consequences of such

choose

destructive to

men

everywhere

mizes patriarchal control of females, "would not have liked a wife nails

ini-

nearly they approximate species-typical standards of

beautv, or as Eliot put

woman's

is

almost always with Spencer's

patriarchal assumptions intact. This status

control the resources

that there

choose

not only

for the viability of offspring. (Lord

Grand-

court's beautiful wife never conceives, and he dies young, without legitimate issue.)

Evolutionary psychologists studying mate preferences today throw the

LOOKTOTHEANIMALS

24 occasional sop to

women lest they mind being told they

should look like Bar-

bie dolls or else despair of becoming successful breeders. David Buss's recent

book, The Evolution of Desire, assured young

women

All

women that:

today are unique, distinctive winners of a

million year

five

Pleistocene beauty contest of sexual selection. Every female ancestor

of the readers of these words was attractive enough to obtain enough

male investment to

Yet, as

I

make

will

raise at least

any Pleistocene

clear,

pull offspring through

was not

.^^

one child to reproductive age.

.

.

woman who relied on looks alone to be

likely to

a

mother very long or

leave

descendants.

But

wasn't just social Darwinist stereotypes about what females should be,

it

or instinctively do, or what they are innately incapable of doing, that both-

ered feminists. Ideas about what infants ated even

more

summed up

instinctively

needed mothers

do gener-

alarm. With her usual magisterial sweep, Simone de Beau voir

such

fears. Biological stereotypes will lead to the

the female to the species and the limitations of her various

Attachment theory

—

the proposal that

for a primary attachment figure in the

are uniquely qualified to

ments

to

suffer irreparable

fill,

human

first

"enslavement of

power s."^^

infants have an innate

years of

life, a

role that

need

mothers

and that human babies deprived of such attach-

damage

—rubbed

precisely the spot

tionary acid burns deepest into feminist sensibilities.

Women

where evolu-

seemed

to be

offered the choice of putting their lives on hold for years or else becoming irresponsible mothers.

meant

a

One able

obvious way for these feminists to avoid

dilemma was

to deny that biology

infants have innate

was to

different

it,

an infant "attached"

insist that

the

fact,

humans

is

this painful

relevant to

human

and irreconcilaffairs

or even

needs for highly personalized care. Another

human

from other animals

choose. In cially

feminists saw

mother enchained.

deny that tic

The way many

brain and our capacity for culture that

humans can

us so

learn to be anything they

can learn a lot, but not anything

not in such ancient emotional domains

make

tac-

we

choose, and espe-

as those involved

with "love."

MOTHERHOOD

AS

A

MINEFIELD

25-

Nevertheless, the idea took hold that maternal love was a socially constructed sentiment without any biological basis, a "gift given."

About the same time John Bowlby was pioneering an evolutionary perspective on infant development, a darker literature was emerging. The diagnosis of "battered child syndrome" Hrst appeared in the 1960s.

From

the 1980s

onward, however, there was increasing awareness that infant abuse, neglect,

abandonment, and

infanticide

were

far

more widespread than even those of

phenomena had realized. already knew ment and infanticide both in humans and other animals us

who

back

studied such

—

—

in evolutionary time.

going on. Even after

that

I

I

I

just

abandon-

stretched far

had not realized the magnitude of what was

grasped the larger picture,

I

had trouble admitting to

myself what the numbers gleaned from so many independent sources were showing, or what they meant. Infanticide less,

many

is

not an appealing topic, especially not to

feminists saw in

silver lining. Historical,

some of these grim

women. Neverthe-

statistics a sort

of intellectual

ethnographic, and demographic case studies docu-

mented the existence of many mothers who did not instinctively care for their voung. Surely the prevalence of so many non-nurturing mothers undermined "essentialist" arguments about mothers

genetically

preprogrammed

to

nurture babies. If

women do

chromosomes are, ran their

not naturally nurture their young, then the parent with

no more

is

innately equipped

argument. Hence,

expected to stay

home from work

why

XX

for child-rearing than fathers

should the breadwinning

mom

be

to tend a sick child, but not the dad?

mothers are no better equipped to be parents than

fathers are,

If

mothers need

no longer shoulder so much blame when things go amiss. Gone, then, would be the dreaded "judgements and condemnations, the fear of her

own

power,

the guilt, the guilt, the guilt," as Adrienne Rich so graphically identified the real "G-spot" for mothers."^'

response

that

is

we

will

And

as for babies?

worry about

One

all-too-current feminist

that another day,

when

data are

"more

conclusive."

Whatever moral one ideals and,

even in

derives, clearly

scientific circles,

one of the West's most cherished

widely accepted pieces of conventional

LOOKTOTHEANIMALS

26

wisdom

—

the view that mothers instinctively nurture their offspring

been receiving bad press of

mentary has

late.

A

rash of poetry and psychoanalytic

—

has

com-

emerged, registering discontent with what Adrienne Rich

also

calls "the invisible

violence of the institution of motherhood ."What Rich

is

referring to was the impossible ideal by which mothers not just willingly but "naturally"

punch

in for

twenty-four-hour lifelong

of unconditional

shifts

love.

Now that the generally accepted view that mothers instinctively love their now that it can be demonstrated (on many the human species is anything but automatic

offspring has been toppled, and fronts) that maternal succor in

or universal,

how can we maintain that there

attachment to her infant? The answer

by "biological

Much

all

depends on what we actually mean

how maternal behavior unfolds in the

everyday environments in which mothers actually

is

both

this

natural selection infants have

which

women

live,

fully

worked

become

to shape the

today.

I

am

My

evolved.

focus in this

human

life -forms

interested in whatever

that

mothers and

windows we have

me

with

for

my quest to

understand maternal emotions, infants' needs, and the implica-

tions of natural selection for

creatures like us originated

hominoid (or as

or in those very

recent historical past and especially the distant past where

peering into and reconstructing these worlds. They help

more

mother's

basis."

different ancient environments in

book

a biological basis to a

lip service has been paid to "Biology," "Instinct," and "Natural Laws"

without a great deal of attention paid to real,

is

apelike),

mothers and

—

infants alike.

creatures that are at once

and human

—

Understanding

how

mammalian, primate,

helps us to understand the deep as well

recent history of the compromises that being a mother, or a father,

inevitably entails. Without such a perspective,

we cannot hope

to

do anything

more than sweep the surface of terrain where landmines are buried deep for these below. Even when it isn't possible to completely defuse a mine dilemmas are tough, sometimes truly irreconcilable to at least

knowing where one

is

buried.

—

—

there are advantages

A New View of Mothers Anything

is

more endurable than

to

change our established

Jormulae about women.

— George

Eliot,

1

8^5

The enormous human talent for self-deception should caution us that anything we conclude sojacilely about our species may serve evolutionary ends we do not recognize.

—

-

When

Patricia Adair

Gowaty, 1998

entered graduate school in 1970, nineteenth-century

I

essentiahst views

still

prevailed.

Mothers were viewed

dimensional automatons whose function was to

pump

nurture babies. These stereotypes were especially pervasive in the

as

one-

out and

field

of pri-

matology, where the creatures being studied were so similar to ourselves and

where in

1

were unlikely to be exposed to

practitioners

8^^ expressly warned about "the

folly

critiques like Eliot's,

who

of absolute definitions of woman's

nature."

According to the

first

women

a

widely cited

1

963 essay on "The Female Primate" by one of

professors of biological anthropology, which was published

in an anthology ironically titled The Potential of

Her primary

focus, a role

motherhood. ...

life, is

her entire adult the

life

in the

In other

life.

.

.

of a female. She

group and seldom

words

this

.

Woman:

which occupies more than 70 percent of her

A

female raises one infant after another for

Dominance

is

if

interaction

is

invariably subordinate to

ever

contests [their]

usually minimal in all

the adult males

superior status.

female potential consisted of her capacity to conceive,

gestate, and suckle babies, period.

No

creature epitomized "the female primate" better than old Flo, Jane

Goodall's wonderfully appealing, droopy-lipped chimpanzee mother "starred" in a half-dozen National Geographic specials. Flo

27

who

seemed the model

LOOK TO THE ANIMALS

28

of maternal patience and devotion, evoking the "Magic Piercy's

poem

of that name, the

Mama"

in

Marge

Mama:

who sweats honey, an aphid enrolled to sweeten the lives of others.

The woman who puts down her work

you

Many

speak.

.

.

like knitting the

moment

.

behavioral biologists assumed that "the normal [female] always

mother" and

pregnant are generally those

Any

lems.'

which had the most

that those "females

who

is

a

becoming

difficulty in

have very severe antisocial and social prob-

reluctance or failure to care for offspring, any diversion of her

energy to other pursuits, especially a mother's demonstration of competitive intent or aggressive behavior

on her

part,

was viewed

as pathological.^

Mothers Out of Context Through the 1960s, comparative psychologists sters, cats,

and other animals

in discrete cages

isolated

mother

rats,

with only their offspring for

company. Subjects were buffered from the complexities of larger

works and the need or opportunity to forage (what one might ning").

These mother-infant units were

housewives of the same

young from other

ham-

call

social net-

"breadwin-

eerily reminiscent of model

era. Inevitably, separation of the

suburban

mother and her

individuals limited the range of behaviors observed, while

the research protocols virtually preordained which behaviors could be

reported.

Mother-infant pairs were kept separate from their ecological or social and "political" surroundings.^

was paid

to

Because food was freely available,

how mothers might

little

attention

differ in foraging abilities or resource

defense. Behaviors other than nurturing, such as striving for status, seeking

out or avoiding particular males, relations with kin and other group bers,

were viewed

realities

as irrelevant to a female's role as a

called "check-sheets" that

these

describe "maternal behavior" recorded

how

early

mem-

mother. The virtual

researchers

drew up

to

often a mother approached, hov-

ered over, licked, carried, or suckled her infant. Categories describing interactions with other animals usually

were

no animals except babies

rarely included. In any event, there

in the cage

were

with her; hence no attention was

— N

A

W

F

V

F.

I

W

O

F

MO

paid to the possible significance of other group

or interfere

—

T H E R

members who might

assist

with infant-rearing.

"Maternal behavior" as defined in

this

narrow way was

tional category to aid in quantitative descriptions of

for their infants. Unfortunately,

mothers themselves. not to describe

how

It

was

all

narrow

definitions

convenient opera-

what mothers do to care

became synonymous with

too easy to continue to "look to the animals"

it

means

to be a

mother mammal. But new ways of

observing animals in their natural habitats, and

new ways

hint that

motherhood was going

of thinking about

would provide

field-

to turn out to be

more

the role individuals play in the evolutionary process, first

a

females in nature actually behave but to confirm precon-

ceptions about what

workers their

29

S

complicated than could be deduced from such limited studies. Instead of interchangeable

members belonging

to a

homogeneous

class

new life-form would include a wide range of highly variable individuals who dealt with a wide array of situations and challenges. "Real-life" mothers were just as much strategic planners and decisioncalled "mothers," this

allies as

they were

the tactics they

employed

makers, opportunists and deal-makers, manipulators and nurturers.

The compromises mothers made and

were everywhere contingent on circumstances rather than being automatic, and might or might not result in nurturing behavior. These were the trends that

such

would eventually transform the way we thought about female primates as old Flo.

The key

to this paradigm shift began almost imperceptibly with the real-

ization by a handful of field biologists that even

the origin of species,

though Darwinians talk about

Darwinian natural selection rarely

if

ever acts at the level

of the species. Mothers did not evolve to benefit the species but to translate

such reproductive effort selves survive

as

they could muster into progeny

and reproduce. What evolves

is

who would them-

not behaviors that benefit

groups but behaviors that contribute to the differential reproductive success of individuals

—

even

From Group

at a cost to

others in the group.

to Individual Selection

David Lack, arguably the

first

"reproductive ecologist," was

evolutionists to analyze the breeding behavior of mothers entific advisor to the British Trust for

War

II,

among

the

first

as individuals. Sci-

Ornithology in the years before World

Lack mobilized amateur bird-watchers

all

over England to collect

— LOOK TO THE ANIMALS

30

Fig. 2.

1

Jane Goodall's droopy-lipped, ever-patient and responsive Flo,

son a half-decade, until the day she died, in the world. Flo

is

is

Hugo

not surpassed, by her talent

if

as

who nursed her last-born

most famous and admired mother ape

shown here with her pouting daughter

along with Flo's then adolescent son Figan,

matched,

justifiably the

who grooms his

Fifi

eyeing her baby brother Flint,

mother. Flo's aptitude

an entrepreneurial dynast of the

first

as a

mother

order.

(Photo

is

fy

van Lawick, courtesy ojjane Goodall Institute)

data still

on

individually

banded swallows, robins, and other

birds, an

endeavor

going on today. Nests were watched, eggs counted and weighed. Lack

paid special attention to

how many

how many

eggs actually hatched.

Of those

hatched,

chicks fledged?

Unprecedented quantities of data on the breeding success of

individually

known mothers living under a broad range of naturally occurring conditions

poured

in.

With

differences exist and are by

no means

negligible."^

Lack saw no evidence that mothers adjusted

group or

managed

Lack noted that "individual

characteristic understatement,

species.

mothers

Rather,

—

their reproductive effort so as to

ular circumstances. The bird

who

laid the

fertility so as to benefit their

with greater or lesser success

make

the best of their

most eggs

in a

own

given season, or

attempted to rear every egg she produced, did not necessarily fledge chicks.

Over her

sarily rear the

entire lifespan, the female

most surviving

who

partic-

who

the most

bred all-out did not neces-

offspring. Lack's findings

marked the beginning

N

A

E

W

V

I

K

W

C)

MO

F

T H

otthinkina about reproduction in terms of tradeotls.

assumed

standinjj maternal behavior

that

R

F.

S

3

I

New models for under-

mothers traded off reproduction

in

the present against the possibility of doing better in the future, and then tested these assumptions against data from the real world.

The Fundamental Tradeoff in the

Life

of Mothers

Lack was particularly struck by the way mother birds staggered egg-laying.

Among gulls,

eagles, herons, boobies,

and other birds, mothers

or so apart. Instead of waiting until her clutch

The

set.

will

first

From

chick laid will be the

first-laid

that point on, the die

first

to hatch, larger and

The older

sib

egg hatches

cast, the stage

is

more mature.

It

is

already have received food from the parents by the time

hatch.

eggs a day

complete, a mother begins

is

to incubate the eggs right away, with the result that the several days before the last one.

lay

later chicks

then easily intimidates younger siblings to a point of "no

contest." Should food

become

weaker soon succumbs to

scarce, the

starva-

tion.

By optimistically aiming high, then allowing the strongest pare

it

down

as

needed, mother birds brought brood

supply by both what they did (lay eggs

at

in

her brood to

size in line

with food

intervals but begin brooding right

away) and what they did not do (intervene or compensate). system, well suited to fluctuating food supplies.

If

It

was

a flexible

food was scarce, the brood

would be reduced prior to the point of maximum demands on the mother bring in food for growing chicks.

brood survived

The

—

including the eggs hatched "on spec."

this

far

from interchangeable. Female reproductive suc-

enormously over the course of their

seasons. Such variation

meant that females were

meant something

else.

Although

identical with those of her brood, this

mother who bravely drove away

a

its

own

commitment

older

to her

sib.

a

and even within single

wide open to

selection.

would not always be the

a predator

case. The

from her nest would not less ferocious

same inter-

but more lethal

This was a highly discriminating mother, whose

young was contingent on circumstances.

Could natural selection decades before

lives,

a sex

mother's interests would often be

vene to protect the last-hatched chick from a

enemy,

more

on the part of females than Herbert Spencer had imagined. Fur-

thermore, females were cess varied

to

food was abundant, however, the entire

cruel efficiency of brood manipulation implied considerably

discretion

And

If

actually favor such

mothers?

It

was

young ornithologist named Caldwell Hahn decided

several to test

LOOKTOTHE

32

ANIMALS

Lack's hypothesis. Like a post-Enhghtenment deus ex machina, she

down upon

colony of laughing gulls in

a

switched eggs around so

mental nests hatch

with eggs

filled

the same time.

at

as to

New

a

swooped

Jersey salt marsh and

rewrite past evolution by producing experi-

laid

Mother

on the same

gulls

with

which would therefore

day,

artificially

equalized broods were

twice as likely to lose their entire reproductive effort as were "control" mothers,

whose eggs were

chronously in

—

as

also

manipulated but rearranged so

they would have

if left

as to

alone. (Eggs had to be

hatch asyn-

moved around

both experimental and control groups so that experimenters could be sure

that

human

intervention by itself did not produce greater mortality.)

David Lack had identified the fundamental tradeoff in the

whether to produce many offspring, investing and invest

little in

life

of mothers:

each, or produce a few

a great deal. This idea of "fitness tradeoffs" laid the

groundwork

for

studying the myriad ways that a mother adjusts maternal investment in line

with ecological conditions. Far from

self-sacrificing, the

mothers

in this

Lackian paradigm were flexible, manipulative opportunists. Lack's insights, subsequently refined and expanded by American biologists

George Williams and Robert Trivers,

laid the

groundwork

for evolutionary

biologists to begin to analyze the evolution of social behavior

spective of each participant. As

bizarre infanticidal behavior had so riveted

would provide one of the

first tests

from the per-

happened, the langur monkeys whose

it

my

attention

when

I

learned of it,

for the idea that the interests of

mothers

and fathers did not necessarily coincide and that males and females behaved

as

they did to promote individual reproductive success rather than the contin-

ued

survival of the species.

Mothers Coping with Males summer

In the

of

1

971

maru Sugiyama had By

this

I

first

traveled to India,

where the Japanese

witnessed infanticidal behavior

biologist Yuki-

in langur

monkeys.

time there was a growing consensus that infanticidal behavior was

brought about by human interference and compression of the monkeys' ranges into unnaturally

would

alternate

habitats

—

crowded

habitats.

For the next nine years

between studying the behavior of these monkeys

village

to forest

—and

at

in a

I

range of

different population densities, while

my graduate work and holding various teaching positions. on in my study it became clear that assaults on infants were not

completing Early

dom

acts of violence by stressed animals. Infants

ran-

were attacked only by

ANEWVIEWOFMOTHF, RS

33

Strange adult males, never by males likely to be their fathers. These attacks

occurred when males from outside the breeding system took over one of the breeding troops and drove out the resident male. Then, goal-directed manner, the

newcomer

stalked

in a relentless

mothers with unweaned

and

infants

and attacked them. Once their infants were eliminated, the mothers became sexually receptive and solicited the

new

male. But why,

I

wondered, were

mothers "rewarding" such behavior by breeding with the same male

that

(Note that langur males never copulate unless

first

killed their infants? solicited; rape

is

unknown.)

By the end of

my

first field

season,

was forced

1

my

to set aside

original

hypothesis. Rather than pathological, this infanticidal behavior appeared to be surprisingly adaptive behavior

on the part of males. By eliminating the

off-

spring of their predecessors, males induced the mother to ovulate again

sooner than she otherwise would have. Thus the

killer

had compressed repro-

ductive access to her into the brief period he was likely to be present in her

From the male's point of view, his advantageous. But why would any mother go along

troop (on average twenty-seven months). behavior was genetically

with

it?

The main reason was in particular, suffered

though her species

that even

from retaining the genes of

as a

whole, and her sex

infanticidal

males

in the

population, mothers could not afford to sexually boycott them. By the time

she lost an infant she had already invested delay of waiting for a nicer male to cial to

in,

she could not afford the further

show up, one with

attributes

more benefi-

the survival of her species. To postpone ovulating again for that long

would put her

at a

disadvantage in competition with other mothers

who went

ahead and bred with the infanticidal male. Furthermore, the sons of such a

mother would be

at a

disadvantage in competition with the sons of infantici-

dal males

who, instead of waiting around

into their

own hands by

In the case of langur

for a chance to breed, took matters

eliminating impediments to their breeding.

monkeys,

like canine teeth has the

a

forty-pound male equipped with dagger-

advantage of size and weaponry over a female,

weighs just over half as much. Even

if

she evades

female relatives intervene on her behalf,

as

him

many

for a time, or even

who

if her

do, the infanticidal male can

try and try again, day after day, until he finally succeeds. The odds are stacked against the mother. 1

the

knew same

that in

size

some

species (hyenas, for example) females evolved to be

or larger than males and as a result could protect their infants

LOOK TO THE ANIMALS

34

^:;:

Z^

Fig. 2

.

2

A

better.

langur male seizes an infant sired by his predecessor.

But animals can evolve larger body

over generations. Being just a

little bit

size

.^"-

(Drawing by Sarah Landry)

only incrementally, bit by bit

bigger helps a female hyena, who, in

addition to fending off cannibalistic group mates, also does better scrambling at carcasses to stay fed. leaf- eating

monkey

However, being

that does not

food. Because growing bigger

a little bit bigger

is

of

little

compete with the monkey next

would require delaying maturity,

it

use to a

to her for

might even

place a bigger female at a reproductive disadvantage relative to a faster-

maturing smaller one. Being bigger might also make her more vulnerable to

would be

starvation in famine times. There

big without the payoff: being a

forty-pound male from killing her Infanticide

among

male

who

accompanied by

phenomenon was

The

fathered

that she has invested in the offspring this

mother could prevent

langurs provides a vivid example of behavior that

his infant victim, the rival

where

these drawbacks to growing

that the

infant.

clearly did not evolve to benefit the species.

keys,

all

enough bigger so

up to

first

it,

killer gains at the

and the mother,

that point.

Among

expense of

who

loses

langur

all

mon-

studied, recurrent male takeovers

infanticide can lead to a decline in

group

size

over time,

potentially even the extinction of a particularly vulnerable group.

Although detrimental to the good of the group, infanticide by unrelated males and collusion by mothers turns out to be

anyone thought possible. Reported

now

for

some

far

more widespread than

thirty-five different species

'

ANEWVIE wo ot

MOTHERS

F

3^

primates belon^in^ to sixteen different primate genera, infanticide

a significant

mountain

is

Dian Fossey's old study

gorillas studied at

site in

often

among

source of infant mortality. In the most extreme cases,

the Virunga volca-

noes of Zaire, 14 percent of all infants born, and among red howler monkeys studied in Venezuela

Among

males.

percent of

2

i

langur

all

infants born, are killed

monkeys studied near Jodhpur,

under the direction of Indian primatologist matologist Volker

Sommer would go on

year period, 33 percent of

all infants

Similarly high infant mortality rates

among one-male at

Moremi

by marauding

team of researchers

M. Mohnot and German

pri-

to estimate that over a twenty-five-

were

born

from

killed

by invading males.

'^

infanticide are also being reported

troops of chacma baboons living in regions of Botswana.

Elsewhere savanna baboons but

S.

a

live in

multimale troops and infanticide

monopolize breeding only

single males

These short tenures of male access to competition for access to

on males to compress

a

fertile

fertile females,

is

rare,

for a brief period.

females intensify male-male

and increase the selection pressure

mother's reproductive career into the brief period he

has access to her.

Even

in

other

members of the same

as

normally gentle and herbivorous primates

hazardous

like langur s

and

gorillas,

species can be a threat to infant survival every bit

as lurking predators.

This was a

on mothers, one not previously dreamed

of.

I

new

kind of selective pressure

was beginning to think

that the

threat of infanticide might explain something else peculiar about females. In the early

1

970s,

it

was

were sexually passive and

still

"coy."

widely assumed by Darwinians that females

Female langur s were anything but.

bands of roving males approached the troop, females would actually leave their troop to

go

in search

of them.

On

solicit

When

them or

occasion, a female

mated with invaders even though she was already pregnant and not ovulating (something else nonhuman primates were not supposed to do). Hence, speculated that mothers were mating with outside males

her troop one day. By casting wide the

web of

who

1

might take over

possible paternity, mothers

could increase the prospects of future survival of offspring, since males

almost never attack infants carried by females that,

in the biblical

sense of the

word, they have "known." Males use past relations with the mother as a cue to attack or tolerate her infant.

'""^

—

.

LOOK TO THE ANIMALS

36

how

Still,

The answer

could something so generally deleterious

is

as infanticide evolve?

sexual selection, a process by which same-sex individuals com-

pete with one another for matings.The loser

left

few or no

offspring.

Dar^vinian Sexual Selection Darwin argued

and thereby increases the

that any trait that enhances survival

chances that an individual breeds and leaves offspring will be favored by natural selection. But he traits that

possessor. Such traits

Darwin was traits that

was aware of some peculiar

variations

seemed

most often

to occur

this

theme

fascinated by the peacock's elaborate

in males.

For example,

and the

stag's antlers,

tail

had no apparent survival value and seemed largely ornamental.

some of these decorative appendages might

Indeed,

on

evolved even though they did not enhance the survival of the

by using up

a scarce

actually hinder survival

resource like calcium for making fancy antlers instead of

making stronger bones. The

flashy

who

appear to make the male

and cumbersome

possessed

it

tail

of a peacock would

both more conspicuous to

its

predators and too clumsy to escape them.

A

hindrance in terms of survival, Darwin suspected that these

served a different function. They helped

one another for mates. Darwin termed

members

of one sex compete with

this special subset

of the evolutionary

process sexual selection, which he believed had special relevance to lution.

Thus he

human evo-

major work on the subject The Descent of Man and

titled his

Selection in Relation to Sex

traits

(

i

87

1

)

Sexually selected traits might help individuals outbreed others of the same

them and excluding them from the langur male probably evolved this way), by mak-

sex by outfighting them, dominating

scene (the canine teeth of a ing the possessor

more

attractive to the opposite sex (like the peacock's tail),

or by canceling a

rival's

genetic contribution and replacing

did the tendency to

kill

infants sired

by

rivals).

it

with

his

own

(as

Sexual selection typically

involved two components: male-male competition for access to females, and

female choice.

The

logic of sexual selection

was not

females (supposedly passive, after basis of

some

all)

The

idea that

were choosing between mates on the

secret logic or seemingly whimsical aesthetic preferences

seemed downright

incredible. Darwin's

disrepute and was largely forgotten.'^ scientists in the

just counterintuitive.

1

most

More

970s revisited the topic. But

original theory

soon

fell

into

than a century elapsed before

when

they did, the groundwork

— N

A

would be

K

W

cxplainina

laid tor

why female

widespread, and

Parental Investment

V

I

K

W

MO

F

()

T H E R

S

37

why male-male competition

for

mates was so

choice was so important.

and Female Choice

Although Darwin pointed out the importance oF sexual selection, he was vague on just

why members

of

ciously for access to the other. liantly

The explanation would be

laid

out

fero-

in a bril-

in 1972.

"Parental investment," according to Tri vers, to

competed so

(typically males)

on "Parental Investment and Sexual Selection" by

original paper

Robert Tri vers

one sex

promote the

is

anything that a parent does

from the parent's

survival of an offspring that also detracts

ability to invest in

other offspring. For most animals, especially

parental investment by mothers and fathers

was

far

mammals,

from equal. Typically the

male contribution consisted of ejaculation, whereas the female's consisted of ovulation, gestation, and lactation

up

that could tie

a

successful, could

—

a

sequence of costly biological processes

mother reproductively

for a long time, while the male,

go right on breeding. This inequality

investment of the sexes

in their

young

is

the key variable controlling the

operation of sexual selection," Tri vers wrote in

Where one

sex invests considerably

compete among themselves

latter will

Where investment two is

sexes.

.

.

."

is

But

1

972.'^

more than to

the other,

"members of the

mate with members of the former.

equal, sexual selection should operate similarly

if

if

in "relative parental

more

not, "the individual investing

on the

(usually the female)

vulnerable to desertion." Since in most species fathers invested less than

mothers, competition between males for access to the limiting resource potential mothers trait that

female

—was

helped males

(as in

intense. This led to no-holds-barred evolution of any in this

competition, even

if it

ultimately hurt the

the case of infanticide). Male efforts to exclude other males, or

herd and sequester females, were

all

outcomes of sexual

attempts by males to control their mates came

at

selection.

Often

the expense of the viability

of mothers and offspring.

The one

area, however,

where sexual

selection

worked

to increase rather

than decrease viability of offspring was female mate choice. As researchers rediscovered this topic, an old objection to Darwin's theory lost

some of its

power. For female choices were not just aesthetic. Burgeoning research on this topic

now

indicates that females

do sometimes

select

mates on the

basis

of cues to the male's genetic merits (what Tri vers called "good genes") that

— LOOK TO THE ANIMALS

Fig. 2.3

Displaying peacock

('Sjra/iB/a//erWrJj//lnf/iro-P/io(oj

can be passed on to offspring

mates provide

little else.

lation differ genetically

—

especially in species such as peacocks,

Furthermore, the more that males

in a given

where popu-

from one another, the greater the selection pressure

on females to avoid being monopolized by one

—

not necessarily the best

male.

Powers of discrimination cal aesthetics.

peahen, for example, go beyond whimsi-

True, females comparison-shop and then mate with the pea-

cock whose blue and green eyespots.

in the

The "eyes have

it,"

train of feathers fans out to reveal the largest

but with a quite practical kicker: recent research

by sociobiologist Marion Petrie demonstrates that seemingly arbitrary preferences for fancy

tails

can have tangible payoffs. Petrie followed the fates of

chicks sired by different males as part of a carefully controlled experiment

undertaken

at

England 'sWhipsnade Park. Offspring of the most ornamented

males grew faster and had better survival Since there the

most

mented

The

is

no evidence

that

plausible interpretation

tails also

rates.

male peafowl do anything to help offspring, is

that males able to

produce the most orna-

provide the most viable genes.

bizarre idea that there

may be

receives support trom biologists

genetic

method

who measure

to feminine aesthetics

to the millimeter

how sym-

N

A

F

W

V

I

K

W OF

M O

I

H

F

R

S

39

metrical animals are. Potentially symmetrical traits include the outermost

eyes on the tanncd-out

tails of

peacocks, side feathers of a swallow's

wings on either side of a male scorpionfly,

or, in

the case of humans,

tail,

two

left

ver-

sus right ear lobes, cheekbones, jawbones, and elbows.

Scarcely perceptible lopsidedness in bilateral traits like

assumed to be

body

a

feathers

tail

is

stress-induced deviation from a perfectly symmetrical ideal

plan, brought about by environmental insults

—

pathogens, food short-

nutrients—thus interfering with the

age, or inability to metabolize critical

organism's development. Indeed, the methodology for measuring such "fluctuating asymmetries" (small,

ment

in

random

deviations from perfect bilateral agree-

what should be perfectly symmetrical

by wildlife biologists worried about the their

environment, pollution, diseases, or

In creatures as diverse as

and

toll

at least

one

mammal

was

initially

developed

on animals taken by changes

new

—humans—degree

some measures of performance such

freedom from

size,

parasites,

and

for a food item or a mate.

most ornamented or symmetrical males

be those best suited to prosper

fish,

of fluctuating asymmetries can

competing

as

in

parasites.

earwigs and scorpionflies, finches, swallows,

be inversely correlated with large body

In short, the brightest,

traits)

are likely to

environment where they grew up or

in the

developed breeding plumage. For females

who

don't have the option of run-

ning lab tests on potential fathers, such up-to-the-minute indices of physical condition provide the next best thing.

Following

this logic,

^^

entomologist Randy Thornhill hypothesized (and

confirmed) that scorpionflies with the most symmetrical wings would have the highest mating success, and that females could detect which males these

were

just

by their scent. Symmetrical males may emit different pheromones,

or perhaps they are

other

little

more

effective in

commandeering the dead

insects

and

prey items that scorpionfly males proffer to potential mates as

nuptial gifts, and this

is

what catches females' attention. Whatever the reason,

svmmetrv, performance, and female preferences were

all

correlated.

Thornhill teamed up with psychologist Steven Gangestad to find out

whether the same principle of "fearful symmetry" that humans ing in art and partners.

find so rivet-

metaphor has anything to do with how humans choose sexual

They applied

of undergraduates

at

their calipers to the cheeks, eyes, ankles,

the University of New Mexico.

fluctuating asymmetries (who, of course, had no

about the various

fairly

quirky

facial

and body

Men

and elbows

with low scores on

way of knowing

traits

this fact

being measured) tended

LOOKTOTHEANIMALS

40

Fig. 2 .4

Degree of symmetry

life

to be the

up

may

pro-

how well he has coped

with

in this swallow's tail

vide females with a cue to assess

to that point. (Drawing

by Michelle Johnson)

same subjects who self-reported

that

they had found opportunities to engage in sex earher,

more

often, and with significantly

different partners than did

scores

—

but who,

as far as

No

ceptibly lopsided.

men

more

with higher

most people consciously

were not per-

register,

one knows yet exactly what cues are being used, how

human mate choices, or exactly what any of these burgeoning data sets on human fluctuating asymmetries mean. However, the evidence suggests that either women somehow pick up tiny important they actually are in overall

cues of male condition, or self-confidence, or else

men

in

good condition

have an inflated self-image and habitually exaggerate their sexual prowess for the benefit of prying professors. Let's say that females really are choosing

they after better

who

are bigger and in better condition?

genetic effects

more symmetrical

partners. Are

genes in potential fathers, or after protectors and providers

The trouble

is,

we

can't yet tease

developmental happenstance. For example,

apart from

recently discovered correlations between degree of fluctuating asymmetries

and performance on IQ

tests

relevant abilities inherited tions early in

the mother's

But

Is It

Fieldworkers

life

—

can be explained either by better genes for the

from one or both parents, or by favorable condi-

a healthier

environment for physical development inside

womb. Really "Choice"? like

Marion Petrie and Randy Thornhill rescued Darwin's con-

troversial concept.

Female choice would play an important role

in burnishing

the emerging image of calculating female strategists, as researchers studying

animals in natural habitats took into account the sary for a

mother

range of activities neces-

to reproduce successfully and be "in control."

closer examination,

more

full

some of

But on

the apparent "choice" in female choices was

nearly like compromise, or worse. Often females

offers they could not refuse. For example,

when

a

were responding

male langur

kills

to

an infant,

ANEWVIEWOFMOTHERS he essentially

nullifies

any previous choice the mother might have exercised

in her selection of the father of the killed offspring.

the infanticidal male constrains the

This

why some

is

41

mother

By distorting her options,

to choose

sociobiologists, such as Patricia Adair

him

as

her next mate.

Gowaty, are intent on

learning not only which male a female chooses to mate with (a topic that was

enough

controversial

choose

in

Darwin's time) but which male a female would

if her choice were not constrained hj otherfactors.

Gowaty and

consortium of coworkers have embarked on an ambitious

a

experimental study to discover the consequences of male-imposed constraints

on female choice. When,

herds females about,

or, for that

there biological costs?

hence greater

men

lock up wives in seraglios, are

improved

constraints

(Gowaty terms

viability for a female's

it

progeny, and

viability for the species?^'^

Early results

William Rice

matter,

Does removal of such

"free female choice") result in

male hamadryas baboon

for example, a

at

from

a related project

—

one under the direction of

this

Cruz

the University of California, Santa

—

suggests that the

costs

borne by females of having mate choices constrained may be consider-

able.

A body

of slowly accumulating evidence

is

showing

that not only does

female choice have profound evolutionary implications, so does

its

curtail-

ment. In a series

of staggeringly ambitious experiments. Rice set out to allow

males to evolve while forcing females to stand feat

was possible because Rice

drosophila, the fast-breeding

bananas are

left

is

still

in evolutionary time. This

who works with fruit flies that materialize in kitchens when

an experimental geneticist

little

out too long. Rice established an elaborate experimental

design involving thousands of flies over forty-one generations. In each generation,

males from the "evolving" population were provided females from the

original stock which, through various technically

Rice held

more or

Although male

less genetically

fruit flies don't

complex manipulations.

constant through time.

out-compete other males by

killing their

offspring as langurs do, they use tactics just as dastardly: toxic molecules in

male seminal

fluid that

destroy the sperm of males that subsequently mate

with the same female. Unfortunately, after

many

ejaculations, toxins

from

the poisons accumulate in the female's reproductive tract, decreasing her

fecundity and shortening her lifespan. "The

more they mate," Rice observes

of the females, "the faster they die." In time, a race of "super males" emerged.

LOOKTOTHEANIMALS

42

especially adapted to this lethal

mode

of sperm competition, but

Because females were taken from the breeding stock and held stant, they

had no opportimity to evolve defenses to

being practiced by their mates.

choose among

If,

for,

who

con-

chemical warfare

been able to

for example, females had only

mates, the genes of females

have been selected

this

at a cost.

artificially

avoided toxic males might

or mothers might have evolved otherwise equipped to

counter toxic sperm. Instead, females prevented from coevolving with these "sexually antagonistic" mates died at higher rates.

have demonstrated

more

clearly the extent to

substantially in response to

Few experiments could

which the two sexes "evolve

one another," and not just

in response to the phys-

environment or to predators.

ical

By the end of the twentieth century, sociobiologists had revealed that females were anything but passive or sexually coy, and certainly not (except in Bill Rice's

experiments)

less evolved.

Females were the genetic custodians

of the species, and through their mate choices

—when permitted—

directed

the course of evolutionary change. Parental investment and female choice not

only called attention to the burdens that motherhood imposes but also

focused attention on the long-standing importance of female autonomy in reproductive decisions, often synonymous with offspring

But

viability.

female decisions were important in the realm of sexual selection, and

if

critical

for selecting progenitors and countering male-male competition, female

"decisions"

were even more important

in the

realm of natural selection gen-

erally.

Over the course of her a series of physiological

grow,

when

between

hfe, a female

bound

for fitness

is

required to

and developmental "decisions" about

how

make

big to

how soon to reproduce, and how much time to allow One of the biggest challenges for understanding selection

to mature,

offspring.

pressures on mothers that confronted sociobiologists in the early years was getting the balance right (for if

between considering

traits that are sexually selected

example, through female choice or male choice) and equally important,

not more important, female

traits that are naturally selected

because they

increased the survival of the mother or her offspring.

The Rare

Self-Sacrificing

For each mother,

how

life is

Mother

a series of turning points

and decisions mostly about

best to allocate resources over the course of her lifetime, be

it

long or

N

A

short. Should she put

ber of offspring

all at

forage in the ocean, parity.) vals

Or

W

V

I

K

W

O

M

F

T H E R

C)

S

her effort into growing big, producing

life

approach reveals

exist,

men

swim upstream, spawn, and (iteroparity), like

just

a large

num-

once, breed in a single fecund burst like the salmon die? (This

is

how

like the

who

known as semelat

long inter-

chimpanzees or humans do?

survey of the natural world through the lens of

sioned by

43

should she bear fewer offspring, with births spaced

over a long

A

all

F

this life-historical

special a creature the self-sacrificing

mother

envi-

French physician Gilibert must be. Such mothers

but they do not evolve as species-typical universals of the female sex

except under the most stringent circumstances. Typically, self-sacrificing

mothers are found

in highly

inbred groups, or

when mothers

are nearing the

end of their reproductive careers. The breed-and-then-die strategy

typical of

semelparous creatures (who reproduce only once in their lifetime) provides the best examples. If

semelparity

mother

in E. B.

is

hard to visualize, think of Charlotte, the

White's beloved children's book

spins to lay her single dies. This

is

classic

pouch of

She

Charlotte's Web.

when her

eggs, and

altruistic spider

life's

work

is

toils

and

done, she

semelparous reproduction.

A human mother who

feels

put-upon by the onslaught of child-related

demands when she arrives home after a long day at work may be heartened to know how much better off she is than one of these more "selfless" mothers. Semelparous mothers are often

The

literally

"eaten alive" by their young.

prize for "extreme maternal care" goes to one of the various mat-

riphagous (yes,

it

means mother-eating)

spiders. After laying her eggs, an

Australian social spider (Diaea ergandros) continues to store nutrients in a

new

batch of eggs

—

odd, oversized eggs,

far

too large to pass through her

oviducts, and lacking genetic instructions. Since she breeds only once,

what

are they for?

These eggs are for eating, not for spiderlings

laying.

But to be eaten by

whom? As

the

mature and begin to mill about, the mother becomes strangely

subdued. She

starts to

turn mu.shy

—

but in a liquefying rather than a senti-

mental way. As her tissue melts, her ravenous young starting with her legs

literally

suck her up,

and eventually devouring the protein-rich eggs dissolv-

ing within her.

Few things seem quite so antisocial as cannibalism Yet dining on mother may be the key ingredient to the evolution of these spiders' unusually gregar.

LOOKTOTHEANIMALS

44 ious lifestyle. lings are selfless

By having the bad manners to

rendered

less likely to eat

mothers, not

all

eat their mother, sated spider-

one another. Furthermore, even among

are equal. There

is

room

for

each mother's attributes. The more efficient a mother bigger she gets; the bigger she less inclined

is,

all is

sorts of selection

on

capturing prey, the

at

the bigger the banquet she provides and the

her progeny are to eat each other and the more her

bals reap the benefits of a social existence.

little

canni-

^^

How to Succeed in Breeding over a Long Life Few mammals breed

in

one semelparous bang. Instead, most are iteroparous,

breeding sequentially over a lifetime. Such mothers

may produce young

singly or in litters. For creatures like ourselves, shaped

potential to breed all

more than once,

her eggs in one basket.

mum

An

it

rarely

makes sense

iteroparous mother

clutch-size for her circumstances,

whose

who

by

this

iteroparous

for a female to put

overshoots the opti-

ovaries are bigger than her

may lose her entire brood to starvation or end up so weak she does not breed next season when conditions improve. Worse, she may succumb trying. Learning just how mothers allocate their time and energy between maklarder,

ing a living, resting, and reproducing, or caring for infants

became

the goal of

primatologist Jeanne Altmann. She and her husband, Stuart, had set out in 1

963 to study the ecology and

social behavior of

baboons on the dusty plains

of Amboseli, in Kenya. Their landmark study, which continues to the present day,

would

also provide the first opportunity to investigate the tradeoffs that

primate mothers make. Her research on the ecology of mothers would

emphasize the extent to which every baboon mother

mother" spending most of each day "making

is

a "dual-career

a living": feeding, walking, avoid-

ing predation, while also caring for her infant.

Acutely sensitive to the problem of observer

oped techniques vidual

for choosing subjects at

Jeanne Altmann devel-

random. She made sure each

was watched for the same number of minutes. Then she used

tests to analyze the results.

human habit of seeing

It

was the best

only what

studying free-ranging animals ists,

bias,

we

indi-

statistical

available antidote to the all-too-

expect to see. In time, such methods for

became standard

practice for animal behavior-

and spread into human behavioral ecology. Instead of relying on asking

mothers what they remembered doing, or thought they should do, accurate accounts of what mothers were actually doing became available.

A

Fig. 2

.

f

N

F

W

V

I

ot observer bias.

Her 974 1

critique of observation

which humans "look to the animals." (Pholo

all

W OF MOTH

Jeanne Altmann's experiences studying wild baboons

problems

"In

K

at

F:

R

S

4?

Amboscli sensitized her to the

methods helped

revise the

aspects of the present study one fact recurs:

baboon mothers

primate mothers, including humans, are dual-career mothers ecological and social setting," Altmann wrote. "They

it.

integral part of that

The baboon world

life

in a

most

complex

baboon

life

goes

and must continue to function within

them, and they

affects

like

do not take care of their

infants while isolated in small houses or cages, as the rest of

on.Thev are an

terms on

courtesy ofJeanne Altmann)

it,

through their lifetime. "^^ With

70 percent of their day going toward making a living, and perhaps another to

I

g

i

o

percent for resting, these baboon mothers were pushing the envelope

of their

own

survival. If they

nal depletion

were to breed any

faster,

they would risk mater-

and death.

Altmann's Held research shifted the focus away from what had become an overemphasis on male-male competition and mate choice back to natural

LOOKTOTHEANIMALS

46

selection. In balancing her tradeoffs so as to stay alive

aspect of a mother's

was shaped by natural

life

and breed, almost every

selection.

At the same time, Altmann was managing her own balancing

two children and doing science under harsh

field conditions.

another concern. The study of mother-infant relations was

widely viewed

as the

act, raising

She also had

time

at that

still

"home economics" of animal behavior, an area of little Altmann feared that her hard work would not be

theoretical significance.

became

1980 monograph Baboon Mothers and

Instead, her

taken seriously.

Infants

a classic in the study of life-history tradeoffs.

The Art of Iteroparity (Breeding More Than Once) A

female's lifetime reproductive success (or fitness) depends

course

—

everything does

—

on luck, of

and, as in the case of Altmann 's baboons, on the

physical constraints of the environment. In an evolutionary sense,

mother

fares relative to another

depends on how well she handles the

of tradeoffs she encounters in the course of her entire

between growing

life.

One

series

tradeoff

is

larger and maintaining herself (somatic effort) versus

reproductive effort. The second main tradeoff involves bodily resources available for reproduction quantity-versus-quality tradeoff. In

mothers invest

how one

little in

some

among

life.

fast;

she allocates

offspring. Again, there

species, such as rabbits

each infant and breed

or a human, breed slowly over a long

how

is

a

and galagos,

others, like a chimpanzee

Others pursue mixed

strategies,

alternating according to conditions.

Golden hamsters, lar rainfall

ment,

quintessentially flexible breeders adapted to the irregu-

and erratic food supplies of their arid Middle Eastern environ-

illustrate the art

— them —

of iteroparity

or,

how

to breed successfully

more

than once over a lifetime. In addition to building a nest, licking her pups clean, protecting and suckling suits

—

a

mother hamster may

pups by eating in line

a few, a

all

also

recoup some of her investment

tactic for adjusting litter size

Among mice

(but not hamsters), mothers

apparently in an effort to configure

litter quality (favor-

ing the heaviest pups) or litter size, occasionally abandoning

the

number of pups

falls

below

a certain threshold,

mammals (lions and bears) also do. Once embarked upon a reproductive lenges.

How

in these

time-honored maternal

with prevailing conditions.

cull right after birth

pleasantly maternal-seeming pur-

to reconcile conflicting

trajectory,

demands of

whole

litters if

something much larger

mothers

face

new

chal-

different offspring? Treat

A

Fig. 2.6 All

NEW VIEW

OF

MOTHERS

47

mothers balance tradeoffs between subsistence and reproduction.

each offspring

or value

as equivalent,

some over

(Photographer unknown)

others? Should a

mother

gamble on an offspring now or reserve herself for some future offspring who might be born under more promising conditions, or might perhaps be born

more advantageous for her to rear? Given that her body is deterioover time, when should she throw in the towel, quit producing, and

sex that rating

a

is

care for her daughter's offspring instead?

The Big Mother Hypothesis When was it worthwhile to delay reproduction

and keep growing? Zoologist

Katherine Ralls hypothesized that a big mother could be a better mother.

The standard answer to why males

are bigger than females

males are selected to be bigger and stronger than

smaller, the ecologically optimal size for their

default

body

size.

During the

1

larger than males,

sexual selection:

Females remain

environment

—

a

sort of

970s, Ralls challenged the fixation with sexual

selection. Playing devil's advocate, she listed

grow

is

rival males.

an eclectic array of

mammals in whichfemales moon rats, musk shrews, chinall

the

chillas, jackrabbits, cottontails, klipspringers, duikers,

water chevrotains,

LOOK TO THE ANIMALS

48

mother offspring quality

offspring quantity

Fig. 2 7 .

Mother's main "life history tradeoffs"

dik-diks,

how

marmosets,

bats, bats,

and more

bats,

Increasing fecundity with

sons so

mates.

many

and on

Among

species

(the best

seek out these "big mothers"

examples are

—

outcompete smaller females so

line

fish

as to

mothers produce bigger

species, big

more

quickly (as whales do),

monopolize resources

available in their

but also defend their infants from carnivorous and extremely

group mates. The

probably explains

her

they

spotted hyena females must do, not only defend their place in

or, as

cannibalistic

as

females seem to live on

fish),

the former for their cachet, the latter for their

babies, deliver larger quantities of rich milk

chow

cases.

one of the main rea-

them. Both fishermen and male

kills

Depending on the

greater fecundity.

group,

to be

where mothers produce more eggs or young

something external

until

many of the

body mass turns out

invertebrates, such as spiders, have females larger than their

grow older and bigger

the

and so forth, and then showed

poorly sexual selection theory accounted for

as the largest

why

fact that bigger

the blue whale female

mammal in the

world.

mothers make better mothers

grows to 196

Even among the anthropoid apes, and

of a venerable history of

in spite

sexually selected males being bigger than females,

hypothesis" helps to explain the emergence around

hominid species with females closer matic decrease

in the

males and females) about the same

i

degree of sexual dimorphism

size as

humans

.

Ralls's "big

Homo

today, and

erectus

were

just

mother

7 million years ago of a

in size to that of males.

in these animals.

tons, qualifying

^^

There was

(size difference

a dra-

between

males and females were

embarking on the

lifestyle

characterized by a division of labor between male hunters and female gatherers.

To understand why Homo

the closely related genus

erectus

Homo

females, as well as females belonging to

ergaster,

grew twice

as large as australo-

NEW VIEW

A

Fig. 2

.

8 In

Homo

ergastcr,

pithecines but in the Amencan Museum

of

i

8

percent larger than females

same ballpark

as

modern humans.

(J.

—

far less

Beckett; Denis

Homo

erec-

dimorphic than australo-

Finnm; Department of Library

Services,

Katural History, NewYork, Image no. 2A226^0)

pithecine females

known

49

considered by some paleontologists to be synonymous with

males were around

tus,

MOTHERS

OF

—

—we need

of which the famous

fossil

known

as

"Lucy"

is

the best

to consider selection pressures on mothers.

Whereas Lucy's mate would have been ^o percent

again larger than she

was, Missus Erectus's fellow was a mere 2o percent bigger than she was,

aroimd the same order of magnitude

body

size that characterizes

with the emergence of Homo

a

became more important

hunter there

may be

erectus,

ence between the two sexes had

larger; but

on

In other

by 1.7 million years ago,

selection pressures favoring larger

just

how

body

Why was this so? For

large he can

grow and

Henry McHenry, the decline

to

do with big

Once hominid mothers became more from

percent or so difference in

still

be

game. Ultimately, though, speculates University of

California, Davis, paleontologist

afield

g

for females than for males.

a ceiling

effective in the pursuit of

i

men and women in modern populations.

words, both males and females grew

size

as the

moms

making better moms.

terrestrial

their usual escape routes (into trees),

to defend themselves and their babies?

Were

in size differ-

and traveled farther

were big

moms

better able

they superior foragers, able to

LOOKTOTHEANIMALS

so

push aside big boulders to get

modate

underground tubers? Better able to accom-

at

larger babies passing through the birth canal, and, after birth, to

carry large, slow-maturing babies long distances? The bigger a mother

example, the more along two-legged.

efficiently she

manages

a

970s,

1

when in order to hear

Katherine Ralls lecture

the other side of Harvard Square, far

women

hypothesis" was infectious.

(who

Ralls

like

to

—

at that

time a

mother

I

can

still

recall the undisguised glee

me is tall) used to rattle off World

times, a Jeremiah-like touch of exasperation

why

think back to

would trek

scholars. Ralls's enthusiasm for the "big

on the correlation between height and

obvious,

1

I

from the Biology Labs (where main-

stream evolution was taught), to the Radcliffe Institute

unique forum for

tics

for

^'^

Listening to paleontologists ponder these questions today,

the early

is,

heavy burden while striding

don't they see

.

.

."

with which

Health Organization

would enter her

how much more

voice.

to the story there

statis-

Other

easier, safer childbirth.

"It's

so

than

is

male-male competition and sexual selection!

Flo's

Metamorphosis from Martyr to Dynast

By the end of the twentieth century, the role of

Flo, Jane Goodall's

most

endearing mother chimp, was expanded and recast. Flo's evident tenderness

and patience were only part of the story about her success this

that

book I

fail

I

assume

to stress sufficiently this nurturing it

is

already well

assumed. But there are secrets to

known,

less

as a

mother.

If in

component, the reason

is

known, widely described, and commonly Flo's reproductive success that are less well

often noted. These include Flo's ability to carve out for herself a

secure and productive territory deep within the boundaries patrolled by the

Gombe

Many of these males were former sexual consorts; others were her own sons who had risen to a high rank in the fluctuating local hierarchy. Flo was as secure as a female chimp could be from outside males who males.

from time to time would

raid her

community and,

if

they could,

kill

not just

unrelated infants but adult males and older females as well.

But Flo did more than commandeer spring late

safe.

a

She supported her offspring

productive larder and keep her politically,

permitting

her mother's advantages into her own. At Flo's death,

Fifi

Fifi

off-

to trans-

parlayed her

mother's local connections into the inestimable privilege of philopatry,

remaining

home

in

her natal place. Philopatry (which means

literally "loving one's

country") meant that instead of migrating away to find a

new

place to

—

— NKW VIEW

A

Fig. 2.9

Growing bigger always

some odder than

otVs

weigh

just as

much

odicrs.

or

OF

MOTHERS

51

involves trade-

Female hyenas often

more than males

do, and

have evolved to he even more aggressive. Being hig

compete

helps a female to

at

carcasses and to dis-

courage other hvenas trom eatino her babies. The hi^h levels of circulating androgens that po.ssible

make

this

have led to ma.sculini/ation of the lemale's

genitalia.

Her

long penis

clitoris looks like a

through which she aives birth.

tvpical

.'\

mam-

malian birth canal extends from the cervix through the pelvis to the vagina.

The hyena's

mammal

usual lenijth for a

of

80-dewree turn. Because the

I

accommodate

to

hours. Mortalitv

a

is

clitoris

four-pound verv high

twice the

must stretch

fetus, labor takes

among primiparous

(Hrst-time) hvena mothers. of infants

is

her size and makes a

Up

to 60 percent

born to primaparac suffocate while pass-

ing through the eye of this needle.

(Drawing by

Christine Drea. Courtesy of Larry Frank)

live, Fifi

—

like half

she was born.

Fifi

of

all

females born

Gombe

at

—managed

to stay

where

continued to use her mother's rich, familiar larder, and

enjov the protection of male kin.

Make no mistake: reproductively, nothing becomes a female more than remaining among kin. Thus advantaged, Fifi began breeding at an unusually early age,

and so

far has

produced seven successive offspring,

six surviving

the all-time record for lifetime reproductive success in a wild Great

Ape

female. She also holds the record for shortest interval between surviving births ever reported in wild chimps.

into the largest just

.

at

below the current alpha male,

Fifi's

8

male on record

Her second-born

Gombe Fifi's

and ranks

son, Frodo, has

grown

in the status hierarchy

firstborn son, Freud, while Fanni,

third-born, holds the record for the earliest ever anogenital swelling, at

^ years.

Thus does

Flo's family prosper.

when Flo approached other females, they gave nervous pant-grunts and moved out of her way. Females could be divided into those that held sway and those that gave way. What Early on, Goodall and her students noticed that

LOOK TO THE ANIMALS

^2

Goodall did not immediately grasp, however, was important.

chimp

Over as

We now know that, given

will kill

and eat babies born to other females.

the decades that records were kept at

many

newborn

as ten,

reported the

mother

two

first

infants

were

Gombe,

killed

at least four, possibly

by females.

crimes of a female

named

still

were "eliminating

lineage

sufficiently vulnerable to

From

a

Passion, she, like

that females

from

a

competitor while the infant was

be dispatched with impunity."

the 1970s onward, isolated cases of infanticide by rival mothers

mammals

continued to be reported for other species of social squirrels, prairie dogs, wild dogs,

cases

Goodall

must be deranged.

that the female killing these infants

few sociobiologists suspected otherwise and suggested

more dominant

When

cases of infant killing and cannibalism by another

in 1977, the so-called

most people, assumed

A

the opportunity,

why female rank was so a more dominant female

were attributed to

marmosets, some

fifty

—ground

species in

Most

all.

either a mineral deficiency or protein lust by a hun-

gry female (since in some cases victims were eaten) or to mothers clearing out a niche and thereby making resources available for her efforts

—

a

model

University. As

looking

more

own

proposed by sociobiologist Paul Sherman

first

more evidence became

available, "the

breeding

at

Cornell

crimes of passion" were

deliberate than anomalous, and in species like chimps, other

females were a hazard that mothers had to watch out

for.

Nevertheless, chimpanzees breed so slowly that

was 1997 before

it

Goodall and zoologist Anne Pusey had collected enough data to show a tically significant correlation

keep her infants

alive.

between female rank and

were reported,

subordinate female, Pusey assumed

Mother chimps

will

—

has

become

grand-offspring

Fifi's it

like Flo, then,

entrepreneurial dynasts as well.

you

alive.

mother's

ability to

This finding caused them to reevaluate their long-

standing diagnosis of Passion's "pathological" behavior. after the first cases

a

statis-

When, two decades

daughter attacked the daughter of a

was

a failed

attempt

at infanticide.

were not simply doting nurturers but

A female's quest for status

—

her ambition,

if

inseparable from her ability to keep her offspring and

Far from conflicting with maternity, such a female's

"ambitious" tendencies are part and parcel of maternal success.

Paradigms Widened Darwin had

set

up

a revolutionary

new framework

behavior unfolding before us in the natural world, but

for understanding the it

took another century

N

A

to

expand

that

both sexes.

H

W

V

I

E

W

C)

paradigm to include the

One

reason

equation was that

it

M

F

full

C)

T H

R

K

S

i^

range of selection pressures on

took so long to tuUy assess the female side

ol the

competition between females tends to be more subtle than

the boisterous, often violent, roaring and bellowing of males. Female

mam-

mals tend to confine overt competition to the spheres that actually matter

terms of status and their

to produce high-quality

ability

new awareness

Several changes contributed to the tion

among mothers. studies

als, field

women were

were

doing

lasting longer,

of reproductive varia-

woman

on individu-

decades rather than months. Also, more

field research. In

a

in

offspring.

In addition to the theoretical shift to focus

lamented that "Only

i

875^

Antoinette

Brown Blackwell had

can approach [evolution] from a feminine

standpoint and there are none but beginners

A

\

among

us in this class of investi-

37 percent of Ph.D.s in biology in the United States were being awarded to women, and the proportion in the field of ani-

gations."^^

century

later,

mal behavior was about the same. Although male and female researchers do

same way, they may be

science the

upshot of all these factors was that

attracted to different problems.

this

time,

when

distaff

male evolutionists on the shoulder, many of the

The

Darwinians tapped

latter

were primed

to

respond.

By the

late

1980s, prominent male biologists were joining their

women

colleagues in pointing out the need to correct "inadvertent machismo" in their respective fields.

Some

of them

made

points similar to those Eliot,

Blackwell, and Royer had tried to communicate

"Research

in biology,"

traditionally

a

century

earlier.

renowned entomologist William Eberhard noted,

been carried out mainly by

possible that, as has

more than

happened

men rather than by women,

in the social sciences, research

and

"has it is

may sometimes

be inadvertently influenced by male-centered outlooks.'

Wherever the evolution of reproductive

strategies

was studied, the

importance of taking into account the reproductive interests of involved

—

female or male, adult or immature

—was

all

players

increasingly recognized.

Whether in entomology, primatology, ornithology, or human behavioral ecology, researchers rushed

mother lode of new

—

insight to

like

prospectors in a gold rush

—

to seek the

be had from incorporating females'

as well as

males' perspectives into their research. Scientific observation of animals living in their natural

environments dur-

ing the last decades of the twentieth century yielded a far

more dynamic and

multifaceted portrait of female nature than anything previously imagined.

— LOOKTOTHEANIMALS

^4

Most

surprising

were

all

the ways that mothers influence their offspring's

development through both genetic (including female choice) and nongenetic effects.

The updated image of old

Flo, for

example, allows us

the significance of such "maternal effects."

world advantaged by her mother's rank,

more

subtle ways

—beyond

a

Fifi,

a

Flo's daughter,

glimpse into entered the

maternal effect that pointed to ever

genetically inherited attributes and succor

through which mothers influence the

fates of their offspring.

By the end of

the twentieth century, the spotlight shifted so as to begin to illuminate in rig-

orous and controlled studies

how

Development would turn out

to be the critical missing link in evolutionary

thinking.

organisms develop in specific contexts.

Underlying Mysteries of Development To

mc

the Development Theory [Spencer's term for evolution}

and

all

other explanations of processes by which things came to be produce ajeeble

impression compared with the mystery that

— George /

suspect that selection

.

.

Eliot, letter to a friend

many .

on reading Darwin's

because oj mysteries such as

reason

under the processes. Origin,

i

859

sophisticated biologists remain skeptical about

—

One

lies

for

how

ontogenies work.

Richard Alexander, 1997

our

fascination

with

Princess

Diana

her

is

Cinderella-like life story: unknown ingenue transformed into a future queen. Beekeepers routinely make such fairy tales come

true just by arranging for the eggs or young larvae (less than three days old) to be fed a substance called "royal jelly."

As an egg or

larva, females are totipotent, able to

ferent forms. In the honeybee world, in

female's lot in

her "caste") her

—

life

—what one might

develop into several

which "you are what you

think of as her

dif-

eat," a

class (strictly speaking,

determined not by her genes but by what her nurses JeeJ

is

and bv the reproductive oppression of dominant individuals. Ditto for

what we might

mother or

call

her gender

—whether

or not she becomes an imperious

servile spinster sister.

At oviposition, the egg

that will

be queen

is

placed in a special compart-

ment. She spends her privileged larvahood being fed tion

—

roval jelly

—prepared

in the salivary glands of

a

chemical concoc-

her nurses. The body of

the immature, specially fed individual matures so as to differ from the ordi-

narv worker in fifty-three different morphological and behavioral respects. Instead of

becoming

a sterile

worker who

she blossoms into a fecund queen

Two

who

will

will never

produce an offspring,

produce several million of them.

females with virtually identical genotypes (genetic composition

55

at

con-

LOOKTOTHEANIMALS

5^6

ception) look forward to

two

resulting in these different

utterly different destinies. Intervening events

outcomes constitute the underlying mysteries.

The Importance of Development Even prior to merging of sperm with egg, even before there could be thought of as sibilities

a

germ

are being shaped by the ambient surroundings of the

mammals,

anything that

is

conceptus, an embryo, or an "organism," future poscells. In

these surroundings are influenced by the mother's internal state,

by nutrients

in the

protoplasm a mother adds to her eggs,

or, as in

the case of

honeybees, by nutrients provided by other members of the colony.

The mysterious development of

individuals, or ontogeny, includes

those complex and opportunistic emergent processes that affect

how

all

each

genotype develops into the phenotype, the tangible properties of the organism

determined by genes." Phenotype

that are influenced but never entirely

one of those awkward umbrella terms

is

began narrow, then opened up

that

through time to cover a larger area. Today the term

is still

used

in the original

way, to describe specific ways that genes are expressed (as in a particular eye color or blood type); but phenotype ism, or

its

is

also

The important point here experiences

is

is

that

all

anyone ever

phenotypes, never genes.

the world and interact with others in

exposed to natural selection. This cially for

used to refer to an entire organ-

behavior.

me who

those like

is

It is

sees, touches, or directly

phenotypes that interface with

Only phenotypes

it.

are directly

why, evolutionarily speaking, and espe-

study behavior, phenotypes are what matters.

Phenotypes are produced by interactions between genes and other environmental or parental influences. They can be affected by ables

—how much

cytoplasm the mother delivers

chemicals she adds, what time of year time, diseases she might have, even her sociobiologist

it is,

own

all

kinds of vari-

what other

in the egg,

what the mother

is

eating at the

recent social history. This

Mary Jane West- Eberhard can

state so adamantly:

cal illiteracy to talk

about

a

.

.

.

It's a

gene for anything other than

why

"Nothing

genetically determined in the sense of determined by genes alone.

expressed except under particular circumstances.

is

is

No gene is

kind ot biologi-

a particular protein

molecule."

West- Eberhard

is

not saying that genes don't matter but rather that their

powers are inseparable from context, including both external context and

— II

NDKR LYING MYST FRIES OF DFVFLOFMFNT

^7

the developmental context, since genes act by influencing a responsive struc-

ture that

already there. This

is

true at every level, from immune-system

is

defenses at the cellular level to character

the personality level.

at

absurd to talk about behavior being "genetically determined" that

as

it is

as

It is

to claim

genes have nothing to do with behavior.

It is

covers

profoundly incorrect to equate "genetic" with "biological," far

more than

and nurture

as separable entities, as in saying

hear the label "biological mother" applied to a

Such

and given

woman

a

is

up

it

term

"The

more

that

nature

just genetic processes. It is also incorrect to treat

genes interact with the

why it is unfortunate woman who has given birth

environment," or "Nurture does not matter." This

a child

a

is

for adoption, or, worse, just provided the

donor

to

to

egg.

nearly the genetic or gestational mother. By contrast to a

genetic donor, the biological mother nourishes, nurtures, and provides the

environment

in

which the

infant develops both physically

and psychologi-

cally. It is

clear that genes are not puppeteers directing behavior.

A range of non-

genetic factors, such as mother's physical condition or social status, the sea-

son

when

she conceived, her

own

presence or absence of father effects

encompass

all

—

diet or the

all

one she provided her baby, the

contribute to individualization. Parental

the nongenetically transmitted attributes that pass from

parent to offspring. Practically speaking, the mediators of such effects are often mothers.

Not hereditary in any

genetic sense, maternal effects can nev-

ertheless influence the speed and course of evolutionary change, trends that

sooner or later lead to changes

in

gene frequency

The dynamics of genetic and maternal

—

the stuff of evolution.

effects are relatively better

under-

stood in the mother-centered worlds of hymenopteran social insects

honevbees, wasps, and ants

—

than they are in other animals.

of chemical signals chart an individual's

life

finite

number

course, thus permitting scientists

to carrv out rigorously controlled experiments showing

ment

A

how

a specific treat-

(such as feeding royal jelly) plays out during development.

One

of the

ironies of the charge "genetic determinism" so often leveled at sociobiologists is

that so

many of

its

earliest practitioners

— Edward

O. Wilson,

West-Eberhard, William Hamilton, and Richard Alexander mologists.

Thev

They were acutely aware

didn't call the

a reason.

new

—were

Mary Jane also ento-

that genetics does not equal biology.

field sociogenetics;

they called

it

sociobiology

—

for

LOOK TO THE ANIMALS

^8

Fig. 3.1

Genetically orchestrated couple on strings dance woodenly across the August

cover of Time. The magazine promises to

What You

tell

how "a new

Do." Images of genes controlling people like puppets are

of SOCiobiology than

its

practitioners. (©

I

gjj Time

i,

1977,

theory would explain" just "Why You

Inc.; reprinted

fy

more

Do

often invoked by critics

permission)

Mother-Centered Worlds Nineteenth-century evolutionists did not

know

lacked a

knew

that traits

were inherited, but they

of the existence of genes or understand

way of conceptualizing

how

they worked. They

the complicated relationship

between inher-

aa

UNDERLYING ited traits

M

Y

T H R

S

DEVELOPMENT

OF

K S

1

and alternative outcomes, or phenotypes. As

animal bchaviorists less creatures like

took

still

it

late as the

1

^9

9^os most

for granted that relatively brainless, culture-

honeybees were born to function instinctively

in a nar-

rowly specified, or species-typical, way. Workers were predestined from birth to serve the queen and maintain the efficiency of the hive.

Thomas Henry Huxley could write

1894, Darwin's associate

In

dently

—

in

what he considered

a progressive

statement

—

confi-

and

that the "vast

fundamental difference between bee society and human society" was that bees "are each organically predestined to the performance of one particular

among men

of functions only," while

class

Among men

"it

cannot be said that one

is

"there fitted

is

by

no such predestination," his organization to

agricultural laborer and nothing else, and another to be a

nothing

landowner and

else."^

No modern human

each

be an

would disagree with Huxley's assessment

sociobiologist

individual

is

that

born with variable potential. But most would

emphatically disagree with Huxley's assumption that the lot of a

hymenop-

teran insect was quite so narrowly predestined. Far from strict destiny direct equation of genotype with a potential.

Even

learns remarkably

become

either a

receives.

in

phenotype

—

a

honeybee's gender

is

an organism born so mindless as a bee, a creature

little in

worker

the course of her

or a

life,

—

merely

who

a female has the potential to

queen, depending on the type of nurture she

Even whether or not

a

worker remains

sterile

or takes a stab

at lay-

ing eggs turns out to be negotiable.

Gender, Relatedness, and Caste The reproductive subservience of worker believed.

castes

The honeybee queen manufactures

is

not quite so voluntary

as

"queen substance"

in

a special

her mandibular gland that broadcasts an imperious olfactory message informing workers of the hive: "Develop your ovaries and you're dead!" The hor-

monal

signals (or pheromones) that the

are derived fi-om ancient in the

hormones emitted by one

this

message

insect to threaten another

course of female-female competition.^ In response to peremptory

pheromonal

signals passed bee-to-bee

ovaries shut

down. Yet occasionally

worker may attempt to will

queen uses to broadcast

most

likely

lay eggs.

during food exchange, the workers'

—

in spite of all this

propaganda

—

But her efforts are usually in vain. Her eggs

be cannibalized by other females

who

detect them.

LOOKTOTHEANIMALS

6o

Ovarian despotism by dominant females has been especially well studied in the ica

genus

Polistes.

These hornet-like wasps range throughout North Amer-

and down to Central America. They sting

many

due to conspicuous black, yellow, and burnt

species are easy to spot

sienna body bands.

moment,

If it is

though,

like fire. Fortunately,

summer

outside, paper wasps are probably, at this

busily constructing parchment-like nests of

chewed wood pulp

in

the eaves of your building.

—

Mary Jane West-Eberhard who the tropical paper wasps near her homes in tethered a reproductive female some distance

In an ingeniously simple manipulation,

for

many

years has studied

Colombia and Costa Rica

—

from where her eggs had been

laid

by tying

a slender

nylon thread around the

wasp's waist. As soon as this dominant female was prevented from aggressively

defending exclusive access to the nest, the previously suppressed

ovaries of her daughters revved

up and they began

Seemingly Utopian, the paper wasps' society police state. This does not necessarily fecundity.

Some Argentinean

sinating the

more

mean there is no

nearly an ovarian

future to unauthorized

nudge by

ants give destiny a helpful

dominant female, usurping her breeding prerogatives

More

selves.

laying eggs.^ is

for

worker

often, however, the better part of valor for a

assas-

them-

in these

mother-centered, mother-dominated societies turns out to be helping their foundress

—

or,

once the colony gets going, their

—

sister

to rear her off-

spring.

Even

in

honeybees, which, most would agree, do approximate buzzing

automatons, genes do not determine outcome

whether to become

a

in life decisions as

mother. Rather, genes set limits on

a

major

mental outcomes, which are very few compared with the situation

humans, where the range of outcomes Genes, with

all

is

enormous

—

albeit

still

not

in

infinite.

their limitations, nevertheless play a very special role in

the puzzle posed by highly cooperative breeding colonies of social insects. all

as

range of develop-

living things strive to reproduce, as

If

Darwin theorized, how could one

explain the dedication of the altruistic worker bees

who will

never reproduce

and transmit genes to future generations? This challenge to Darwinian theory yielded to an ingenious solution proposed in

1963 by British geneticist

William Hamilton. This reserved and self-effacing young with

a

bold idea

—

selection at the level of kin

queen's sterile attendants.

—

scientist

came up

to explain the altruism of the

— UNDERLYING

Fig. 3.2

M

Y

S

T K R

I

OF

K S

D

age for pollen and then regurgitate

it

is

K L

()

F

M

i;

N T

6

surrounded by her worker-bee daughters

as nectar into the

add special enzymes to produce honey before storing

comb. The queen

1

lays

up

it

in the

cells

of the honey-

Only one

in tens of

One of the queen's daughters odd men out, disadvantaged because left:

libraries full of dissertations analyzing "gender, relatedness,

style. (Reprinted by permission of the publisberjrom Insect Societies by

Harvard University

for-

distantly related. If entomologists got their degrees in humanities departments,

we would have

honeybee

hexagonal wax

to 2,000 eggs a day, tended by these workers."

drags away a drone by his wings. Males in this world are the

more

who

mouths of other workers. These workers

thousands of females ever becomes a mother herself. Lower

perhaps

V

Eusocial insects live in colonies with overlapping generations that include sterile, nonre-

productive castes. Here a honeybee queen

thev are

K

Press,

Copyright

©

197 1 fy

^^^ President

and

and caste"

E. O. Wilson [illustration by

Fellows of Harvard College)

Sarab landrjj.

LOOKTOTHEANIMALS

62

Hamilton's Rule The civic-mindedness of

workers earns honeybees the Utopian desig-

sterile

nation eusocial (or, "perfectly social"), which applies to any society with over-

lapping generations devoted to the cooperative care of immatures and

by specialized reproductive and nonreproductive

characterized

Although young are produced that enables so

many

in great quantity,

it is

to survive. Busy workers spend the first three

their short lives in the hive, tending their sister's young, final)

castes.

the quality of the care

weeks of

and their next (and

three weeks foraging for nectar in the riskier world outside.

To explain

this

world, Hamilton drew on his knowledge of the special

reproductive attributes of social insects. social insects so often

He proposed

hymenopteran

that

put the colony's interests ahead of their

own

because of

an especially close degree of genetic relatedness between the workers and the

queen. This comes about because of an odd biological circumstance by which

males have just one set of chromosomes (haploid) while females have two ,

(diploid), so that organisms such as tion. In haplodiploid organisms,

more genes

in

wasps engage

two

sisters

in "haplodiploid"

with the same father will share

common than a mother shares with her own offspring. may seem, even insects have hidden zones Once a honeybee queen or a reproductive wasp

Primitive as they

decision-making. stores the

sperm

in a special

pouch

called a spermatheca.

egg, she has the option of opening a valve, permitting it

passes through her reproductive tract.

chromosomes

A

sets

reproduc-

fertilized

When

sperm

'"

of ovarian mates, she she lays an

to fertilize

egg with two

it

sets

as

of

As with most sexually

(diploid) develops into a daughter.

reproducing animals, the resulting daughter receives half of her chromo-

somes from her mother, the other mated. But

The

if

half

from the male with

one

set of

it

develops into a haploid individ-

chromosomes, derived

loid eggs always develop into sons. Since any

haploid, this creates a peculiar

skew

in

the

queen's

entirely

from

her.

Hap-

male the queen mates with

for her female offspring, such that

ters are especially closely related. This

investing

the queen

the queen withholds sperm, something unusual happens.

unfertilized egg develops anyway, but

ual with only

whom

is

offspring

her own. Male honeybees don't have

why

is

ship to the queen's offspring and also don't

sis-

the genetic payoff for a worker

than

greater

this

is

same

meet

These drones, or "winged sperm dispensers"

she

if

produced

especially close relation-

this

(as

same

test

of citizenship.

Ed Wilson terms them),

LI

live

N D

R LY

i:

I

M

N C

Y

S

T

R

1

I

S

1-:

OF

i:>

K

V F L

M

V

()

F

NT

63

only long enough to mate and then die. After reaching adulthood, they

spend

few davs

a

on the matina

in the nest

before taking off for their big (also

Nonmating males

Hiirht.

final)

moment

are either driven out of the colony or

killed."

Instead of focusing on the sterile worker's genetic representation in the

next CTeneration

—which would be

zero

— Hamilton expanded

the concept of

an individual's lifetime reproductive success (or fitness) to include the

inclusive

jitness of the individual. By inclusive fitness Hamilton meant the effect that

on her own

the female worker's behavior has

behavior has on the fitness of close kin

who

her

fitness plus the effects

share genes by

common

descent.

Hamilton derived simple mathematical expressions pre-

Using this principle,

dicting that altruism should evolve

he desi2;nated C) was

less

whenever the cost to the giver (which

than the fitness benefits (B) obtained by helping

another individual who was related by

r,

a

term designating the proportion of

common descent. simple-looking equation C < Br underlies

genes these two individuals shared by Hamilton's deceptively

lution of helping behavior in

social creatures.

all

The

the evo-

rule together with the

general theory behind kin selection were almost immediately confirmed by

West-Eberhard for wasps, '^ and soon

ultimate level, kin selection explains the kin. In

humans

outcome

is

different beliefs

many other animals. At an universal human pattern of favoring

after for

and customs underlie these patterns, but the Indeed, as

evervwhere the same: kin preferred to nonkin.

we

will see, many unexpected features of maternal behavior can be understood as special cases

No

of Hamilton's rule.

gene or

set of genes,

been

to favor kin, has

or even any one mechanism influencing people

identified.

that kin selection works. Yet

We

do not know even

a fraction

of the ways

wherever biologists or anthropologists have

looked, animals, including people, behave as if there were such genes.

wav or another

(and, as

I

say,

nobody understands how)

have through evolutionary time

Hamilton's rule. sition to prefer tive svstems,

'*^

In

our

—

probably in different ways

humans we can only assume

own

all

One

social creatures

—

internalized

that our powerful predispo-

kin derives from very ancient emotional and cogni-

such as learning to recognize people familiar from a very early

age and having a lower threshold for altruism in our behavior toward them.

This

is

the simplest explanation for our similarities with other social crea-

tures in this respect.

LOOKTOTHEANIMALS

64

As Hamilton expressed

it:

theory] a gene causing altruistic behaviour towards brothers or

[In

be selected only

ters will

if

generally such that the gain

matter more its life if it

vividly,

sis-

the behaviour and the circumstances are

is

more than twice

an animal acting on

the loss.

.

.

.To put the

would

this principle

sacrifice

could thereby save more than two brothers, but not for

less.

And

this is

selection"

where the matter has stood

on the

However, not

tems have

this

all

social insects

is

initial

The honeybee queen,

a

years, the emphasis in "kin

with remarkably cooperative breeding

this reason, attention has

components of Hamilton's She

many

super-mother

recall,

in a class

begun to

on the other hand, even

if

grows up to be

by herself,

a

the other

a specialist in egg-laying.

female of enlarged ovaries, able

she manages to produce

limited prospects of rearing them.

up by

shift to

equation: the ratio of costs and benefits to

to lay an egg a minute, day and night, for up to five years.

actually give

sys-

kind of special haplodiploid reproduction. (Termites, for

example, do not.) For

actors.

for

close relatedness of the actors.

How

altruistically helping

Her worker

some

eggs, has severely

much, then, does

her mother or her

sister,

a sterile sister

worker

reproduce,

accepting a fractional interest in millions of eggs instead of laying a few fated ones herself?

What

ill-

are the costs in relation to benefits, given the

females' degree of relatedness?

By themselves, the

peculiarities of haplodiploid genetic systems

do not

why ants, wasps, bees, termites, and other eusocial insects must be counted among nature's longest-lived and most fecund success stories. fully explain

Something

else

is

needed to explain 140 million years of eusocial prosperity.

We need to keep in mind enough

to

Mother Nature's

cardinal rule for mothers:

It's

not

produce offspring; to succeed through evolutionary time mothers

must produce offspring who

will survive

consider the importance of what

I

and prosper. In short,

we need

to

think of as "the daycare factor."

In an unrivaled reproductive success story, expeditions of leaf-cutting

and

across the forest floor, while battalions of army

ants

harvester ants blaze terrorize

mammals

trails

in their path.

Bees and wasps dot trees with their nests,

N D

II

and termites

Amazonian

R

K

L

Y

infest rotting

Y

S

T

K

secret to their success

many egg

OF

S

D

F

V F L

quite simply, the

is,

if

cells. It's

amazing

is

M

1

;

N T

6^

what

starts

if

most dedicated and

some army-ant queens can

out her

effi-

lay

up

with more than three times

life

not the insect queen's fecundity that

her success rate translating eggs into adult survivors. insects so

P

C)

chmbs, and swarms with biUions upon biUions

two million eggs? A woman

that

E

I

^°

cient daycare in the biosphere. So

to

R

wood. One -third of the animal biomass of the

rain forest teems,

of these social insects.

The

M

N C

I

the dedicated assistance of

all

is

so special,

What makes

it's

social

those allomothers. Even

the mother dies, so long as the colony persists, her progeny will be cared

for.^' It is a

mother-centered world geared toward one aim: the survival of

progeny.

Controlling Mothers? She's a real Queen Bee! We use

the term, often with a tinge of disapproba-

tion, to describe a despot, a figure in charge.

on

closer inspection

queendom, some cooperatives

manage

—

is

more

solitary

It's

one of those metaphors

apt than people realize. But even without a

wasp mothers who do not found

like the fig

that

wasp mother who

breeds alone

large breeding

—

nevertheless

to exercise remarkable control over their posterity. Their

power

derives from their ability to predetermine the sex of each offspring.

William Hamilton showed manipulates her progeny ests.

As the female

lays

in

how

a solitary

ways that

mother

fig

wasp

ruthlessly

her long-term reproductive inter-

suit

each egg, she either

fertilizes

it

or not, thus determin-

ing the exact configuration of daughters and sons, which she can translate into the greatest

number of grand -offspring. Out of a batch of

2^7 eggs, one

mother produced 235 daughters and just 22 sons. To explain this wildly female-biased sex ratio, Hamilton devised a theory based on local competimate competition."

tion for mates, generally referred to as "local

Local mate competition? What could a mother's production of sons versus

daughters possibly have to do with competition to breed? Normally not

much, not lings.

But

in

outbred creatures

in the incestuous

like ourselves

world of the

for every son matters a great deal. The

fig

who

avoid mating with

wasp, the number of daughters

wasp mother's brood

breed, right there within the fleshy pink confines of the petition"

is

full sib-

fig.

will

be born, and

''Local

mate com-

an understatement. Brothers born just a hairsbreadth away from

one another wait outside the nursery

until the sisters hatch, then use their

,

LOOK TO THE ANIMALS

66

7^

Fig. 3.3 fig

and

her eggs in first

are social, but

gall flowers,

and

fight

new

first as a

most are

where they

nursery and next finally as

begin the cycle anew.

It is

reproductive interests.

a

Here

as a seraglio to

as the

to gain access to females,

first fig is

fig

wasp tunnels

a gravid

Such males

struggle clear of the

one. In the process, pollen from the

her few sons, and

solitary.

will mature.

among themselves

The newly inseminated females then

off to find a

serve

.-^tULJ

Some Hymenoptera

lays

duces emerge after.

a.

who emerge

as a

tomb

an embarkation point for the gravid daughters,

new

for the

who

J

fly

fig that will

mother and

will

female-centered world demographically structured to

(Drawing by Sarah Landry from Hrdy and Bennett

shortly

where they were born and

transported to a

her progeny, then

into a

mother wasp pro-

decamp

suit

to

maternal

979, reproduced by permission

0/^

Harvard

Magazine^

enormous jaws with

his

looks

to

emerging

at

dismember one sisters.

once vicious

reflection, this

human terms

The

victorious male gets to

—

cowardly would be the word except in a situation that

darkened room

full

that,

can only be likened

on in

among whom,

of jostling people

or else lurking in cupboards and recesses which open on

all sides,

dozen or so maniacal homicides armed with knives. One lethal.''

mate

"Their fighting," Hamilton recalls,

seems unfair

to a

another.

bite

is

are a easily

N

II

When

1)

is

L Y

I

M

N C

Hamilton spent

kept a special

He

R

F

vial

labeled

Y

T K R

S

Within

mother

this lusty

sen sex ratio

is

O

E S

D

F

a year in Brazil doin^r

C-A-R-N-A-G-E

sets.

And

V F

for

L

()

P

M

Heklwork on

to collect the

NT

F

i\^

needed to

fantasy

fertilize

makes the most

body parts of males.

a social insect sister incest

queendom,

a Victorian

incest, the

mother's cho-

as

many

sons

S. Byatt's allegorical

country estate eerily reminiscent of

will be relieved to

know that the theme

of brother-

does not derive from any special information she possesses about

the sordid underside of domestic

knows?)

Such

efficient use of all the bodily

her daughters. Readers of A.

Morpho Eugenia, about

wasps, he

a fig tree fruits.

resources she has to allocate to reproduction. She produces only as as are

67

what?

microcosm, custom-made for

the one that

F

murdered each time

estimates that a million sons are

the stage the

1

much

as

life in

Victorian households (although,

from the author's knowledge of Hymenoptera.

book's film version, Angels and

Insects,

who

In the

the matriarch's daughters wear fabu-

lous Hymenoptera-styled ball gowns, complete with wasp-waists and flam-

boyant yellow and black

By the end of the

1

stripes.

970s, manipulative

mother wasps had upended the

tvpe of a passive, nonstrategizing, "egg-laying" machine

—

at least

stereo-

among

the

entomological cognoscenti. Previously, the idea of mothers manipulating the sex of their offspring, or controlling the reproductive careers of other females,

seemed more

like science fiction

was once again proving stranger than

An

than science. But natural history

fiction.

arcane subfield know^n as "sex ratio theory" arose within sociobiology

to deal with the complexities of

mothers who

bias production of offspring

who bias investment toward preoccupation among human parents as

toward either sons or daughters, and of parents offspring of one or the other sex

well (see chapter 13, below).

—

a

The study of

biased investment in sons and

daughters illustrates what Hamilton refers to as his

own

"perverse, unsexy,

yet fundamental (geneticist's) angle" on reproduction.^^

Confirmation from the Jewel Wasp Within decades, what

at first

seemed

to

some almost

delusional speculations

about adaptive control of sex ratios by mothers yielded spectacularly precise science.

The organism whose behavior would confirm

the validity of Hamil-

LOOK TO THE ANIMALS

68

Fig. 3

.4William D. Hamilton describes the incestuous microcosm inside a

theorist

Robert Trivers looks on. Hamilton's 1967

why

mother

my

the

fig

wasp produces mostly daughters.

infant daughter with me. Since she was asleep

take this photograph.

in all

parasitoid wasp, smaller than a fruit

on the pupae of blowflies

The

is

"a

consummate

Hamilton's

eggs,

most of which

fig

fly,

the

as the

in birds' nests. This parasite

jewel wasp.

words of biologist John

sex of [her] offspring." Simi-

artist at controlling the

will hatch as daughters, with just

—

to inseminate

mother

first

is

enough sons

them Unattractive .

in short supply.

—

as their

perhaps

housing

What happens, John Wer-

arrives at her host, injects her stinger (which

also a sensory organ) into the

mother got there

vitripennis is a tiny

with the unsavory habit of laying eggs

under carcasses and

requirements happen to be, space if

hands were free to

wasps, jewel wasp mothers locate a blowfly pupa and lay

percent of the eggs

ren wondered,

my

every detail, the jewel in this

in

but name. Nasonia

parasitic jewel wasp, turns out to be, in the

Werren,

^

laid

commonly known

lar to

I

used to attend their seminars, bringing

in a canvas carry-all,

mate competition

crown, was an unlikely candidate

a parasite

I

while evolutionary

Sex Ratios" explained

(Sarah Blajfer Hrdj-/Antbro-Pboto)

ton's theory of local

upon

fig,

article "Extraordinary

mush, only to detect chemically

and had already deposited

her eggs?

is

that another

At that point,

this

family-planner par excellence inserts only a single, unfertilized (and therefore male) egg.

Her son

will hatch into a

world

join the fray with sons of the first female,

daughters.

full

of opportunities: he will

competing to copulate with her

UNDKRLYINC MYSTERIES OF DEVELOPMENT Yet even a mother so

much

word. Werren discovered

in control as the jewel

a "parasite"

upon

wasp

nal sex ratio element." If the

transmits

it

rarely has the last

this calculating parasite.

percent of jewel wasps carry a particular virus-like gene

69

known

About

i

o

as "the pater-

male the mother mates with carries

it,

that

mate

to her in his sperm. This parasitic gene destroys the paternal

chromosomes

in all the

into haploid ones.

The

fertilized eggs that

become

into daughters

eggs that she fertilizes, converting

diploid eggs

normally would have developed

sons, the only sex host capable of transmitting the

parasitic gene. This parasite cally cause jewel

all

upon

a parasite

upon

wasps to become extinct by

a parasite could theoreti-

artificially

producing an

all-

male population. But Werren, with the geneticist's optimism that every dilemma

is

only a

mutation away from some sort of solution, chose to look on the bright

side.

Instead of predicting extinction, he quotes Jonathan Swift:

So, Nat'ralists observe,

Hath smaller

And

a Flea

Fleas that on

him

prey;

these have smallerfleas to bite 'em

And so proceed ad

infinitum.

By the 1970s, then, entomologists exploring cooperative maternal manipulation of sex just discovering

ratios,

new dimensions

infant rearing,

and suppression of ovulation were not

to being female; they

were uncovering new

dimensions to individuality that had to do with development. Hamilton's rule provided sociobiologists with a universal truth: isms, all other things being equal. But

when

Especially in a formula that has built into

ism" and "benefit."

environment vidual,

in

It's

it

it

are

applied to

all

all

social organ-

other things ever equal?

functions like "cost to an organ-

impossible to consider these without reference to the

which organisms develop, the age and condition of the

and constraints imposed by others

in that

indi-

environment.

Maternal Effects For species such

as primates, the

most important feature ual's existence.

Her

in

it

mother

is

the environment, or at least the

during the most perilous phase in any individ-

luck, plus

how

well she copes with her world

—

its

LOOKTOTHEANIMALS

JO

pathogens, along with her conspecifics in

scarcities, its predators, its

what determine whether or not

What mothers

are and

a fertihzation

do can

impede adaptation

facihtate or

conditions, impart to immatures a mother's

—

it

are

ever counts.

own immunological

to

new

defenses

(through lactation) or otherwise give youngsters a boost. These head-start

programs can begin even before

During the ture man, a

late

little

fertilization (see Plate

i

).

seventeenth century, scientists thought they saw a minia-

"homunculus," through their microscopes, folded up inside

human sperm, waiting to be deposited inside the womb. Even after 1827, when embryologist Karl Ernst von Baer provided a more accurate description of the mammalian egg and convinced his colleagues that miniature humans were not planted ready-made into the uteruses of women, ^^ it cona

tinued to be assumed for another century that males alone directed the

course of evolution. Even though mothers contributed egg

viewed

this, too,

was not quite

Rather than being penetrated by a

right.

sperm, the egg (or oocyte) more nearly engulfs

which sperm to accept, and producing for fertilization to take place.

sperm

is

it,

quite possibly selecting

specific chemicals that are necessary

The sperm

oocyte contains several ingredients

they were

conveyed by males.

as passive vessels, awaiting the life force

But

cells,

—

cell is

almost pure nucleus; the

nucleus and cytoplasm.

inside the egg, maternally transmitted instructions

Once

the

go to work.

Nutrients stockpiled prior to fertilization supply the needs of the developing

embryo.

In particular, the mother's oocyte

is

derived from

cells that,

even

prior to fertilization, have begun dividing. Prior to any contact with the

sperm, the maternal germ

cell has

divided four times, into sixteen

of these continues on as the oocyte. The others

become "nurse

cells.

cells,"

One

which

manufacture nutrients and other materials that will be transmitted through the cytoplasm.

This means that early embryonic development

is

under maternal control

before the father's genes, carried by the sperm, are even activated. At the outset, the egg's acceptance of a

plasm from the mother

many

up the embryo

effects.

Proto-

for development, prelude to

possible maternal effects.

One has to

sets

sperm launches maternal

of the strangest and least anticipated maternal effects ever described

do with

just

such special ingredients transmitted by the mother to

the cytoplasm in her eggs.

It is

a case that belies all stereotypical expecta-

tions about maternal virtue, defying the conventional expectation that a

.

UNDERLYING

Fig. 3.5

Drawing

ol

M

Y

T K K

S

O

E S

I

D

V

E

V K L

C)

F

M

H

N

71

I"

"homunculus" from Nicolas Hartsoeker's Essay de Dioptrique, 1694.

"madonna" ought than

a

"whore." In

who make

to

make

a

more

this instance,

mother

suitable

thejemmesjatales

it is

the best mothers.

Imagine flashing

lights blinking

on

a sultry night.

summer

vacationers

to visit discos. The strobe effect emanates

from lumi-

But these

lights are

not inviting

nous, phosphorescent organs on the abdomens of Photuris fireflies. cally

produced

These female

emit chemi-

fireflies

flashes of light that

mimic

the mate-

attracting signal of another species, a type of firefly

belonging to the related genus Photinus, in which females really did evolve to signal readiness to mate

by flashing and males evolved through sexual selection to seek

them out when they

But

did.

when

an

eager Photinus suitor shows up, the alluring Photuris female eats him instead of

mating with him

The

P/7oturi5-mother-to-be gets

more than

a

meal out of this male. She

also

gets his armor, since her victim has the unusual capacity to manufacture

defensive steroids that

make him

The mother promptly

passes this chemical protection

laying,

unpalatable to birds and predatory spiders.

on to the eggs she

endowing them with her chemical booty.

Such cases are the stock-in-trade of those sociobiologists

West-Eberhard who focus on development. To as a

maternal

effect.

"An animal egg or

nized and active phenotype before the beginning

of a frog's

blastula (the early

strong,

is

life.

it is

Hours

a plant

like

Mary Jane

her, individualization begins

seed

fertilized."

is

already a highly orga-

She entreats us to consider

after fertilization, with the fast-dividing

development phase of an animal) already 4,000

none of the embryo's own genes have been

activated.

cells

The only

instructions to be had are from hormones and proteins circulating in the

LOOK TO THE ANIMALS

72

Fig. 3.6

ally

Female Photuns

fireflies

mimic

the sexu-

selected mating signal of another species,

Photinus.

When unsuspecting Photinus males arrive

to mate, the deceptive females eat them, ingesting their defensive chemicals,

which are passed along

to their offspring. Thus through the trickery of ,

their mothers, Photuris offspring enjoy an

increased chance of surviving to adulthood. (Courtesy of Thomas Eisner)

cytoplasm. Far from genetically determined, individual, with

its

initial

"hand-me-down phenotype,"

maternal condition, her nutritional status or

Eberhard means when she

scoffs that

is

development of this new very

much

life history.

This

influenced by is

whatWest-

"The bare genes are among the most

impotent and useless materials imaginable." Thus the phenotype of the early

embryo

is

determined by the mother alone. This represents

maternal effect

a

undreamed of before the closing years of the twentieth century." West-Eberhard has been foremost among those working to integrate behavioral plasticity in both sexes into evolutionary theory. this

wasp

specialist

What

fascinates

the extent to which genetically similar individuals can

is

be shunted into different pathways of development according to conditions

encountered early

in life.

The

identical

genotype (or

at least

genotypes that

are very similar, as in full siblings) could develop into an organism that looks

or behaves very differently (that

is,

exhibits a different phenotype)."

The phenomenon of environmentally cued the

same population

is

known

alternative phenotypes within

as polyphenism (i.e.,

same genotype produces

than one phenotype). Long overlooked, polyphenism, the outcome of

more so many underlying mysteries, is assuming greater importance in the thinking of geneticists. Anyone tempted by cascading research that identihes genes "for" particular traits

of how

much

would do well

context

still

to keep these cases in mind, as reminders

matters.

Catkins or Twigs The reason

all

the best examples of polyphenism derive from plants and

insects rather than vertebrates

is

purely practical. To obtain unambiguous

experimental results requires the experimenter to rear identical individuals

UNDERLYING MYSTERIES OF DEVELOPMENT under different conditions. Distinctive life-forms (or morphs) found

73

in easy-

to-manipulate insects, together with their short Hfespans, means that study subjects can

grow

funding to study

My

up, breed, die, and yield definitive results quickly

them runs

example comes from

favorite

—

before

out. caterpillars belonging to a species of

gfeometrid moths (Nemoria arizonaria) that breed in oak woodlands across the

American Southwest. Entomologist Erick Greene used these to demonstrate

morphs

how

different diets early in

—organisms

showed how

two

as different as

life

produce utterly different

species. In the process,

peculiar contingencies of a mother's existence

gave birth early in the season or later

—

caterpillars

Greene

—whether

she

factor into the shapes her offspring

must assume to survive. In the case of the lars

geometrid moths, mothers hatch two broods of caterpil-

each year. In nature, spring broods feed on the protein-rich pollen of the

oak's drooping flowers, called catkins.

name

derives from the

Long

Dutch diminutive,

after these kittens' tails (their

katte,

precisely because of this

resemblance) have dropped from the trees, the second (summer) brood of caterpillars hatches. Since the catkins are gone, all that caterpillars are tough,

mature oak

leaves, laden

is

left for

with tannins, which are poi-

sonous compounds produced by oaks to discourage nibblers. But

where

caterpillars are

what they

eat, these

tough leaves are just the

Whereas pollen-eating grubs metamorphose pillars that

resemble oak stamens, looking to

all

morphs

in a

world

ticket.

into knobby, wrinkled cater-

the world (especially to hun-

gry birds that prey on insect larvae but not plants) later-born

summer

like

drooping catkins,

are gray-green, less knobby, and utterly twiglike, blending

in with their leafy dinner and once again fooling predators. High levels of tan-

nin from the leaves (or something associated with them) trigger the develop-

ment of this

twiglike

morph.

Greene's elegant experiments showed that the pathway taken by the genetically

coded developmental program

eats in the first three days. If early thev, too,

The

come

triggered by what the caterpillar

broods eat fibery leaves instead of pollen,

to resemble twigs.

nutritionally superior catkin diet permits spring broods to attain a

larger size by the time they pupate, to

they

is

become

mature

faster,

survive better, and (once

moths) to be more fecund breeders. Despite the disadvantages

of being born

late, caterpillar lines that failed

to produce

miss out on the opportunity to breed twice in the same year.

summer broods

LOOK TO THE ANIMALS

74

m

%^.

B^Sl Figs. 3.7a

and

bWhen

zonaria different diets,

same when they

first

and grow up to look

Erick Greene experimentally fed

two

different

of the caterpillar Nemoria

ari-

morphs developed. Spring and summer broods look

the

full sibs

hatch, but subsequently the early-born (spring) broods feed like

on oak

catkins

drooping flowers. Later-born (summer) broods subsist on leaves and

develop into alternative morphs camouflaged

as twigs. If

summer broods were

out-of-season catkin meals, they would stand out like solitary kitten's

twigs and leaves, easily spotted by predators.

tails

artificially

fed

within an inland sea of

(Reprinted with permissionfrom Science 243:644.

© 1989 American

Association Jor the Advancement of Science)

Alternative

Outcomes of Development

Genetically identical individuals can

have very different phenotypes early in development.

These

grow up

to be very different

—depending on

flexible

—

that

is,

to

circumstances encountered

phenotypes result

in different

"morphs"

or types of individuals. Simply put, in varied and unpredictable worlds there will

be more than one way to survive and reproduce. Through the course of

development, individuals adopt alternative their

morphology and

strategies, manifested either in

physical appearance or in their behavior. Resulting

phenotypes depend on circumstances, on which genes or receptors are switched on, which cellular and bodily responses triggered. Alternate phenotypes, or ways of being, are coded right into the genetic constitution (or

genome) of the same

individual.

Polyphenism, with

its

multiple developmental courses,

is

too useful a con-

cept to confine to "simple" creatures like wasps and caterpillars. Increasingly, biologists are

aware that mammals

—

including primates like ourselves

—

can

develop along different pathways, even assume different forms or exhibit quite different behavioral profiles, depending

on what developmental track

they find themselves on. However, the underlying mysteries in large-bodied, socially

complex, and long-lived organisms are

far

harder to pin

down

expcr-

UNDERLYING MYSTERIES OF DEVELOPMENT imentallv, and

none of the cases could be so well documented

as in the

75^

honey-

bees and caterpillars. Consider the "Peter Pan" orangutans.

Researchers engaged in long-term studies of orangutans in the wild have long been puzzled by the curious case of males

from

who

never seem to grow up.

adult males that the legendary nat-

The "Peter Pans" are

so different

uralist Alfred Russell

Wallace (the codiscoverer of Darwin's theory of natural

selection),

full

on encountering one, assumed he belonged to

made

the

The two orangutan body types

(or

Various biologists since have

different patterns of

males get

But

vears.

undergoes

classified as adolescents if,

one

morphs) are characterized by utterly

growth and reproduction; year

day, the

—

a different species.

same mistake.

some

in

same

after year, the

twenty

cases, for as long as

dominant male disappears, the Peter Pan male

a transformation:

within months his face

and he accumulates bulk. Abandoning

low

his

fills

out, his hair grows,

profile for the life of a bully,

it is

Peter Pan's turn to patrol the forest like a quarrelsome troubadour in quest of a

maiden, uttering deep roars and fighting any other adult male he meets. Primatologists Peter

Rodman and

Birute Galdikas,

who

study orangs in

the forests of Borneo, have described the low-cost, low-benefit mating strat-

egy pursued by undersized, adolescent-looking males

who

skulk about

females and copulate with them even though they are not sexually receptive. (Galdikas labels this the "sneak /rape" strategy, the only thing approaching

rape in a primate other than humans.) Such males are seemingly unselective,

attempting to copulate as often as possible, even the female

By

is

at

when

times of her cycle

unlikely to conceive.

contrast, a full adult

male

is

more

discriminating and concentrates on

ovulating females. Such a male fiercely defends access to one, and fights to the

death to drive rival males from her

vicinity,

thus maximizing his chance of

being the father of her next offspring. This "combat /consort" strategy

more

costly than the sneaker's tactics in

is

far

terms of risk to the male from com-

bat. Furthermore, the adult male's discriminating standards

mean

that big

males copulate only rarely (ovulating female orangs being an exceedingly scarce

commodity

in these highly dispersed

and slow-breeding apes). Never-

theless,

such copulations as the consorting big males do obtain are

likely to

culminate in conception.

West-Eberhard was so impressed by the evolutionary kind of variation

—

far

more common

possibilities

than generally realized

—

more of this

that she sug-

LOOK TO THE ANIMALS

76

\g&i^

Figs. 3.8a is

and bThe orang on the

a full adult

exudes

a

left is a

male with beard and

musky

full

"developmentally arrested" Peter Pan male.

cheek

flanges.

Pan male grows up, develops protruding cheek flanges, and emits long a

Darwinian male

fierce contests

with

who

his rivals, in

(as

gested organisms

may

and

etc." (Photos bj Jessie Cohen, National Zoological

Park,

use multiple morphologies or lifestyles

proves successful, and animals pursuing

new

removed, the Peter

turning into the very

much

force in

in search of the female, in exerting his voice,

new

food rather than another) to "experiment" with

better, then

is

calls,

described in the Descent of Man) "expends

wandering about

pouring out odoriferous secretions,

duce

levels,

odor. Developmentally arrested males maintain a low profile and attract less

aggression from dominant males. But as soon as the locally dominant male

model of

On the right

He has much higher testosterone

this

new

© Smithsonian Institution)

(say,

eating one

niches. If the trial run

lifestyle

survive and repro-

evolutionary opportunities are opened up. For exam-

ple, a population of caterpillars could conceivably evolve to specialize in eating

leaves high in tannins

all

forest fires continued to

the time.

burn

Or

(to really

in Indonesia

selection might favor a Peter Pan

engage in science

fiction), if

and food was chronically short,

morph who was

inclined to never

grow

big.

Multiple phenotypes provide natural selection an opportunity to either favor or penalize genetic combinations that predispose animals to live

some

novel way. Such phenotypic flexibility means that evolution and speciation

can occur

at a faster

pace than would otherwise be possible.

Memes and Other Special Maternal

Effects

In terms of evolution, some of the most stunning maternal effects are pro-

duced by information about the world communicated by infant. rats

a

mother

to her

Such information can be transmitted chemically (experiments with

show

that food choices later in

life

are influenced by molecules in

— UNDERLYING

M

Y

S

T K R

K S

I

OF D

mother's milk) or throug^h cultural concepts, which

endowed with language and symbolic

The hand

H L

(0

M

P

Homo

sapiens

77

may have been

is

the unique possessor

^^

that rocks the cradle rarely controls the world.

that sinas the lullabies

N T

E

possible only in species

is

reasoning. Though there

other hominids so endowed in the past, of these capacities today.

V

E

and barks cautionary messages

But the voice of

in the first years

life

provides critical information about the social niche into which the child has

been born. Such experiences can have

upon

a lasting effect

his

mental and

emotional outlook. Through her example and direct teaching, a mother shapes critical assumptions about

who

there

is

to be

afraid of,

who

how

the world works, what there

likely to

is

is

to eat,

be well-disposed, and so forth

mvriad units of culturally transmitted information, or"memes."

Human through

self-images and beliefs are not frozen and continue to change

life as

individuals (active agents in their

social opportunities

and constraints. But the

own

fact that

encounter

right)

new

immature humans are

so impressionable has evolutionary consequences out of proportion to the brief time period

when immatures

are intimately exposed to their

and to her immediate circumstances, or "local

A

mothers

history."

distinguished roster of evolutionists (including Ernst Mayr, John Emlen,

George Williams, Edward O.Wilson, and Richard Dawkins) have

mented on

the extraordinary gullibility of our species, especially

all

com-

when we

are young. Call children gullible, or "learning ready," but their spongelike

aptitudes function to spare small and vulnerable creatures the fatal costs of

learning through

trial

and error. "Don't go near the water," and especially

"Don't tease the saber-tooth fatherly

^^

mind of George Williams.

medium

is

sell

One

that even infants less than

the screen, yet

or to

tiger," are the

what appears there

rather than by

is

examples that came to the grand-

reason television

two years old

imitate

is

such a perilous

what they see on

determined by what happens to appeal

what behavior helped individuals

in a particular past

environment to survive or prosper.

Few

geneticists question the

learning since they

know

importance of maternal

effects or early

that the course of evolution (used here to

mean

changes in gene frequency) can be altered by nothing more substantial than a

powerful idea acquired

early.

A

Hutterite daughter

doctrine along with her mother's milk

is

more

who

likely to

imbibes Anabaptist

grow up

to bear ten

children (the average for her group) and be the least likely of any

any population ever studied to die without surviving offspring.

woman

in

Meanwhile,

.

LOOKTOTHEANIMALS

78

another

little girl

down

the way,

nent second coming, and such

as that

any children In part effects in

at all. In

as a

consequence joins

II,

I

what

will return to

terms of infant survival:

part

1975^

community

a religious

at all

III, I

and

in

some

a

is

most important of

the

cases even

onward,

dependent phenotypes and maternal

began

effects,

maternal

whether to nurture her

infant learns about

sociobiologists

all

how much

mother's decisions about

speculate about the significance of maternal

what the developing human

From

convinced of Christ's immi-

of the celibate Shaking Quakers, decreases her odds of bearing

invest in her offspring,

for

who

who grows up

its

to

social

to

infant

commitment

environment.

incorporate

situation-

along with natural selection, kin

selection, and sexual selection, into our understanding of evolution. "Look-

ing to the animals" in this

new way made

mothers would be recognized

it

as playing active

lutionary stage. But other factors, including

ory builders, sped increasingly diverse

inevitable that sooner or later

up the revision.

An

and variable roles on the evo-

new protagonists among the

explosion of

group of researchers

in

field

the-

studies by an

animal behavior and

human

behavioral ecology unveiled previously unimaginable variation in the natural history of mothers.

Unimaginable Variation If

there were one level ojjeminine incompetence as strict as the ability

count three and no more, the social

to

lot

of women might be treated

with scientific certitude. Meanwhile the indefniteness remains

and

much wider than anyone would

the limits cf variation are really

imaginefrom the sameness of women's coiffure and thefavourite love-stories in prose and verse.

— George

Eliot,

1871-72

The most signifcant impact of this new [evolutionary ecological] thinking was in itsjocus on variability

.

.

and how children fare.

—

how

in

.

.

parents behave

.

.

Jane Lancaster, 1997

female who becomes mother does Every tionary perspective, what mothers have a

it

in

her way.

common

From an is

their high

quite certain degree of relatedness to each infant. What costs that caring for a particular infant will

evolu-

and

varies are the

impose and the potential payoff in

terms of that offspring's prospects of translating her investment into subsequent reproductive success. So

far as natural selection is

concerned, mother-

anything and everything a female does to ensure genetic representation

ing

is

in

subsequent generations. Narrower prescriptions implying that every

mother would be

a fully

committed, "loving" mother were

just

somebody's

wishful thinking.

When sociobiologists followed the advice of early moralists by looking "to the animals," they did so not in search of moral guidance but to learn why creatures behave as they do. Instead of natural laws demonstrating

how moth-

ers should behave, nature yielded a series of contingent statements.

Whether

or not a female produces offspring depends on her age, status, and physical condition.

Whether or

she bears depends

humans

—on who

not, and

how much,

she

on her circumstances, and else

is

around to help

79

her.

commits

—

in

to such offspring as

cooperative breeders like

LOOKTOTHEANIMALS

8o

Incorporating Mothers into the Evolutionary Process

whom

Through the choice of the males with

she mates, the bodily resources

she provides her developing young, and the social

them, each mother's legacy

is

twofold.

microcosm she

creates for

includes the intertwined non-

It

genetic and genetic endowments, which are very difficult to tease apart.

Back

in the earliest days

of evolutionary thinking, long before the Austrian

monk and botanist Gregor Mendel showed how genes

work, and long before

Darwinian thinking merged with population genetics to produce the "new

one of the very

synthesis" of the mid-twentieth century,

evolutionists,

first

the great eighteenth-century French naturalist Jean Baptiste Lamarck, had

mother passed on the

proposed that

a

The

example was the

oft-cited

she acquired during her lifetime.

traits

giraffe's

years of high browsing, and passed from

neck, supposedly stretched long by

mother to

offspring.

Darwinian, and especially genetic, thinking, Lamarck's ideas impossibly quaint.

With the were

rise of

set aside as

Now biologists realize that there are important respects in

which nongenetic, acquired

attributes

ognizing relatives, social networks

—

effects," attributes that are inherited,

—

like

pass

immunities, templates for rec-

between generations

as

"maternal

but not as genes.

Tandem transmission of genetic and acquired attributes means that modern evolutionary theorists are having to combine Darwin, Mendel, and Lamarck into one interactive and cumbersome maternal situation. Compared with maternal relatively simple

effects,

were

it

understanding paternal contributions would be

not for the

fact that

male reproductive

strategies can

rarely be understood apart from what mothers are doing. All through the

the

new view

1

970s, in the years before sociobiology fully incorporated

of mothers as complex, variable creatures, there was a wide-

spread presumption that "Most adult females in most animal populations are likely to

be breeding

produce or rear young

assumed

that "there

is

or close to the theoretical limit of their capacity to

at .

.

."

while, by contrast, with regard to males,

species

was

always the possibility of doing better."

Researchers fixated on simple measures gists' slang for

it

counting the

number

like

—

"counting cops"

primatolo-

of times each male copulates. But in

where maternal reproductive success

varies a great deal, the

number

of matings provides only a crude and unreliable measure of any given male's reproductive success. Whether a copulation results in surviving offspring will

depend on

a

whole range of contingencies having to do with which female

a

UNIMAGINABLK VARIATION male mates with. Unless mating selves survive infancy

sex

is

only so

and

results in production of offspring who them-

the juvenile jears

much sound and

8l

and position themselves

so as to reproduce,

undulation signifying nothing.

Consideration of maternal effects and other underlying mysteries takes evolutionists

beyond the habitual questions

raised by sexual selection theory,

and the staple of so many sociobiological studies: "Will she or won't she?"

"Can he or

can't he?"

More

recently, questions like

"Which mother?" and

"Under what circumstances?" have become more important.

Whereas males would be under heavy rival just to gain

selection pressure to best rival after

opportunities to copulate one

need to compete for mates

more

time, females have no

in this way. This correct generalization

was often

misunderstood to mean that females lacked any "preadaptation for competi-

toward the creation of hierarchy," which

tion" or any "genetic predisposition

was

rarely true.^

It

was

aspects of mothers' lives

certainly not true

if

one takes into account those

where competition matters.

Darwin's ingenious theory of sexual selection promoted a blinding hubris. If

evolutionists could explain

male

strategies for

out-competing other males

and inseminating the most females, they could explain the different natures of males and females.

The trouble was

theory, tailor-made as

that this

crown jewel of evolutionary

was to explain competition between males, was

it

poorly suited to explain the

many preoccupations

of females. Important

sources of variance in the reproductive success of one female

compared

to

another were overlooked. Factors that were routinely overlooked in those early days included the female's age at

first birth,

social factors influencing

reproduces

Nor

at all.

the duration of the intervals between her births,

whether her

did

it

infants live or die, or

even whether she

always register that unless mothers gauged their

reproductive effort in line with fluctuating resources and other prevailing conditions, few

would manage

to rear infants that survived.

The poorly

adapted or unlucky would die trying.

Viewing mothers the old way, no one had paid much attention to these sources of variation.'^ For example, high- and low-ranking bilities it.

when Jeanne Altmann

baboon mothers

of giving birth to a son versus a

Many found

it

at

first

Amboseli differed

showed

that

in their proba-

daughter, few knew what to make of

hard to believe, because in order to understand what was

going on one also had to take into account the social and ecological context

in

LOOK TO THE ANIMALS which each mother was operating, and to understand

born to low-ranking females were

that

less likely to survive

baboon daughters

than sons were. Why?

Studies of captive macaques with a similar social system provide one reason.

Higher-ranking females in the same group harass mothers with daughters

remain

(the sex of offspring that will

own

group and compete with her

in the natal

daughters) but leave low-ranking mothers with sons alone. As a conse-

quence, infant daughters suffer higher mortality than would sons born to

mothers of the same low rank.^

With

the support of their mothers and other matrilineal kin, daughters

born to high-ranking baboon females on the advantages of

rise in the hierarchy and, in turn, pass

their acquired rank (along with such perks as early

reproductive maturity, and greater offspring survival) to daughters. The

female baboon,

work of

like

most

social

mammals, introduces her baby Daughters

social relationships she has forged.

rounded by high-ranking kin give birth

who grow up

an earlier age to offspring

baboon daughters

survive. Since

likely to

at

into the netsur-

more

from

inherit their rank

mother, these social advantages are transmitted across generations

as

their

mater-

nal effects, and the reproductive advantages accumulate through time in her

matriline. But this strange bias in production of progeny only

made

sense in

the light of variation between females.^

lumped together

Prior to sociobiology, females had been see one

was

to see

them

all.

By obscuring

variation

as a class, as if to

between one female and

another, researchers also inadvertently obscured the extent to which natural selection has operated

species could have

we

on

this sex. In retrospect,

been lumped into

a

it

seems absurd

homogeneous group

that half the

this

way

—

until

take into account the nineteenth-century contexts in which evolutionary

theory emerged.

Spencer

like

successful

who

Once

again, the idea goes

back to Victorian evolutionists

observed that with the exception of fecund insect queens,

a

male can produce more surviving offspring, or have greater repro-

ductive success, than females.

From

fruit flies to

humankind,

it

was taken

as

axiomatic that

mate and become mothers, while among males only the competitive manage to

become

fathers.^

It

seemed

ductive success of different mothers would be that tial

among males would

all

females

luckiest or

most

to follow that the repro-

more or

less equivalent,

while

vary tremendously. The greater reproductive poten-

of males was one reason that biologists focused on their behavior. Another

reason was that competition between males was so conspicuous and exciting.

UNIMAGINABLE VARIATION

83

Females, by contrast, were viewed as plodding constants whose steady per-

formance could be taken

Convinced

that the

for granted.

most important

twentieth -century biologists

—

were

Why?

evolved than males.

less

of one individual ation,

no

like

variation occurs

between males, some

—

that

Spencer Because

assumed

still

relative to another is essential for natural selection to occur.

No

selection.

females

variation in the reproductive success

No vari-

no evolution.

selection,

and Selection

Variation

The old premise

more modern

strongly on males than females

that selection acts

forward into

uncritically carried

was

evolutionary thought. Indisputably,

sexual selection weighs heavily on male traits that affect their access to mates.

But competition for mates

work. The theory but casts

is

not the only sphere where Mother Nature

on Desdemona beyond

why

clarifying

at

concerns of Othello,

brilliantly illuminates the obsessive

little light

is

it

would be neces-

sary for her to counter such detrimental effects as being suspected, chased,

herded, dominated, sequestered, punished for straying, or (switching

another Shakespeare

play, Titus Andronicus)

now

to

having offspring sired by a male

other than her mate killed.

Males and females pursue different reproductive males compete for sible.

There

benefits

is

a strict limit,

from insemination.

strategies. Theoretically,

many females as poson the other hand, to how many times a female Her reproductive success depends not on num-

fertilizations, trying to

inseminate as

ber of fertilizations but on the contingencies of her

mates she chooses, and, above

all,

how

life,

successful she

is

the qualities of the at keeping alive such

ir^ants as she does produce.

By the

last

quarter of the twentieth century, a previously undreamed of

variation in reproductive success

from one female

being documented. At the same time, unexpected inable

—

—

relative to another

was

even previously unimag-

sources of this variation were being unveiled.

Not So Coy Females Darwin assumed

that females

were

"coy," holding themselves in reserve for

the one best male. Yet field studies for primates suggested that, once again, the behavior of females was

more

"promiscuous,"

by that term we mean attempting to mate with

many

like

males,

if

variable than expected. Females could be

partners. But to what end? Given that a female could support only one

LOOK TO THE ANIMALS

84

Fig. 4.1

Lucky Moulay Ismail the Bloodthirsty of Morocco (1646— 1727) has earned

immortality. His in the space of

first

one three-month period

many wives and

in

born

from

frequent citation by sociobiologists

mous

his

double

1704, leading to an impressive lifetime total of 888

offspring

to his

a

derives from an astonishing reproductive success, supposedly 40 sons born

concubines. Moulay 's second source of immortality derives

who

used him

as a

chestnut to illustrate the enor-

gulf separating a "big loser" (zero offspring) and a "big winner" like him.

The world's

records for maternity pales by comparison. Pity

poor Madalena Carnauba

ample wet nurses, would with the rest of her tion

or

means

as she

in Brazil

A woman,

children (fates unknown).

still

even

who married if

at thirteen

and gave birth to thirty-two

fed ad libitum like a Stra.sbourg goose and provided

be constrained by inter-birth intervals that inevitably spread out

approaches menopause. Theoretically,

a

man's life-long sperm produc-

that only the duration of refractory periods after ejaculation, declining

acce.ss to ovulating

women

limit his fertility.

Hence he always

sperm counts,

has a chance of doing better.

Fine, so far as this scoring system goes. But even the potency of a potentate should not be

considered in a vacuum. discussing

Moulay

How many

Ismail's

offspring actually survive? For balance, shouldn't

mother, about

whom

almost nothing

Moulay 's own scheming empress, Zidana? Based on was quite

effective at discrediting rivals

(From Blum /95/j

a

few

details

is

we

also be

known? Was she anything

like

about Zidana that survived, she

and eliminating their sons from the

line of succession.

UNIMAGINABLK VARIATION pregnancy

at a

time,

why would

85"

she do this? Such soHcitations not only take

time and energy, but render females vulnerable to attacks from other males,

and expose them to sexually transmitted diseases. Consider the case of chimpanzees.

A

female chimp mates on average 138

times with some thirteen different males for every infant she gives birth

Female bonobos also mate many more times than

do other species of primates

tion, as

living in

is

to.

necessary for concep-

multimale groups, such

as bar-

barv macaques and baboons.

1997 the first-ever paternity

In

tests

from

chimps were analyzed, with unanticipated infants, their

tained, and

assumed

West African

a population of

results.

Samples of hair from

mothers, and from the males in their community were ob-

DNA markers from the hair were compared. The researchers had

that

chimps

live in

more or

less discrete

communities whose bound-

were patrolled by bands of related males who share access to females

aries

the community. These bands of males

who

within their territorial boundaries but also the breeding females there.

When

Pascal

in

were not just defending food resources live

Gagneux, David Woodruff, and Christophe Boesch ana-

lyzed the genetic data, however, they found that just over half the infants born in this

The

community (seven out of thirteen

births)

were

sired

by

outside males.

fathers not only lived outside the study sample, but included males that

the observers had never even seen the female traveling with,

much

less

mat-

ing with."^

Undetected by observers, female chimps were slipping away to outsiders in spite of appalling risks. tories patrolled

Even

if

Lone chimps caught trespassing

solicit

in terri-

by other chimps may be viciously attacked, bitten to death.

males tolerate a "foreign" female sporting the bright-pink swellings

her anogenital region that signal ovulation, resident females that particular passport.

Wandering through unfamiliar

may not honor makes

terrain also

female more vulnerable to predation, not to mention the risk of disease.

almost certainly no coincidence that the virus causing chimps.

in

(It is

AIDS evolved

Promiscuous habits provide the perfect niche for

a

a

in

sexually-

transmitted virus.)

Why,

then, in spite of

all

these drawbacks did female chimps furtively

home communities to breed? Were all the resident males simply familiar? Were the females behaving so as to avoid inbreeding? Was it

leave their

too

because males next-door seemed genetically superior in some way that was

— LOOK TO THE ANIMALS

86

communicated

to females? Were females manipulating the information avail-

able to males about paternity as insurance lest

one or more of these males

community one day?

invade their

Mother's Sexual History as a Maternal Effect In the wild, baby

chimps are born to mothers who, on average, have mated

more than a hundred times with as many as a dozen or more different males. The mother's frenetic (if transient) libido would make it impossible for any male to be certain of paternity. Nevertheless, so long

as the

only with males in her local community, those males will

female mates

still

tend to be

related as uncle, cousin, or grandfather to offspring sired by their relations.

The

possibility that an unrelated

breeding fraternity would be these "brotherhoods."

male might grow up undetected

Community males would not be expected

another community's son in their midst

—and

in the local

breeding integrity of

a serious threat to the

welcome

to

apparently they do not.

Offspring born to a mother like Flo, secure in her feeding range deep inside the territorial boundaries of the

There, she and her young are

community, would be

visit

it

enough.

exposed to incursions by males from other

less

communities than are mothers on the margins. side male,

safe

If

would have been on her own terms

Flo ever bred with an out-

—

perhaps during

a furtive

undetected by her community's resident males. But females living

home

ranges at the edge of the

community

in

are less fortunate. According to

Japanese primatologist Mariko Hiraiwa Hasegawa, offspring of these mothers are at double jeopardy, likely to be killed

munities

well as by males in their

as

consorted with the enemy.

margins are

killed,

When

own who

by males

in

neighboring com-

suspect their mothers of having

offspring of these mothers at

Hiraiwa-Hasegawa reports, sons are more

community

likely to

be the

victims than daughters are.

Langur males, however,

differ

tually never attack any infant

even

if

she has

from male chimps

born to females with

mated with other males

as well.

That

in this respect.

whom is,

They

vir-

they have mated,

unlike chimps, langur

males err on the conservative side of the margin of error that surrounds paternity.

They

attack only

if

unlike chimps (for example), fident

were

Among

sired by

they can be certain the offspring

who tolerate

members

is

not theirs

only those infants they can be con-

of their fraternal interest group.

the langurs studied by

German

primatologist Carola Borries in

lowland forests of Nepal, infanticide accounts for 30 to 60 percent of

all

UNIMAGINABLE VARIATION

Fig. 4.

2

"No

case,"

Darwin confessed, "interested and perplexed

me

so

much

as the brightly col-

In about one fifth of all primate ored hinder ends and adjoining parts of certain primates." bright pink around the time a turns and the anogenital region fills with fluid

species, tissue in

female ovulates. Normally swellings

last just

days— a week

at

most. But bonobo females

like

to three weeks at a stretch. "Sexual these remain swollen and eager to initiate sex for up Primate order, almost always in species swellings" evolved at least three different times in the evolved to be sexually diswhere females reside in groups with multiple adult males. If females species so blatantly advertise their criminating and "coy," as Darwin assumed, why do these (Courusj ofAmy Pansh) only solicit but copulate with many partners, many times?

receptivity and not

infant mortality.

DNA evidence indicates that none of the infants killed could

have been sired by the males infant will

female.

be accepted

It is

the

in the

who

killed

them. Even

group, so long as

mother and her

it is

a

completely unrelated

being carried by a famihar

past relationship with the

male

that provide

infant. As with the the cue for a male to either tolerate or attack a particular would be an example Jemmesfatales fireflies, the mother's recent sexual history

for her progeny. of a maternal effect with life-or-death consequences

awareness of female reproductive interests is transforming to understanding of animal mating systems. Wherever males attempt

This

our

new

constrain female reproductive options, that help females to evade

them.

What

we

can expect selection for

traits

make of such far-flung are being documented for creatures are

we

to

and enterprising sexuality as After all, applied to females, as diverse as fireflies, langurs, and chimps? from the perpejorative-sounding words like "promiscuous" only make sense

solicitations

LOOK TO THE ANIMALS spective of the males

who had been

attempting to control them

the origin of such famous dichotomies as that

"whore."

From

understood

—no doubt

between "madonna" and

the perspective of the female, however, her behavior

as "assiduously

maternal." For this

a

is

mother doing

is

better

that she

all

can to secure the survival of her offspring.

Whatever

else these apes

and monkeys are up

ing the one best male from available suitors

work

choice would

—

is

scarcely the

whole

—

to,

it is

obvious that select-

as

Darwin imagined female

story.

Females are also actively

manipulating information available to males about paternity. Is

a

male animal capable of remembering whether he mated with

ular female?

The best experimental evidence

can derives not from the langur monkeys,

a partic-

testing the proposition that he

who

first

inspired the hypothesis

A

about confusing paternity, but from European sparrows called dunnocks.

male dunnock but

how

acts as if

likely copulations at a particular

Female dunnocks solicits

he can not only recall which females he mated with,

live in

time were to result

cooperative breeding groups in which a female

multiple males. These males, in turn, help provision the chicks

or less in proportion to

mother when she was

how much

last fertile.

to bring food to

According to Nick Davies of Cambridge

were

significantly

more

young they fathered, or even young they might have

just as the "several possible fathers" hypothesis

fingerprinting (which pins

down

more

opportunity they had to inseminate the

University, both alpha and subordinate males

And

in conception.

paternity

more

would

likely

fathered.

predict,

precisely than

DNA

human

observers possibly could) revealed that males were often but not always accurate in their guesstimates.

Pro-Choice Mothers

in cooperatively

their vicinity

Mothers

Mammals

is

breeding species are especially sensitive to

likely either to help or

size,

mother

invests

in

hinder their reproductive endeavors.

calibrate their reproductive effort according to

which intentions, and which females are a given

who

may depend on

the ratio of sons to daughters in the

which males, with

also present. After birth,

how much

particular attributes of her litter,

litter, its

or even the qualities of partic-

ular offspring. Deteriorating social conditions, loss of helpful kin or a mate,

or the presence of dangerous strangers can have a profound effect on maternal

commitment.

UNIMAGINABLE VARIATION The

California

monogamous

mouse

is

an unusual rodent, not just because

but because both

members

pletely faithful to their partners,

do

many pups

com-

pair are

and never mate with others. This as

socially

it is

is

because

weaning age

to

single mothers, so both sexes are better off staying rather than straying.

presence of a male

Outside of

captivity, the

large

to keep the pups

mav

monogamous

of the

mothers with the help of mates rear four times as

89

litter,

kill

their

warm

and

is

absolutely essential to rear a

Mothers who

fed.

pups rather than attempt to rear the

In the California

lack assistance from a male.

of rodents, however,

litter alone.

mouse, mothers eliminate offspring

is

A

for a

far

more common

mother

because she has reason to fear male

pattern

mates

lose their ^ '

after birth if they

among

other species

to terminate investment prior to birth interference. In

house mice, deer mice,

Djungerian hamsters, collared lemmings, and some species of voles, pregnant females respond to the arrival of a strange, potentially infanticidal male in their territory

by reabsorbing their embryos.'^ With

this efficient

form of

early-stage abortion, the female avoids the even greater misfortune of losing a full-term litter later on.

smell of unfamiliar males

Bruce,

who

in

1

95^9 first

is

Early-pregnancy reabsorption triggered by the

known

reported

"Bruce

as the it,

effect," after biologist

Hilda

even though the phenomenon was not

then understood.'^

Even not

all

in strains of mice that

experimenters already knew to be

individuals are equally likely to

kill

infanticidal,

young. In some strains, almost

all

males are infanticidal; in others, only males of a certain "type" kill infants. For

example, only socially dominant males may be

infanticidal, or only

males that

could not possibly be the father of any infants they encounter because they have not ejaculated in the past twenty-one days, the equivalent of one

mouse

gestation period. In 1994, biologists

Glenn Perrigo and Frederick vom

unique neural safeguard system

own

infants.

An

in

mice

internal "clock" starts

Saal described a

that ensures males

up

in

do not

kill

their

response to ejaculation and

thereafter keeps track of light-dark cycles for a period of

two months. This

unusual timer adaptively schedules a male mouse's transformation from cad into dad and back to cad. dal long

enough

for any

The male who

mate

again.

It

becomes

noninfantici-

pups he might have sired to be gestated, born,

weaned, and out of the way. After until they

has ejaculated

that,

males revert to their infanticidal ways

was the "switch

in

time that saves mine," quipped

— LOOKTOTHEANIMALS

90

Irish biologist

Robert Elwood, describing the transformation from the per-

spective of a male rodent.

As with most

really critical functions,

Mother Nature has retained redun-

dant safeguards. In addition to the "switches in time," there are

systems so males can be absolutely certain not to

tive fallback

young. Hence, a male in most

mouse

strains can

being tolerant toward infants long after the

remains

more

kill

primi-

their

own

be induced to keep right on

first litter is

in contact with his mate, or with her smell.

weaned, so long

Somehow

as

he

(probably

through androgen-mediated pheromones), females can assess which males are and

which aren't

infanticidal. Pregnancies

were

significantly

more

likely

when the mother encountered a mouse that the observers knew from other evidence was likely to be an infanticidal male.'^

to be reabsorbed

already

Reabsorption of embryos

nancy

—

is

—

the

most

efficient

way

to terminate a preg-

not physically possible in primates. However, pregnant monkeys

(baboons, langurs, geladas, and other monkeys) whose social groups have

been recently usurped by

a

new male

have been reported to spontaneously

abort.'*

At

first, it

seems counterintuitive

fewer offspring than she fetus or an infant in

whom

iteroparity (or, breeding

when

is

capable of,

that any female

much

less

terminate investment in a

she has already invested so

more than once over

to cut your losses and weather

would ever produce much. But the

a lifetime) involves

art of

knowing

poor conditions, the sooner to breed

again under better ones. In species

where

survival of young requires extensive care, the single

important source of variation in female reproductive success

young are born; what matters

is

is

not

how many survive and grow up

themselves.'^ For such creatures, survival of at least

reproductive discretion. This

is

to reproduce

some young

why being pro-life means

most

how many requires

being pro-choice.

The Importance of Allomothers In

most animals

off.

When

a

(reptiles, fish, insects), the

mother does care

mother

lays

her eggs and takes

for her young, she does so alone. In

species of birds, and in about lo percent of

mammals, including

many

a tiny frac-

tion of primates (humans and a few species of monkeys and prosimians that

bear multiple young), infant survival depends on the mother being assisted

by others

—

the father and /or various individuals other than the parents

UNIMAGINABLE VARIATION alloparents. rats,

Sometimes,

or the rare case ot naked mole

as in social insects,

such individuals provide more care than the mother does/"

Ornithologists used to

them

call

such assistants "helpers"; primatologists called

"aunts" (after the British "auntie," to designate a female relative or

trusted familv friend). In 1975^,

more

Edward O.Wilson decided

digniHed designation: alio- (from the

Since

ent.

9I

printing

it is

Greek

it

was time

for "other than") plus par-

only the wise animal behaviorist with access to

who knows

for sure

who

the father

confine ourselves to the term allomothers

than the mother (whose identity

we

is, it

DNA

finger-

would be more precise

—meaning

are likely to

for a

all

to

the caretakers other

know

for sure)

who

help

care for or provision voung;.

Although

means

this

is

it

may seem odd

that he

care for her infant. all

is

to refer to a male caretaker as an allomother,

However we

define them, alloparents play critical roles in

cooperative-breeding species and in

assistance allows

mothers to breed

wise be possible.

Among humans

at a

many primate societies where such much faster rate than would other-

living in foraging societies, a helpful

and /or alloparents were usually essential for all.

In a surprisingly

vide

many

all

an individual other than the mother helping the mother

a

mother

mate

to rear anj infant at

broad range of creatures, indispensable alloparents pro-

of the same forms of care a mother might, protecting and provi-

sioning, even suckling another female's infant in cases

where the alloparent

is

lactatin^.

Communal

suckling

their matrilineal kin, as

is

most often reported where mothers

do elephants, dwarf mongooses,

live

among

prairie dogs, lions,

ruffed lemurs, cebus monkeys, and bats.' Occasionally, however, dominant

mothers force unrelated females to provide milk, w'olves or wild dogs.

The hired wet-nursing

as in the case

that Linnaeus

of

some

and Gilibert so

objected to was essentially a case of our highly inventive species consciously

converging on a solution similar to that already found in nature. Just as the labor of legions of larvae-minders has earned social insects the

prize for greatest biomass, alloparental assistance permits

rear

young under

difficult conditions, to

breed

especially costly because they are large, quite

we

will see in part

II,

alloparenting

a special role in the evolution of

extraordinarily inventive species.

is

our

fast,

some mammals

to

or to rear young that are

numerous, or slow-growing. As

particularly well developed and played

own

large -brained, slow-growing, and

LOOK TO THE ANIMALS

92

Those Who Can, Breed; Kin Who Can't, Help Out With

their big htters

and fast-growing, costly young, the dwarf mongoose of

East Africa provides a classic

example of cooperative breeding. Typically only

the oldest female in a large group breeds, but

Each animal takes

all

help her rear her young.

a turn as baby-sitter or sentinel, standing upright

vast arid savanna, vigilantly scanning the horizon for predators.

on the

Why do other

females, themselves sufficiently mature to breed, forgo ovulating and help their kin rear super-litters instead?

Research by Purdue University behavioral ecologist Scott Creel illumi-

odd breeding system. The

nates the physiological underpinnings of this

among dwarf mongooses, as among honeybees and other cooperative breeders, is clear: Those who can, breed, while those who can't, help out. rule

Assistance to mothers rearing these super-litters

subordinate females

who

act so

much

is

provided primarily by

mothers

like real

that,

although they

have never been pregnant, they spontaneously lactate to feed their charges.

Harassed and often underweight, these subordinates could not hope to provide for a

kin

is

whole

litter

of their own.

Under

the circumstances, helping rear

their next best option, better than trying

alpha female and being

wounded

and

failing,

or challenging the

or driven away.^^

Mongoose nursemaids respond to the presence of dominant females by a downward adjustment of estrogen levels, which temporarily suppresses ovulation. But why not breed anyway, on the off chance that a subordinate can successfully raise just a small litter? Bonn University's Anne Rasa may have discovered the answer in a related species of African dwarf mongoose. As in

marmoset monkeys and wild dogs, dominant breeding females ensure availability of

allomothers by killing such infants as subordinate females have

the audacity to produce. ^^ The alpha female

worth the ovulation

the

cost.

makes giving birth an option not

At the same time, the subordinate's prudent postponement

means more care

available for the alpha female's big litter, to

ot

whom

the allomothers are related as well.

Contingent Commitment Clearly, for cooperatively breeding

conceive and bear viable young also

is

mammals,

a female's physical capacity to

only a small part of the equation. She must

be able to carry through with the enterprise

pendence. Over sixteen years of monitoring

—

a

rearing offspring to inde-

population of black-tailed

UNIMAGINABLK VARIATION

93

W«"/ *««!' KttB

Fig.

Among

4.3

members a rapid

cooperatively breeding tamarins, former mates and prereproductivc group

carry the infants

when

pace of reproduction

the

mother

is

not suckUng.This allomaternal assistance sustains

— some mothers produce twins twice

crickets and other tidbits as the twins

make

the transition

Her helpers

a year.

from mother's milk

to feeding

offer

them-

selves. {Diawmg hy Sarah LanJrj)

prairie dogs, biologist

John Hoogland found that the vast majority of mothers

(91 percent) are satisfied that, having

committed themselves to gestation and

birth, they have a chance to pull these infants through.

cent of mothers terminate investment

pups

alive.

at

birth and

The remaining

make no

Unprotected, their young are eaten by other females

sometimes with the mother joining

in. In

9 per-

effort to in the

keep

group,

other words, the endocrinological

changes that accompany pregnancy and parturition do not, by themselves, guarantee that a prairie dog mother will behave in what most people think of as a

motherly way.

These "nonmaternally acting" mothers, less

Hoogland

called

them, weighed

than the others (though they were not necessarily younger). Hoogland

hypothesized that these females had a

as

hawk

become pregnant "on

carrying off a dominant female or

fortunes before their due date. But

her lot has

still

when

not improved, the odds are that

At

that point, the

up, sooner rather than to throw good calories

later,

a larger

mother

litters are

first

is

going to

if

kill

destroyed by other

mother who gambled and

within the

after bad,^'^

on

in their

the small female's time comes,

her offspring. Nearly a quarter of all prairie dog lactating females.

spec," gambling

some other improvement

failed gives

it

day or so of birth: better that than

LOOKTOTHEANIMALS

94

The Real

Mother

Self-Sacrificing

A survey of the natural world from a life -historical perspective reveals just how special a creature the self-sacrificing mother envisioned by Gilibert must Such mothers

be.

exist.

Women

do, for example, risk their lives to save their

children. After three marriages,

At

issue

offspring

is

more than

their

inbred groups, or

tive careers.

her

but the medications would

The baby

is

survived.

The

not whether some mothers value the survival of one of their

own

lives.

The question

evolve as species-typical universals of thefemale

in highly

of a

^^

after giving birth.

narrowly defined circumstances. Typically,

child

her,

the fetus. She opted to postpone treatment.

mother died soon

stillbirth

learned she was pregnant, and also

had leukemia. Treatment could save

that she

harm

two miscarriages, and the

woman

daughter, a forty-one-year-old

when mothers

sex.

The answer

self-sacrificing

are near the

The forty-one-year-old mother who

who

not the same individual

whether such mothers

is

is

yes, but

under

mothers are found

end of their reproduc-

gives her

life

for her only

decades earlier might well have aborted

first.

Mothers as Amalgams of the

Past

Pregnancy and motherhood forever change

a

woman.

I

do not merely mean

depletion of maternal resources like calcium, a stretching and redistribution

of her tissues, or alterations in her small ways. For starters, a fetus

an alien organism

mother's

immune

—

secretes

—

hormone

half of

enzymes

profile.

There are innumerable

whose genetic material comes from

that block a key

component of

response, providing a protected zone in which the

the

embryo

develops and the pregnancy can proceed. Such processes may or may not end

known to linger on in the mother's body for as long as twenty- seven jears. In some instances, scleroderma, a disease that involves hardening of the connective tissue, may be triggered by autoimmune with delivery. Fetal

cells

have been

reactions to lingering fetal cells. ^^ sue,

becoming

a

mother

is

a

Beyond changes

the level of cells and

at

turning point in a female's

prospects, opportunities, and, especially, a

woman's

life

history, altering

priorities.

Pregnancy, labor, and delivery alter the brain. They lead to

pathways and the accentuation of certain sensory capacities, such hearing.

Most research on these transformations

has been

animals, but almost certainly similar changes occur

new mothers

feel their

baby

is

so

much

a part

tis-

in

new

neural

as smell

and

done on laboratory

women

as well.

Many

of themselves that seconds

LI

N

I

M

A G

1

N A

B

I.

K

VARIATION

9^

bctorc the infant hejiins to whimper, necdlc-likc sensations can be nipples, and

warm, wet milk

leaks out.

When

a

new mother

that the birth ot her first baby transformed her, she

is

ielt in

says (as

I

the

did)

not speaking just

metaphorically.

A

mother's body merges into synchrony with her baby's needs, and the

baby's well-beina incredibly old.

becomes her pressing concern.

Prolactin, the

same hormone

Parts of these responses are that

coordinates maternal

responses to infant demands for milk, was already orchestrating metamor-

phoses

in

amphibians and controlling water balance

freshwater for

fish

more on

millions of years before any

of bony

existed (see chapter 6

the role of this versatile hormone). Every aspect of our neuro-

chcmistry and emotions has

a rich

and convoluted history, bearing witness to

multiple long-running legacies that small

mammal

in the tissues

we

share with earthworms, amphibians,

mammals, and other primates.

Many

we

many of our autonomic responses, first evolved in environments inhabited by ancient ancestors. Many of these conditions no longer pertain or have long since disappeared, yet, as we shall see in the following chapter, their legacy remains relevant to what we are. of the emotions

feel today,

The

Variable Environments

of Evolutionary Relevance The tabula of human nature was never rasa and The inscription Jound

is

it is

now being

no dogma or world system and

build no empire whose later painful collapse will sweep

Thirty years ago

I

had no idea

that a critique I

could reach so Jar into the

and explain

—William

My

mother,

like

from being with

its

warm

a

own

blank

slate,

much.

.

it

be

bids to

away.

had a hand

.

.

.

in

sphere

.

.

D. Hamilton, 1997

most college-educated women

believed that babies slates waiting to

so

human

it

read.

came

into this

filled in.

world with

in the

1940s,

essentially blank

We now know that isn't the case. human

or tabula rasa, a

infant, like all apes,

agenda, preprogrammed to want to be close to whichever

creature cares for

it

after birth,

more than

likely its

Far

born

is

soft,

mother. With

a

repertoire of inborn "fixed action patterns," babies "root" with their lips for a nipple, suck, grasp, and nestle close, traits that have vival

been crucial

for the sur-

of primate infants over tens of millions of years. By crying out, signal-

ing, clasping tight,

and

primates do whatever

it

in

emotional terms, by caring desperately, baby

takes to feel secure.

They achieve what John Bowlby

termed the "set-goal of proximity to mother." Innate behavioral systems are activated and reinforced by the same types

encountered tion

in the past.^ In the

would be among the

programmed

would have

case, the mother's voice

and intona-

stimuli babies are

most

sensitive to; they are pre-

to learn the language that she speaks, as well as to learn

readily at certain infant

human

—

that primate infants

of stimuli—touch, sounds, tastes, smells

life

phases than

at others.

development would be the more or

pathetic and responsive caretaker.

96

But the most

less

critical

more

stimulus for

continuous presence of a sym-

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE

97

Bowlby's "Environment of Evolutionary Adaptedness" John Bowlby was the Hrst modern psychologist to follow Darwin's lead, exploring the implications ot humankind's primate heritage for our earliest desires, fears, needs,

and

capacities. For

more than

thirty-five million years,

primate infants stayed safe by remaining close to their mothers day and night.

To

was death. This explains why, even

lose touch

today, separation

from

a

familiar caretaker provokes first unease, then desperation, followed by rage,

and

finallv despair.

An

infant safe inside a nursery

distressed at being left alone. infants learn to

is still

Under

well within his or her rights to feel

pressure, and with tough conditioning,

cope with the unnatural expectations of modern parents, but

few can be imagined to look forward to spending the night

in a

dark

room

by themselves. The sensory and cognitive makeup of modern infants, the panic they

which the

from

ration

bad a

is

still

feel at separation,

infants

most

is

distilled

likely to survive

their mothers.

Even

when our

lives in

children's fantastical fears that something

lurking under the bed are assumed by

time

from innumerable past

were those who could prevent sepa-

some psychologists

to date

from

ancestors spent nights in trees and predators threatened

from below.

The next time you

are so frightened that your skin tingles and the hairs

your arms stand up, remember that once upon threatened

mammal seem more

a time, bristling fur

formidable. Bowlby 's

described in 191

8

by German pediatrician

E.

a

embrace-reflex) accidentally

in closure. This

occurs whenever a baby hears a loud noise or experi-

some sudden change

The Moro If

startle

a

newborn's arms flung

symmetrical spasm, and then arced together again

same spasmodic ences

(or,

Moro, who

jostled a baby he had just delivered. Spontaneously, the

out in

made

own favorite reminder

of our hirsute birthright was the Umklammerungs-Reflex first

on

in position.

reflex causes infants to flap their

arms and then clutch inward.

the infant's hands are already touching something soft, they simply cling

tighter, hopefully to

mother; but even a tree limb would be better than

unchecked

If

ensues.

free

Of

fall.

nothing

less utility to

is

there to catch on to, a desperate wail

smooth-skinned humans, the

Moro

reflex, like

other grasping reflexes of the hands and feet, persists as a relict from past times,

when

survival

depended on hanging on to

might suddenly stand up and push

^

off.

a hairy protectress

who

LOOK TO THE ANIMALS

98

and just

In the decades just before

to understand the psychological

after

World War

development of human

the environments in w^hich their emotions evolved. survival kit of ape babies

would remain the same

much was

tocene ancestors. Not

then

He

Bowlby was trying

II,

infants

by imagining

believed that the basic

in infants

known about how

born to our

these early

Pleis-

humans

but Bowlby assumed (correctly) that they were nomadic hunters and

lived,

gatherers.

Borrowing the

ment" from

1

930s concept of "man's ordinary expectable environ-

German psychologist, Bowlby recast it into something he could in terms of evolution [with] a new term that

"more rigorously

define

make

[will]

a

late

.

Environment of Evolutionary Adaptedness"

"the

(EEA)

—

is still

man's today" would have evolved.^

the millions of years during which "the behavioral equipment which

Bowlby understood

that the

EEA would

its

mother,

Adaptedness has changed relatively tion.

Compared

how mothers

close by since

vary according to exactly which

or "system" was being considered, but in the case of the

emotional attachment to

as

.

explicit that organisms are adapted to particular environments."

Bowlby 's new term was

trait

.

to other behaviors that

infant's

over the course of hominoid evolu-

Bowlby might have focused on (such

care for their infants), the infant's powerful desire to be held

caretaker has changed remarkably

its

humans, chimpanzees, and

Bowlby 's

little

human

Environment of Evolutionary

this

little

over the ten million years

common ancestor. EEA were bounded on either side by what

gorillas last shared a

efforts to reconstruct the

he knew about hunter-gatherers' maternal

and those of surviving

styles,

Great Apes.

The reason

a

an African ape's

human is

infant's

that the

attachment to

relevance for infants was the mother Pleistocene

its

mother

still

resembles

most immediate environment of evolutionary herself,

humans and Pliocene apes

not the physical or social world

inhabited.

It

was the mother who con-

tinuously carried the infant in skin-to-skin contact

—stomach

to stomach,

chest to breast. Soothed by her heartbeat, nestled in the heat of her body,

rocked by her movements, the

infant's entire

who

safe.

kept

it

warm,

fed,

and

It

was she

mother was the

infant's

world was

Essentially the

its

mother.

niche, and for those baby apes that survived to breed, the boundaries of that

niche were

fairly constant.

Since 1969,

Bowlby 's concept of an Environment of Evolutionary Adapt-

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE

Fi^. 5.

1

The model mother Bowlby had

in

99

mind when he

envisioned humankind's Pleistocene Environment of

Evolutionary Adaptedness was a

San mother

in

woman

with her infant during the

first

two

has

!

Kung

to four years of (Alel

edness

like this

nearly continuous skin-to-skin contact life.

Konncr / Am hro- Photo)

been enormously valuable for

explaining infant attachment to a caretaker.

EEA had become

But by the 1990s, the

onymous with tocene.^ This

a

specific period, the

syn-

Pleis-

more narrowly circumscribed

million-and-a-half-year phase in our evolution \\

as

then used by evolutionary psychologists

to explain the totality of human nature, every-

human motivations to enhance inclusive fitness (which humans share with many other social creatures) to more recent and quite specific adaptations like language. Some evolutionary psychologists even claim that we can use contemporary human behaviors (such as our mate preferences) to thing from

reconstruct this ancestral Pleistocene environment.

but

it

ignores just

notice,

much

and

all

how much

human

Body and mind, As

is

an ambitious goal,

of what humans are, think about, care about,

feel predates the Pleistocene, as well as giving short shrift to

social

how

systems depend on local history.

Expanding the EEA cible.

It is

in

Both Directions

for better or worse,

we

passed through the Pleistocene cru-

frequently noted, our ancestors lived as hunters and gatherers for

99 percent of the time the genus Homo has been on Earth. This is why 1 rely so heavily in this book on evidence from parents who still lived as huntergatherers

when

they were

there are important respects ing.

Many

first

in

studied by anthropologists. Nevertheless,

which

a fixation

traits that affect infant survival

are far older than the Pleistocene, and

with the Pleistocene

is

limit-

and women's reproductive success

some

are

more

recent.

At present, no one knows which types of environment characterized the tiny population of ten

thousand or so anatomically modern humans that

LOOK TO THE ANIMALS Mother Nature allowed

to pass through the eye of the needle to migrate out

of Africa between 5^0,000 and 1^0,000 years ago. Most people assume they

were hunters of the African savannas. However, one might that these

were the survivors of some ecological perturbation of the time.

Perhaps they were coastal -dwellers depending more on

game, making

we

just as well guess

way along the

their

than big

shellfish

water's edge out of Africa. But the point

don't know.

The

twilight of the twentieth century brought with

anthropologists to chronicle the vanishing

life ways

Richard Lee, Mel Konner, Hillard Kaplan,

Kim

it

last-ditch efforts

people pursuing

Hill, Eric

Alden Smith, Kris-

concept

Given

—

how

variable

like the

human who

EEA.

subsistence styles and family compositions

even those of people

live as foragers

still

—we

should not be sur-

prised to learn that their social arrangements are very flexible, even

than those of other primates.

among

than can comfortably be accommodated

this ancient lifestyle

in a one-size-fits-all

by

of foragers. Fieldworkby

ten Hawkes, James O'Connell and others revealed greater variation

are

is,

And some nonhuman primates,

widespread "weedy" and very adaptable species

(like

more

so

especially other

savanna baboons or lan-

gur monkeys) are very variable indeed, living in multi-male groups one place, "harems" in another, aggressive in All primates are social.

can be said to share

is

But the only

one

locale, peaceful

the prolonged relationship between a

infant during the first years of

someplace

specific social relationship every

else.

group

mother and her

Even the duration (although not the

its life.

intensity) of this universal relationship fluctuates drastically, especially in

humans.

There

is

good reason

most arduous

to suppose that those foraging

habitats, such as the

old, he

would have been carried by

thousand miles. Under the conditions infants had to suckle frequently

few

in

just to

By the time

a

age, survival

depended on nursing well

its

mother was

his

a toddler

mother some four

which these nomadic foragers keep hydrated

as well as

would have been introduced by

Even though

solid foods

living in the

!Kung San of the Kalahari Desert, gave

birth only after very long, four- to five-year intervals.

was three years

mothers

six

lived,

nourished.

months of

into the fourth year. To such an infant,

cradle, protection, mobility, breakfast,

midmorning

juice,

lunch, and dinner.

The !Kung

extreme

are an

million years or so,

case. Still, there

is little

doubt that over the

last

infants have always striven to remain in continuous con-

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE tact

with their mothers for

at least

the

first

few years of

lOl

was the

hfe. This

may even in the Pleistocene. The human have been tough for a mother to do infant for four or five years more with her mother in continuous contact nearly represents a primate infant's favored scenario, the scenario most cominfant's first choice,

patible with

its

but Hving up to

from foraging peoples

Aka and

a

human

case, the

new

the Efe, as well as

to continuous one-on-one contact with the

were

in foraging

do. Ethnographic evidence

still

other primates, suggests that alloparents were

In the

not the only one

many mothers

use of them, as

and South America

like the

is

reasonably safe alloparental options

human mothers made

societies in Central Africa

of mothering

—

well-being. But this preferred scenario

mothers employed. Wherever available,

this "Pleistocene ideal"

evidence from

more important

alternatives

mother than Bowlby had

realized.

extended half-decade of physical closeness between

mother and her infant so typical of other apes

tells

us

more about

the harsh-

ness of local conditions and the mother's lack of safe alternatives than the "natural state" of all Pleistocene mothers.

As Emory University anthropolo-

gist and nutritionist Daniel Sellen joked recently, the only people in the

who nurse their babies

world

for five years are the

!Kung and

women

anthro-

pologists.

Rather than turning the assumptions about the

EEA

into boilerplate for a host of unverifiable

of

lifestyles

humans

in the

last

hundred

several

number of

possible

environments might be evolutionarily relevant, depending on which

trait is at

thousand years, behavioral ecologists recognize that

a

Invoking environments of evolutionary relevance

issue.

ment of accumulated

is

an acknowledg-

past effects, without necessarily specifying

when and

where. So

let's

be

clear:

humans today

are an

amalgam of past

on ancestors who were mammals, primates, and, most

who

lived as foragers in

a range of ecological and

selection pressures recently,

hominids

social settings.

Like

baboons, langurs, and other particularly adaptable primates, humans are

found

in a

habitats.

broad range of climates,

Humans

at different altitudes,

over a broad array of

readily adapt to different habitats as other "weedy" species

do; but being culture-bearing, technologically clever primates, they have

even more scope to change their environment to True, there are some things like all

members

we

suit their needs.

can be quite certain

of.

Human

mothers,

of the family Hominidae, lived in social communities. Off-

spring learned to recognize individuals likely to be kin by using cues provided

LOOK TO THE ANIMALS

I02

by their mother, particularly by her patterns of association. As they matured, youngsters learned to discriminate the smell and appearance of close kin and

of their mothers' close associates, and to behave

them.

women must

know

for

about these early social environments

example how long bonds between mates

is

certain.

(whose "in-laws," for example, they lived nearest

One on

one, there

dominate

that,

men's

his

mate,

is little

as is

doubt that

a

ability to control

where

all

women

women

up.

Who

else

sus-

women lived

almost always be able

simian primates. But beyond

group went and what

in their

they did would have varied a great deal, depending on

back the

cannot

one

to).

man would

true for virtually

We

lasted (though

pects that duration of marriages varied) or what kind of families

to

have lived

took unusually long to become independent. But beyond these points,

relatively little

in

toward

altruistically

and relied on other group members to help provision children

in families

who

more

Great Apes,

also certain that unlike other

It is

who

was there would depend on

else

was there to

local subsistence

patterns and history, for apart from a universal tendency for primate females to avoid mating with close kin,

women exhibit no clear and consistent predis-

positions either to leave or to remain near kin.

People

who

live

by foraging may move

daily,

or almost never. They live in

desolate terrain at population densities lower than one person per

25^0

square

kilometers, in groups that rarely meet and defend no territories, or in

densely occupied habitats with one person per square kilometer. Hunters can

among the made up by tubers,

contribute anywhere from 100 percent of daily calories (as

Eski-

mos) to 20 percent, with the remainder being

nuts,

seeds, and other foods gathered by

women. When people

rely

on

shellfish

or

hunt with nets, both sexes often participate. Large maternal contributions to subsistence would have meant that moth-

come and go, with important implications for whether females stayed among kin or left home at marriage, all critical, as we shall sec, for how much autonomy a woman retains over reproductive decisions, how free she is to choose when and with whom she will mate. Female ers had

more freedom

to

autonomy depends on the all

availability of

support from her kin. This

well-studied primates as well as most

more

likely to

move

at marriage.

more autonomy than when they among their mate's kin. retain

human

When

societies in

from

true for

which one sex

mothers remain among

travel far

is

is

kin, they

their natal place to live

E

N V

R

I

N M

C)

N T

F

O

S

K V

¥

O

L

U T

C)

I

N A R

R

Y

1

L F

!

VA N C E

I

O3

Long Before the Pleistocene

— human

Foragers, primates,

mammals

time, like the coils of

DNA that connect us, linking us to long-ago life-forms.

humans

Evolutionarilv, "Snips, snails,

are a

and puppy-dog

A

boys but for everybody.

Nature

is

pain of my

tails," isn't

thrifty

this

far off the

—

mark

why

not just for

recycler.

Mother

made

the same endorphins, the natural morphine that

children's births bearable, are also released in an

my body

form

too

from an old nursery rhyme,

matron and inveterate

the

earthworm when

immune system

that pro-

from bacteria makes use of the same kind of proteins

that per-

garden spade accidentally severs

tects

bag." A line

backward through

slow to discard leftovers. Conservative retention of useful mole-

cules explains

my

"mixed

legacies spiral

function in fruit Hies.

new problem. Mother

Nature's

it.

The

innate

Confronted with the necessity of solving first,

and typically only, recourse

is

a

to use

what she has on hand. Just for fun, imagine that

tocene.

What might

designed baby would

a

all

human

traits really

did evolve in the Pleis-

made-to-order Pleistocene baby be

fit

the

bill

for any

like?

mother who works nine

This ideally

to five, but he

human baby ever born. Adapted for twice-daily morning and night, this PPB ("Perfect Pleistocene Baby") would be

or she would resemble no feedings,

capable of digesting high-protein, high-fat milk, just like baby tree shrews and

other

mammal

infants

whose mothers

Mothers would produce

this rich fare

leave

their digging sticks (or briefcases), leaving

no one-on-one

attention.

hunting the day before nurserv

till

in nests for

hours on end.

behind babies that required almost

individuals had

gone out foraging or

a turn resting at

camp, protecting the

Whichever

would take

them

and then trot off every morning with

the foragers returned.

Because learning would be postponed, the Perfect Pleistocene Baby

would spend

its

day in a frozen or hypnotic

state,

curious about nothing,

emotionally uninvolved, conserving energy, never crying or calling attention to

itself,

and requiring

little in

the

way of monitoring.

In the evening,

the mother returned, she would take the baby to a defecation

tance from camp, so that settle

suite

down for a good

all

when

some

dis-

excretions could take place before returning to

feed and a restful night. With this carefully engineered

of adaptations, mothers could forage more

provender, breed

site

efficiently,

bring back

more

much faster.

Of course it never happened that way. And if it had, the end product would

LOOKTOTHEANIMALS

I04

not be human. As Bowlby realized, the reason foraging mothers never pro-

duced such accommodating youngsters already

is

that

committed to mothers who produce

and to babies Every

our species evolved as primates,

dilute low-fat, low-protein milk,

who suckle semicontinuously throughout the day and night.

living organism, every

organ of every organism, not to mention

sues and molecules, whether or not they are lated imprints of multiple past lives.

a

accumu-

Never permitted the luxury of

from scratch to produce the perfect workable solutions for

in use, bears the

still

tis-

starting

solution, natural selection recycles

"good -enough"

fit,

meaning simply: better than the

competition.

Consider melatonin, a hormone the body clocks. Melatonin has

become

among jet-setters, who

take

it

fashionably in pill

zone to convince their body that likely to

it

relies

known

upon

to regulate internal

form just before bedtime really

is

hormone"

as the "miracle

in a

new time

nighttime. Scientists are

dub melatonin the "Dracula hormone" because

its

more

production

is

stimulated by darkness and inhibited by bright light.

An

compound, melatonin

ancient, pre-Pleistocene

amphibians. In humans

it is

found

is

produced by the pineal gland,

once mistakenly assumed to be

a functionless vestige. Far

in the skin of

a pea-sized

organ

One

of the

from

it.

pineal gland's products, this venerable light-sensitive secretion plays a key still

(if

poorly understood) role in regulating body rhythms. Melatonin levels

rise at night

during the hours most primates sleep and

fall

during the day,

permitting a pregnant mother to chemically communicate information about

day length to her fetus.

We primates are, by and that

makes night

large, diurnal beings,

shifts particularly

adapted for daylight

(a fact

dangerous and subject to accidents).

Instead of bungling about in the dark, risking an encounter with predators like leopards,

safely

up

who

see better in

trees, high

on

cliffs, in

dim

light

than

we

do, primates spend nights

arboreal nests (like chimps), or swinging gen-

tly in a hammock by the fire. We do not just sleep, perchance to dream,

as to

but so

not to be eaten.

Ape bodies

take advantage of a mother's enforced respite to do their

endocrinological equivalent of paperwork. The frequency of an infant's night-

time suckling serves the mother's body

baby

is

as

an index of

consuming. Complex feedback loops then act

regulating

how

how much

like a

milk the

master control,

long the mother should delay before ovulating again and con-

ceiving her next baby (explained below, in chapter 8). Nighttime feedings

ENVIRONMENTS

OF

EVOLUTIONARY RELEVANCE

lO^

turn out to be the key ledger entry for a mother's reproductive budgeting. Surges in plasma prolactin levels produced in response to her baby's sucking are four to six times greater

(when melatonin

between the hours of midnight and four a.m.

levels are highest) than

when

a

mother nurses during day-

time. For this reason, three or four breast-feeds during the night areater impact

on delaying the next pregnancy than

The next time vou hear

a nursing;

six

may have

daytime feeds.

mother who unexpectedly

finds herself

pregnant grumble that breast-feeding did not suppress her ovulation, remind

her of her primate past and trees. In

all

the ancient evenings her ancestors spent

her eagerness to get a good night's

rest, she

up

in

probably overlooked the

importance of breast-feeding during the night. She forgot, or more probably never considered, that for seventy million years, till

dawn,

as

mothers dozed on and

off

whiled away those sunless hours by alternating between

infants

As they suckled, they triggered the release of ancient

right nipple

and

compounds

dating from amphibian,

left.

mammahan, and primate

past lives that

delay the next conception.

Every

detail of

our bodies has

its

history,

and many of them have conse-

quences. Accustomed to the beat of the mother's heart in utero, the infant prefers left nipple to right.

Not

surprisingly, today 83 percent of right-

handed women, and 78 percent of left-handed mothers, on the same sance is

side as their heart. Presumably, this explains

Madonnas

are depicted holding babies

on the

cradle their baby

still

why most Renaisand why one ear

left side,

better at recognizing music and the melodic aspects of language than the

other

ear.

From

fretting babies to

that unless

unplanned pregnancies, these examples suggest

acknowledged and understood, ancient

legacies can prove incon-

venient to our efforts to chart the future. But natural selection didn't stop

dead

in its tracks

think so.

when

the Pleistocene ended. We are kidding ourselves

A mother today, whether

in

New York, Tokyo,

or Dacca,

is

if

we

not just a

gatherer caught in a shopping mall without her digging stick.

We

and not so subtly different from our Pleistocene ancestors

ways that have

been transmitted genetically

as well as

in

are subtly

through multiple parental effects

between generations.

Evolution Since the Pleistocene There

is

a

widespread assumption that evolution only occurs very slowly,

over vast geological time spans. By and large this

is

true. But too

many

ex-

LOOK TO THE ANIMALS

Io6

ceptions to this rule have been documented, both in lab and

anyone to take for granted that the pace of evolution Genetically produced

life -history

changes in mother

fish

field, to

allow

necessarily slow.

is

can be documented

new environment, with mothers evolving to longer intervals when predation pressures are

after only forty generations in a

produce bigger babies

after

reduced.'^

Humans

much

are unusual in this respect. Cultures can change

bodies evolve. This puts humans in a special category, but outside the reach of evolutionary change.

tocene foragers and altered specimens.

We

it

faster than

does not place us

are at once relicts of Pleis-

Many people descend from

ancestors

lucky enough to have survived past epidemics of common post-Neolithic

dis-

eases like plague and cholera because they possessed versions of genes that

conferred some degree of protection against these diseases.'^

produce nearsightedness or diabetes. Whenever humans ing under novel conditions, there are

An example would be ongoing

new

Some

new environment

unlucky enough to have genes that interact with our

are to

find themselves liv-

opportunities for selection to act.

selection for heavier birth weights in babies

whose mothers have recently migrated

to higher elevations of the Himalayas

''^

of Kashmir.

For most of us alive today, the environments of our ancestors underwent massive changes in the recent past. Almost no one you

know

traces his or her

ancestry directly to hunters and gatherers. Rather, the vast majority of us are

descended from peasants. Many were born to mothers in cradles or

swaddled them, leaving babies with

porary caretaker while they engaged

These more recent legacies In

mammals,

in seasonal

a

who

kinswoman or other tem-

work, planting or harvesting.

also leave their traces.

natural selection will almost always have

on the vulnerable

life

kept their babies

its

greatest impact

phases: in utero, during infancy, and just post-weaning.

Assuming twenty-five years per generation, there have been about four hundred generations from the

start of the Neolithic* until

four hundred opportunities for natural selection to act. tial

of just

from

2

A

selective differen-

percent can boost a gene from rarity to near fixation (that

a genetic

frequency of

ten thousand years or

For purposes

now. This represents

of this

less.

less

than

2

percent to

Theoretically, changes

example, say ten thousand years ago.

more than 98 in

is,

percent) in

humankind's biological

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE and

social

environments since the Neolithic should be reflected

genome of modern humans, and many are.^° Not surprisingly, the best documented cases have and infant mortality

—

three areas

do with

to

1

in

07

the

disease, diet,

where the Neolithic would be expected to

expose humans to novel selection pressures. The end of the Pleistocene and

dawn of agriculture brought new

the

types and greater abundance of food, as

well as settled living, increased population, tion,

more sewage and water

and the compression of people into smaller

presented

many new

areas.

Crowded

pollu-

conditions

opportunities for water- and mosquito -borne diseases

Dense populations with open sewers allowed typhoid,

to infect people.

cholera, and other gastrointestinal diseases to spread quickly through a popuIrrigation ditches brought mosquito-transmitted diseases to drier

lation.

parts of the world

where such

been

infections had previously

rare. Respira-

tory diseases like tuberculosis spread from person to person in populations large

enough and crowded enough to supply the pathogens with host

after

mammals, such as jump across species

host. Several old diseases previously confined to other

bubonic plague and AIDS, found boundaries and infect

As

a

new

opportunities to

human hosts.

consequence of heavy selection pressure from these diseases, any

genetic trait that conferred resistance to

them was

selected for

—

even against

strong counterselective pressures. For example, 4 to ^ percent of people of

European descent have inherited will

be born with

(until

a single

from both parents. this lethal

copy of a gene that causes cystic

In these populations,

fibrosis

when

about one in 2,^00 babies

double dose and will develop the disease, which

medical treatments became available) killed by age two.

Normally such

human

lethal

genes would have long since been selected out of the

population. Yet cystic fibrosis has been around for at least ^0,000

years, and, according to microbiologist Gerald Pier at

School, there

is

a reason. In

people against typhoid

its

single

form, the cystic

fever, just as in the

cell

gene, which protects

both

mother and

its

father, the

Harvard Medical

fibrosis

gene protects

better-known case of the

possessor against malaria.

When

sickle-

inherited

from

bearer suffers from sickle -cell anemia.

Rapid selection could also be going on currently with respect to AIDS.

There are areas

in Africa

today where as

many

as 2^

have a reduced chance of becoming pregnant.^' There survival chances of their offspring. Such babies are

percent of

women

childbearing age are HIV-positive. Such HIV-positive

is

women

of

are thought to

also a decline in the

exposed to maternally

LOOK TO THE ANIMALS

Io8

transmitted infection either from mother's blood during birth or from

mother's milk afterward. Even

orphaned

at a

young

if

babies escape infection, they are likely to be

human immunodeficiency

are resistant to the

some African women

age. Yet there are already hints that

virus (HIV) that causes

AIDS.

We would expect any genetic resistance to be disproportionately represented among

the survivors. As selection works against those

mothers and

will favor the AIDS-resistant

offspring.

who

are infected,

it

^^

A surprising amount of epidemiological history can be read into the genes human populations. Genes

of surviving

foods people were adapted to All

tell

us something about what

Consider the genes for lactose tolerance.

baby mammals are born with the digestive equipment to synthesize

enzyme

the

eat.

can also

lactase. This

enzyme enables them

tose, the carbohydrates in milk. ability to digest

to break

Among many humans

would be completely

not herd animals. Individuals

around the world the

who

typically included

powdered milk, got such

of sub-Saharan Africa in the

made people

1

is

a

is

who do to drink

why Western

bad name

aid,

in large areas

pow-

970s. Instead of helping, the donated milk

sick.

Today, the main explanation for exists

enzyme

lack the appropriate

being

all,

useless to adult foragers,

unprocessed milk may suffer from gas or diarrhea. This

der

digest lac-

milk sugars does not persist into adulthood. After

able to digest milk

which

down and

that since the

why

so

much

diversity in milk tolerance

end of the Pleistocene, some human populations began

herding cows and consuming dairy products; others did not. In another

example of rapid evolution,

promote

just in the last ten

thousand years, the genes that

lactase synthesis past infancy spread in populations

fed long past weaning, and were lost

where

it

where milk was

was not. Fewer than

2

percent

of adults in a population with a horticultural history, such as the Bantu of Central Africa, test positive for lactose digestion, and no !Kung do. By contrast,

90 to 100 percent of Tutsi populations

descended from milk-dependent milk sugars throughout their

Some

legacies

pastoralists

in

Rwanda and

—

the

Congo

—

retain the capacity to digest

lives.

from our hominid past may be adaptive

in

new

our

crowded, high-speed, high-tech, twenty-four-hour-a-day environments. are, indeed, highly adaptable creatures

acquire traits,

new

tastes,

who

and learn new tasks

such as our lust for

impossible to get too

fats

much

all

—

and sweets

adjust quickly to

especially

(left

when

new

Wc

habitats,

young. Yet other

over from a time

when

of either), can be extremely maladaptive

it

was

when

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE they lead to obesity and clogged arteries.

work and

lifestyle

modern workplaces. Mothers

physical separation required by

to go off to

leave their infants behind. Babies find

Balancing Motherhood and Work are not new. For most of human

Working mothers

find

it

work with motherhood

ciency by toting babies everywhere (the

mothers, though, lives.

The

is

so.

lives

with

has always lost effi-

way baboons and !Kung mothers do)

or else located an alloparent to take on the task.

ductive

stressful

existence, and for millions

Mothers either sustained energetic costs and

entailed tradeoffs.

the

is

even more

it

of years before that, primate mothers have combined productive reproduction. This combination of

09

For mothers and infants, the

between ancient predispositions and modern

biggest clash

1

What

is

new

for

modern

the compartmentalization of their productive and repro-

where women

factories, laboratories,

and

offices

go to "forage" are even

less

compatible with childcare than

industrial societies

jaguar-infested forests and distant groves of

mongongo

in post-

nuts reached by

trekking across desert.

The economic

reality of

most people's

—

lives

today

is

that families require

more than one wage-earner or forager. Single parents are especially hardmake ends meet. Only brief periods of prosperity or isolated blips of elite privilege have made this untrue for some people during a few periods

pressed to

in

human

existence.

for example,

meant

An

expansion of the U.S. economy after World

many married women could

that

with their babies. But no more. Most mothers, even

if

War II, home

afford to stay

they want to, do not

home to care for their babies. modern rub. During the Pleistocene, women could

have the option of staying

And

that's the

their babies as they foraged or gathered firewood. Dual-career strive

carry

mothers

still

to balance their subsistence needs against the time, energy, and

resources needed to rear their children. But the physical

(if

not always the

made is consome respects,

emotional) environment in which these compromises must be siderably different

omnipresent

from the workplace of our ancestors.

conflicts create

because the incentives to

measured their

in

quences.

them

terms of the personal

mothers

change are

fix

—

In

even more tension today than strike toll

mothers

—

as optional.

insecurities

among

in the past,

Outcomes

are

infants, stress in

rather than increased mortality. Simply put, the pressures to

less intense

when

children can (literally) live with the conse-

LOOK TO THE ANIMALS If infants feel

stressed by the separation, so

do millions of working moth-

At the same time, the evolutionarily novel modern workaday world

ers.

opened the door motivation

—

for

untrammeled expression of another ancient female what one might

striving for status, or, in the case of a forager,

think of as "local clout."

Maternity and Ambition It

is

widely assumed that competitiveness, status-striving, and ambition,

qualities that are essential for success in

with being a "good mother,"

"There

is

who

no getting around the

Motherhood and ambition Shari Thurer, a

are

is

demanding

careers, are incompatible

expected to be ambition

fact that

selfless is

and nurturing.

not a maternal

trait.

largely seen as opposing forces," states

still

prominent contemporary psychologist. Sociologists can doc-

ument at length the "cultural contradictions" produced by women combining motherhood with jobs in the American workplace. ^^ Under conditions of the modern world, and if we assume the old definition of mothering as an innately charitable and selfless pursuit, the point

well taken. But as different

I

described in chapter

2

,

mothering

in the natural

world

is is

from the Victorian image of mothers. Mothers' work has not always

been so compartmentalized from child-rearing

as

it is

today, nor her status so

separate from the prospects that a mother's offspring

would survive and

prosper.

Modern women may

think of status as the icing on their economic cake.

But once the significance of social rank as a

is

understood for such

mother keeping another female from eating her baby

vital

functions

(as in the case

of

chimps), or for keeping another female from monopolizing resources needed

by her

own

offspring (as in the case of other cooperatively breeding

mals), the struggle for status seems a

frill.

more

mam-

nearly a foothold on posterity than

"Ambition" was an integral part of producing offspring

who

survived

and prospered. Establishing an advantageous niche for herself

was how

Flo, the

chim-

panzee female that Jane Goodall studied for so many years, stayed fed, guaranteed access to food for her offspring, and kept them safe from interference

by other mothers. Eventually Flo's high status made ter

Fifi

breed

to be

—

sive data

among

the few females

in Fifi's case, inheriting

it

possible for her daugh-

who would remain

in

her natal place to

her mother's territory. Even more impres-

documenting the connection between female

status

and

all

sorts of

ENVIRONMKNTS OF EVOLUTIONARY RELEVANCE

— —

reproductive parameters sex ratios of offspring

monkeys

age of menarche, infant-survival rates, and even

have been compiled for Old World cercopithecine

macaques and baboons. These data strongly suggest

like

III

alized striving for local clout

that gener-

was genetically programmed into the psyches of

when

female primates during a distant past

status

and motherhood were

convergent/^

totally

human primates

Evidence for

is

less clear, in part

because husbands

fig-

ure so prominently in the social status of most mothers. Yet both fiction

and ethnography provide multiple examples. For example, Nisa, the IKung

woman,

what happened when her

tells

second wife.

first

husband, Tashay, brought

home

a

chased her away and she went back to her parents," Nisa says

"1

own mother had done the same thing a generation before. The of this new wife would have competed with Nisa's for food provided

simply. Nisa's

children

by her husband and other community members. Nisa acted so

maintain

as to

her status as her husband's only, primary wife. Her actions were in keeping

with being

a

"good mother." Such

women do not compete men (for example,

utation in the spheres that matter to

great hunter or warrior) they ;

compete

for status

being

and rep-

known

in the spheres that actually

as a

matter to

mothers." Occasionally,

we

can detect bizarre manifestations of these old connec-

tions, as in the case of the Texas

mother who hired

mother of her daughter's cheerleading ally.

rival in

a

hit-man to murder the

order to derail her emotion-

But for the most part, status-striving by mothers seeking to enhance

the prospects of their children

is

more

subtle.

Think of the womanly

rivalries

chronicled for early-nineteenth-century England by Jane Austen, or by Edith

Wharton

for the early -twentieth- century tribal life of

subtle, private,

tions close ranks so as to

(which

in that

"Old

New York."

and scarcely perceptible ways, both mothers and their

In

rela-

promote and protect the marriage opportunities

world meant access to resources) of young kinswomen, while

locking out other young

women. We tend

trolling," "pushy," "interfering"

ancestry of such traits

is

tionary relevance, these

—and

I

to think of these mothers as "con-

don't disagree

worth considering.

women would

In their

—

but the venerable

environments of evolu-

have been behaving like successful

mothers. Far from "opposing forces," maternity and ambition are inseparably linked.

The circumstances of modern

nection. This

is

life

tend, however, to obscure the con-

because jobs, status, and resource defense occur in separate

LOOK TO THE ANIMALS

112

domains from

child-rearing.

At the same time, civihzed mores and laws mean

mothers do not have to

that

and keep their offspring ing this

book worry

safe

far less

rely

on intimidation to drive

from competing

about famine,

interests.

and

tigers,

mothers

off rival

Most mothers read-

infanticidal conspecifics

than they worry over job promotions, health benefits, and finding adequate daycare.

For the most part, mothers striving for status in the modern workplace do so outside the

home. Often working mothers

interests for long hours, far

help their baby cope with nity and ambition, but

from home,

life.

The

in

conflict,

if

ways

just as likely to

however,

is

modern world,

women who

as to

woman's

a

^^

(whether socioeconomic or professional)

status

anything, infersely correlated with reproductive success. This

true for

harm

not between mater-

between the needs of infants and the way

ambition plays out in modern workplaces. In the

are driven to pursue status

earn their status.

Not long

is

is,

especially

ago, sociobiologist Susan

Essock-Vitale looked at the reproductive success of people listed on Forbes Magazine's annual listing of the four hundred wealthiest Americans. Those

women who

had inherited wealth had

than successful businesswomen

own

efforts. This

many women

We

should not

at the

and research

as lawyers, doctors,

what we

are,

The answer

how is

can

But

this

acquired their wealth through their

as a surprise.

if

scientists, careers

no safeguards

to rearing a family.

with demands

as insa-

be?

where there was no

celibate, there

was no

and maternal reproductive success could be

status

When given the opportunity,

our evolutionary heritage has any relevance

simple. In worlds

where no female was ever

built in

children on average

grueling hours that working mothers put into jobs

tiable as those of children.

to

who had

come

more

upward mobility over time devoted

value

need only look

significantly

to ambition run awry, as

birth control, and

possibility that female

other than correlated. it

rank

Nature

were, to energies diverted to

ends that were not linked to the production, survival, and prosperity of

offspring. will there

Now that status and the survival of offspring have been decoupled, be selection against

to achieve? Probably,

if

women who

are especially inclined or driven

our species survives long enough, and

if

circum-

stances in the workplace don't change.

Torn between two ancient, pressing, and now incompatible urges,

women

are forced to

make new

infant needs

and maternal ambition requires considerable ingenuity,

tradeoffs. Forging workable compromises between self-

— ENVIRONMENTS OF EVOLUTIONARY RELEVANCE understanding;, and tive

and demanding

most

common

sense. This

especially true in highly competi-

is

Science provides the case studies with which

fields.

II3

I

am

familiar.

Novel Compromises In

1

976, the year after

I

completed

my

Ph.D., an article appeared titled "The

high price of success in science," written by a young molecular biologist,

Nancy Hopkins, who would go on that

it

was not possible

demanding,

to

become

a leader in

her

She argued

field.

woman in such a competitive profession minimum of seventy hours a week in the lab

for a

—

in her case, a

to

"be a successful wife and mother as well as a successful scientist."

Her words

were sobering and, looking back on

called "the

bionic kins

woman

hard

wrote that

sell

that era of

what Hopkins

of the '70s," unusually honest. About the time Hop-

article, there

were ten tenured

women professors

at

Harvard

Medical School; nine of the ten had no children.

women who managed

Yet there were

None

with motherhood.

I

know took

to successfully

ordinary routes.

combine science

Mary Jane West-

Eberhard, for example, whose ideas about the role of development in evoludiscussed in chapter

tionary processes

I

biologists for the

way

lives. "It's

what we

promises

field

syncratic

life."

all

managed

she

do," she told

to

me

3

,

is

"We

live in

each construct our

own idio-

opted to forgo a conventional

major university to take

allowed the Eberhards to

field

combine her family and professional

In West-Eberhard's case, she at a

among women

once, apropos of the extra-tough com-

biology requires of mothers.

teaching position

legendary

a research job.

The

position

Central America, where they could afford

housekeeping help, and, more importantly, where they could do research while keeping an eye on their three children

—

literally,

since the wasps they

studied were on the roof of their house.

My own compromises took me in the opposite direction. tramping around forested research on

human

hillsides,

I

switched from

following monkeys in India, to doing

parents in archives in the United States, where

part-time daycare, and along with ing opportunities to

work

eventually the Internet, to

less

my husband

took

full

I

used

advantage of emerg-

than full-time and to use fax machines, and

work

at

home.

When my

third child

was born,

I

hired a generous-hearted allomother on a very long-term basis. She lives

with us

still,

though

my

youngest child

is

pursues a part-time profession of her own.

twelve, and the allomother

now

LOOK TO THE ANIMALS

114

Pretty obviously, not one of us was living the same

Yet

we were

way

as

we

required to resolve similar dilemmas, and so

solutions for doing so

—

a

theme

throughout

that recurs

our ancestors.

new

forged

book.

this

Why the Past Matters Many

of us

at different stages

of our

lives desperately desire a child.

Others,

out of commitment to career or for other reasons, are determined to have none.

Many women

their

mind.

are certain they will never

want

who

others have babies by accident. Those

Still

and then change

a child,

consciously

decide are often making pragmatic decisions with a watchful eye on the effects

upon

family.

Few people

their career, existing children, or the overall well-being of their

give

much thought to the

evolutionary origins of the

emo-

am

con-

tions that inform such conscious or unconscious "decisions." But

vinced

we

are

more

Whether we

tightly linked to

think about

it

I

our past than most people imagine.

or act "on impulse," each of us constantly

makes myriad small decisions on

a daily basis that in ancestral

would have been correlated with reproductive

success. Like

it

environments or not, each of

us lives with the emotional legacy and decision-making equipment of mothers w^ho acted so as to ensure that at least one offspring survived to reproduce.

Prudent allocation of reproductive effort and the construction of an advantageous

social niche in

which her offspring could survive and prosper were

linked to ultimate reproductive success.

Women far

a

—and men—

environments and the

today have an unprecedented range of choices. So

few children, be confident that they

women

menopause limits are

postindustrial

in

later than

still

fixed.

was true

will survive,

more or

one. Yet certain constraints are

although

make

availability of birth control

for

possible to have

and invest heavily in each

immutable. For example,

live

longer and experience

most of our foraging ancestors, the outer

Few women conceive

until forty to bear her first child

less

societies

it

is

past

fifty.

Any woman who

waits

taking a chance that she will never con-

ceive one.

we are primates, adoption and the rearing of genetically unrecome easily. Unlike herd-dwelling ungulates, we do not have a critical period minutes after birth when a mother must imprint on her baby's smell and bond with it then or never. If we were sheep, wc would not have to Because

lated babies

worry about babies getting mixed up, switched

at birth in

maternity wards.

F.

Fig. g.2

N V

I

R

{)

N M

F

N T

S

F

()

Mary Jane West- Ebcrhard

is

F

V O L

legendary

LI

T

I

()

N A R

among women

R

Y

F L F

V A N C F 11^

biologists for the practicality of

her research choices. Here, she has climbed a ladder to study a colony of rare Metapolyhia wasps

on the roof of her house. While enclosed patio below, as

if,

.she

she said,

worked, she had a "I

full

view of her children playing

was god [watching over

a]

true deus ex machina, she would from time to time intervene, calling bling sibs. As her children fledged and

went

down

to

reprimand squab-

to college, West-Eberhard increasingly combined

doing research with work on the National Academy of Science's Committee on finding there an even wider scope in

which to express what George

component" to men's and women's nature.

in the

large tropical playpen." Like a

Eliot

(Courtesy of Mary JaneWest-Eberhard)

Human

Rights,

termed the "maternal

LOOK TO THE ANIMALS

Il6

But

we

are primates, and primate females in the right frame of

mind

find

all

babies fascinating and attractive. For such females, the most important ingre-

dient for eliciting love

is

not the molecules producing a particular scent, or

genetic relatedness, but physical proximity over time. Whether a

new mother

be willing and able to keep her baby close long enough for

this old pri-

will

mate magic to work depends on her psychological cal

and

well as her physi-

state, as

social circumstances.

Human mothers learn to recognize their own babies in the days right after and gradually

birth,

Since babies return the favor, the baby's

"fall in love."

attachment to the mother further reinforces her commitment. This

when

more or developmental needs of infants. The same

forty- to fifty-year lifespan of a standard-issue ape ovary less

why

is

babies are adopted, the younger the better. But just as surely as the

immutable, fixed also are the

is

fixed and

processes by which babies attach to and learn to love their caretakers impose a

tremendous cost when such attachments never form, or when sequential

attachments are ruptured. Below a certain level of nurturing, the develop-

mental outcome

is

disastrous. If a

growing up among committed

baby does not perceive that he or she

kin,

quate for development within normal limits

who

an adult

By

itself,

realizes his or her full

baby, while a

This

is

may not be enough

human potential

giving birth does not guarantee that a

baby she bears.

what

A woman

to

produce

of empathy for others.

mother

will care for every

predisposed to be a mother can learn to love any

mother not so disposed does not even learn it

is

even a measure of care considered ade-

own.

to love her

means to live with the emotional legacy of a

human who

evolved in a hominid context where mothers relied on assistance from others to help rear offspring.

We

are a clever and highly innovative species, but not infinitely so.

past matters, not just

mean we have no

on the

physical, but

conscious choice over

People exercise free will

all

the time

—

on an emotional

how we

front.

lead our lives?

Our

Does

Not

this

at all.

but only in those areas where Mother

A woman can choose which baby she will adopt, Nature cut them some but falling in love with that child will not be automatic. Nor can a woman just slack.

will herself to love a child, or

This

is

one reason why

respond to

a certain

number

adopted end up being returned

few adoptive parents wish to

—

legal prescriptions that she

of children placed

a painful

discuss. This

outcome

book

will

for

make

in foster all

do

concerned

clear

so.

homes or that

why efforts to

ENVIRONMENTS OF EVOLUTIONARY RELEVANCE legislate a

mother's love

badly.

—by

telling a

must carry

for example, that she

term

—

are so often destined to end

'°

Many

biological constraints

—

especially those having to

and with increasing or decreasing innovations. Today,

we have more

But such options only crop up

new

mother with an unwanted pregnancy,

to

it

II7

technologies. Yet these

them new

fertility

—

options than

disease,

humans have ever had

in the interstices

new

do with

have been removed by medical

we

before.

carved for ourselves with

technologies, as often as not, bring with

constraints. Consider just one.

It

takes longer, and requires

more

investment from parents than ever before, for children to acquire the educa-

need to negotiate

tion they

Such costs

some

in

effectively in an increasingly

complex world.

turn alter emotional equations in the lives of parents, rendering

less willing to

have children.

By placing human mothers and lutionary framework,

I

offer a

infants in a

new

slant

broader comparative and evo-

on what babies need from

mothers, what mothers need from others in order to provide why. Explanations

do

more

from

infant care

little

affordable daycare. But

to solve such practical problems as

fathers I

and alloparents.

at least

history

make such

—

care a priority.

be the

first

offer

how

no plan

to enlist

for safe and

why it would be worth any community's Knowing more about

both deep and more recent

infant needs has to

I

and explain

provide rough outlines for what adequate

allomaternal care has to include, and

while to

it,

their

—

the processes and

that underlie maternal

step in meeting them.

emotions and

j

PART TWO

Mothers and Allomothers Literature

is

mostlj about having sex

and not much about having Lije

is

the other

— David

children.

way around.

Lodge,

1

96

-4 '?'"^^BK^

*^^'

k

Priming an alloparent (Courtesy

oj Geert Van Jen Broeck)

m

—

The Milky Way Our deeds determine

us,

as

much

— George

as we determine our deeds.

Eliot,

1

859

When this question is posed, it's a safe bet that the underISlying agenda has to do with what women should be doing. Should they be home caring for their children or off pursuing other interests? A comparsex destiny?"

ative

look

at

other creatures that (like humans) breed cooperatively and share

responsibilities for rearing

per se

is

not the

young with other group members

issue. Lactation

reveals that sex

is.

Caretakers of both sexes, wet-nurses, even "daycare"

—none

of these are

uniquely human, nor particularly new. They are standard features of cooperatively breeding species. As itely

we

saw, cooperative breeding

is

many

exquis-

well developed in insects such as honeybees and wasps. Shared provi-

sioning

is

also

common among birds

dunnocks, and scrub

among mammals

jays.

generally,

such as acorn woodpeckers, bee-eaters,

Although cooperative breeding it is

is

uncommon

richly developed in species such as wolves,

wild dogs, dwarf mongooses, elephants, tamarins, marmosets, and humans. In all these animals, individuals other than the

mother ("allomothers") help

her provision or otherwise care for her young. Typically, allomothers will include the mother's mate (often but not necessarily the genetic progenitor). Individuals other than either parent ("alloparents") also help. These helpers

are

most often recruited from kin who

selves, or

are not yet ready to reproduce

from subordinates who do not currently

better options. In the

human

case, the

older, post-reproductive relatives

Among mammals,

who

—

or

them-

may never have

most important alloparents are often have already reproduced.

the trend toward having young

long-term care began modestly enough.

It

who

require costly

probably began with an egg- laying

brooding reptile that started to secrete something milklike. Such egg-layers graduallv developed glands especially equipped for milk production. Only

among mammals did one sex come to specialize in manufacturing custommade baby formula, to provide something critical for infant survival that

I

21

MOTHERS AND ALLOMOTHERS

122

6

Fig.

.

1

Female sea horse depositing her eggs

in the male's

pouch, "impregnating" him.

(Drawing bj Dafila Scott)

the other sex could not. This pecuharity has

had many ramifications, especially

became dependent primate

as

infants

for longer periods in the

line.

The ante was upped

substantially

mate mothers, instead of bearing

when

pri-

began

litters,

focusing care on one baby at a time. These singletons were born mature enough to cling to

be carried by her right

their mother's fur, to

from birth and for months or not this intimate and prolonged association

not the

issue. Lactation

is

thereafter.

Whether

the mother's destiny, sex

is

is.

What Is Lactation About? Other forms of caretaking

— Why—

babies

—

fathers brooding eggs, bringing food, protecting

Even gestation

are not nearly so sex-specific.

is

a function that in

rare cases (for example, the sea horse) a male takes on. But not lactation.

with the sole exception of one rare

to be exclusively female?

At sallies

first

glance, a

sea horse might

injects her eggs

free, propels herself off to feed

ballooning brood chamber of the as

i

lactation appear

seem

to have a sweet deal. She

into his belly

pouch, and then, care-

and make more eggs. Meanwhile, back

male's pouch, the sea-mare's last batch

many

—does

How did these curious secretions get started?

mother

up to her mate,

fruit bat

,^oo fully formed but

now

still

is

fertilized, toted,

and kept

at

the

safe in the

extremely pregnant male. At birth, as

minuscule and defenseless sea-foals are

sprayed out into the open ocean. The sea around them teems with predators

and competitors, many bigger than they immediately after birth, almost Viviparity

means keeping

the parent's body till

till

hatching. But by

all

Forced to fend for themselves

starve.

infants safe inside

they can be born itself,

are.

alive, as

some

sealed

chamber within

opposed to protected

viviparity offers tiny,

still

in

an egg

helpless creatures only

THE MILKY WAY

m

i

Fig. 6.2

Parental care

rare in reptiles. But there are exceptions, such as maternal protection of

is

young by mother crocodiles, or the reconstructed behavior of tionately

named

Maiasaura, "the

good mother

reptile."

Her

eggs which hatched so early and so helpless that family

them

.

this

duck-billed dinosaur affec-

nest contained ten to twenty altricial

members were

required to provision

(Drawing by Marianne Collins; reproduced with permissionfrom Random House, London)

the slimmest toehold

on

posterity.

grow bigger before venturing The parent well,

^-m^

.'..^

'??>

«-t>

123

is

so

Why

not linger in the

encumbered becomes

less able to

growth

in

if

it

beat avail-

warm-blooded babies while

allowing a foraging mother to safely stash immatures

burrow than

longer, and

less efficient at foraging, eats less

evade predators. Lactation evolved because

able alternatives for fueling rapid

safer in a nest or

womb

into the world?

who

will

be somewhat

they must fend for themselves.

Merits of Lactation The currently favored hypothesis

for

why dinosaurs disappeared is that global among immatures. Mammals pur-

climate fluctuations led to mass starvation

suing "the milky way" had an obvious advantage. Maternal provisioning

through lactation spares immatures the hazards of foraging and competing with more mature animals to stay fed. Being able to rely on the maternal larder long after birth buffers immatures from local scarcity. Remaining with a lactating

and viable environment for immatures

who would

mother provides

a stable

otherwise be unable to

survive severe climate fluctuations. As the dinosaurs died out, lactators into their

own.

came

MOTHERS AND ALLOMOTHERS

124

Mammalian mothers were der

—

shellfish, grass, insects,

alchemists, able to transform available fod-

other

mammals, even

toxic plants

logical white gold: a blend of highly digestible nutrients fuels

and protects immatures during the hazardous days

mother

into bio-

A

just after birth.

stockpiles energy, protein, and minerals as fat deposits

and doles out these repackaged nutrients on

—

and antibiotics that

on her body

mutually beneficial, often quite

a

flexible, schedule.

Like the young of a cold-blooded reptile, the young of a mother bear enter the world just a fraction of their mother's bulk. But thereafter baby reptile

and baby

mammal grow differently. Take the American black bear. During the

abundance of summer, the mother mates. Copulating induces her to ovulate, but the fertilized ova do not immediately implant. They enter a state of sus-

pended development. As winter approaches, the mother grows drowsy and retreats to her cave to save

body

continuing her pregnancy

is

the bear has

managed

fuel

by hibernating for the winter. Even then,

not automatic.

up enough

fat

to sustain lactation, the fer-

tilized eggs (or blastocysts) implant, gestation

and birth ensue, and the

If

mother

to store

sleepily suckles her babies

till

spring.

Not enough

fat,

and the

earliest

abortion nature offers takes place: implantation never occurs. The next conception If

is

postponed pending improvement

there

is

enough

fat

on board to

in the

mother's circumstances.

sustain lactation, implantation proceeds

and the mother gives birth to two to four cubs. After birth, cubs have months to

grow before

their

mother brings them out

before they must forage on their own. sionally

abandons

interval

between

ment of which

it

is

one

is

open, and years more

born, the mother occa-

rather than allow a singleton to monopolize such a long

births.

she

If just

in the

That way she gives birth sooner to the

full

comple-

capable.

By the time the three-year-old bears launch out on

their

own, they are

respectably burly versions of their mother, able to eat what she eats and at least to threaten

whomever

she scares

off.

By

contrast, at independence, their

reptile counterparts are but twinkles in the eyes of competitors

and preda-

tors alike.

Even without such gimmicks ible lactation schedules

as hibernation

permit mammals that originated

adapt to freezing climes. Macaques the

summer

or delayed implantation, flexin the tropics to

in northern Japan give birth and spend

feeding and suckhng their

new

babies.

young are weaned. Both mother and weanling forage

As

fall

approaches, the

furiously to lay

down

fat

THE MILKY WAY

6.3 Fat

Fig. it is

may or may not be

a feminist issue, but

definitely a reproductive one.

Human

tions have long celebrated links fertility as in this

lU

imagina-

between

fat

and

25,000-year-old statue called the

"Grimaldi venus." (©

Photo

RMN—J. G. Berizzi, Musees Jes

Antiquites Nationales, St.-Germain-en-Laye)

By midwinter,

Stores before winter.

other fare

is

all

buried under a blanket of

snow, and the monkeys must subsist on tree bark far too formidable for

immature

teeth to gnaw. At this nadir in food avail-

months

ability,

young were

after their

weaned, mothers miraculously

first

sume

re-

lactation.^

Storing Fat It is

advantageous for mother

on layaway, Fat

is

to be

mammals

drawn upon

stored out of the

way

later as

to be able to stockpile fat in advance,

needed.

in tails, buttocks,

mobility will not be impeded. Deposition trol,

and often

—

as in the case

is

Still,

or

timing remains crucial.

humps on

under

the body,

where

tight physiological con-

of the Japanese macaques

—postponed

as

long

as possible.

Consider our to secrete a

own species. With sufficient fat on board, some

hormone

called leptin,

becomes

fertile.

By then she

which triggers endocrinological

Some time

mations leading to menarche.

fat cells start

after that, a

will have laid

down

transfor-

young woman

actually

sufficient fat to help carry

her through pregnancy and lactation, what some anthropologists term "reproductive

A woman's

fat."

reproductive

fat is

concentrated in the but-

tocks and upper thighs, or around the abdomen. Inadvertently,

women

relive these

estrogen

No and

—

golden years of

a reproductive

comparable

little girls

fat

hormone

fat

—

deposition

after

when

menopause.

deposition occurs in men. Prior" to puberty,

have equivalent layers of

however, the proportion of

fat

preparation for reproduction.

on

fat.

a girl's

modern

they take synthetic

In the

two years

after

little

boys

menarche,

body increases by 214 percent,

Recognizing

this,

many

cent girls special foods and lessen their workloads. In

in

societies give pubes-

many

areas of village

MOTHERS AND ALLOMOTHERS

126

6.4 Steatopygia, or extreme accumulation of

Fig. fat

on the buttocks, probably evolved

tion to unpredictable food resources.

as an adapta-

A woman

needs approximately 74,000 calories beyond maintenance costs to sustain pregnancy, and thereafter

on the order of 600—700 lactation.

Pregnant

calories a day to sustain

women may

respond to

also

recurring seasons of scarcity by reducing activity levels or

lowering their basal metabolic rate, reduc-

ing the total

pregnancy

number of calories needed

—though

at

an

unknown

to sustain

cost in terms

of infant mortahty or to themselves in terms of

"maternal depletion"

as critical

calcium are used up.

(From Schultze 1928)

India, for

bodily reserves like

example, boys may be generally

preferred and better fed, but

when

begin

are

menstruate,

to

they

girls

given

sweets and other special treats, like eggs.

A cottage industry has grown up busily generating hypotheses to explain the special

buildup of fatty tissue around an ado-

lescent

range from the idea that breasts, nient place to store lescents

like

girl's

mammary

glands.

buttocks or a camel's hump, are a conve-

to the proposal that large breasts helped

fat,

These

compete with other females

for a

hominid ado-

good husband by advertising

(either "deceptively" or "honestly") that she has stockpiled sufficient fat to sustain lactation. Unless the

breasts (as

is

mother

opposed to generalized body

fat)

more milk. What is unusual about womanly development begins is

is

starving, however, fat stored in the

not normally metabolized to make milk, nor are large breasts per se

at

correlated with being able to produce

breasts

is

how

early they appear. Breast

puberty, even before menarche, years before a

woman

capable of conceiving or needs breasts to suckle babies. Other primates

have prominent breasts, but this tissue builds up only prior to and during tation. After

lac-

weaning, monkey mothers revert to the flat-chested, button-

nippled look of females

who

have never had a baby.

— THEMILKYWAY

\

The disconnect between permanently enlarged

some just

Ij

breasts and lactation leads

biologists to speculate that breasts evolved as advertisements, but not

of their nutritional stores. Symmetrical spheres of fatty tissue might

show

off a

woman's phenotypic

quality,

demonstrating

been to disease and the various other developmental

how

resistant she has

insults life dishes

out/

The primary function of breasts, however, remains milk production.

Lactation and Lifestyles Mother's milk surprising

—how

lean or

amount about

fat it is,

lifestyle.

how

long lactation

Among

small

lasts

—

can reveal a

mammals, such

tree

as

shrews or hares, high metaboHc rates mean mothers must constantly forage to support themselves and their litters.

hours or days

at a stretch.

Mothers are away from

Only unusually

rich, high-fat

their nests

milk tides the infants

over these long absences. By comparison, infants born to early hominids

whose mothers carried them Hence,

nipples.

like all

—were

in constant access to their

moderate amounts of protein and

fat

composed of 88 percent water and,

like

and high

adapted to the needs of an infant

cially

mother's

primates, they could survive on dilute milk with levels of sugars. This milk,

cow's milk,

who

will

3

to

4 percent

fat, is

be able to nurse for

a

spe-

few

minutes several times an hour and go on nursing for many months. Lactation

is

a

perpetual buyer's market, in the sense that intensity of suck-

ling adjusts supply to

mals the

seller

demand from

the consumer, except that in

(meaning the mother) determines the

size

of the consumer to

begin with. Mothers in good condition produce larger infants

more milk sooner litter

It is

if

sooner.

she

is

Depending on her own condition,

finding the

burden too much to

a

some mam-

who

require

mother may wean

bear, or later,

if

she has a small

or they are growing slowly.

easy for

there

is

humans

to

fall

into the anthropocentric trap of assuming that

something inherently superior about placental mammals

like

our-

who gestate embryos till they become babies. In fact, whether or not our own slower, more deliberate mode of reproduction is actually superior selves

depends on the environment.

mammals who breed

In

terms of the art of iteroparity

sequentially in totally unpredictable,

ments, none surpasses

that of marsupials. Marsupial

as practiced

by

extreme environ-

mammals

give birth

MOTHERS AND ALLOMOTHERS

128

6.^

Fig.

Mammary

tissue builds

up during pregnancy.

enlarged breasts are invariably a sign that a female

develop prominent breasts prior to

after short pregnancies to

that develop outside the

first birth,

is

In other apes, like this gorilla mother,

lactating.

Only among humjins do

during adolescence.

immatures the

size

(Alexander

women

Harcoun /Amhw-Photo)

of thumbnails, virtual fetuses

womb.

Adapted to the unpredictable

rainfall

of the Australian outback, kangaroos

have evolved a veritable breast-milk cafeteria to cater to infants of different ages.

At one nipple, the mother produces

tiny joey latched is

producing

her

on

in

lovi^-fat

"growth formula" for the

her pouch. Simultaneously, a distended nipple beside

a high-fat "activity

who comes back for

formula" for the older joey hopping beside

an occasional drink.

The kangaroo's ovarian assembly turnover. Should either the joey in her

line

is

specifically

pouch or the joey

geared for high

at foot for

son cease to suckle, levels of the nursing hormone prolactin

work order

for

more milk

—

fall

precipitously.

cyst in waiting (a nearly hollow globe of cells inside of

it

which an embryo

will develop)

is

At

—

any rea-

her body's

this signal the tiny blasto-

produced by the activated.

fertilized egg,

The spare

'emerges from developmental dormancy (diapause) to serve

blastocyst

as a replace-

ment. Mortality in the outback species

would by now be

is

so high that a reproductively less flexible

as extinct as dinosaurs.

for any season. She simultaneously juggles

But a kangaroo

progeny

is

a

mother

at three different

phases

a

THFMILKYWAY

129

of development: blastocyst in the pipeline, exterogestatc Fetus on the teat, nursing joey

She can abort

at toot.

process at any phase, with minimal

this

and without breaking her reproductive

risk,

closely

scoop

it

up, the

kangaroo

a predator can jettison, or just allow to topple out, the

pursued by

joey in her pouch.

A mother

stride.

'^

It's

safe (for her),

mother — —

and very quick. Instead of stopping to

her load suddenly lighter and her pursuer tem-

escapes with plan B already under way, since cessation

porarily distracted

of suckling activates the dormant blastocyst.

High-fat milk does not always like a tree shrew.

where mother and

Hooded

seals,

mean

the manufacturer

Sometimes rich milk

is

—

known

as brief as a

an eight-ounce

who

fat,

imbibe pure cream

pup can gain

pounds

nursery platforms crack apart, weaning can befall them

at

With

fifty

alone in a frigid

in a

Dyak

fruit bat, lactation

Males do not normally produce milk.

parent

'^

This

may have

with internal fertilization and gestation,

who

can be absolutely certain the infant

more wary about

should evolve to be

needs

to. If brittle

any moment, leav-

world where only the plump survive.

rare exceptions like the

in animals

is

to

is

a female specialty.

do with the

the mother

is

fact that

the only

hers; males, by contrast,

investing in offspring possibly not their

own. Taking into account the resources she has already committed to tion,

her

it is

her infant's dependence on milk and her ability to provide

own sex per se)

—

approximately 1,400 calo-

It

pup

gestait

(not

that seals her fate.

Given that infant provisioning has not always been sex-specific, and that is

not necessarily

in

glass.

matter of days.

ing a

needs to be.

week. Mothers stockpile blubber

high-protein formula containing 60 percent

seal

it

although relatively large mammals, have one of the shortest

advance, then give birth atop ice floes to pups

A

an absentee mother

be separated soon,

infant are likely to

periods of lactation

ries in

is

delivered in a hurry: in worlds

so,

how

did lactation

uniquelv female specialization? What

left

come

it

to be this utterly critical,

mothers holding the

teat?

MOTHERS AND ALLOMOTHERS

130

Prolactin

No

one knows

and Caretaking how

lactation first evolved, but

the fact," the lactation-promoting

hormone

among

the "accessories after

called prolactin

is

pect. This simple protein, clearly implicated in lactation, and

of its pro-lactating function, spread, that

its

is

an obvious sus-

named

in

honor

so ancient, versatile, multipurpose, and wide-

—

fingerprints are everywhere

at the

"crime scene" and every-

place else as well. Prolactin could just as well be called the "stress hormone," or,

even more

aptly, the

"parenting hormone."

Unquestionably, prolactin was around, and a player,

under way. But unfortunately

was

around and a player

also

when

lactation got

(for those seeking simple answers), prolactin

in bird

and

fish species,

among which

lactation

never got started. Secreted by the pituitary, prolactin molecules crop up in

both sexes of a broad array of animals and are implicated puberty,

fat

metabolism, and coping with

mammals

years before sis

in

it is

in hair maturation,

For several hundred million

stress.

ever appeared, prolactin was regulating metamorpho-

amphibians and water balance in the tissues of bony freshwater

hormone

a curious feature of this

that

fish.

Yet

wherever mothers or allomothers

are motivated to protect or provision young, prolactin can be detected at ele-

vated levels.

The

role of prolactin

is

not easy to interpret. When Cambridge University

primatologist Alan Dixson

first

reported levels of circulating prolactin

five

times higher in male marmosets carrying offspring around than in males not carrying any, his report was greeted with skepticism by experienced endocri-

who knew

nologists

They hypothesized parity

—

that prolactin also goes

that the testing

specifically, that a

by having

his

procedure

itself

form of this experiment,

a

male on

scientists

effect of prolactin, then artificially replace the effect these

We have

stressed.

was the source of the

male on childcare duty would be

blood sampled than would

In an ideal

up when animals are

his

far

more

stressed

own.

would somehow block the

hormone and monitor what

molecules have on caretaking. But technically,

this is

hard to do.

only tantalizing hints about the function of this protean and ubiqui-

tous hormone, nothing definitive. Even without the perfect experiment, already clear that

found high

from also

dis-

unrestrained

found

stress

was not causing Dixson 's

levels of prolactin in

donors

Experimenters also

male caretakers when samples were obtained

who were

in the California

results.

it is

not stressed. Later, similar patterns were

mouse, where monogamously mated males are

heavily involved in caretaking from birth to weaning.

THEMILKYWAY Prolactin levels spike

when male

I3I

sea horses gestate.

'^

They

are elevated in

both sexes whenever scrub jay alloparents (typically year-old nonbreeders of

both sexes)

fly

lactin levels

go up

rise higher in

also true for

off

and bring food back to nestlings. in

Among

tamarins, pro-

males right after their mates give birth. Prolactin levels

experienced than in inexperienced, first-time fathers, which

mothers

in species

Curiously, prolactin

where mothers do most of the

caring.

also unusually high in contexts that

is

is

^ '

seem more

nearly offensive or defensive than nurturing, such as aggression in defense of infants,

a

or

when birds engage

wide variety of birds,

in tactics of disinformation to fool predators. In

especially those that nest

mallards, or gadwalls), the

on the ground

mother (often both parents)

(like kildeer,

will flounder con-

spicuously on the ground, seemingly helpless, pretending to have a broken

wing or other incapacitating injury

to distract predators

who

have gotten too

close to her nest. The nearer her eggs are to hatching, and especially

if

chicks, the greater the risks this daredevil takes, letting the coyote or

she has

dog get

heart- stoppingly close before she takes evasive action. I've seen mother gadwalls in the grass, flushed by a dog, just

and dragging one wing in pursuit of

it

to the water's edge, flapping

the way, and then lead the dog

all

what looks to

before she dives one

make

last

all

swimming

in circles

the world like a hopelessly crippled bird,

time, surfaces, and miraculously

away, her

flies

chicks hidden in the grass on the other side of the pond. Either as instigator for this behavior, or as a in these displays

consequence of it, prolactin

shoot up.

levels in birds

Heroics aside, the higher the prolactin levels, the

more

attentive to infant are.

Somehow

and when

alloparents

needs both males and females, both parents and alloparents, high prolactin levels are implicated just help out. Possibly

prolactin

more

it,

when mothers

lactate

they interact with other hormones in ways that

make

nearly accomplice than ringleader. Engaging in nurturing

behaviors, in turn, seems to Eliot put

engaging

'^

make

"Our deeds determine

the pituitary secrete us, as

more

prolactin. (As

much as we determine our

deeds.")

The Ambassador of Caretaking Hormones

like prolactin specialize in cell-to-cell

ambassadors, not so

much empowered

communication. They are

to cause results as equipped to alter

the probability that, once activated, signals are passed on. (The

derives from the

Neurons

Greek "to urge

word hormone

on.")

in the brain are the actual orchestrators

of behavioral acts, and

MOTHERS AND ALLOMOTHERS

132

Hormones

the integrators of behavioral states.

tissues are.

how

depends on

their effectiveness

Hormones have an

are just the instigators, and

receptive to their message the target

effect only

where

tissues are predisposed to

The behavioral endocrinologist John Wingfield sums up current knowledge on this subject thusly: it's the neuronal circuits that "cause behavlisten.

ior";

hormones merely

"influence the rate at

which

a behavioral trait

may be

expressed under appropriate circumstances."

The cowbirds Wingfield birds are

brood

Cuckolded parents

nests,

who

parasites

feed an alien chick

studies provide a curious example. These justifi-

no

ably unpopular birds build

nor do they care for young. Rather, cow-

lay their eggs in the nests of other birds.

find themselves in the position of bringing food

who has grown to

of the nest, and easily lords

it

back to

twice the size of the legitimate denizens

over them, out-competing the host's

own

chicks for food.*

Yet even

among

these nest parasites, levels of prolactin circulating in the

The

blood go up after egg-laying. then caretake.

One

suggestion

lactin are insensitive to its

present to

what

is

become

elicit caring.

already clear

is

difference

is,

cowbird mothers do not

that in cowbirds the neural receptors to pro-

message.

Or

perhaps other stimuli must also be

Even while experiments with cowbirds continue,

is

that,

once targeted

tissue starts to "listen," cells

may induce changes in why when endocrinologists are

increasingly sensitized to the message and

production of the message elsewhere. This asked "Does the

hormone

is

cause behavior or does the behavior cause the hor-

mone?" they smile wryly and answer, "Yes."

There are very few good ideas that are

really

new; there are even fewer new

molecules. Rather than resorting to spanking

new

products, which might

require waiting eons for the right mutations, natural selection relies on what is

already available in the larder. After

selection operating tion that

more than

mammal mothers

manufacture

is

fast:

their freeloading

hundred million years of

so perfectly suited to both as to

* Life-history tradeoff's provide the best explanation For so

a

on both "producer" and "consumer," however, the concoc-

why cowbird

babies are so big and

mothers can devote more resources to egg production than

can, since the brood parasites won't need to allocate resources to caretaking.

grow

their hosts

THE MILKY WAY appear to have been designed. lactation

It is

I33

easy to forget that the original recipe for

was slapped together from

leftovers.

Origin of Lactation Prolactin

broad

a true endocrinological jack-of-all-trades, implicated in a

is

range of physiological activities, from maintaining water balance to seemingly bizarre displays its

undertaken to lure predators away from

eclectic heritage, this versatile

production

—and

later

named

hormone

best

known

for that connection

—was

nests.

True to

for inducing milk

not even

first dis-

covered in a mammal. Prolactin

was

first identified

when

endocrinologists injected a mystery

substance into birds and noticed that, whatever birds of both sexes to develop

it

brood patches on

was, these molecules caused their breasts, areas of heavily

vascularized naked skin that brooding birds apply, like heating pads, against

incubating eggs. In 1935^

Oscar Riddle identified the substance

that an injection of

it

as prolactin

induces broodiness in birds.

Whether

and discovered in

hens or cas-

trated males, increased levels of prolactin are associated with a bird's urge to

hover over, cover, and keep either eggs or young

warm

and

safe.

Brooding

urges can be so strong that they are extended indiscriminately to young of other species.

Among

such birds

as pigeons, doves,

emperor penguins, and flamingos,

prolactin also stimulates males and females to produce "crop milk," a cheesy

concoction of partially digested food diluted with mucus sloughed off from cells lining their throats.

These ingredients may sound unappetizing to people

accustomed to our own

fare of lipid-rich excretions

this fatty stuff has

an avid following

among

from cows' udders, but

just-hatched squabs, pigeon

fanciers, and intellectuals intrigued by unisex roles in nurturing young.

"Though

a

man

does not brood

like a

Jacques Rousseau in the eighteenth century,

pigeon

.

.

.

monogamous

,"

lamented Jean-

father birds

among

mourning doves regularly regurgitate more crop milk into the beckoning beaks of babes than the mothers do. ^° This makes one wonder what a shot of prolactin might

do

for the sensibilities of indifferent fathers. (For

this father of the Enlightenment's

own

more on

fathering, see p. 310.)

Here and there parentally manufactured baby foods can be found:

for

example, the protein provided her young by the breed-and-then-die spider mothers, whose dissolving bodies are consumed, or the milky substance

MOTHERS AND ALLOMOTHERS

134

Fig.

6.6

Among

wolves, subordinate females sometimes undergo pregnancy-like hormonal

changes, including elevated prolactin levels and milk production, even though not actually pregnant. Pseudopregnancy can lead to fascinating,

if

maladaptive, behaviors

among

their descen-

now living under very different conditions. The mother of these kittens was no doubt puzzled when a pseudopregnant Jack Russell terrier bitch drove her away, adopted her kittens, and then settled down to suckle them. (Sarah Blaffer Hrdj/Anthro- Photo) dants

cichlid fish secrete

on

off by fingerlings. But

tation

their scales, a

compared

stands out because

it

mixture of skin and mucus that

is

nibbled

to crop milk and these other substances, lac-

involves specialized

equipment (mammary

glands) developed in only one sex.

The

fact that

mammary glands developed in just one sex indicates that lac-

tation originally evolved in

some animal where eggs were tended primarily

by mothers, and newly hatched infants were already

in close

their mothers. Otherwise, there seems to be no reason

wouldn't

The

lactate, just as

both sexes

in birds

best extant facsimiles for ancient

Monotremes

proximity to

why both

produce crop milk.

mammals

are the

monotremes.

are egg- layers, like birds, but after the eggs hatch only

ever care for them.

The female duck-billed

sexes

mothers

platypus, for example, incubates

her eggs safe inside a grass-lined burrow. Sealed up with their mother, the hatchlings feed on milk dripping from hairs surrounding teatless milk-

producing glands on her front. Suppose, Darwin had speculated, a sweat gland of an egg-layer got plugged up in

some

reptilian precursor to

mam-

mals. Suppose the resulting secretions just happened to enhance the survival

THEMILKYWAY

135^

'"'^

m.

%''^,:.^r-4^~.

Fig. 8.3

warns

"Women who

a

.A,.:.':4^^-:^m:

have one birth after another like an animal have a permanent backache!"

!Kung proverb. This

woman

in the last

four-year-old son riding on her shoulders.

Her

months of pregnancy returns

to

camp with her

leather sling, or kaross, permits her to carry nuts

or gathered food weighing twenty-five pounds or more, together with another

five

personal possessions and water for the trip in an ostrich egg canteen, and her child,

almost thirty pounds. miles. (Richard

B.

A

child this age

would already have been carried by

his

pounds of

who

weighs

mother some 4,900

Lee/ Anihro- Photo)

out our understanding of Pleistocene that the Kalahari

was

just

lifestyles,

it is

important to remember

one of many possible permutations for hunter-

gatherers. Far to the north of Botswana, in the rock-strewn hillsides of Tanzania,

Hadza foragers

having to travel

collect

all

the tubers and baobab pods they need without

more than two

miles from camp. Mothers are rarely gone

longer than an hour (average travel time left

behind

teristic

at a

among

much younger

is

twenty-five minutes). Infants are

age (closer to age two than four, as

is

charac-

the !Kung), often with subadult caretakers. Because they have

the option to leave babies with an allomother, Hadza mothers can produce infants after shorter intervals than

!Kung mothers without compromising

— FAMILY PLANNING infant survival.

As

a

R

M

T

consequence, the Hadza population

is

I

cent a vear rather than holdina steady. Similarly,

American

forests,

women, birth

where Ache foragers

live,

intervals even shorter than

growth

lation

rates.

A T K

S

1>

The

-

Y L E

growing by

abundant game

99

1

in the

means more protein and

i

per-

South for

fat

among the Hadza, and higher popu-

"sleeper" here, the nonobvious but very important

determiner of population regulation,

is

the

whose suckling

infant,

little

transforms ecological differences into demographic ones.

Division of Labor the adoption of slings, like the leather kaross !Kung

With

mothers could transport both technology of such carryalls

is

as early as

of labor based on

A

^0,000 years ago

—

still

use,

and quantities of gathered food. The

infants

so unassuming that

it is all

the significance of this early technological revolution.

perhaps

women

It

too easy to overlook

was the beginning

of an economically significant division

sharing.

rudimentary chimpanzee-style division of labor whereby males ob-

tained meat from hunting while females specialized in vegetable foods and

more than

small prey items has characterized hominoids for years. But with mothers' capacity to carry

would have had

men

provender

The new

stores of food to share.

sufficient gathered

food back

Anthropologist Jane Lancaster notes that

more

babies and also for obtaining food

ging sticks) meant that mothers

at

division of labor

camp

new

if

meant

they failed,

they that

women

to tide everyone over.

technologies for carrying

efficiently (spears

who were

million

in addition to babies,

could go hunting confident in the knowledge that

would have

five

and sharpened dig-

better fed could give birth after

shorter intervals. Improved efficiency in food-getting contributed to shorter birth intervals, and to the expanding their

human

populations that were edging

wav out of Africa.

The Real Neolithic Revolutions As the modern world closed

in,

bringing outsiders to once remote locales to

claim land once freely used by peoples like the !Kung, the

last vestiges

of

Former hunters and gatherers

Pleistocene lifestyles

came to a more and more time in one

standstill.

spent

place.

relied

on handouts, or otherwise traded the freedom (and the uncertainty) of

a

nomadic

life

Many kept

livestock, or a garden, or

for greater security. In the case of the

!

Kung, former foragers

MOTHERS AND ALLOMOTHERS

200

Fig.

8.4 Leather slings, nets, or

woven

baskets

made

it

possible for

mothers to

tances carrying several offspring, or food plus offspring. These innovations fossil

record.

employed

.

The balancing baskets

like these

used by

this

left

travel long dis-

no

Japanese mother are

trace in the still

widely

(Courtesy ofAndy McCarthy)

indentured themselves to Herrero pastoralists in exchange for milk. Instead of making long treks to find food, carrying dependent children with them,

women

stayed close to

home

Whenever people

cease

sites.

wandering, intervals between births grow

shorter. For ethnographer Richard Lee, observing the transformation of the

!Kung San was early

like

fast-forwarding through the Neolithic transformation of

humans.

"This sudden embarrassment of riches in terms of births," he noted,

"is

already imposing hardships on !Kung mothers and children alike, a degree of

FAMILY

P L A N N

1

N

PRIMA T

c;

Stress that reveals the existence of a third

—

and reproduction

a

system

1

nomic

sense;

what was

so

-

S

20

Y L H

r

1

system interlocked with production

will call the

The Neolithic revolution did not

K

emotional economy of the San."

much mean

a radical overhaul in an eco-

was the abrupt

radically different

arrival of the

next

infant.

No

one had to bear the brunt of these changes more acutely than the

weaned

infants themselves. For a child in a village

"The

effects are striking,"

The most miserable i.^- to

2

after just a year

and

a halt,

wrote Lee.

kids

I

have seen

among

the !Kung are

some of the

-year-old youngsters with younger siblings on the way. Their

weaning and continues to the birth of the

misery begins

at

months

and beyond. The mother, for her part, has not only

later

demanding newborn angry, sullen

2

sibling 6 to 8 a

to care for but the constant intrusions of an

-year-old.

A

grandmother or aunt may do her best to

feed and cheer up the older child and to give the overworked mother

some

relief,

but

it

is

clear to the observer that

something

is

out of

kilter.

The scene contrasted markedly with infinitely tolerant

!

Kung mothers

Lee's

own

earlier descriptions of loving,

attending deftly to the cooing and crying of

each infant born. Gradual transitions from foraging to settled living

some

refer to as the Neolithic revolution

as a series

—

—what

were experienced by the infants

of neonatal crises.

The prelude

was long and

to the Neolithic

slow, dating back a million years or

more. People gradually became already more

efficient at extracting food,

using sticks to dig tubers, traps or nets to catch

fish

as

I

will discuss in chapter

i

i ,

a

new

type of allomother became available,

helping to provision offspring and making children sooner and space births

more

and game. Furthermore,

it

closely.

possible for

Some

early

mothers to wean

humans, especially

those living in rich riparian or lakeside habitats, would not have needed to forage quite so widely. As

spent

more time

began to grow.

in

new food

sources became available, and as people

fewer places, birth intervals shortened and populations

MOTHERS AND ALLOMOTHERS

2o2

with the introduction of agricuhure, these effects were greatly

Later,

magnified. By

Middle

East,

years ago

i

i

,^oo years ago in central China, by 10,000 years ago in the

Mexico, and parts of highland South America, and closer

among such remnant

foragers as the

changed completely. Foragers lingered in

Ache and the !Kung,

few locales,

a

depending more and more on cultivated

roots,

Woman

woman cook

it

The

availability

meant gruel was

infants could

be weaned

available

as early as

New

down

emmer,

World, squash and

more sedentary

the forager adjusted to the

the grinder. in,

putting

strains of wild rice,

einkorn, oats, barley, wheat, millet, or, in the

maize.

literally

tojjfty

lifestyles

routine of

of ground grain, and fired pottery to

year-round

around

six

as a

weaning food, so that

months and

survive."

still

Population after population, independently, each according to

its

own

schedule, traded the freedom of a nomadic lifestyle for short-term security.

The long-term

be measured

costs could

in the classic

^"^

combination of higher

birth rates coupled with higher rates of infant mortality in the face of recur-

rent famines, epidemics, and war.

For humans, the long birth intervals typical of chimpanzees and other apes

grew

Human

shorter.

infants were, if anything, more costly than those of

other apes, yet these slow-maturing, big-brained "ape" babies were arriving often as every

two years or

less.

Large-bodied ape babies were being born

monkey-like intervals. In areas where food was

once again favored multiple

as at

plentiful, selection actually

births. In parts of the

world where famines were

rare, the incidence of twinning increased. Scientists at the University of Turku in Finland have living

on

islands,

of twinning than

shown

that

women

with plentiful and constant supplies offish, had higher rates

women on

the mainland. Island mothers

who

gave birth to

twins had a higher lifetime reproductive success, but the same was not true

on the mainland, perhaps because crop that

both twins and the mothers

failures

and recurrent famines meant

who bore them were more

likely to die.

Indeed, in parts of the world where food has traditionally been

less plentiful,

the only twins ever born are identical twins. Such twins represent an accident

of early cell division rather than an inherited tendency toward multiple ovulations.

Replacing Singleton Births with Clutches Long

birth intervals

mothers and their

were

infants.

a staple feature

of the coevolution between ape

However, over tens or even hundreds of thousands

FAMILY PLANNING PRIMATE-STYLE

Fig. 8. J

ArcheologistTheya Molleson has found bone wear

of 7,000-year-old skeletons from

Abu Hureyra

in

in the big toes, vertebrae,

northern Syria that indicate

much

hours on their knees grinding domestic cereals against

a stone base,

Bemba mother is

this daily grind,

doing.

While

a

mother is occupied by

203

and knees

women spent long

as this

Central African

her baby might be held by

an allomother, cradled nearby, or wrapped on to her mother's back using a sling arrangement like this one. (Photo by Audrey Richards, African

Institute)

of years, hominid mothers were beginning to produce infants after shorter intervals. Like the island-hving Finns, tively favored for

producing two

some mothers were even reproduc-

at a time. Increasingly,

periods of heavy

investment in successive infants overlapped, creating the functional equivalent of litters (or the asynchronous hatching of broods

At some point ologies and

in

human

in

some

birds).

evolution, ape mothers with reproductive physi-

temperaments adapted to rearing singleton young found them-

selves simultaneously nurturing several

dependents became the

"facts

and eventuallv even adapt

What humans, monkeys

found

like

young of

on the ground"

that

different ages. Multiple

mothers had to adjust to

to.

ruffed lemurs, and a handful of cooperatively breeding

tamarins have in

apes, they live in families

common

where

with

many

birds

is

that, unlike

other

mothers simultaneously care for multiple

young. Closer birth spacing over the course of human evolution exacerbated

dilemmas confronted by mothers who must then decide how to

allocate

MOTHERS AND ALLOMOTHERS

2o4

8.6

Fig.

A

wicker basket on wheels permits

work with her

in flooded rice fields,

infant survival.

Baby carriages,

strollers,

—

this

Japanese mother to take her nursing infant to

with important consequences for both birth spacing and

and infant car-seats that strap into motorized vehicles

—

modern innovations that like the Pleistocene sling permit mothers them as they forage, or just run errands. (Counesj oJKawai Takahi) are

resources

among dependent young with competing

to bring infants with

needs. These pressures

increased as the Neohthic brought about an unprecedented level of

but (in

at a potential cost to particular infants

who may

fertility,

not have been just what

terms of sex or other attributes) or been born when the stork ordered.

A

mother's genes would continue to be represented in the population or

disappear, depending

on her

translate her investment into

ability to assess

which offspring would best

long-term reproductive success, and on

how

much assistance she managed to elicit from fathers and alloparents. turn now to the means by which mothers sought such help. First on the list: how 1

to elicit help from males in caring for infants.

.

Men

Three A capon

will sit

upon

eggs, as well as,

and a Baby

and

often better than a female.

— —

this

full of interest; for [there are] latent instincts even in brain of male.

animal surely hermaphrodite

—

Mother-infant

Charles Darwin's notebook, 1838

relations are particularly intimate

by comparison, are rarely

20. Fathers,

Even when,

often the case in humans,

as is

mother, one-on-one care of infants by the father the

voung George

emotions

—

Everj

and long-lasting

Great Ape mothers carry their infants wherever they

in primates.

babies.

—

is

Eliot

is

men

help provision the

unusual. Observing this,

pondered the question of "a

the maternal ones

class

of sensations and

—which must remain unknown

Later she changed her mind. Like

with

in direct contact

Darwin puzzling over

to

man.

." .

.

capon he saw

a

brooding eggs, Eliot became fascinated by the possibility that males could

we normally associate with mothers. manage with a two-year-old man

express the tenderness and compassion

How, she wondered, would child.

.

.

"a lone

.

.

.

."What would happen, the novelist asked,

motherless two-year-

if a

old toddled through a blizzard and ended up at the door of a lonely titled

her thought experiment

ing for English majors. In

documented. Care

is

most

it,

Silas

Marner, a novel that

Eliot intuited

readily elicited

is still

man? She

required read-

what primatologists have since

from

a

male primate under three

conditions:

1

long-standing familiarity with the immature;

2.

the nearby infant

3.

the male has a relationship with the mother.

In Silas

Marner 's

combined with

a

is

urgently in need of rescue; and, especially

case, solicitude

was

elicited

perception of kinship (Eliot

golden-haired orphan with his long-lost

Marner's tenderness came

by

little Effie's

obvious need,

Marner

identified the

tells

"little

us

sister").

Once

naturally as he lifted the toddler and she

20^

triggered,

MOTHERS AND ALLOMOTHERS

2o6

Fig. 9. Lihrary,

I

Peasant father spoon-feeds gruel to child.

(Etching by A. von Ostade, 1648, courtesy

oJWelkome

Institute

London)

clung around his neck, and burst louder and louder into that mingling of inarticulate cries with "mammy" by which

bewilderment of waking.

Silas

pressed

it

little

children express the

to him, and almost uncon-

sciously uttered sounds of hushing tenderness.

I

know

of no better

human

case history for exploring

what Darwin termed

the "latent instincts" for nurturing that lurk "even in brain of male."

—

What does it take to get a man to care for infants? And why don't question much on the minds of mothers today

—

more?

I'll first

fathers help

explain the immediate, or proximate, reasons why, in general,

primate mothers hold babies more than causes for

turning to a

why male

fathers do, then turn to the ultimate

primates are not more inclined to care for infants.

THREEMKNANDABABY In

all

creatures

where

A

mother many

fertilization takes place inside the

weeks or months before the nity.

207

infant

is

horn, males cannot be certain of pater-

male's best clue to whether or not he

had sexual relations with the mother, and

is

the father will be whether he

and their

their timing,

if so,

fre-

quency. Most female primates have evolved to mate over a period of days,

and (when

feasible)

with a range of male partners. There are few species

in

the order Primates in which males can be certain of paternity.

This evolutionary history can

women

behavior in

and

today,

still

the chastity of their mates.

No

and assertive sexuality

vacuum.

in a

be detected

in the psyches of

in the patterning

men who

of sexual

are obsessed with

matter that females did not evolve a flexible (It

was an

essential tactic for ensuring

well-being of their infants that would scarcely have been necessary

if

females

could choose an acceptable partner and count on him.) Given the situation as

we

find

choice.

it,

females mate with

They must mate with

more than one male. This leaves males httle many females as they can, or else find them-

as

selves at a relative disadvantage vis-a-vis their rivals' efforts to transmit their

own

genes to the next generation. Like mothers, males make tradeoffs of

their

own. Males must choose between parenting offspring they may have

sired,

and seeking to mate with additional females and possibly siring more.

Often such tradeoffs (along with uncertain paternity) make geous for males to respond to the magic of alacrity that

mothers do. Mother Nature has

ing high. Yet

it is

not the case

(as

infantile signals

set

it

disadvanta-

with the same

male thresholds for respond-

an egg-sitting capon led Darwin to suspect)

that males never care for infants. "Instincts" to care

slumber

in the hearts of

primate males, including men. Under what circumstances are they activated?

Godfather Gorillas Far stranger transformations than Silas Marner's

abound

tory of other primates. Binti Jua, the mother gorilla

boy

at the

boy on the

Chicago Zoo, got Isle

of Jersey

fell

there. That time the simian

Jambo,

who

all

in the natural his-

who

rescued the

little

the press, but a decade earlier another

little

onto the floor of the gorilla enclosure

good Samaritan was

a silverback

stroked the boy's back and kept other apes away.

Primatological lore

is

at

male named

^

rich in anecdotes about aloof males transformed

into instant heroes by endangered infants. Adoptions of ape infants

mothers have disappeared

the zoo

is

whose

almost always by kin, typically brothers or possi-

MOTHERS AND ALLOMOTHERS

2o8

Fig.

9.2 Babies elicit the tenderest responses

(better

known

carries in

as

one hand, holds the babyTelephos ever so gently

Heracles had a brief

baby

at birth.

The

affair

ble fathers.

in the other.

with a (supposedly chaste) priestess of Athena

baby, Telephos, was being suckled by

(Statuejrom theViIla d'Este in

will, at

from the toughest guys. The Greek hero Heracles

Hercules), draped in the skin of the lion he has just battered with the club he

Tivoli, Italy,

2nd

c.

A.D.

a wild

deer

According to legend,

who abandoned

their

when Heracles found him.

CoUTtesj oj the LouvTc)

The same males notorious

for kilHng infants unhkely to be theirs

other times, look out for those that might be/ Picture the extremely

domineering hamadryas baboon male,

a snout the color of raw beefsteak

the intrusive habit of biting the neck of females

when one

of "his" females

which the term "harem"

(this

is

the only

actually applies)

who

stray

from

his

nonhuman primate

went

with

harem. Yet species for

into labor too close to a

cliff,

-

THREE MEN AND this tyrant

BABY

A

209

responded with deft tenderness to catch the baby.

vention was witnessed in captivity, but this time the midwife was a male orang

—

A

—even more

similar inter-

amazingly

—

an event almost beyond the imaginings of

fieldworkers, for in the wild male orangutans are solitary. Shaggy hundredkilo titans crash

through the jungle oblivious to mothers and infants, passing

females by like ships in the night, meeting with them only to mate.

No

less bizarre are the

multiple cases of care-in-a-contingency offered by

notoriously nonnurturing langur males, best

known

for stalking babies, not

caring for them. Yet in a pinch, a brother or former consort of the takes custody of an infant deposited with

niscent of the film Three

weaned

infant with a

Men and

juvenile

who now

showed no

the mother. In a plot remi-

mother langur

leaves a nearly

group of males recently driven out of her breeding

group by an usurping male. She ticidal "stepfather"

him by

a Baby, a

mother

will return alone to face the potentially infan-

resides there.

The same langur male

interest in joining his sisters as they

that as a

scampered about

with borrowed babies becomes transformed into a solicitous custodian by the overtures of a needy youngster.

Why Males Don't Mother More (Proximate Causes) If

the circumstances are conducive, almost any primate male can be induced

to behave in a nurturing way.

who end up

How is it, then, that it is

almost always females

holding babies? In only a tiny minority of species do males care

for infants even remotely as

much as mothers do. Confronted with such over-

whelming evidence,

seems "natural" to conclude that since mothers

provide the

it

just

womb, develop

the

mammae, and

energetically invest the most,

they therefore are the sex selected to nurture babies.

But what

if

we

don't end the story there? What

ous to inquire further: Why

is it

that,

even

if

if

End of story.

we look beyond the obvi-

they are not hungry, baby pri-

mates prefer mothers? Or, to bring the question closer to home: Why, even

among

bottle-fed babies with both parents working outside the

the traditional division of labor

between

home, does

father and maternal caretaker so

often emerge?

many mammals, retrieving, licking, "brooding," or protecting pups are unisex potentials. What Darwin termed the "latent instincts," the basic wiring, In

for such behavior

there;

it's

just

seems to be there. ^ The underpinnings for caretaking are

not expressed under ordinary circumstances. Why not?

.

MOTHERS AND ALLOMOTHERS

2IO

Fig.

9.3

lives

The

film Three

Men and

a

Baby

is

the ethologically correct chronicle of a few weeks in the

of three incorrigible, field-playing bachelors with no previous space in their brain for

mitment of any kind

until they find a

baby outside their door, dropped off by

Like a male rat sensitized to caretake, the bachelors

The cues

eliciting care are

the mother. (© Touchstone

Pictures, courtesy

Gender ideology roles in

mammals

both the

is

no

infant's

a

com-

former girlfriend

become not only competent but committed.

obvious need and the males' past relationship with

Disney Publishing Group, reproduced with permission)

help.

How can culture and socialization explain sex

lacking language and symbolic thought? There must be

evolved emotional differences between males and females, differences that

go beyond the two major physical differences, birth and

lactation.

What

besides ideology produces this seemingly unbridgeable chasm of difference

between aloof

fathers aiid "instinctively" caring mothers? Initial differences

turn out to be surprisingly minor eventual dichotomy.

—

tiny

compared with the magnitude of the

M

T H R K K

Fig.

9.4 Even

when

N

AND

A

BABY

During the

will hold her less than

2

first

six months of his daughter's

percent of the time.*

is

son put

it,

"At birth the twig

nations lead depends on

is

already bent a

how much

effort

is

rarely trans-

life, this

doting

of labor? The simplest

that people do, by following the path of least resistance.

answer

is

I

(Mel Konner / Amhro-Photo)

Small Differences Much Magnified What magnifies small differences into major divisions

Among

21

fathers are obviously devoted to their offspring, fatherly love

lated into direct care of infants.

!Kung San father

K

little bit."^

Where

As Ed Wil-

natural incli-

expended bending them back.

humans, conscious effort can minimize preexisting differences. More

— MOTHERS AND ALLOMOTHERS

2l2

often, small initial differences in responsiveness are exaggerated by

riences and then

blown out of all proportion by

cultural

life

expe-

customs and norms.

who start out with the noble intention of an new baby. The benefits of breast milk are too important to forgo, so the mother uses a pump and stores bottles in the freezer for the father to heat up when she can't be there. Within weeks, they Imagine two working parents

equal partnership caring for their

notice the baby has developed a preference for the mother. Soon

obvious that the baby wants

baby

mother. Aware that her husband

all,"

Why

it is

painfully

hurt and her the baby.

Mother Nature."

she sighs, "you can't fool

did this young couple's

is

home with

unhappy, the mother quits her job and stays

is

"After

its

good

intentions go for naught? Recent

Worthman

findings by anthropologists Joy Stallings and Carol

at

Emory

University, collaborating with developmental psychologist Alison Fleming

and coworkers

University of Toronto, provide relevant clues.

at the

new

researchers asked

parents to listen to

sound of a day-old infant crying be

fed.

first

The second tape contained

thing in the

the

The

two recordings. One was the morning when he wanted

more jagged and alarming

to

cries of a

baby being circumcised. Reactions of mothers and fathers were carefully monitored, and hormone

measured. At the

first

responded with equal

levels (of Cortisol, testosterone,

both mothers and fathers

signal of real distress,

alacrity.

able but not in extremis,

if

But

if

and prolactin)

the infant merely sounded uncomfort-

the cry was merely

Help!" the mother was the quicker to respond.

"I

want" rather than "Help!

It's

possible that the mother's

greater responsiveness and the physiological reactions that accompany

More probably her lower

learned. is

it

are

threshold for responding to infant signals

innate.

So the mother cares?

And

habits of ies" that

is

more

sensitive to infant needs than the father. So

that's just the point.

The

act of caring has

mind and emotion. When we

George

that simple.

No

get

down

its

what? Who

own consequences

to the "underlying myster-

Eliot called attention to, the causes of difference can be just

doubt, other things are going on. The point

is,

consequences

are magnified out of proportion to initial causes. Just because the

demands does

not

mother

mean

is

more

readily galvanized to respond to infant

that fathers are not able to

do

so, or that they

cannot

THREEMENANDABABY

caretakers, "good enough" caretakers, or that baby pri-

become adequate

mates cannot Form primary attachments to

marked

by step, without invoking

a single

ery wafts the

first

home from

who

needlesslv intrusive," the father

Mother has of course,

baby.

is

Why

all

tells

himself. There

that the baby's attachment to his is

is

the nurs-

already out

full cry. All is quiet. "1

superfluous.

is

disturb the peace by taking

complain whenever he

Mother

never even reaches

Baby coos contentedly. Further intervention

From

the hospital.

sputtering sound of fretful wakening.

of her chair. She soothes baby,

Yet

other cause, produces a

division of labor by sex.

Recall our imaginary couple, just

starts to

Rather, a seemingly

a male.

responding to infant cues gradually,

insignificant difference in thresholds for insidiously, step

213

would only be

no reason to move.

is

him from her? The

mother

intensifies.

transferred from her to

someone

result,

The baby else.

along there were alternatives. She could leave her baby alone with

her husband more.

He

could request that his wife wear earplugs,

or, like

Odysseus, bind herself to the mast so she will not be able to respond to the irresistible call

of her

little siren.

Mother Nature opted

The neural equivalent of earplugs

for in the case of

indifferent to the allure of infant cues. fathers,

and the males

"just naturally,"

titi

The

is

what

monkeys, rendering mothers result? Infants strongly prefer

without conscious determination or

outside intervention, do most of the childcare.

Eliciting Paternal Titi

monkeys

are as

Devotion

monogamous

as

primates get. The mother

is

so attached

to her mate that she borders on indifference toward her infant. After birth,

newborn 93 percent of the time. This unusual monkey is proves a larger rule: when a male primate's reproductive

the father carries his

the exception that success

is

substantially

enhanced by

assisting his

mate rear

offspring,

and

when he has no better reproductive alternatives (the female titi makes sure of that by driving away any female who enters her territory), he helps. Sure, either titi partner may occasionally stray. They are primates, after all,

never so Hindered that given an opportunity they won't

at least lust in

their hearts or, should his or her partner's vigilance lapse, copulate with an

outsider. (Extra-pair copulations

were

first

reported in

1960s, long before reports of female philandering in

caused a sensation in ornithological circles.)

commitment

of these lovebirds

is

to each other.

titi

monkeys

monogamous

in the

birds

Nevertheless, the primary

MOTHERS AND ALLOMOTHERS

214

Fig.

9.5 In togetherness titi-style,

seen side by side,

The

tails

monogamous

mother

more

is

When

Mendoza

at

pairs are often

(Drawing hy Virginia Savage)

may

threat that his adultery

ation of his care

baby.

entwined.

from her

lead to alien-

infant explains

why

a

titi

attached to her mate than to her

Mason and

psychologists William

Sally

the California Primate Center used var-

ious endocrine measures to monitor responses to different circumstances, they found that

were

ers

tion

from

Once

branch,

tails

a

its

father

their

the infant has suckled, the

pair typically is

not really so strange.

or allofathers end up

sit

side

titi

mother wea-

it off.

Since the

by side on the same

nearby. Rejected by

its

mother, the baby

time to suckle again. Thus does the baby form ,

is

mates than from their babies.

mated

till it's

moth-

temporary separa-

her heavy baby. She pushes

primary attachment with him not This

stressed by a

ries of

entwined, the father

climbs aboard

more

far

titi

On

her.

the rare occasions

when human

fathers

the sole caretaker, infants

form primary attachments

who

Silas

them. As the kindly neighbor

volunteers to teach

Marner how

to care for a child observes: "See there, she's fondest of you. She wants to

to your lap,

I'll

be bound.

Go then: Take her Master Marner.

to

go

." .

.

When Care Is Neither Exclusive nor Costly Any male who provides to sire children

exclusive care to an unrelated baby, and thereby

of his own,

may

find

increase his reproductive success. This

fails

many satisfactions. But he does not is why Mother Nature sets the thresh-

old for direct and exclusive care of young higher in fathers than in mothers.

primate mothers respond to infant needs

If

right after birth, they are unlikely

to ever misdirect their care. Males cannot be so sure.

But what about assistance divisible among a number of babies? care

is

only intermittently required? Far

all-consuming care given by

be their

own

is

titi

monkey

more common

What

if

than the exclusive,

fathers to offspring almost certain to

the flashier brand of male care, the quick intervention of a

THREEMENANDABABY Robin Hood who shows up every so often, behaves Hke away. Such fathering

among many

is

2l^

a hero,

and then fades

divisible (or "partible" in the lingo of primatologists)

recipients.

The important point

is

male need not be cer-

that a

tain of paternity to proffer paternal-like assistance.

Between the "dad" who

them

lies a

is

devoted to

broad intermediate zone

rarv heroes." Such fathers spring. If an infant

is

may

his kids

divide their time

possibly theirs,

and the "cad"

predator or another male

a

and intervention

scarcely afford to withhold

there

a

is

as

from an

off-

not too risky, these

protection of an infant

If

essential for

infant that

is

its

survival, males can

might be

tendency to assume that early hominids lived

wav married people do

how

it

is

deserts

between many possible

scattershot fathers can afford to be less than certain.

from

who

with occasional dads, and "tempo-

filled

theirs.

Although

in nuclear families the

today, or perhaps in small "harems,"

no one knows

they lived. Hence, this "temporary hero" type of father must be included

one of the various possible alternatives for

how

early

hominid males

inter-

acted with their kids.

Savanna baboon mothers breed in multi-male troops and stay favorite

former consorts. These

possiblv their

own.

same

the

child.

operation"

However,

among

it

we

find in

human

the infanticide -prone baboons

Ryne Palombit, Robert sitv

might provide

took the equivalent of

some males had the well-being of the

touch with

male friends look out for progeny

special

Hence, their relationships

formation of the kind of pair-bonds

in

infant in

Seyfarth, and

at

insights into the

parents committed to

a primatological "sting

Moremi

to prove that

mind.

Dorothy Cheney from the Univer-

of Pennsylvania set up the sting by discreetly placing speakers where they

knew

the baboons would pass. As each target male passed, he would hear the

taped sounds of a newly immigrant male harassing one of the recent mothers

he had

a special relationship with.

ing to the defense of

mother and

The

adult male reacted immediately, rush-

infant.

However,

if

the tape recording indi-

cated that the animal harassing her was just another female, the same male

exhibited

little

interest. If the

mother's infant was no longer

alive,

the

"strange-male-hassling-your-girlfriend" tape elicited no response whatsoever

from him." The researchers concluded strange males was indeed high on

that protection of infants

the possible father's list of priorities.

from

MOTHERS AND ALLOMOTHERS

2l6

MOTHER-INFANT

Fig.

9.6 Jeanne Altmann's

1

980 diagram shows the special relationships forged between savanna

baboon mothers and adult males they have mated with. During the birth of her infant Moshi, his mother,

Mom,

stays closest to

quent grooming with Peter. These "godfathers," of the genus infant

first

three

male Slim, but

from other baboons. This may not be "quantity time" but

Papio, it is

months

after the

also engages in fre-

defend the mother and her

"quality time" in the

most

ele-

mental sense. Occasional intervention by former consorts can mean the difference between an infant's life

or death.

(Courtesy

ofJeanmAhmann)

Several primatologists,

most notably Carel van Schaik and Robin Dunbar,

have proposed that one of the main selection pressures on males to remain

— —was

near their mates after breeding

any form of the nuclear family other males

—

TheWar Between

an essential precursor to

to guard mothers and offspring from

especially infanticidal ones. thcTates,

monogamy and

As novelist Alison Lurie put

it

in

her savagely funny dissection of American marriage,

"We need [men] sometimes, if only to protect us from other men." A primate mother's best bet in such a system would be to find strong enough to protect her. However,

if

her mate dies, or

is

a

mate

driven off by

.

THRFKMHNANDABABY another male, she would be better

217

she had associated with several

oft if

males, thereby improving the odds that there will be several candidates in the

neighborhood

who

classify

her offspring as possibly "kin." At issue here

whether males can help protect or care motivate them to do ate mate, the

for infants, but

is

how mothers

not can

Next

to ensuring that she conceive with an appropri-

most important

selection pressures shaping female sexuality in

so.

primates have to do with forging relationships that promote tolerant, even protective, relations

between

a past or present consort

and her

infant.

TheTrouble with Being a Male Primate A mother mammal relies on proximity right after birth to learn to recognize the smells and sounds of her newborn baby. A male has only his past relationship with the

mother

to

go on.

he has managed to control access to the

If

mother during every moment when she was anteed. This contrasts with the situation it's

last fertile, his

for, say,

paternity

is

guar-

pronghorn antelopes: when

time to breed, the pronghorn female surveys the scene, selects the most

vigorous male, and mates with him

—

^just

once. Then the matter

is

closed

till

next season.

Among

such prosimians as the

little

African galago, the female

with more than one male, but only during a brief period, lasting

The

rest of the

time an epithelial

and intromission

is

membrane

a

seals the galago 's vagina shut,

impossible. But for simian primates, the

opportunity during which copulations can occur

(from the male's point of view),

in

is

more

most primates there

midcycle signal advertising ovulation, such

may mate

few hours.

as the

is

window of Worse

flexible.

no conspicuous

red swelling on a baboon or

chimpanzee. Under some circumstances (for example, when strange males enter her troop) a lating,

monkey female may

solicit

males although she

is

not ovu-

something neither Saint Augustine nor the Catholic Church was aware

of when they mistakenly assumed that intercourse without possibility of con-

ception was unnatural Exactly

why monkey and ape

go to so much trouble to

Among

females are so sexually flexible, or

matings from extra males,

the various explanations proposed

conception occurs. sired

solicit

Or they might be

is

is

much

why

they

debated.

that females are ensuring that

increasing the odds of bearing offspring

by males with superior genes. Perhaps they are reducing the chances of

inbred offspring sired by close relatives.'^ derlust

is

that only a

male who

One consequence

of female wan-

completely excludes other males from his

MOTHERS AND ALLOMOTHERS

2l8

:-ja^^^. Fig.

9.7 Relatively few primate species advertise ovulation with conspicuous sexual swellings. In

most

species, females are

presenting her

Females vary

rump and

more

subtle.

frenetically

in the intensity of their

A

langur around the time of ovulation

solicits

shuddering her head. She exhibits no other

head shudder, so only

tion about her actual cycle phase and probable fertility.

a resident

male has

males by

visible sign.

reliable informa-

(Daniel B. Hrdy/Amhro-Photo)

mate's vicinity can afford to regard his recent sexual history with the mother as a rehable

cue for paternity. By the same token, the margin of uncertainty

surrounding paternity could forestall males

who

mother from harming her subsequent offspring theirs. This is

—

recently

mated with the

an infant that just might be

one of several benefits mothers derive from being able

to

manipulate the information available to males concerning paternity.

Whatever the explanation

for this polyandrous

component

to female mat-

ing habits, there are obvious repercussions for males. To remain competitive

with other males to

in his vicinity, a

male primate must grow large enough

dominate and control females, and to exclude

nant male gorillas do). plentiful, high-quahty

Or

else

sperm

in

rival

he must evolve large order to compete

males (the way domitesticles

and ejaculate

in a different arena, inside

the reproductive tract of a female he will never

manage

to monopolize.

THREE MEN AND

Fig.

9.8 Comparisons of the genitalia of Great Apes

male breeding in species

where

a

number of males mate on

from getting anywhere near to the

i

the

same day with

7o-k:ilogram male gorilla

who

"harem" has

o\'ulating females in his

enormous 140-gram

is

a

rule.

sperm of

rival

males.

Humans

Males

among

primarily

monandrous

one-

female

who

conspicuously

able to prevent other males

testes

weighing just 27 grams,

his

chimp. Because a

sperm competes

inside the

have testes proportionally larger

than those of the underendowed gorilla, but considerably smaller than those of chimps.

with orangs

in

body weight than do males

testes of a considerably smaller, 4^-kilo

chimp does not have the luxury of excluding competing males, female's vaginal tract with the

219

conform with the general

units, like gorillas, have smaller testes relative to their

advertises ovulation. Hence, a

compared

BABY

A

Men

fall

(or one-male-at-a-time) breeders. This might be

interpreted as showing that our ancestors lived in one-male breeding systems, but with just

enough could

lapses to maintain continuing selection for

mean

that selection favoring large testes

moderately large

testicles. Alternatively,

was once important but no longer

is,

and

it

men are

slowly evolving smaller testes. With no advantage to maintain the extra sperm -producing capacity

of testes, through time the average testes size in humans might

counts lower.

become

smaller

still,

sperm

(Courtesy of the A. H. Schultz-Stifwng, Anthropological Institute, University of Zurich)

Larger testes give a competitive edge to the male

most competitive) sperm. But without

DNA

who produces the most (or who knows which male

tests,

that is?"

Woman's Sexual Legacy From

galagos to bonobos, female primates range from being sexually recep-

tive for just a

few hours right around midcycle to being

able to copulate

(although not necessarily desirous of doing so) across extended periods of the

MOTHERS AND ALLOMOTHERS

220

A

Fig.

9.9 a and

b.

Early reports about bonobos sounded like flights of feminist fancy. In addition to

their free-wheeling sexual ways, females have feeding priority,

with the offspring of female friends. Bonobo swellings can ual attractiveness helps females to

cement

last

and may share food they obtain

weeks

at a stretch.

Prolonged sex-

and to exchange sexual favors for food,

alliances

(a)

This bonobo engages in face-to-face sex, rubbing her genitals against those of the female beneath her.

As

common

in

than that of a

chimps, the bonobo 's

woman.

In

bonobos

it is

clitoris (insert b) is

frontally placed,

both absolutely and relatively larger

presumably to

facilitate

the achievement

of orgasm during genital-to-genital rubbing and to provide a proximate reward for alliance building.

Some

evolutionists have argued that the clitoris

present in females because

it is

necessary in males.

More

ated independently on the clitoris and the penis. This clitoris is larger

larger in

cycle.

nothing more than a vestigial penis,

likely,

Human

in either

females

flexible,

bonobos or chimps.

fall at

^ '

however, selection has also oper-

would explain why the chimp and bonobo

than that found in humans, while the opposite

humans than

edge of

is

is

the case for the penis, which

is

(Courtesy ofAmy Parish)

the extreme end of this continuum, at the far

situation-dependent receptivity. Although in most cultures

people avoid intercourse during menstruation and for lon^ periods post-

partum,

women

are capable of mating

on any day of the menstrual

cycle. Yet

vestiges of "estrus" (or cyclical sexual urges) persist.

Like other primates, libido

when

women

experience a mild to pronounced increase in

between menstruation and ovulation, during the phase of the cycle the follicle ripens

iri

preparation for releasing the egg. The exact time of

ovulation can be speeded up or slowed for example, a

down depending on

woman is exposed to pheromones from

circumstances.

If,

the armpits of another

— T H R

woman who

is

i:

K

M

K

N

A N n

about to ovulate,

just

it

may

A

B A B Y

2 2

I

cause her to ovulate sooner. In

1998 Martha McClintock, one of the pioneers of biosocial psychology, experimentally confirmed the existence of these long-suspected airborne chemicals wafting from one

woman

woman

was able to entrain one

to another. She

to another's cycle by attaching cotton swabs

donor to the upper

lip

of a

woman

in

from the armpit of the

another cycle phase.

'^

This olfactory component to female cycling has to be very old.

may be

The same

said for behavioral predispositions linked to ovulation, such as a

woman's increased sexual yearnings

at

midcycle. These responses serve as

reminders that even though our rear ends do not swell up and turn bright red

and although we rationalize our actions more than baboons

like a chimp's,

and langurs do, the origins of our sexual urges predate the Pleistocene. Modern hominids have not entirely

although

its

manifestations

become much modified and subdued.

have

A

broad range of

field

and laboratory studies

around the time of ovulation

more

are

lost cyclical estrus,

—when

a

likely to feel self-confident, to

initiate sex.

This pattern

now

women

confirm that

monkey or ape would be

in estrus

experience erotic fantasies, and to

became apparent when researchers excluded sexual

behavior initiated by husbands or lovers and just focused on female-initiated sex.

A woman

also has a

around ovulation

—

somewhat lower threshold

a patterning to

orgasm

for experiencing

female libido found in both heterosexual

and lesbian pairings, and during both intercourse and masturbation.'^

Women

at

midcycle are more restless and move around more. They have

enhanced motor

capability, possibly a

heightened sense of smell, '^ and are

probably better able to discriminate healthy from unhealthy people. All in

women ter,

at

midcycle

test higher, including in

an academic sense

—

all

all,

the bet-

one assumes, to use their "wanderlust" to greatest advantage by assaying

the available males and choosing well, and perhaps also using heightened sensitivity to

danger to avoid punishment by possessive mates. Recall

West African chimps who slipped away

to the neighboring

back without anyone (apparently other chimps

as well as

(p.

85) the

community and

human

observers)

the wiser.

So

far the

only in-depth study of hunter-gatherers that combines personal

interviews with information on a woman's cycle state (determined from

blood samples) to the

is

the one done in the 1970s

same community

Konner documented

as Nisa.

among

eight

Anthropologists Carol

statistically

significant

increases

women

belonging

Worthman and Mel in

"sexual

desire"

.

MOTHERS AND ALLOMOTHERS

222

around the time of ovulation. These

women were more

hkely to report hav-

ing had sex with their husband during the foHicular phase of their cycle than

during the postovulatory, luteal phase. They were also to have sex with it

orgasm.

For

a

men

time more

likely

other than their husbands. Midcycle also brought with

higher probability (not

a slightly

at that

statistically significant)

of experiencing

19

long time,

it

was assumed

that the female

orgasm was

a

uniquely

human

trait. Some even suggested that female orgasms evolved in the course of human evolution to make women satisfied with one male. But this is unlikely. For one thing, we now know that female orgasms occur in at least some other

primates, although in a different context than in humans. It is

^*^

possible that in baboons and chimps the pleasurable sensations of sex-

once functioned to condition females to seek sustained

ual climax

clitoral

stimulation by mating with successive partners, one right after the other, and that

orgasms have since become secondarily enlisted by humans to serve

other ends (such as enhancing pair-bonds) Anyone .

the occurrence of female orgasm

is,

who

notices

how

erratic

from intercourse alone, compared with

male orgasm, which invariably accompanies ejaculation, might well wonder

whether this curious psychophysiological response currently has any adaptive function at

all.

Recently, British biologists Robin Baker and

Mark

Bellis

suggested that

female orgasms do currently have a function: to ensure that a mother's egg fertilized

by the best male. Their hypothesis

rests

on three

as yet

is

unproven

assumptions:

1

that

orgasm produces an "upsuck" response

that increases

sperm reten-

tion; 2. 3.

that

orgasm increases the probability of impregnation; and

that

women are more likely to experience orgasm when who have superior genes.

mating with

males

So

far, all

that has

clitoral stimulation,

been conclusively demonstrated any female achieves orgasm

is

that given sufficient

—with

a

female partner, or masturbating alone, although females

male partner,

a

may experience

THREEMENANDABABY

— which may

orgasms more readily

at

more

become pregnant but

likely

not only to

A persuasive

midcycle

case can be

made

that

also

223

when women

be

are

to seek extra-pair copulations.^'

orgasms (whether

in

women

or bono-

bos) dispel tension and strengthen bonds between partners. But such observations are not sufficient to argue that orgasms evolved for this purpose, or that

orgasms currently have any

keep her infants

alive. If

effect

on

woman's

anything, the opposite seems

that the vast majority of

women

fertility

more

or ability to

nearly true, given

today across large areas of the world (much

of Asia, North Africa, and the Middle East) eties.

a

live in

coercively patriarchal soci-

Female libido and sexual assertiveness are dangerous predispositions

such contexts, more

likely to get a

woman

to increase her reproductive success.

For compared to other primates,

in

beaten, disfigured, or killed than

^^

men

have

many more

sources of infor-

mation about where their mates have been, and what they have been doing is gossip). Knowing how risky extra-pair sex can often my own species has led me to wonder if female orgasms may adaptive retention now no longer selected for, like the grasp of a

(not the least of which

be for females in

be a once

just-born baby for maternal fur that no longer exists, a reflex gradually fading

human repertoire. If so, our descendants living on starships eons from now may find themselves wondering what all the fuss was about. out of the

Much

has been

made of the

fact that

do. In Darwin's time, experts sive

men

have stronger libidos than

were convinced

and that "the appetite never asserts

that

itself."

women were Today

it

is

women

sexually pas-

assumed

that

women are interested, albeit not nearly so much so as men. When asked by a psychotherapist how often she and her husband have sex, Diane Keaton I'd

in the title role

say three times a week."

answers, "Hardly ever.

of the film Annie Hall complains, "Constantly!

By

Maybe

contrast,

Woody

three times a

Allen, playing her husband,

week ."To make

this

same point

using quantitative data, evolutionary psychologists have a favorite experi-

ment. They send out student

shills

to proposition opposite-sexed "research

subjects" encountered about campus. In line with both the old stereotypes

and the widely accepted predictions from evolutionary theory, 7^ percent of the male students approached agreed to "go to bed" with the experimenter (no information available on what happens next), while none of the coeds

MOTHERS AND ALLOMOTHERS

224

The dichotomous

did.

results

conform to the widespread expectation

that

ardent and lustful males pursue discriminating, chaste, or even, as Darwin

termed them, "coy" females.

The

experiment are taken

results of the solicitation

tion of Robert Trivers's truism: since

more males.

^

much more

invest so

much

cannot afford to be indiscriminate;

selective about

But the tricky part comes

powerful confirma-

mammalian mothers

in offspring than fathers do, they

they need to be

as

when

who

they mate with than do

the interpretation of these results

is

taken a step further, cited as proof that there has been far stronger selection

on male sexual desire than on been no selection the sexes

in

that of females, or even to

women for sexual desire.

Such

a

show

that there has

black-and-white view of

seriously at odds with field observations of female chimpanzees

is

and barbary macaques

in estrus soliciting

and copulating with multiple part-

ners with a lust and avidity that evolutionary theorists traditionally reserve for males.

extreme forms, such stereotypes derive not only from wishful

In their

thinking on the part of Victorian

experiments ignore

woman

to

soliciting

social context.

go home with

her to be perceived

a strange

is

and then, after

is

doing

dangerous to her reputation for

so, especially

when

the individual

an only intermittently

if a

counters his

may go down

a continu-

fertile female. all

the time. Males ejac-

in successive ejaculations,

a male's batteries

novel and desirable partner

own

on

in the testes goes

is

An

a refractory period, can, given the opportunity, ejacu-

Their sperm count

soon replenished. Indeed, than later

both physically dangerous for a

is

one of the subjects being compared

that

men, production of sperm

late again.

It

her behaves so peculiarly and indiscreetly as the experimenter.

ously potent male, the other

ulate,

but from an invalid comparison. The

man and

as interested in

even bigger problem

In

men

but

may be recharged sooner

is

introduced, or

partner after a long separation. In short,

if a

it is

rather

male reen-

this is a

gamete-

making machine almost continuously charged and ready to reproduce, not just ever-ready to

to a

mate but ever-ready to

fertilize.

Compare Mr. Ever-Ready

woman.

Women,

like

men

(indeed, even

more

so than

men,

since

no erection

need be sustained) are continuously able to copulate, even though they may not, and often

do not, desire

to.

men's and women's libidos to

However,

just the

if

we

period

confine the comparison of

when women

are actually

reproductive, comparing Mr. Ever-Ready with Ms. Intermittently Fertile,

"

THREEMENANDABABY

22^

much-remarked dichotomy between ardent males and coy females begins

the

to pale.

but

it

Given the boorish behavior of the

would be informative

if

to detect whether or not she

shills,

the coed

the experimenters had

still

more

ought to say no;

sensitive

methods

was aroused by the proposal.

Why Smart Women Make Foolish Choices Adaptive or not, holding steady or fading out, estimate the

we

power of libidinous

No to

would be

a

mistake to under-

love ."Ancient legacies figure here as well.

call "falling in

one has been more innovative

Dutch sexologist Koos

cyclicity than

it

retentions. Consider the mysterious process

in

examining the subtleties of women's

Slob. Slob

was among the

measure uterine contractions and increased heart

first scientists

rate in female

macaques

during sexual climax, thus helping to confirm that female orgasms occur in other primates and were almost certainly part of the package of traits the earliest

hominids brought to the human experiment.

cated

new

techniques to measure sexual arousal in

not just by

how

During the

first

more aroused by

half (or, follicular phase) of their cycle,

erotic films

—

were

culturally constructed, or

a result

on context. But

work

Slob's

human mate

an animal whose sexual responses

in

among whom

love and

was more

it

be sexually aroused by

romance depend only

warning for those

also carries a

choices to simple chemistry. first

likely to

responded to

was

cycle state.

It

dence over

how

Along with

it

the

time she saw the film footage

than were controls

same way she had the

as if recollections

fertile she

all

was on

who would

A woman who happened to

film at other times. But the second time the test subject

film, she

women were

than during their postovulatory (luteal)

one would expect

be in the follicular phase of her cycle the

same

women, he was amazed

implications of that cyclicity could be.

phase

not

Slob used sophisti-

profoundly cyclical women's sexual responses were, but by

how far-ranging the

reduce

When

first

who saw

the

saw the same

time, regardless of her

of her past libidinous feelings took prece-

that day.

the sensible things a prospective

ing to (such as a potential mate's health,

body

mother should be attend-

size, strength, ability to

protect

her and her children, his intelligence, and indicators of "good genes"),

women may cycle day

also

be influenced by such seemingly extraneous variables

on which they

Imagine: a

woman

first

at

as the

met.

midcycle looks

might otherwise do. Chronically alert to

at a

man more

intently than she

just such opportunities, the

man

— MOTHERS AND ALLOMOTHERS

226

Stares back. Subconsciously,

pupils,

he notes her body language, the dilation of her

and gauges her interest and responds accordingly.

another

.

.

.

when,

but,

emotions will be colored not just by aroused.

make

It is

a

warning to

women

An

thing leads to

how she felt when first on why smart women so often

his merits,

comparative sexologist's angle

foolish choices.

One

her cycle, she remembers that man, her

later in

but by

awareness of our primate heritage carries with

it

a

of good sense to keep an eye on their calendars. Ovula-

tion can be hazardous to your judgment.

Some

Fathers Who

Can Afford to Care

Human mothers need male

investment

as

never before.

No

other primate

produces babies quite so needy, or dependent, for quite so long. Yet theoretically only a

vide

it.

Of the 40

care, only ity

male with

a high certainty of paternity should

monogamously mated males

of being the father provide

tion for different

human

direct

like titi

and

monkeys with

extensive care.

Ethnographic informa-

is

most

intensive

a high certainty of paternity.

where monogamously

^^

Consider the Aka pygmies of Central Africa. During the life,

the average father holds his infant

marry just one

fathers mostly

months of

first six

more than 20 percent of the time and

remains within arm's reach of the baby an unheard-of

Aka

a high probabil-

societies (these data all referring to the same species)

similarly suggests that paternal care

mated men have

be willing to pro-

percent of primate species that exhibit some form of male

5^0

percent of the time.

wife. They spend long periods at

camp and

appear to have invented "flex-time." Help from fathers sustains relatively high fertility

(Aka

women

average 6

among

to rise any higher than

Aka togetherness

all

safely

—

is

births) without causing child mortality

the !Kung,

facilitated

is

mostly for small game

dren can

3 live .

by

who reproduce

a family-friendly

done using

nets, so that

How

slowly.

men, women, and

When men

chil-

go

off to hunt,

was the Aka

lifestyle for forest-dwellers in the Pleistocene?

logical discoveries indicate,

more

typical or atypical

and practically participate.

mothers and children go with them.

far

workplace. Hunting

Not known. Recent archaeo-

however, that hunting with nets

is

very old, dat-

ing back 30,000 years or more. In Western industrial countries like the

hailed as the

viewed

new "era

in a recent

United

States, the

1

990s are being

of the involved father." Fifty-six percent of

study by the

spend more time with their

DuPont company

families.

But

is

men

inter-

indicated that they want to

this really so

new? Ethnographic

—

'

THREEMENANDABABY men were

and historical sources suggest that some with their families. Variation ilar

among men

227

always interested in being

in the past jDrobably fell

continuum ranging from the "new man," proudly and euphorically

"engrossed" in his baby son, to the stereotypical self-absorbed as

along a sim-

if they do not know they have children,

them

to investing in

fathers" notwithstanding, the

tion to a valid observation. Across cultures, the is

act

.

Hype about "new caring for kids

CEOs who

to "deadbeat dads," totally resistant

DuPont survey

calls atten-

amount of time men spend

the best predictor of how connected they feel toward them.

For example, the same proximity that puts a foraging father on the spot to help out, and induces him to

become emotionally involved with

An Aka

brings greater certainty of paternity.

day within view of his wife. This

become

to ethnography

ideal types

—

father spends

one reason such peoples

is

his kids, also

46 percent of each as

the'Aka have

what titi monkeys are to primatology. Both represent

"chestnuts," as

between pair-bonding and

it

were

—

useful for illustrating a correlation

direct and extensive

male

care.

The Hearts of Men Given the obvious advantages of male

care,

—

human fathers in particular always tend to more attention to infants? Part of the reason,

why

don't primate fathers

their progeny, or at least devote as

I

hope I have shown,

is

simply

opportunity and exposure. Given the right circumstances, males do care. But

why women have lower thresholds for responding to infant needs than men do. Males who invested in infants not their own would be genetically out-competed by males whose priority was there are also

more fundamental

reasons

seeking additional mates. Males are torn between impulses to protect and care for their offspring, at least a ners.

and their desire for novel part-

little bit,

30

From a man's perspective, time when she is most fertile

a is

mate with heightened a

dangerous

liability.

Not long

economist Claudia Golden assumed she was making fathering

when

men whether know.

."^' .

.

"We

she quipped that

they have children.

But truth to

tell,

I

how

libido at precisely the

a joke

ago, feminist

about remote

never ask [high-powered career]

guess

we assume some

of them don't

could they? Golden had inadvertently

stumbled on one of the ultimate causes of bad fathering, the nagging problem

male primates have always faced: mates are not

like fish,

How

to be certain of paternity?

where males come along and

fertilize

We

pri-

eggs that

228

MOTHERS AND ALLOMOTHERS

are already laid.

Nor

are

we

absolutely monandrous, like the pronghorn

among whom a female mates just one time per conception. It's not wise father who knows his own child," it's either a father who runs his

antelopes, just "a

home like a seraglio with a eunuch at the gate,

or else one

who has a DNA fin-

gerprinting lab at his disposal.

True enough,

as

economist Golden

stresses,

striving for status (in part to impress other

men

many men

are far

too busy

and additional mates) to be

anything other than oblivious to their children. But there

is

another reason

men ignore their infants: their thresholds for paternal investment are set high. And the reason for this is that female primates did not evolve so as to

these

guarantee their mates certain paternity. For humans the consequences can be surprising.

The Show-Off Hypothesis In 1986 a

group of behavioral ecologists embarked on

a re-study of the

Hadza

of northern Tanzania. Aware that hunting was the main source of protein, they began with the classic premise of optimal foraging theory. They predicted that

men would plan their hunts so

as to

maximize the amount of meat

they brought back to camp, consistent with acceptable risk-taking. But the researchers were surprised to discover

This

how

inefficient the hunters were.

a full

out for the biggest prey they could take

and marvelously fleshy eland.

Men

—

creatures like the sleek, elusive,

tracked these imposing beasts for days,

even though the same effort devoted to lesser prey fowl

A

month of failures for every successful kill. was not because game was hard to come by, but because the hunters held

Hadza hunter could expect

—would

Whenever sights, the

the researchers could persuade the hunters to lower their

Hadza

invariably

The second was discovering Hadza hunter did

own

came out ahead

family.

A

it

in

terms of protein and calories

Self-inflicted inefficiency

that after a

something

kill

hunter

enormous 3^0-kilogram majority of

hyraxes or guinea

yield higher returns.

earned for effort expended.

for his

—rock

big,

who

month

was the

first

surprise.

of unsuccessful hunts,

when

a

he retained only a fraction of the meat

killed an eland kept only

carcass for his

own

1

9 percent of the

wife and children. The vast

was shared with other group members who spontaneously

appeared "to help" eat

it.

resort to hunting small

Only

game

if

a

hunter repeatedly

failed

and was forced to

did his family get to keep the entire portion.

THREEMENANDABABY Well, such

meat

for

one

is

the price of success, one might argue.

family.

But the Hadza climate

is

229

An

eland

is

too

much

very dry. Sliced meat quickly

develops a crusty rind and could easily be stored, or traded as jerky. Yet

does not happen. As

is

typical of hunter-gatherers,

this

Hadza hunters neither

brag about success nor attempt to claim meat as personal property.

^^

Instead,

—sometimes memory —

they tolerate a system in which the families of failed hunters including families of men

who have not killed

prey in anyone's

can

end up with the most meat.

more a hunter obtains, the more he gives away. This is a fairly general pattern among hunter-gatherers. From each according to his means, to everybody else. Had evolutionary storytelling come full circle, back to group selection? Were men storing up credit for another day, against an unlucky stint when the hunter would have nothing, According to the Hadza

ethic, the

while another, luckier, group

meat so

member might

have meat to reciprocate?

rich and succulent, so desired and public a good, that

Or were men

afford to retain exclusive access?

Was

no man could

choosing to hunt larger prey

because by killing a creature with mythical status some of the animal's chais when one of the team, Kristen game meat that a man would have to might not be worth more to a man in terms of prestige than as

risma rubbed off on the hunter? This

Hawkes, started to wonder give away

—

if

large

—

food in the mouths of his children.

According to Hawkes 's "show-off" hypothesis,

it

was reputation

hunters were maximizing, not protein. Not only would other

him more, but women wowed by of

gifts

effort

his

respect

prowess and intrigued by the prospect

of meat might grant him sexual favors.

was more nearly reproductive

men

that

What looked

effort, as hunters

like parental

exchanged food for

sex in a time-honored performance characteristic of every primate in which

males hunt.^^ That for

"women

like

meat" was the standard !Kung explanation

why a particularly poor hunter remains a bachelor and has no prospects

of

ever being anything but celibate.

How^

typical are

Hadza show-offs? Not known. However,

a recent

survey

of the shopping habits of 167 British couples was eerily consistent with

Hawkes 's view of male

foragers: "showing off" took priority over

economy.

MOTHERS AND ALLOMOTHERS

230

men

Even when

have the same amount of shopping experience as

husbands and boyfriends shop

less

women,

economically. Seventy-three percent of the

time they chose different brand names than their wives, almost always more expensive ones.

Men

butter, ^ percent

spent

more on

o percent

i

coffee.

more on shampoo,

Men

apparently find

brand names and the occasional big-ticket items

burgundy are

more

—

6 percent

it

hard to

the thirty-dollar bottle of

that magically materializes in the shopping cart.^^

tantalized than

women

more on

resist the

Male shoppers

by the prospect of showing off with the

"grand gesture."

Economic surveys from developing countries and Ghana

different as India, Guatemala,

as far afield

and

as culturally

reveal that the nutritional level of

children in a family does not increase in direct proportion to paternal

income. Only increasing women's income has a direct hypothesis

is

not only consistent with the

man who

pint with his buddies while the kids are hungry at tistics

from the United

The show-off

effect.

stops off at a

home, but with

pub

for a

actual sta-

Department of Health and Human Services

States

concerning the large number of men

who

are

more amenable

to

making car

payments than paying child support.

Monogamy as a Compromise That Children Win Once

again, Nisa's biography provides a

the tensions underlying

human

monogamously. When her Nisa recalls,

"1

first

!Kung San forager's perspective on

pair-bonds. Nisa marries four times, always

husband, Tashay, brings

home

a

second wife,

chased her away and she went back to her parents." Several of

Nisa's marriages dissolved

under the

strain of infidelities, either her hus-

band's or her own. In addition to her four husbands, eight lovers pass in and

out of her

Nisa

life.

is

quite obviously in love with several of them. "Pair-

bonds" were formed, but the relationships did not

Two

of Nisa's pregnancies probably derive from

than her husband

and more

when

last.

like

at the time.

As

Nisa's daughter Twi

her husband's brother, with

whom

affairs

with

men

other

grows up to look more

Nisa was having an

affair

the child was conceived, her husband reminds her that his younger

brother

is

the likely progenitor and therefore "will help take care of her."

Whenever Nisa

finds herself

between husbands, when she

is

widowed or

divorced, she sets out across the Kalahari to find her brother and live with

him.

MENANDABABY

THREE Hunter-gatherer societies

tional societies ever get. Nisa's

dominate

able to

her, but

if

!Kung San are

like the

231

as egahtarian as tradi-

husbands were physically stronger than she,

she was unhappy enough, Nisa could always vote

with her feet and leave. Even

when

Nisa was caught by her husband in

fla-

grante delicto with a lover and beaten and threatened with murder, others

stood up tor her, and ual adulteries

life

went on.

would have been

In

more

patriarchal societies, her perpet-

lethal.

Since none of Nisa's children survived to adulthood, the

woman

life

of this spunky

can scarcely be said to typify success in evolutionary terms. Yet the

tensions that characterized her marriages are the same ones that Nisa's

mother mentions. Again and

up

again, her predicaments crop

in

women's

life

stories.

Nisa cherished her freedom of movement, her freedom to choose mates, and,

if

her husband did not provide sufficient food, her freedom to negotiate

with lovers. Each husband, on the other hand, wanted multiple wives for himself but also to maintain exclusive sexual access to Nisa. There

dynamic tug-of-war pipe dreams about

in these relationships that

humans having an

is

at

is

a

odds with conventional

innate tendency to

pair-bonds, unions in which both sexes have a powerful

form

long-lasting

commitment from

within to adhere. Such cases make it hard to sustain the illusion that lifelong monogamous families are the natural human condition. Monogamy in Nisa's case is more nearly a compromise than a speciestypical universal. Monogamy is the most harmonious common ground she and her husband of the moment can arrive at. And when it works, children benefit. Monogamy reduces inherent conflicts of interest between the sexes.

Her reproductive success becomes relations

between genetically

his,

and vice versa, promoting harmonious

distinct individuals striving

toward

common

goals.

Sociobiology sex. Yet

its

is

not

a field

most promising

time, lifelong

monogamy

known

for the encouraging

news

it

turns out to be the cure for

all

sorts of detrimental

devices that one sex uses to exploit the other. As usual, this point vincingly demonstrated in organisms that breed do.

Once

offers either

revelation to date has to be that over evolutionary

again, fruit flies are the

much faster

is

than

most con-

we humans

organism of choice, the current favorites for

studying coevolution between the sexes. This time, the experiments have a

"happy ending."

MOTHERS AND ALLOMOTHERS

232

Recall that female fruit

flies

mate promiscuously with many partners. To

counter female promiscuity and thwart their

rivals,

male ejaculate

laced

is

with special components that enhance an ejaculator's reproductive success,

even though their cumulative effects in

in

females are toxic. Amazingly though,

monogamy,

forty-seven generations of experimentally imposed

just

Rice produced strains of male

researchers Brett Holland and William

drosophila whose seminal fluid was no longer toxic to females. At one level,

monogamy

compromise

a

is

offering something for everyone

immatures. All males got to breed,

among

males, but they lived longer.

who

So

—

Females had

at least a little.

especially

choice

less

Meanwhile, offspring were more

viable.

says evolutionists are necessarily antithetical to family valuesPThe-

oretically at least,

1

would not produce

know

of no reason

why Holland and

similar results in the

experiment

Rice's

temperaments of men and women,

although the experimenters would need to locate a population of volunteers

who

could precommit for descendants, guaranteeing their absolute

for fifty or

whose

No

more

generations. The result

first priorities

more

mother

as a

monogamous

and emotional

in the

modern world, where

life,

satisfaction.

1

personally

1

am

made.

assume

made

they

1

am

aware of my

as

would cause

me

under different circumstances

to project

—

the

we

two

bias,

1

have for

upon my ances-

same choices

I

have

40

1

I

lived

if

place a high priority on the benefits that

hominid mating systems

—who

children

marriage. Long-term trust permits unparalleled efficiency

consciously guard against distorted readings of such evidence

tors

women

partial to the companion-

cooperating parents offer children. Precisely because

early

and

parental investment than ever before over a longer time

are to prepare for a successful ate

a strain of men

were to the well-being of their children.

wonder, then, that

require

would be

fidelity

that

mothers

their decisions

would

in the past

under

scarcely be wise, or

were

emotionally similar to

different, vastly

fair,

more arduous,

to extrapolate

my

me. But they

circumstances.

It

self-interested priorities to

them. Nevertheless, from Victorian times to the present,

this

is

what many

anthropologists and evolutionists have blithely done.

Earher commentators

failed to

consider

how

unusual are the particular

environmental and demographic conditions that make long-term

monogamy

THREE MEN AND

Fig.

9.10 Underlying male tradeoffs between investing

ings have not

changed

between what

fathers

all

that

much

News/ Cartoonists

Si.

must be

in a position to protect

233

parenting effort versus additional mat-

women

Nor have

the perennial tensions

and children need them to do.

(Signe

Writers Syndicate)

advantageous for both sexes. For

rates

BABY

in the last million years.

might prefer to do and what

U'i/iinson /Philadelphia Daily

in

A

monogamy

to benefit a mother, her

mate

her or to reHably provision her. Demographic

and sources of mortahty are also important. High adult survival rates

among men make

it

worthwhile for them to invest

in relationships.

But does

the protection they offer matter? This depends on what the sources of infant

mortality are (pathogens, or

human

enemies?).

Where

ence and infants also have good prospects of survival,

emotional luxury of sharing

When, however,

An

a differ-

can afford the

to quality over quantity.

men go

to great lengths to sire as

many

it

as possi-

hopes that some will by chance survive.

old ditty provided by psychologist William James

sociobiologists.

It

runs: "Higamous,

Hogamus, higamus, men ald

commitment

a father

make

children are susceptible to sudden, unpredictable demise,

should not be surprising that ble, in the

his mate's

fathers

is

a great favorite

with

hogamous, woman's monogamous.

are polygamous."

Contemporary Darwinians Don-

Symons, Roger Short, and Laura Betzig have made strong cases

that

men in

— MOTHERS AND ALLOMOTHERS

234-

the past sought

many mates because by doing

ductive success.

Women,

so they increased their repro-

by contrast, did better locating one good

ing and able to invest in her offspring. But there ditty:

"Except where males are poor providers,

resources are unpredictable if

they can be so

safely.

"fathers" than with

—

then mothers are

A woman's

children

is

man

will-

a missing caveat to James's

likely to die

young, or

when

far better off polyandrous"

may be

better off with several

one inferior or unreliable one.

Unpredictable providers confront mothers with a dilemma: Should she rely

on one man

for

much, or on

several for something? What about in patri-

archal societies,

where maternal choices

Should she seek

i

are circumscribed

oo percent of a poor mate or

settle for

from the

some

fraction of the

investment to be provided by a polygynously mated potentate? mother's perspective, the optimal number of "fathers"

all

outset.

depends.

From

a

o

I

The Optimal Number of Fathers seemed that [Rosamond] had no more identified herself with [her husband,

It

Lydgate] than if they had been creatures oj different species and

opposing

— George

That

fathers matter

interests.

.

Eliot, in Middlemarch,

.

1872

obvious. But they cannot always be relied

is

upon. When fathers die or defect;

and then decamp, or when they violence of other

.

when men seduce

fail

or rape

to protect their wives

women

from the

men; when husbands seek other mates, prospects

are

diminished for the offspring they leave behind. In the absence of effective laws protecting the person or property rights of to rely

on such

or, failing

women,

fathers or alloparents as they could enlist

them, male

No

kin.

how good

skilled a hunter,

early

—

mothers had

husbands, lovers,

how Apollo-like the progenitor, how genes, how viable his immune system, his

matter

his

absence put his children at a disadvantage. Even in matrilineal societies,

where descent and transmission of rights line

are transmitted through the female

and mothers typically have an unusual degree of reproductive autonomy,

when property

rights are transmitted, they

still

brother to her son. Parents recognize that sons are

pass

more

from the mother's likely to

be able to

hold on to property than daughters are.

Being Fatherless In industrialized countries, disadvantages to fatherless families include eco-

nomic hardship, reduced

status,

and generally declining prospects. Costs to

children are measurable in poorer school performance, higher rates of delin-

quency less

for boys,

children are

"I

when

am

and early pregnancies for

more

she lost her

foraging societies father-

likely to die.

." the !Kung San woman Nisa wailed man married first husband. Men were the main providers of protein.

without the

Well might she

girls. In

ask:

I

"Where

.

will

I

.

see the food that will help

23^

my

children

MOTHERS AND ALLOMOTHERS

236

grow? Who

is

going to help

younger brother are

Among

me raise this newborn? My older brother and my

far away."^

the Ache, an infant

who

to die before the age of two. Even

whose parents divorced were riage endured.

When

lost his father if

was four times more

the father was

three times

more

still

alive,

likely to he killed

widowed or abandoned mother

a

risks to her infants shoot up. Terrible prospects are

likely

Ache children

than

if

the mar-

new

takes a

mate,

one reason why some

for-

aging peoples bury orphans alive along with the deceased parent.^

Stepfathers Worse Than

No Father

Westerners appalled by such barbaric treatment of the fatherless should take a

look

at their local

nowhere less, in

newspapers. Child homicide

tolerated, very

much

against the law, and

North America when the

longer lives in the

home and

instead, this rare event

The murder of

is

is

uncommon. Neverthe-

father of offspring

under two years of age no

man

or stepfather lives there

an unrelated

seventy times

infants

in civilized societies

more

likely to occur.'*

by stepfathers or mothers' boyfriends resembles

the circumstances under which sexually selected infanticide evolved in other

primates: males from outside the breeding system increase their to breed by eliminating offspring sired by rivals.

The

own chances

superficial similarities

have sometimes led to the erroneous conclusion that child abuse it

today

is

or once was adaptive.^

Some

clarification

is

as

we know

in order.

Canadian psychologists Martin Daly and Margo Wilson were the demonstrate increased risk to infants from having unrelated house. They were careful to stress that in postindustrial neither child abuse nor infanticide

boyfriend goes to tant, the attacker

side

it:

jail is

and the mother

is

is

adaptive.

More

men

human

first

to

in the

societies,

likely than not, the

prosecuted for neglect.

More impor-

not some invader entering the breeding system from out-

he already has keys to the apartment and access to the mother's bed.

Imagine: the mother goes off on an errand, leaving her baby in the boyfriend's care. She

may

or

may not have an

inkling of the risk. Perhaps she

senses that her boyfriend resents diversion of household resources, including

her attention, to some other man's child. selves

sometimes

(Among

kill fatherless infants after a

the Ache, mothers them-

conscious evaluation ot what

— THE OPTIMAL

N U M

OF FA T

B H R

H

H

R

237

S

the future holds.) Perhaps hoytVicnd and baby arc already off to a bad start all

the

more reason why

the baby

may

reject such tentative

man

offers.

cries,

makes demands not

way

sensitized for this task.

Mother Nature has

The baby

willingly

comfort

met by

a

as this

man

in

no

set high his threshold against

altruism toward this insatiable stranger. Because of the low degree of related-

between the man and the

ness

child, the benefits don't

come

close to out-

wei2;hin^ the costs of care.

But beyond his lack of solicitude for an unrelated, very vulnerable but

demanding dependent, the abusive boyfriend may have

mon

monkey

with an infanticidal

little

more

in

com-

than a certain nonspecific impatience, a

general predisposition to respond violently to repeated annoyance. By con-

with the boyfriend's violence, the infanticidal langur's attack

trast ful

and goal-oriented. Injury comes

after

purpose-

is

hours of single-minded stalking of

the infant. Such males are often in a special state of arousal, as evidenced by

an erect penis, though without other indications of sexual interest. The lan-

gur utters

a distinctive

hacking vocalization,

other contexts. His attack If

male die

is

if

in the skull.

mother eludes him, the langur

the

starts over, inching closer. Infants killed

is

in

organized and focused as a shark's.

relatives of the infant intervene, or

from puncture wounds

way

as

heard

a "cackle bark," rarely

by infanticidal langurs typically

To use canine teeth to

bite a

baby that

the simian equivalent of pulling out a hunting knife and stabbing the

quarry. This behavior,

when

Infant-biting bv usurping

observed, cannot be considered accidental.

male langurs bears

little

resemblance to the tragic

blend of frustration, brutality, and terrible judgment that results

in

"shaken

baby syndrome."

A more

appropriate animal analogue for a brutal stepfather would be an

alloparent of either sex compelled to invest in an infant he or she has lost interest in.

The motive

tive access to the is

is

not to

kill

the infant in order to increase reproduc-

mother, but to rid oneself of an encumbrance.

What

evolved

not the bizarre and maladaptive alternation of solicitude with torture that

we know

as "child

in a solicitous

abuse ."What evolved was a high threshold for responding

way toward an

offspring not likely to be genetically related

the equivalent of emotional earplugs.

When Strangers Capture Mothers Boyfriends their

own

who

fatally

abuse babies in their charge do not thereby enhance

opportunities to mate. But

when

raiders abduct

women

and leave

MOTHERS AND ALLOMOTHERS

238

Fig.

I

o.

I

When an experienced, middle-aged

langur uses her back foot to scrape off a babv she has borrowed and then tired of, abusive. But she does not so

harm

much

the infant as to prevent

to her. Free of her

it

it

looks

seek to

from clinging

encumbrance, she leaves

the infant alone. Fortunatelv, an abandoned

baby the

Blajfer

behind or savagely

men

It

has the

(Sarah

Hrdj/Amhro-Pboto)

infants, they often do.

same outcome

mean that the killing

ilar in its

males

What then? Are

these

as

as infanticide

of infants by such

does in other primates. Does

men is homologous

mechanisms and evolutionary origins

—

—

that

is,

sim-

to infanticide by raiding

other animals?

in

Some war

picked up within minutes by either

expressing infanticidal tendencies such as those that evolved in other

primates? this

unweaned

kill

is

mother or another allomother.

cultural anthropologists dismiss such behaviors as infanticide during

pathological,

produced by colonial transformations of otherwise

peaceful tribal worlds.

Some

dismiss

all

forms of murder

deranged. They assume evidence from other species

is

as idiosyncratic

or

irrelevant because

animals have no symbolic culture. They assume that infanticide, to the extent that

it is

really

condone

going on, must be due to culturally constructed attitudes that

brutality.

Yet the earliest evidence tives, suggests that raiding

we

have, from the Iliad and other ancient narra-

goes way back.

New assessments of archaeological

evidence (recently and cogently summarized in Lawrence Keeley's War Before Civilization) flict

convinces

me

that

men

over access to resources, just

have always en^a^ed in intcrgroup con-

as

males do

in

other primates using

less

among

the

elaborate or calculated means. Intertribal conflict

is

very ancient, and fertile females arc

resources likely to be competed difficulty

comes

in trying to

be

for.

Clearly, animal evidence

specific

about just how

does the capture of mothers put their children

bad enough that infants are often forcibly

left

at

it is

is

relevant. The

relevant. yu5f why

such horrifying risk?

behind to starve. Worse

It is

still is

T H

Fig.

10.2 "What's

secretly, then lets

OPTIMAL

F

wrong with him? He them

die,"

N

II

44O

in a play

is

AT H

V

by Hfth-century

R

S

239

He

fathers children

B.C. dramatist Euripi-

(Detail of an Attic red-figured hydriajrom Capua, attributed to the

B.C. British Museum, London, Inventory no. E

immediate threat to them. The matter

little

F

rapes young girls, and then takes off?

I

JO)

the propensity of some raiders to deliberately

behavior

OF

B K R

observes a character

des of Apollo's habit of raping lovely maidens. Coghill painter, ca.

M

gruesome and the evidence

is

kill a

vulnerable child that

is

no

problematic not just because the

sketchy, but also because

we know

so

about the mechanisms involved.

Observing phenomena understand

fairly

well

like

how

suppression of ovulation,

lactational

we

innate neuro-endocrinological feedback loops

adjust birth intervals in primates.

The mechanisms work

the

same way

in a

langur as in a human. So long as the mother's infant suckles frequently, ovulation

is

suppressed, although nutrition and energy expenditure are also rele-

vant variables. .survival

what,

if

is

birth intervals compatible with both infant

and maternal success over anything,

her infant. brutal

The outcome

men

We

is

the

don't

same when

know

if,

a

long breeding career.

a strange

It is

male appropriating

at a physiological level, brutal

are motivated in anything like the

far less clear

a female kills

monkeys and

same way.

Rational Actors Can Also Behave Like Brutes One of the most reliable accounts of infanticide by tribal raiders comes from Elena Valero, a Brazilian woman kidnaped byYanamamo warriors when .she

MOTHERS AND ALLOMOTHERS

240

Fig.

10.3 Today the

term "trophy wife"

is

Hkely to crop up in

glamorous young wife of an aging, self-important CEO. But

mary

objective of warfare. In this vase painting from

Greek army, Agamemnon, commandeers the most lieutenant, Achilles.

Agamemnon

leads Briseis

480

a

Gary Trudeau cartoon about the

in the past B.C. the

such trophies were a pri-

commander-in-chief of the

beautiful of their recent captives

away by the wrist

in the

from

his

time-honored gesture

denoting both "taking possession of" and the marriage union. "She trailed on behind, reluctant, every step

.

.

."adds

Homer. "Women

are the constant cause of war," said Darwin, and the stronger

"carries off the prize." Friedrich Engels concurred: "In

Homer young women

are booty and are

handed over to the pleasure of the conquerors," he wrote, "the handsomest being picked off by the

commanders

in

order of rank ."

(Attic red-figure skjphos attributed to Alakron

and siijncd by Hicron on one bundle,

cour-

tesy of the Louvre)

was eleven years old

women was

still

at a

endemic

time when intertribal warfare and raiding for

in the forested

region between the Upper Orinoco

River and the Upper Rio Negro.

No

Valero 's captors, Kohoroshiwetari

Yanamamo, were themselves attacked by

rival

Yanamamo,

sooner was she kidnaped than Elena

the Karawetari. Again Elena was taken captive and handed

over to one of her abductors as a wife. She would spend the next twenty years

THE OPTIMAL NUMBER OF FATHERS

Fig.

Rumored

10.4

atrocities against children

wartime attacks on children are

manded later,

all

outnumber accurate eyewitness accounts. Yet many

too real. The Bible (Exodus 1:16)

Shiphrah, Puah, and the other

King Herod "sent forth, and slew

Hebrew midwives all

no immediate threat to him?

GirauJon, courtesy

among

c>f.\lusee

They

marry twice with

kill

I

us Pharaoh at birth.

Bethlehem, and true,

com-

Much

in all its

bor-

why should Herod

kill

many.

I

different captors and bear three

would witness, and hear about, many

But none were so horrifying

killed so

nothing

in it's

tells

male children

Conde, Chantilly)

the Karawetari,

raids.

were

Assuming

2: 16).

all

rrhe Slaying of the Innocents, Nicholas Poussin,[l ^94- 1.66s}, Photographic

children before finally escaping. She

more

to kill

the children that

ders from two years old and under" (Matthew infants of

241

was weeping

as the

second one:

for fear and for pity, but there

was

could do. They snatched the children from their mothers to

them, while the others held the mothers

wrists as they stood

up

in a line. All the

tightly

women

wept.

by the arms and

MOTHERS AND ALLOMOTHERS

242

Elena Valero and the other children with them.

women

Were mothers with

especially vulnerable, or

were they

fled before the raiders, taking their

babies victimized because they were

specifically targeted?

With

ease and

absolute callousness, one of the Karawetari raiders "took the baby by his feet

and bashed him against the rock. His head brains spurted out

When much

on the

ent Yanamamo groups, people told infants

merely

Chagnon interviewed

differ-

him about women being kidnaped,

behind to starve. But

left

—and

women

children of captured

white

stone."

anthropologist Napoleon

later,

open and the

little

split

in

their

Elena Valero 's account, the

especially sons

—were

very deliberately

targeted:

the

men began

many

to

kill

the children;

little

ones, bigger ones, they killed

of them. They tried to run away, but [the Karawetari raiders]

caught them, and threw them to the ground, and stuck them with

bows, which went through their bodies and rooted them to the ground. Taking the smallest by the

feet,

they beat

them

against the trees

and the rocks. The children's eyes trembled. Then the

men

took the

dead bodies and threw them among the rocks, saying, "Stay there, so that your fathers can find

you and

Elena Valero goes on to describe

eat you."

how mothers

raiders in conversation and dissuade

them from

woman pleaded, "It's a little girl, you mustn't kill perately to save the

the raider, "Don't

life

kill

tried in vain to engage the

killing their offspring.

her." Another

One

gambled des-

of a two-year-old snatched from her arms by telling

him, he's your son. The mother was with you and she

when she was already pregnant with this child. He's one of your sons!"The man pauses as he mulls over this possibility before replying, "No, he's [another group's] child. It's too long since [that woman was] with us." The man then took the baby by his feet and bashed him against the rocks. ran away

Grisly recollections, whether they derive from the Yanamamo or Bosnia, raise special problems. "Rational actors"

seem

to behave as brutally as chimps,

eliminating other males and old females, carrying off fertile females, killing

immatures, and

(like

chimps and langurs) especially targeting immature

THE OPTIMAL males.

Some

"

similarities

both) to a

N

M

II

B F

OF

R

F

A T H F R

Wrangham,

sociobiologists, like Harvard's Richard

between human and simian genocide (and he uses

common

243

S

that

attribute

term

for

genetic attributes in both that cause males to behave in

"demonic" way. Some evolutionary psychologists propose that humans

evolved distinct psychological mechanisms, or "modules homicide."

But so

The argument

in the brain for

far these are speculations.

that infanticide can be attributed to the

who

of chimps and humans,

common

heritage

share 98 percent of their genetic material

(Wrangham 's homology argument),

is

weakened by the

fact that

bonobo

males also share 98 percent of their genetic material with humans yet have

been reported to behave

(so far) never ever, as

bonobo

specialists

Amy

son bonobos do not engage

in quite so

is

out,

one rea-

because even though females do

among kin, the strong alliances make mothers too formidable.

not remain females

deWaal point

Parish and Frans

in infanticide

"demonic" a manner. How-

that females forge with other

''^

Gorilla males, like chimps, share nearly 98 percent of their genes with

men, and

they, too, are highly infanticidal.Yet infanticide

tary activity, not the

demonic work of males

in

by gorillas

is

a soli-

groups. At the same time,

equivalently "demonic" patterns (infanticide, perhaps special targeting of

male

who

be found

infants) can

share with

not clear what

Some

only so

more

humans only about

we

9

distantly related 2

monkeys

like langurs,

percent of their genetic material.

^ '

It is

are dealing with here.

suspect (and

behavior derive from a mates.

in

agree) that superficially similar patterns in men's

I

much more open-ended program

than in other pri-

Humans endowed with similar general motivations and emotions have many practical options for solving similar problems they confront, so

Human

they converge on the same solution as other primates.

mit similarly brutal acts

as gorilla,

raiders

com-

men

con-

chimp, or langur males. But

sciously evaluate costs and benefits, as well as future consequences of their actions.

are

They

calculate contingencies:

mothers burdened by

son spared will

grow up

How much more

infants likely to travel?

to avenge his father?

What

slowly, for example,

are the chances that a

Might these children be useful

alive?

Yanamamo

articulate their unwillingness to share resources with the off-

spring of others. They have learned through observation that the fiercer they are, the

more other Yanamamo

to control

—

fear

—

enemies, comrades, and

women

they seek

and respect them. Yet they worry out loud about fears that

MOTHERS AND ALLOMOTHERS

244 Other

men

will retaliate or

some men

Valero witnessed, kill,

engage talk to

rationalizing their actions.

same sort of

in the

mothers whose

One

father of the infant he

is

about to

The

kill.

his

As Elena

infants they are about to

some quick

raider even performs

metic to assess the woman's claim that one of

is

atrocities.

comrades might be the

calculus of Hamilton's rule

ingrained not just in his genes but in his

memes

arith-

—

in

(C*rr^

Fig.

1

2. 5

T'-iz/iafe^nXo'^ia^^. Jk^*^ ^^/tf^ft,

The

artist

William Hogarth presented

this

the letterhead for stationery to solicit funding to hire

terhead depicts

a

naked baby

in the bushes, a

British Art, Paul

St.

wet

home. The

used

it

home

official.

as

letits

Older foundlings are shown indus-

the boys preparing to be sailors, the girls, domestics. (CounesjofYale

Center for

Mellon Collection)

The very and

—

who

nurses for the foundling

swaddled baby being deposited on the ground by

mother, and another in the arms of a foundling triously occupied

drawing to Captain Coram,

tangible results

were the imperial foundling homes

Moscow

in

Petersburg, intended to qualify Russia as a player in the mid-

eighteenth-century European Enlightenment. The doors of these grand repositories

Moscow

in

1764. Both the

foundling homes were soon admitting

applicants.

died.

were formally opened

Of

St.

a steady

the ^23 children admitted during the

Petersburg and

stream of

first year,

ill-fated

81 percent

There followed two years of improved survival prospects, culminating

in the catastrophe

of 1767. Ninety-nine percent of 1,089 infants admitted

that year failed to survive to the next.

The foundling homes became syphilis,

without introducing fortified

focal points of contagion for smallpox,

and dysentery. But the key problem was always lethal diarrhea-causing pathogens.

baby formulas and

sterile

to feed infants

Without

water to mix with them, the

breast milk has always been, and in

the single

how

many

nutritionally availability of

parts of the world continues to be,

most important predictor of infant

survival.

As

this reality

emerged

MOTHERS AND ALLOMOTHERS

302

from

grim period of

a

trial

and error, administrators

Petersburg developed plans to contract with peasant

Moscow and

in

women

St.

to breast-feed

babies from the foundling homes.

A

but the administrators failed to foresee the

fine plan in principle,

number

of parents

who would

seize the

chance to delegate care of their

dren to others. By providing payments to wet nurses, the

homes

also created financial incentives for the torgovki,

state foundling

women

scoured the countryside for abandoned babies to deposit

chil-

peddlers

who

the foundling

at

homes. These babies were then transported from the foundling homes back to

where they generated

the countryside,

Many

women.

of these "wet nurses" kept the passbooks guaranteeing payment and

passed their charges on to even tating

peasant

pitiful stipends for

—women.

managed

to secure for themselves

own baby

depositing their

nurse a foundling for pay.

anyone

more poorly

paid

—and

not necessarily

Even more desperate were the unmarried

in this tragic

at a

A

lac-

women who

skimpy sinecures by getting pregnant,

foundling home, and then qualifying to wet-

lucky percentage of the hired wet nurses

tiny,

network can be

called lucky)

foundling-home employee to assign them their

own

managed

(if

to bribe a

infants. In the

words of

historian David Ransel, the state's well-intentioned plan for caring for infants

became

a case study in

"unintended consequences on

Foundling homes offered ambivalent parents an

massive scale."

easy, blameless

delegating the costs of lactation and provisioning to nately, unless they essentially

a

someone

option for

else.

Unfortu-

adopt the baby, unrelated alloparents can rarely

be counted on for wholehearted commitment. access to birth control, not suckling their

And

for

mothers without

newborns often meant

that they

conceived again soon, sometimes within the year, only adding to the number of unwanted babies.

Epidemics of Foundlings Because there were rarely enough lactating nurses to go around, foundling

homes

did

little

more than

to ensure that the baby

forestall

foundling

beyond

homes

—

^just

long enough

was baptized. Without the nutritional and immuno-

logical benefits of mother's milk,

diseases or starvation.

death from exposure

We know

most died

this

in the first

because of just

months, of infectious

how

well the staff at the

did at least part of their job. Keeping infants alive was often

their capacity. But an extraordinary bureaucracy

grew up

to record.

UNNATURAL MOTH in neat

have

303

sex, age, and

its

whether or not the baby was bap-

any identifying tokens, coins, or scraps of cloth or notes parents might

with the baby; and date of death. As historical demographers began,

left

by

locality

and

RS

columns, detailed information on each of their charges: the exact date

the infant was admitted; tized;

F.

totals,

locality, to it

became

transform neatly scripted columns of figures into rates

homes were magnets

clear that foundling

for a

much

wider population than simply unwed mothers and poor domestics seduced bv employers. Parents

—

often married couples

area saw the orphanages as a

way

—from

a

broad catchment

to delegate to others parental effort for off-

spring they could scarce afford to rear. Mothers poured in from the rural

What

areas to deposit babies in the cities.

patchwork of various,

has generally been studied as a

discrete, local crises

wide -scale, demo-

really a

is

graphic catastrophe of unprecedented dimensions. recall the crisp

still

I

autumn day

in the old cathedral city of

Durham,

when at a conference on abandoned children, the full extent of a phenomenon had been aware of for years sank in. The talks were routine England,

1

scientific fare.

Overhead projectors

flashed graphs and charts onto a screen.

The black lines sprawling across the grid summarized data from European foundling homes, tracking changes in infant mortality rates over time. the

As

morning wore on, the phenomenon of child abandonment was described,

country by country, epoch by epoch, for England, Sweden, gal's

colony in the Azores. Gradually

it

dawned on me

Italy,

that this

even Portu-

phenomenon

affected not tens of thousands or even hundreds of thousands of infants, as

had long assumed, but millions of babies. that

1

had

findings

difficulty breathing.

As

1

I

grew

increasingly

numb.

I

I

recall

distanced myself emotionally from these

by seeking to analyze what they meant,

I

may have experienced

(in a

verv remote and quite insulated way) the sort of surreal distancing other

mothers long ago must have undergone feel

what was before

them.

children, dredged up, of

My all

as

subconscious, no doubt dwelling on

things, fantastical illustrations

Sendak's ominous classic Outside Over There.

my own

children. Sendak depicted

over bridges, and

down

they adjusted so as not to see or

It

was

a

from Maurice

book had read

columns of babies

paths and stream beds. At that

my own

1

to each of

floating mysteriously

moment

they clearly

represented ghosts, streams of babies flowing from the city out to wet nurses in the

country

in

one direction, and from poor peasant households

in the

countryside into urban foundling homes, flowing back the other way. There

— MOTHERS AND ALLOMOTHERS

304

was nothing exotic about

this heritage. It

was

my own.

desensitized to this information. In what follows,

other material that scientists Italy

provides

I

In time,

treat

it

like

became

I

any of the

call "data."

some of the most complete records on

and these data have been analyzed by

infant

abandonment,

a roster of distinguished historians

and demographers, among them the anthropological demographer David

By

Kertzer. that

640,

2 2

percent of all children baptized in Florence were babies

had been abandoned. Between

below of

1

all

I

2

1

5^00

and

1

700, this proportion never

percent. In the worst years on record, during the

infants baptized in Florence

were abandoned.

i

In the

Tuscany around the same time, ^,000 were abandoned

—

fell

840s, 43 percent

Grand Duchy of

practically 10 per-

cent of all those born.

As

much

in

of Catholic Europe, a ruota, or rotating barrel, was installed in

1660 to replace the old marble basin

at

Florence's

main foundling home, the

By 699, however, it was necessary to place a grill across the opening to prevent parents from shoving in older children as well. Innocenti.

1

To the north,

between

165^9

at the

foundling

home

and 1900. For Milan

in Milan,

343,406 children were percent of

in the year 187^, 91

left

illegiti-

mate children whose births managed to get recorded were abandoned. But the

Italian cities

were not

isolated cases.

Comparative data compiled by

Kertzer for the period 1880—89 reveal an annual average of 1^,47^ infants

abandoned

in

Moscow;

9,45^8 in St. Petersburg,

which

comparable to

is

fig-

ures showing 9,101 abandoned in Vienna during the 1860s, and 2,200 in

Madrid between

i

800 and

i

809.

The majority would not

survive. In

one of

the worst sets of statistics, of 72,000 infants abandoned in Sicily between

1783 and 1809, about 20 percent survived. The scale of mortality was so appalling, and so openly that a

acknowledged, that residents of Brescia proposed

motto be carved over the gate of the foundling home: "Here children

are killed at public expense."^^

Putting Espositos in Perspective In the "civilized" world, a woman who suffocates her newborn a crime.

She goes to

jail.

But a

logically distances herself

woman whose

committed

from her newborn and opts not to breast-feed,

with the result that the baby succumbs to dysentery, rant. Similarly, a

has

baby dies because she psycho-

mother who

is

viewed merely

abandons her infant to a foundling

even those where mortality rates are

in the vicinity

as igno-

home

of 90 percent

—

is

UNNATURAL MOTHERS

Fi^J.

I

From medieval

2.6

homes

times onward, rotating barrels were set up in the walls of foundling

so that parents could deposit an

the night.

It

would have been unusual

engraving oi V Hospice ture Librarj,

30s

unwanted

baby, ring a bell, and fade

for the father to

des Enfants Trouves (Paris)

accompany the mother,

by Henri Pottin

(i

820—64).

anonymously into as

depicted in this

(Counesj of Marj Evans

regarded

as unfortunate,

but legally and spiritually blameless. Technically, her

infant will die of malnutrition or dysentery, not neglect; she did not kill

Even ern

Pic-

London)

slate

as cultural

it.

amnesia and other sleights of mind wipe clear the West-

concerning acts and omissions responsible for more infant deaths

than from several plagues combined, tangible reminders of the West's legacy of "unnatural mothers" persist in marble statues, stately Renaissance buildings

where unwanted

infants

were warehoused,

in police reports,

crumbling ledgers from the foundling homes. Even phone books large metropolitan cities

Throughout Europe

name

as

still

it

he or she was logged

like Esposito (Italian for

Milan,

many were given in

i

most

in, a first

for each foundling to be given a

name and then

a

generic

last

one,

"exposed") orTrouve (French for "found"). In

the last

name Colombo,

for the pigeons that alighted

on the roof of the foundling home there and adorned was abandoned

in

in

bear witness.

was the practice

names

tice

and

its

emblem. (This prac-

82^, as the Milanese authorities found

it

awkward

to

MOTHERS AND ALLOMOTHERS

3o6

Fig.

I

2.7

When Napoleon

decreed that every hospice

device similar to the Italian ruota, the thing

French poet Lamartine extolled the wheel

came

as

in

to be

France should he equipped with a

known

as the

an "ingenious invention of Christian charity, which

has hands to receive but neither eyes to see nor a

mouth

to tell."

As

late as the

century, Kertzer counted 1,200 such depositories for babies around after revolving for

two

Italy.

mid-nineteenth

By 1875, however,

centuries, these wheels of misfortune began to be shut

intentioned system had spun out of control. "

tour, a

"Napoleonic wheel ."The

(Courtesy of Mary Evans Picture Library London)

down. A

well-

UNNATURAL MOTHERS have tens ot thousands ot people with the same

last

name, and they worried

A

durable fraction of these

about the stigma attached to being abandoned.) foundlings were

I

counted

enough to

lucky, robust, or resourceful

up and went on to have

families of their

own. During

phonebook 86 people of

in the

307

Italian

survive.

name

vided

Esposito

—sometimes

descent in the metropolitan

Esposti,

2

institutionally pro-

Exposito, but always meaning "an exposed

1996 there were 46 Espositos,

one."'^ In "Les Pages Blanches" for Paris

Espostos, 8 variants on Degli Esposti, 64Trouves, plus

advertise just

how

this family's

Boston,

a recent visit to

whose male ancestors years ago had been given the

area

They grew

fortunes have improved

familv business that read: "Trouve, Per et

—one

—

i

as if to

listing for a

Fils."

Desperation, Destitution, Self-Delusion

When

parents

doing? At the outset, (likely to

tryside,

foundling homes, did they

left infants at

when

an infant was

left

know what

they were

there by an unmarried

woman

be destitute) or sent in by desperately poor people from the coun-

it's

possible that the baby

surviving at the foundling

home

would

actually have a better chance of

than with

mother.

its

Many

foundlings in

Renaissance Florence were illegitimate children of slaves or domestics and, as

would have died

such,

at

three times the average rate. Such abandonments

could be construed to be in the child's best interests. But what about decisions

made

after mortality at the foundling

levels that they

same choice.

almost inevitably did,

When

mothers

how

did they have any idea

as

homes

more and more mothers made

set their infants in the barrel

idea that foundling

shrewd suggestions survival.

Some

left

to send this baby to

in

and rang the

the

bell,

staggering the mortality rates were? Surviving

documents from fifteenth-century Florence suggest

some

rose to the catastrophic

homes were dangerous

that parents not only

places, but

had

some even made

an attempt to tip the balance in favor of their infant's

pathetic instructions begging personnel at the Innocenti

some outside wet nurse, not keep

it

at the hospital,

where

chances of survival were worse. Volker Hunecke records case studies from eighteenth- and nineteenth-

century Milan for tailor "Filippo

son

at

home and

B

"

and

his wife,

who

kept their

then deposited the next six (in the space of

years) at the nearest tour. "

A

When

his first

and together they deposited

five

five

and

first

a half

wife died, he remarried "Cecilia

more

infants in five years. After a

year and a half, the mother tried to retrieve them, but only two of

all

these

MOTHERS AND ALLOMOTHERS

3o8

children were

"Francesco

still alive.

similarly

produced twelve children

birth,

the others

all

The point here the foundling

is

"

and

"Amalia

his wife

in thirteen years. The first died

S-

soon

after

went to foundling homes. Only one daughter survived.

that these parents

home had

communicated

G

had the information

to

know that things

at

not gone well; and, being human, they would have

their misfortune to others.

After a point, parents had to have known. But they were making decisions

unwed mother;

based on immediate costs (discovery, in the case of an

lost

wages; destitution) rather than on the basis of rumored misfortunes behind distant walls. In doing so, they relied

on the all-too-human

self-delusion. Hetty cries that she did not

who

left their infants at

destinies of

upward

foundling

mean

homes found

social mobility for

to

kill

gift

of fantasy and

her child. Mothers

solace by fantasizing fabulous

abandoned progeny, who

and Remus, the abandoned twins supposedly adopted by

lus

might be miraculously saved and survive to found

like

Romu-

a she-wolf,

a dynasty.

Questioning Maternal Instinct Decades before the sudden-infant-death-syndrome scandals surfaced 1990s, or before data from the foundling

homes

started to be quantified in

the 1970s, psychiatrists, historians, and social scientists

match between

real-life

in the

all

noted the poor

mothers and the nineteenth- and early-twentieth-

century stereotypes of instinctively nurturing mothers. Feminists in particular

had long ago

as essentialist

lost patience

with Darwinian perspectives that struck them

and which patently disregarded women's

keep up with what was going on

They continued

in reproductive

to project onto these fields their

experience. They

felt

were eager to discount biological explanations, and had

little

incentive to

ecology or sociobiology.

own worst

assessments

about essentialist and determinist assessments of "female nature" even after biologists themselves had

was

abandoned these types of explanations. The

that feminist theorists

essentially a biological

were producing models

phenomenon

nurturing responses from

its

to explain

result

what was

(namely, the failure of an infant to

elicit

mother) but without any reference to biology.

They used the evidence of high numbers of non-nurturing mothers

as a tool

to jettison altogether the confining stereotype of the instinctively nurturing

mother

that

had long been used to prescribe

social roles for

women.

UNNATURAL

MO

T H H R

309

S

Instead of taking a closer, critical look at the original, biologically based

explanations to see

perhaps something had been

if

who were

with other social scientists

out, feminists (along

trying to explain the widespread

abandonment by mothers) patently rejected evolutionary expla-

practice of nations.

left

The

biological basis for

mentalism. The way

motherhood was replaced by

mother

a

feels

a

new

environ-

toward her infant must be solely

determined by her cultural milieu. In France,

where

this

view of "socially constructed" mothers originated

and then gradually spread, Badinter, in 1980 the

first

a brilliant

and animated philosopher, Elisabeth

woman to become a professor at Paris

's

prestigious

Ecole Poly technique, and an appropriately iconoclastic descendant of Cle-

mence Royer, could velle

Observateur

and

stare straight into the eyes of a reporter

say: "I

knows what comes next

from the Nou-

—

am not questioning maternal love" pause, for she "I am questioning maternal will be scandalous

—

mstmct. in nature

make

built into sociobiology (discussed above, in chapter 2),

most

Although David Lack's ideas about the tradeoffs mothers

were by then

social scientists

still

assumed

that in nature,

mammal mothers

instinctively

and automatically care for every infant they produce. Badinter 's reasoning

was simple. However,

if

If

mother love

missed

own

instead, this

as aberrations.

were unwed and ents to the

instinctive, all

normal mothers should be

loving.

the vast majority of mothers in eighteenth-century France had

opted not to rear their

wet nurses

is

infants but to delegate their care to inadequate

was more mothers than could reasonably be

Furthermore, Badinter knew that not

destitute.

It

was

all

these

dis-

women

also apparent that children related to par-

same degree were not being treated

in the

same way, which to her

could not be consistent with a biological basis for maternal love.

Such maternal love and

selective.

A wet

as

Badinter could document was often discriminatory

nurse might be brought in from the outside to nurse an

older son while the younger son was sent far away.

If

not spontaneous and

automatic, Badinter argued, maternal love had to be a nonbiological social construction.

It

was

a sentiment

produced by

peculiar to a specific historical time and place.

"myth" of

a

a particular cultural context,

Her

best-selling

book on the

mother's instinctive love for her infants stressed the fact that

many mothers who abandoned infants or sent them to wet nurses were destitute, many others were "bourgeois" mothers whose banishment of

although

their babies

was discretionary.

(I

will return to this topic in chapter 14.)

MOTHERS AND ALLOMOTHERS

3IO

Social Construction of Mother Love

The

idea caught on

among

concept of childhood

social historians that

itself,

must be

"good mothering," even the

a recent cultural invention.^'' Social his-

torians like Philippe Aries in France and

Edward Shorter

United States

in the

hypothesized that parental emotions and the internal workings of family

life

derived from particular attitudes and customs. Such customs are built up and

change over time. Not only do such cultural constructions take on their

own, they were never influenced by

safely

biology.

It

was

eschew any discussion of an evolved human nature.

a

model

a life

of

that could

""^"^

Fired by the notion that parental attitudes change over time, the American

Mause compiled masses of evidence on

psychohistorian Lloyd de

and abandonment

in earlier times.

nightmare from which

we

Childhood, he announced, was actually "a

have only recently begun to awaken."

succession of stages, beginning with an "infanticidal

century A.D.,

when

He

mode" prior to

laid

out a

the fourth

parents "routinely resolved their anxieties about taking

care of children by killing them." sive" child-rearing

infanticide

ushered

in

By the eighteenth century

a

phase of "intru-

by reformers led to the child being "nursed by

the mother, not swaddled, not given regular enemas, toilet trained early,

prayed with but not played with, masturbation,

made

to

hit

but not regularly whipped, punished for

obey promptly," culminating

in the "socialization

mode" of the nineteenth and twentieth centuries, when newly empathetic parents became more concerned with training than conquering children, and today's

modern "helping mode.'

Anthropologists as well were inclined to set aside Rousseau, Spencer, and the various essentialists.

They followed the

historians, divorcing maternal

emotions from biological predispositions and situating them

economic and

in particular

political contexts.

"Anthropologist Calls Mother Love a Bourgeois Myth," announced one headline. ^^ Years of studying desperately poor mothers in Brazilian shanty-

towns

as

they distanced themselves from

die had convinced

doomed

Nancy Scheper- Hughes

that

children and watched

"Mother love

is

them

anything other

than natural and instead represents a matrix of images, meanings, senti-

ments, and practices that are everywhere socially and culturally produced."

how mothers convince themselves that their children and how they subsequently draw back. The cultural art of

She vividly describes lack the will to live,

breast-feeding, she decided, had been lost, so that the baby

is

fed

powdered

formula diluted with water teeming with diarrhea-inducing microorganisms.

UNNATIIRALMOTHERS When, almost behind

inevitably, death ensues,

a stoic Facade

—

311

mothers do not disguise

their grief

they feel none. "The traumatized individual," writes

Scheper- Hughes in Death Without Weeping, does not "shrug her shoulders and say cheerily,

'It's

better the baby should die than either you or me.'

"

Rather

(paraphrasing General William Westmoreland's famous observation about his allies

during the Vietnam war), "They do not grieve the way

she argues, by attributing to Third

'norm' [of maternal love] from our

World women

own

Bourgeois

we do."We

err,

"a very specific cultural

Mi

society.'

Universality of Parental Emotions Scholar after scholar detailed massive mortality owing to such "unnatural

mothers," then sought to ascribe the absence of maternal tural constructs

—

commitment

to cul-

attitudes or historical factors peculiar to particular peri-

ods: the absence of a "concept of childhood";

the notion that "mother love"

had not yet been invented;"^ mothers conditioned to expect children to

die;"^^

unwed mothers by the Catholic Church, together with the creation of foundling homes that serve as magnets for abandoning parents; unprecedented population growth (the doubling of the human population pressure put on

"^^

between 16^0 and 18^0);

colonial and capitalist oppression to explain

lethal child neglect in the

Third World today ;'^^ and so on. These circum-

stances

were indeed highly pertinent. Historical and ecological context had

important implications for

how mothers

ticular infant's, prospects were. Social

to

do with what

alternatives a

assessed

what

their

own, or

this par-

and economic context had everything

mother had

to choose from. But whereas these

represent highly relevant circumstances, they are not explanations for whj

mothers were abandoning babies. And "mother

love," such variation in

in the debates

over the construction of

maternal responses by no means disproved

the involvement of innate mechanisms. Indeed, understanding the biological basis of "mother love"

is

essential for understanding

Long before populations eighteenth-century

boom

in

what

is

going on here.

western Europe burgeoned, well prior to the

in sending children

away to wet nurses or aban-

doning them outright, European parents sought ways to cope with unwanted children.

Around

the world, hunter-gatherer societies have suffered high

rates of child mortality without

compromising close mother-infant

relation-

— MOTHERS AND ALLOMOTHERS

312

made me

"Their death

ships.

feel pain,"

moaned

Nisa, the !Kung mother, in a

cuhure where on average ^o percent of children die before adulthood loo percent of hers had. "Eh, Mother!

Hundreds of

mostly fathers) between tions

—from

i

5^00

spective, since

few mothers

^'

my hand,

Giovanni Morelli,

the

same

one

that

finds in

his

story, albeit

from

a

male per-

"How great a joy it was to me

movements

womb

in the

which

noted

I

awaiting his birth with the greatest eagerness," wrote

fourteenth-century father from middle-class urban

a

Morelli sounds like a textbook example of the

Italy.

modern "engrossed" father

a historical novelty.

And then when he was happiness, what joy

I

born, male, sound, well-proportioned, what

experienced; and then as he grew from good to

words, pleasing to

better, such satisfaction, such pleasure in his childish all,

—

Further back in time the record grows tell

written diaries.

left

mother; and soon came

carefully with

supposedly

literate parents (alas,

indulgent to abusive, distant to engrossed

skimpy. But such accounts as exist

his

almost died of that pain."^°

and 1900 reveal the same continuum of emo-

cross-sections of parents today.

and

I

and American diaries kept by

British

—and

loving towards

me

his father

and

his

mother, precocious for

his

age."

How

profoundly modern

same

father

sound the guilty self-recriminations of the

as well

when his beloved

firstborn, Alberto, dies in 1406 at age ten:

his loss,"

he berates himself. "You loved him

stranger than a son kissed

.

.

.

.

.

.

but treated him more

you never looked approvingly

him when he wanted

it.

.

.

at

him

"You

was greater

had a son, intelligent, lively, and healthy so that your anguish

.

.

.

at

like a

you never

.You have lost him and will never see him

again in this world."

writes

Madame d'Epinay sounds like the woman of her new baby: "I think of nothing but this little

ing

evening." Advantaged

In 1746,

till

enough

next door

creature from

him. is

no

.

.

.

I

sometimes think

me

when he

satisfaction equal to that of

she

morn-

to hire both a governess and a tutor, she

chose to breast-feed the baby herself and was so attentive to

he developed "a passion for having

when

always near him.

He

smiles as he looks at

when

cries

me

needs that

his

.

.

.

I

leave

that there

making one's fellow creature happy." This

obvious bond between mother and infant blossomed during the historical

UNNATURAL MOTHERS

Fig.

12.8

"Man "to

Women

like

313

Madame d'Epinay were following the advice He admonished men who "cannot fulfill

of Jean-Jacques Rousseau

of Nature" (1712-78).

become

one." Nothing, he wrote "can dispense

bringing them up himself."

He

offered this advice later in

the duties of a father" not

from caring

[a father]

after

life,

for his children

poor writer seeking to better himself. Rousseau was rationalizing to himself how five

and

he himself was no longer it

was

that

a

all

of his children ended up in foundling homes. At the time he noted that the arrangement

"seemed

to

me

.so

good, so sensible, so appropriate, that

solely out of regard for their mother.

.

dren, or what

in all,

I

thought was best ."All

the children, because

if they

had been

and transformed into "monsters."

It

.

.

I

Rousseau mused

did not boast of I

in his Reveries,

a

publicly

it

it

was

my chil-

was quite lucky for

matter of "principle" for him to do what he did. Like

other early moral philosophers, Rousseau was .strong on what

mothers to do, and took for granted both

that "in the animal

unencumbered."' He also took for granted that he knew what Claude Le Grande, IjS^, private collection)

it

chose what was best for

with their mother they would have been spoiled by her

left

was

if

All things considered,

it

was

biologically "natural" for

kingdom the laws of nature reign tho.se

laws were.

(Engraving byAuguste

MOTHERS AND ALLOMOTHERS

314

heyday of French wet-nursing. The parents of less fortunate infants sent them to languish, often to die, far

from home."

When Circumstances Change Most

telling

perhaps are real-world case histories that allow us to ask:

happens when the same mothers, with the same in different circumstances? this century,

between

Among

What

social constructs, are placed

the Ayoreo Indians of Bolivia earlier in

following a period of grave social disruption (the Chaco War,

woman in one village women in this sample One mother code-named

Bolivia and Paraguay, 1932—3^) nearly every

had committed infanticide. Between them, the had buried

percent of

alive 38

"Asago" viewed her port and buried

infants born.

three husbands as poor prospects for long-term sup-

first

at birth thejirst

Yet infants born to

all

six

of the ten children she bore in her lifetime.

women who had managed to

who, having grown

older,

forge stable relationships, or

had decided to proceed with

what, were loved and cherished. "Even

when

the ethnographers noted,

to believe that

a family

no matter

trained as an anthropologist,"

someone known

as a

charming friend, devoted wife, and doting mother could do something

that

one's

own

New

Guinea, Europe

culture

timed neonate

"it is difficult

deems repugnant."

—

Across cultures

mother who

the same

—

South America,

in

regretfully eliminates a poorly

will lovingly care for later ones if circumstances improve.

among both the Ayoreo and North Americans in Martin Daly and Margo Wilson's sample of infanticidal mothers, those under the age of twenty Indeed,

were the most ticide,

likely to

respond to poor circumstances by committing infan-

while older mothers were

How

a

far less likely to

do

so.

mother, particularly a very young mother, treats one infant turns

out to be a poor predictor of how she might treat another one born is

older, or faced with

stant,

observing

attitudes.

how

modern Western women

effective a

Older

likely to sacrifice

all

inculcated with

more or

mother would be than

women describe motherhood

as

specific personality traits or

more meaningful, are more mourn lost preg-

themselves on behalf of a needy child, and

—

more than do younger women presumably because 58 more opportunities to conceive agam.

Sometimes an improvement child-care style.

less the

values, maternal age turned out to be a better pre-

nancies see

she

improved circumstances. Even with culture held con-

same post-Enlightenment dictor of

when

in

the latter fore-

circumstances leads to an entirely different

Nancy Scheper-Hughes describes

a

poor

Brazilian

woman

IINNATURALMOTHERS who

finally finds herself

income. Spontaneously,

mother

31^

attached to a husband with a small but predictable this

woman

reinvents the "bourgeois" concept of

love and readopts the lost art of breast-feeding,

which supposedly

had disappeared from her shantytown subculture. She invests emotionally

and Hnanciallv almost

all

each child, and marvels

in

our babies

at

"From then on

the outcome:

lived."

Unintended Experiment at La Maternite Even when circumstances remain grim, extended contact between mother and infant (especially

if

the

mother

is

undermine the strongest pragmatic

whose research

breast-feeding) can elicit emotions that resolve. Social historian Rachel Fuchs,

deals with the effect of public policies

on

infant

abandon-

ment, describes an unusual experiment that resulted from an attempt social engineering

undertaken

in Paris in the years

i

830—69.

It

dates

at

from the

when Europe's epidemic of abandonment was winding down.^° Exceedingly poor women who could not afford a midwife gave birth

time

at

La

Maternite, the major state-run charity hospital in the Seine region. The hospital

was

directly across the street

from the Hospice des Enfants Assistes, the

only place around where infants could be abandoned

reduce the numbers of abandoned babies,

up with

a plan.

A

subset of indigent

infants for eight days after birth.

a

legally. In

group of French reformers came

women was

obliged to remain with their

What most people would

manipulation today produced remarkable results. Under

regimen, the proportion of destitute mothers their babies

who

consider unethical

this

"experimental"

subsequently abandoned

dropped from 24 to 10 percent. Neither

their cultural concepts

about babies nor their economic circumstances had changed.

was the degree to which they had become attached to infants.

It

was

Fuchs 's analysis

mothers

being

left

left

What changed

their breast-feeding

though their decision to abandon their babies and their

as

attachment to their babies operated

tute

an effort to

is

as

two

different systems.

consistent with this interpretation. Infants

whose

desti-

the hospital on the day of birth had a fifty-to-one chance of

behind. Infants whose mothers

left just

two days

later

had a six-to-

one chance of being abandoned.

Underpinnings of Contingent Commitment A

mother's commitment to her infant

what we mean by "mother love"

—

is

—and

neither a

in the case of

myth nor

humans,

this

is

a cultural construct.

MOTHERS AND ALLOMOTHERS

3l6

As with Other mammals,

mother's emotional commitment to her infant

a

can be highly contingent on ecologically and historically produced circumstances.

No

one knows

how

the underlying mechanisms work. But

it is

a rea-

sonable guess that such mechanisms involve thresholds for responding to infant cues.

These would be endocrinologically and neurologically

bly during pregnancy and prior to birth, rendering a likely to

much

become engaged by

infantile cues as she

set, possi-

mother more or

less

makes decisions about how

of herself to invest in her infant.

Most mothers remain

close to their infants in the period after birth, and

over a period of days, weeks, and months the attachment between mother

and infant grows stronger. But some mothers are so detached

—

own actions ensure this never happens common in apes and monkeys than in humans

their

a situation

at birth that

rendered

since (and this

far less

may not be

the

only reason) neonates are able to catch hold of the mother's fur and cling to

her from birth long enough for backup systems related to maternal responsiveness to kick in. Such cases of "unnatural"-seeming abandoning offer far

cases

more

insight into the underlying processes than

where babies

mothers

do the more usual

are born, picked up, and cared for.

Across primates, including humans, wherever mothers abandon babies, they almost invariably do so within the

first

seventy-two hours

—

as in the

case of Lynn Fairbanks 's "teenage" vervet mothers, or the hyperfertile captive

tamarin mothers with inadequate allomaternal assistance. This does not necessarily

mean

that there

mothers must bond or

a critical

is

else. Rather,

period right after birth during which

what

it

suggests

is

that close proximity

between mother and

infant during this period produces feelings in the

mother about her baby

that

more depth below,

make abandonment

unbearable.

(I

discuss this in

in chapter 22).

Far from invalidating biological bases for maternal behavior, a closer look at the historical and ethnographic record reveals mothers

of circumstances with a to infants

fairly

who respond to a range

predictable range of emotions. Their responses

remain consistent across vast spans of time and space,

in the face of

bewilderingly variable social histories. These consistencies remind us that

descend from creatures for

made an enormous

whom

we

the timing of reproduction has always

difference, and that the physiological and motivational

UNNATURAL MOTHERS

Fig.

12.9

Budapest

A modern in

1997 to

was discontinued.

tour.

317

This incubator was set up outside the Schopf-Merci Hospital in

cope with

a surge of

unwanted

births after free contraception in

Hungary

(AP / WideWorld Photos)

underpinnings of

"pro-choice"

a quintessentially

mammal

are not new. These

consistencies in maternal nature transcend historical peculiarities, and the It

was not the response of moth-

Rome, or eighteenth-century

France, or twentieth- century

vagaries of local ecologies and demography. ers in ancient Brazil that

was unnatural.

In fact,

what was unnatural was the unusually high

proportion of very young females, or females under dismal circumstances,

who,

in the

absence of other forms of birth control, conceived and carried to

term babies unlikely to prosper. In the next chapter

I

explore circumstances under which mothers treat

offspring differently not because of

be born, but because the baby

is

when

in the

mother's

born one sex or the

involved are not necessarily immature or poor.

Many

life

they happen to

other.

The mothers

have mates or kin net-

works to help support them, or are otherwise well-positioned to rear baby. Indeed, in cide, elites

Why?

—

many of the best-documented

their

cases of sex-selected infanti-

those with the most resources, not the least

—

are implicated.

I

3

Daughters or Sons? All

It

'The son was alive then,

and

—from George

Depends the daughter was at a discount.

." .

.

Eliot in Middlemarch, 1872

thousand calories, nine months, seventeen-plus years of

Seventy

room, board, and extras

—and

yes, there

is

returns from their investment in children.

heard a parent telling a child that he or she

a charge. Parents

expect

How often have you over-

"a disgrace," "good for nothing,"

is

or complaining that a son or daughter "will never amount to much"?

many

parents have entertained such thoughts themselves?

Or

good."

especially, "I just

young people

this

way

melodramas. What

There to

is

is

so

want you to

commonplace

at issue

here?

a contract stored

deep

is

live

in the

"It's

for your

How own

up to your potential ."Talking to

that

it

has

become

routine fare in

minds of parents: they expect those

whom they give so much to bring credit to the family name, or to translate its

former correlate:

justify their

behavior by claim-

parental investment into either cultural success or

enhanced

fitness for the lineage. Parents

may

ing to act in "the child's interests." Closer scrutiny often reveals parents defining those interests in line with their In the West, such conflicts have

own.

tended to be over education, inheritances,

career decisions, social or sexual choices. Parental preferences rarely place infants in

mortal

to family goals.

peril.

Elsewhere, though, parents

Nowhere

are underlying tensions

eties

where parents resort

cific

family configurations.

literally sacrifice

children

more manifest than

in soci-

to sex-selective infanticide in order to obtain spe-

China's Missing Daughters In

I

99

I,

became gone?"'

results

from China's massive census of every hundredth household

available, It is

sparking worldwide

normal

for slightly

comment. "Where have

more boys than

318

girls to

the girls

be born: 104 to 106

9

DAUGHTERS OR SONS? boys per loo ratios

girls

is

1

990 census revealed that out of a

lion people, millions ot girls that should have

as

i

i

boys per

i

1

00

girls.

.

2 bil-

expected

1

06

Demog-

suggested."

on

raphers, however, are convinced that girls are being eliminated scale, either

i

Perhaps Asians are genetically

more sons than other people, some

disposed to produce

total

born, or else eliminated so

as to escape notice in the census. Instead of the

sex ratio there were

1

been counted seemed either not

been born, not to have been reported

soon after birth

3

considered normal. But comparisons of expected sex

with those From China's

to have

ALL DEPENDS

IT

a massive

through prenatal sex determination followed by selective abor-

tion of female fetuses, or through neonaticide.^

Later-born children are most child-per-family policy

means

two

is

children. But that

at risk.

Westerners assume that the one-

that Chinese families only have

who

only have

at

most

not necessarily the case, especially in rural areas.

—

Dispensations for extra offspring can also be obtained ents

one or

But often

girls.

a fine

is

especially for par-

imposed, and many families are

reluctant to bear penalties for an extra child without getting the sex they

want. Either sex

may be

acceptable for the

rent Chinese sex ratio for

reported for every 100 start to climb.

first

girls.

births

is

first

within the normal range

1

—

the cur-

106 boys

For higher birth orders, however, sex ratios

For families producing a

reported for every

why

birth. This explains

fifth

child,

i

2^

male births are

00 daughters.

—

Policy to Blame or Parental Preferences? Viewed in historical perspective, China's one -child policy

has enhanced the

well-being of wanted children and helped the country to catch up economically.^

But small families also increased pressure for a son. China's "missing

daughters" have

become an

international cause celebre, with special

nation reserved for the one-child policy

Female policies

infanticide,

itself.

however, was practiced long before Mao's population

were introduced

southern regions

condem-

like the

in the

second half of the twentieth century. In

Lower Yangtze, where Shanghai

plausible explanation for 50

many missing daughters

is

situated, the only

is

either sex-selective

abortion or infanticide.^ Infanticide rates are higher today than ten years ago,

but they are lower than in centuries past. In some areas, childhood sex ratios in the eighteenth

and nineteenth centuries were

as

high as

i

54:

1

00.

In large

MOTHERS AND ALLOMOTHERS

320

wagons made scheduled rounds

cities like Beijing,

collect corpses of

unwanted daughters

that

morning

to

had been soundlessly drowned

in

in the early

a bucket of milk while the mother looked away. One nineteenth-century woman interviewed recalled eliminating eleven newborn daughters. Another

could not recall the exact number, except that she had borne more daughters than she wanted.

A

Such anti-daughter prejudice was scarcely new. 2,^00 years ago celebrated the arrival of a son ery, laid

on an elaborate bed, and given

would be dressed

contrast,

wooden

whirligig.

in a

According to

Chinese

laid

poem

recited

should be dressed in

a jade insignia to hold.

wrapper, a

who

A

fin-

daughter, by

on the ground, and given

a

popular proverb: "More sons, the more

happiness and prosperity."

Whether current

distortions in China's sex ratios are due to selective

abortion of female fetuses or female infanticide, existing laws are not effective.

sons

Sex ratios are most skewed

more

is

essential there,

are found in southern China,

in

remote rural

areas.

Labor provided by

and laws harder to enforce. The strongest skews

where discrimination

more pronounced. The call for more and tougher

against daughters

was

tra-

ditionally

laws detracts attention from the underlying

problem: long-standing parental desires for This means that unwanted infants,

unwanted children who

will

be fed

if

a particular family composition.

grow

into

less attention

paid

they survive, are likely to

last

and fed

least,

have

to their education and medical needs, and suffer physical and emotional abuse. tal

A more effective and humane solution would focus on changing paren-

mindsets. But

signs posted

all

how? Ongoing propaganda campaigns

—

for example, the

over proclaiming "Little Boy, Little Girl, Both Okay"

—

have

had limited impact.

imm-^ Fig.

13.

1

Public sign from urban China. Essentially

(Courtesy of Craig Kirkpalnck)

it

says: "Little Boy, Little Girl,

Both Okay.'

:

DAUGHTERS OR SONS?

ALL DEPENDS

IT

321

A Widespread and Very Ancient Bias The

first

step

what ancient and deep-rooted parental prefer-

to understand

is

ences for sons versus daughters are about. Sex ratios as high as those found in

China today

(

1

1

6:

i

oo) can be documented for other Asian countries that do Far beyond the boundaries of China,

not have such coercive family planning.

wherever preferences for offspring of one sex are so extreme selective infanticide

is

that sex-

practiced (in about 9 percent of the world's cultures),

sons are the desired sex.

Outside of China, female infanticide

among

Asia,

ancient

tribes in highland

Italy.

Wherever

it is

New

I

delivered of child

chanted

when

for other parts of

Guinea and South America,

as well as in

it

go hand

in

hand with patriarchal ideolo-

soldier sent his wife in the first century B.C.

ask and beg you to take

In India, special

documented

of daughters can be stunning, as evidenced by

gies. Indifference to the fates

Roman

well

found, extreme son preference and the devalua-

tion of daughters that accompanies

the note of a

is

.

.

.

good care of our baby

if it is a

boy keep

mantras from the

a wife

Veda,

it, if

son.

...

a girl discard

If

you are

it.

sacred texts of Hinduism, are

becomes pregnant.

If

still

by some mischance the fetus

is

female, this text expresses the hope that she will be magically transformed into a son.'^

Various well-meaning pundits have proposed letting the "mania for sons" take

its

course. Playwright, congresswoman, and ambassador Clare Boothe

Luce was among the most outspoken of them. She correctly noted that the Chinese desire for sons motivated parents to have larger families, since those with only daughters kept trying for sons. She proposed pill" as

the "quickest

way of peacefully slowing down

Furthermore, Luce suggested,

as

a "male-child birth

the Ipopulation] clock."

daughters became scarcer, the status of

women would rise. Laws of supply and demand, however, do not always work,

where odds

are stacked against a sex that

is

not only scarce but

enfranchised. In urban China, scarcity has indeed provided

especially not is

undreamed-of opportunities.

In television broadcasts that

between The Dating Game and

talent shows, desperate bachelors

appeals, then anxiously await a

potential mates. But the very

summons,

same

as

socially dis-

women

fall

with

somewhere

make their among

female viewers choose

scarcity that drives urban bachelors to

MOTHERS AND ALLOMOTHERS

322

these extremes

makes women's

lives

more

perilous than ever in rural areas.

The incidence of rape, kidnap, and even women being bought and sold, has risen along with the number of wifeless men. '^ Women may be in short supply,

but as a class they are no better

in the

off. In 1995^,

world where the suicide rate for

women

China was the only country

exceeded the rate for men.'^

For parts of the world where "a daughter's birth makes even a philosophical

man

.

.

.

gloomy

[while] a son's birth

is

like sunrise in the

abode of gods,"'^

prenatal sex diagnosis with the option of selective abortion arrived on the

scene like a divine like

gift.

The old proverb according to which "eighteen goddess-

daughters are not equal to one son with a

parents

who

taken quite

literally

by

use prenatal diagnosis not to guard against genetic defects, but

against paired

XX chromosomes. Of 8,000 abortions performed at a clinic in

India, 7,997 eliminated fetuses parents (Typically,

hump" is

had been told would be daughters.

mothers being tested already had one or more daughters.) such discrimination

Officially,

banned. Asian countries have

is

laws against using prenatal tests this

way than do Western

far stricter

countries.

But the

laws are unenforceable. In 1988 Maharashtra state in south India banned all

prenatal sex determinations. India's Parliament followed suit. In 1994,

nationwide penalties of three years

were imposed on anyone found tests solely to

making

it

a

in prison

determine the sex of a

crime to abort

a

and

a fine (equal to

about

$

320)

guilty of administering or taking prenatal

female

fetus. fetus.

Korea followed

suit the

same

year,

Such laws notwithstanding, volun-

teer organizations in India estimate that around 80,000 abortions after sex tests are

still

performed every year (surely an underestimate). The

similar in Korea.

Meanwhile

in the poorest areas of Asia,

situation

where prenatal

is

test-

Nadu or Rajasthan in India), female infanticide continues. Unwanted daughters may be dispatched either the traditional way (by smearing opium on the mother's nipples or by poisoning denying a daughter breast milk, with plant extracts) or the "modern" way ing

is

largely unavailable (e.g., in Tamil

—

so that she dies of unavoidable (and unprosecutable) "natural" causes.

How Much Say Do Mothers Have? How

could

a

mother, a

woman

herself, kill a daughter because her baby

female? To discriminate on these grounds would seem to validate her

is

own

DAUGHTF. RS OR SONS?

ALL DEPENDS

IT

323

.?fii

Fig. 13.2

At birth the female twin was taken by the mother-in-law and bottle-fed, while the son

remained with

his

mother and was

clinic, the difference

breast-fed. When they

between them was

all

were reunited

at five

months of age

too apparent. Intervention was too

late.

fed daughter, limp and marasmic, died shortly after this photograph was taken."

The

at a

bottle-

(Photograph by Gul

Kayyei Rehman, courtesy of Dr. Mushtaq A. Khan, Children 's Hospital, Islamabad)

inferiority.

It is

interesting to note that in places like China and Bangladesh

daughters are most ters

—

at risk in families that already

in precisely those families

daughter. She can

remember what

have one or

more daugh-

where the mother has already nursed it

was

like to love a

baby

girl. It is

a

hard to

believe, yet maternal compliance with daughter infanticide cannot be under-

stood without taking into account her situation. ^"^ She

lives

with her husband,

MOTHERS AND ALLOMOTHERS

324

among

his relatives,

dependent upon them. The well-being of the children

she rears will rely on their

wanted

good

will.

women. From an

sons, therefore so did the

were conditioned to place on the sons born to

their

Quite simply, the

men

of the family

women

early age, these

hopes on sons they would bear one

day,

and

their sons.^^

Even today, in many societies mothers without sons are pitied and looked down upon. Wives with sons are more highly prized, their male children favored. "Soon after delivered my son, my parents-in-law moved us into a larger apartment," recalled one Korean woman who happened to be a winner I

in this

to

chromosomal

lottery.

Such pervasive conditioning makes

view maternal preferences separately from her husband's

One modern mother who

ests.

disapproved of

this

it

impossible

family's inter-

prejudice nevertheless

voluntarily opted for an (illegal) abortion

when

told that her second child

would be another daughter. She knew

were

scarce, but after agonizing,

still

girls

chose not to bear another daughter. Often, the matter

out of a mother's hands,

as in the case

is literally

taken

of the Pakistani twins where the

mother-in-law bottle-feeds the daughter, consigning the

girl (but

not breast-

fed son) to die of dysentery and malnutrition (see figure 13.2).

Such cases led anthropologist Susan Scrimshaw to argue

may

passage that "the decline of infanticide infants

and children, and even

adults, than

result in

when

more

in a

much

cited

suffering for older

an infant's

fate,

be

it life

or

death, was determined swiftly, early and irrevocably." Scrimshaw was not

advocating infanticide. Rather, she was making a realistic and compassionate

comparison between one leads

fate

many educated people

and

a "far crueler" alternative."

in Asia

—

Similar logic

including medical personnel

—

to view

sex-selective abortion not only as a family's right but as preferable to un-

wanted

births.

^^

Reasons for Preferring Sons "Daughters are no better than crows" observes

on

this

a

Tibetan proverb. Variations

theme can be heard throughout northern

them and when they get

their wings, they fly away."

plain, leave at marriage; resources patriline.

India. "Their parents feed

With them depart

Daughters, people com-

devoted to rearing them are

lost to the

substantial dowries, enriching their husbands'

families while impoverishing their

own. Parents dread the prospect of marry-

ing off several daughters almost (but not quite)

as

much

as

they dread poten-

D AU G H T

F

R

S

OR SONS?

disgrace should a daughter

tial

tus,

or be seduced and

By

itself,

system

set

is

left

fail

to

IF

marry

ALL

1)

1-;

l^

K

NHS

32^

into a family of appropriate sta-

pregnant but unmarried.

why the daughters decamping. Nor does it

the "daughters depart" rationale begs the question of

up

this

way, with sons staying,

explain whv parents voluntarily fork over exorbitant dowries. Attention, then, gravitates to the traditional rationales for son preference, explanations

of "pride and purse," sons' special labor value, the ritual role accorded to sons, and their symbolic value.

cil

In

one of the few studies of its kind. Mead Caine of the Population Coun-

of

New York

quantified the value of labor provided by sons as

compared

with daughters in Bangladesh. By ten to thirteen years of age, a boy producer. By age fifteen a son has repaid his parents for what rear him, and by age twenty-one repaid ters,

them

for

one

it

is

them

cost

home

to

Daugh-

sister as well.

by contrast, though they work early and hard, leave

a net

before they

repay parental outlays.

Bv themselves, neither family "pride" nor "purse" (economic

interests)

why sons earn more in the first place, why parents continue them, or why parents send daughters away with large dowries. explains

The Reproductive

to favor

Potential of Sons

A long history of male-male competition for mates has left a sexually selected men who are somewhat larger, and much more muscular, than women. This is one reason men make more effective allies than women. The legacy of

other

is

that in patrilocal breeding systems, these allies will also be kin.

Whether protecting

access to females in the

community or helping

tain a patriline's rights over sources of production,

"resource holding ability."This fact of life

is

not

lost

to main-

males have greater

on parents

in parts of the

world where possession has long been ten-tenths of what law there

where resources have been inseparably linked time.

Where

is,

and

to family survival through

"sons are guns" (an old Rajasthani saying), the alternative to

passing property to sons

who

can defend

it

against

competing lineages

is

to

lose control of a legacy. In patriarchal social systems, a wealthy

productive resources that

women

need.

He

son finds himself in control of will

be

in a position to attract

multiple mates. In a stratified society such as Rajasthan's, families seeking social

advancement compete among themselves to amass

a

dowry

large

326

MOTHERS AND ALLOMOTHERS

enough to secure

a place for their

daughter in an ehte household. This brings

a prestigious alliance for parents along

grandsons. Should calamity strike, surviving at

the only prospect for descendants

women marry men

marry

to

elites lead to

hypergamy,

of higher status. At the top of the

hypergamy dooms daughters. There

hierarchy, however,

them

is

Thus does son preference among

all.

the custom by which

family for

it

with the prospect of well-endowed

is

no higher-ranking

into.^'

Selective elimination of daughters

attracted attention in the

first

West

during the years of the British Raj. Nineteenth- century travelers visiting Rajasthan and Uttar Pradesh in northern India remarked on the rarity of seeing girls

among any

of the elite clans.

was assumed

have been nearly four years in India and never beheld any

"I

but those in attendance

purdah

that as part of

proud descendants of warrior-kings were kept

the daughters of these seclusion.

It

as servants in

European

families, the

low

in

women

caste wives

of petty shopkeepers and [dancing] women," wrote Fanny Parks in her 185^0 travelogue through northern India.

It

did not occur to the observer that there

were no daughters. Bit

by

bit,

the light dawned.

One

enon of missing daughters while engaged owners.

He

stumbled on the phenom-

British official

in negotiations

with local land-

men

mistakenly referred to one of these mustachioed

as the

son-in-law of the other, evoking sarcastic laughter. This was scarcely possible, they told him. The birth of a daughter would be such a calamity to families of their rank that she

would never

survive.

daughters would reach marriageable age. the Jhareja Rajputs and the Bedi Sikhs

"daughter destroyers"

—

ters; lesser elites killed

ranking clans high as 400

who

little

Among the most

—known

all

boys surviving for every

from Uttar

When

a

1

little

00

such

as

girls.

among nineteenth-century i

to alleviate the often lethal neglect of girls

nineteenth-century British

Pradesh why

Britons back

870s. British colonial legislation

official

asked a landholder

the majority of Rajput families continued to elimi-

nate their daughters in spite of British laws against point:

elite clans

locally as the Kuri Mar, or

daughters, sex ratios in the region were as

led to the anti- infanticide laws of the

survived.

that anj of their

only later born daughters. Overall, including lower-

kept some or

reduced infanticide but did

who

was unthinkable

censuses confirmed the near total absence of daugh-

Public outrage against infanticide

home

It

"The father who preserves

a

it,

daughter will never

his reply

live to see

was to the her suitably

D AU G H married, or

[else]

.

F

1

.

R

S

()

R

N

S C)

S

?

ALL

1'

1

the family into which she docs

.

he ruined." The man then went on to itemize point that "those

who

\:

I'

l.

marry

N

327

S

1)

will perish

and

confirming

his

specific cases

preserve their daughters never prosper" and end by los-

^

ing their land.

world fraught with ecological

In a

D

peril, recurring droughts, famines,

and

warfare, the best hope for long-term persistence of a lineage was concentra-

male heir with several wives or

tion of resources in a strong, well-situated

concubines.

family circumstances

If

two provide insurance

make

this tactic

doubtful, a daughter or

against total extinction of the family line.

truly wretched, the best

it

can hope for

move up

is

If a

family

be able,

that daughters will

is

as

where

slaves, wives,

or concubines, to

their children

might possibly survive. Such systems did not originate because

men

sought to

the goal

sire as

—both

offspring as possible, although

subliminal and consciously stated

some of their own in

many

the social scale into positions

lineage, "honor"

—was

and advantages

subsequent generations. Ultimately,

this

many

did. Rather,

to ensure that at least

intact,

were represented

conservative course tended to

prevent local extinction of the family, and in that way was correlated long-

term with lineage

survival.

From turbaned warriors on the dusty plains of Rajasthan to modern urbanites, we are endlessly fascinated by how families fare over time. Witness the worldwide popularity of such Dynasty.

drawn stakes

Whether

in.

it

is

They want

game

to

TV

programs

a television family

know how

as Dallas, Falcon Crest,

and

or their own, people are easily

different characters will fare in the high-

of marriage, reproduction, and maintaining access to resources.

Who will survive and prevail? Who succumb?

People discuss such matters ad

nauseam. Voyeurs and gossips weigh the merits of alternative solutions to each familv's posterity problems. heirship,

We

In nineteenth-century Rajasthan,

were

are a species obsessed by strategies of

and superbly equipped to devise them.

where periodic droughts and famines extreme measures. Heart-

a certainty, survival of family lines required

less? Definitely.

And ruthless. But prevailing rules

for deciding

which sex

off-

spring will contribute most to family ends were devised over generations.

Outcomes of

successive trial and error, observation of the trials of others,

imitation of those

who

succeed

—

these

became

for particular family systems. Adaptive solutions

codified as preferences

were retained

because families that followed these rules survived and prospered.

as

custom

MOTHERS AND ALLOMOTHERS

328

Ideology Alone Cannot Explain Sex Preferences Sex preferences obviously have vival of family lines

is

a lot to

do with

would expect

at stake, evolutionists

for the underlying emotions. They

would

ideologies. Yet if genetic sura biological basis

also expect parents in other species

to bias investment by sex as well.

Animals have no

traffic

with symbolism, gender constructs, or concepts

age insurance." Hence

like "old

it is

sobering to discover that humans are not

the only creatures shaping offspring sets to achieve particular compositions.

When

many animal mothers

they can,

selectively abort fetuses,

Humans

and

bias sex ratios prior to conception,

differentially nurture

sons and daughters.

do so consciously and to

are merely the only animals to

reasons for their biases. Only the mechanisms

differ.

articulate

As Aldous Huxley put it:

"Ends are ape-chosen; only the means are man's."

One

difficulty

are very large,

it

with research on sex ratios

can be devilishly

difficult to

is

that unless the

daughters and sons.

It is

fish, reptiles,

sizes

be sure that small fluctuations

the proportion of sons and daughters are not due to chance.

of circumstances, birds,

sample

and mammals invest

Under

a

in

range

differentially in

instructive to take a closer look at the pattern of sex-

biased parental investment in these other animals before returning to the

question of why humans bias sex ratios as they do, using techniques as crude, cruel, and wasteful as

many

routinely do. Far

more

efficient

mechanisms

biasing sex ratios prior to birth are evolutionarily feasible. Fig

for

wasp mothers,

for example, evolved the capacity to custom-configure the sex ratios of their

clutches. (See p. 6^.)

ductively

Somehow

assessing

which sex offspring

will

be repro-

most advantageous, the mother adds or withholds Y-bearing sperm

as she lays

each egg.

When

William Hamilton published

his

1967 paper

"Extraordinary Sex Ratios," he launched one of the wildest and woolliest pursuits

within evolutionary biology,

known

as "sex ratio theory."

More "Extraordinary Sex In turtles, alligators, crocodiles, is

not predetermined

when

Ratios" and many fish,

the egg

is

laid

a

mother's task

is

simple. Sex

but gradually crystallizes during

embryonic development, determined by temperature or other environmental

conditions.

A mother American

alligator, for

example, ensures that most

of her eggs hatch female.simply by locating her nest

in a

sunny spot.

If,

on the

other hand, she clambers ashore and lays her eggs in a shady part ol the

DAUGHTERS OR SONS?

ALL DEPENDS

IT

beach, her eggs develop into males. In the case of some versides, the adaptive rationale for environmentally

fish, like

329

Atlantic

sil-

determined sex seems

clear-cut. Fry released into the cool waters at the outset of each breeding sea-

son are always female, while those born mostly male. In

a

later, after

world where big mothers

the water has

warmed,

be more fecund ones,

will

are

"his"

and "her" time-sharing of the birth season means daughters born early have

more time

to

grow

big before they lay eggs. Biasing sex ratios in

more complicated, and Skews

in

less well

is

understood.

secondary sex ratios have been documented

deviations from ^o-^o are rarely so

pronounced

in

as in fish

mammals, but

or wasps

one notable exception, wood lemmings. These denizens of

Northern Europe have the most skewed sex

Wood lemming

mammals

ratios of any

fir

—

with

forests in

mammal known.

many daughters as sons. Their secret is a curious alteration on the sex chromosomes that causes genes carried on theY chromosome to remain unexpressed. In humans and other mammals, a female with just one X chromosome (denoted "XO") would not be fertile, but for some reason, these "XY" lemmings exhibit mothers produce three to four times

female phenotypes and are

as

fertile.

Just why such a capacity evolved is not known. Zoologist Nils Stenseth suggests that manipulative

lemming mothers have adapted

characterized by an inbreeding phase.

Wood lemming

to reproductive cycles

sons in the past con-

fronted the same local competition for mates that wasp sons confront

circumstances force them to breed with their sisters inside a

"dominant" X chromosome allows Like other small arctic

may

crash.

alone in a

A

are prone to excesses,

pregnant female lucky enough to survive would find herself

lemmingless land, with no females for her sons to mate with. What

daughters

to colonize a

—

like

known

modest

Hamilton's

new wide-open

Wood lemmings nation

popu-

by population busts. In bad years, the population

better tactic at that point than producing only as tilize

This very

XY sons to be transformed into daughters.

mammals, lemmings

lation explosions followed

fig.

when

fig

wasps.

to bias sex ratios to such

abortions are unnatural.

Her grandchildren

mammals with chromosomal

sex-ratio biases are widely

—

sons as needed to ferwill

move out

niche.

are the only

tions that are sex selective

many

sex determi-

hymenopteran extremes. But more

documented, including spontaneous abor-

a surprise, perhaps, to

anyone

who assumes

that

— MOTHERS AND ALLOMOTHERS

33°

Sex-Selective Abortion in Animals Few funding agencies are interested in spending money other animals bias their sex ratios. Fewer

still

to find out for sure

if

compelled to study spon-

feel

taneous abortion of daughters in aquatic rodents. Fortunately, though, gov-

ernments are very interested

in eliminating introduced pests. This

Britain's Ministry of Agriculture set

large

(

i

up

program

a massive

why

is

to trap coypu,

o-kg) guinea pig— like animals brought to Europe from South America

for fur breeding.

When some

of the coypu (also

known

as nutria) escaped,

they proved as footloose as they were furry and prolific, spreading like kudzu

weed across the marshlands of eastern England. The coypu trapped in this pest-control program provided the first opportunity to test sex-ratio theory in free-ranging mammals. Hired by the government to eliminate his quarry, biologist Morris Gosling decided to inspect their innards in the process.

embryos old enough first

He

dissected

to count and to sex.

coypu.

5^,85^3

Of these,

had

1,485^

Examining them. Gosling made the

of several startling discoveries.

Prior to fourteen weeks of pregnancy, a coypu uterus was as likely to contain a

mostly male

as a

mostly female

litter.

Later in gestation, however,

hard to find a mother pregnant with a small that

litter

was anything other than mostly male. The only

that females carrying small, mostly female litters

(of four

embryos or

Were

so.

less)

plausible explanation

was

were spontaneously abort-

ing them. Surprisingly, the fattest females in best condition were the

prone to do

was

it

most

these abortions really reproductive failures. Gosling

wondered, or were they adaptive maternal management?

EtTu, Coypu? Late in her pregnancy, after particularly fat

week fourteen of her nineteen-week

coypu carrying the "wrong" type of

stances spontaneously aborts. stores

needed to

By

this point, she

tide her through lactation. So

stage gain by bailing out so late? What she gains

litter for

would have

what can is

a fat

gestation, a

her circum-

laid

down

female

fat

at this

the opportunity to do even

better reproductively in her next pregnancy. Instead of squandering a somatic windfall

on

a

handful of daughters, she aborts and quickly conceives again

possibly conceiving a mostly male

enough to take advantage of being

litter, or, failing that, at least a litter

in

such fine

fettle.

"Abortion might be advantageous," Gosling reasoned, female to transfer resources to

a litter that

large

is

if "it

allows the

likely to achieve higher

RS

DAUGHTERS OR SONS?

IT

ALL DEPENDS who

[reproductive success]." Females in good condition

pregnant with small, mostly male

litters,

large-bodied, competitive sons. But

no

ters reap

fat

special reward. Pregnant

331

find themselves

can count on producing especially

females pregnant with mostly daugh-

coypu are somehow assessing their

own

condition, and aborting or continuing with pregnancies accordingly.

was an astonishing observation, but not

It

decade

earlier, in

mathematician

totally unforeseen. Just over a

1973, two graduate students, biologist Robert Tri vers and

Dan

Willard, had published a paper in Science predicting

Gosling's result.

Custom-Made

Families

TheTrivers-Willard hypothesis states that wherever variation in reproductive success

is

greater for one sex than for the other, and where the reproductive

success of individuals of that sex depends on maternal effects, then mothers in

good condition should

favor the sex with the greatest variance in repro-

ductive success. Mothers in poor condition should favor the sex with the

Under most circumstances,

least.

the sex with the greatest variance in repro-

ductive success, and the one that benefits most from maternal advantages, sons. This

is

why

in a species like

is

coypu, mothers in good condition should

theoretically prefer sons (or else a very large litter), while those in

poor con-

dition should prefer daughters. Just how mothers might do

a mystery.

Some

this

is

have speculated that sex ratios are biased prior to conception by differ-

ent hormonal conditions in the mother and differential survival of X- and

Y-bearing sperm inside the mother en route to the egg^ or else through ferential survival of male

and female embryos.

In devising the theory, Trivers like

deer or caribou, in mind.

well fed

would grow

a

and Willard actually had large mammals,

A male

deer whose mother was healthy and

into a particularly large and competitive stag, able to

out-compete and exclude

mother of

dif-

rivals

born to mothers

poor condition. The

in

noncompetitive son would be better off producing

a daughter:

even a hind in poor condition should be able to conceive and pull through least

some

at

offspring.

Today, the logic of Trivers-Willard has been found to predict sex ratios at birth

among

animals ranging from the noble red deer of Scotland to pudgy

possums ambling about on the

forest floor of Central

America, not to men-

tion footloose coypu everywhere. The hypothesis even explains the near com-

plete specialization in daughters by low-ranking spider

monkey mothers

in

MOTHERS AND ALLOMOTHERS

332

—^

good

mother biases investment to favor sex with greater variance

competitive offspring

in r.s.

maternal condition

poor

-r^

noncompetitive offspring

~^

mother biases investment to favor sex with less variance in r.s.

Fig. 13.3

TheTrivers-Willard hypothesis seemed to explain sex-biased termination of pregnancy

in coypus.

Peruvian rain forests. success

is

It

applies

when

the main determinant of reproductive

access to females.

But what happens resources? What

if

when

the critical factor

is

not access to mates but

offspring of one sex are better than the other at protecting

a territory, or converting

offspring of one sex

its

resources into reproductive success?

What

if

do more than the other sex to enhance or protect the

value of local resources at the parents' disposal

—known

as "local

resource

enhancement"?''^^

Today the

classic

demonstration of biased production of daughters or sons

depending on which sex most enhances the value of parental resources derives from a remarkable study of a rare species of bird

known

as the Sey-

chelles warbler.

The

Seychelles are a motley group of islands in the western Indian ocean,

some rocky and

waterless, others lushly tropical. These islands provide the

natural "laboratory" that permitted

Dutch ornithologist Jan Komdeur

prove conclusively that bird parents adjust sex

most

ratios,

to

producing offspring of

enhance the family's situation, depending on the

cir-

cumstances prevailing when they hatch. These birds clinch the case that

ani-

the sex

likely to

mals can custom-tailor their families.

Up

until 1988, the entire

''^'

world population of Seychelles warblers was

confined to a single island. Three hundred and twenty perky, white-chested little

on

birds the color of

cinnamon

that island. Breeding pairs

toast had saturated locally available habitats

were spread out

in territories,

remained for up to nine years, producing a clutch once

where they

a year, usually just

one

^§§ per clutch. Although warblers can breed in their first year, daughters remained where they were born, helping parents catch insects to Iced

— DAUGHTERS OR SONS? younger

siblings.

When

this

is

is

more

1)

K P L

who compete

a liability than an asset. In line

who do

parents on poor territories

N D

S

333

a catch.

are scarce, having helpers around

ents for sustenance

ALL

allomother was removed, reproductive success

of the parents went down. But there If insects

IT

with their par-

with

this calculus,

not benefit from having helpers produce

mostlv sons (who are not inclined to stick around). Noticing

new

researchers decided to experiment. Parents were transplanted to tories

this,

the

terri-

under controlled conditions.

Warbler pairs placed on food-rich, wide-open territories could presum-

As predicted, 87 percent of these privileged parents produced daughters, the sex most inclined to stay and help out. Of parents ablv afford "au pairs."

How? Not

placed on poor territories, only 23 percent had daughters fledge.

known. One rule"

—

possibility

might be that the birds use some sort of "starting

incubating eggs of the "right sex" but abandoning nests containing the

wrong sex and

starting over. This

much

certain: Seychelles warblers are

is

adaptivelv configuring offspring sets in response to family history and local

conditions just as surely as that the mechanisms in

some human parents

humans

are.

It is

unlikely,

however,

are the same. Rather, there appears to have

been selection on the human psyche for general decision rules that produce

outcomes from

locking parents into

make

still

assume

a biological

parental attitudes toward sons versus

daughters imminently changeable. By now,

who

in other animals. Far

some preordained response, however,

basis for these preferences should

to readers

produced

similar to those physiologically

this

claim will seem curious only

immutable

that evolved traits are necessarily

which they are not.

When the "Rules" Themselves Are Contingent The perennial question "which sex

.

.

to produce" can be mind-boggling, espe-

baboons and macaques, "weedy" species

ciallv in

such flexible primates

humans

are, readily adapting to diverse habitats. As in

as

.

all

Old World cercopithecine monkeys, baboon and macaque daughters rank from their mothers. Because daughters remain nearby, high-ranking mother to produce the sex that status, as well as bolster matrilineal interests

will benefit

like

the well-studied

it

inherit

behooves

by supporting kin (another form

of local resource enhancement). In habitats like Amboseli, where food scarce, high-ranking mothers do

same pattern can

also

just this

—

a

most from her own

is

they overproduce daughters. The

be documented for some populations of macaques.

— MOTHERS AND ALLOMOTHERS

334

Year after year, mothers in the highest-ranking matrihnes consistently

produce

more daughters

significantly

than sons, while low-ranking females

produce few daughters and more sons. Low-ranking females not only produce few daughters, but such daughters

as

they do produce are

likely to

born to mothers of equivalently low rank. Based on captive

die than are sons

studies of bonnet macaques, Joan Silk

showed

that

whereas sons

group can leave the disadvantages of

their natal

more

who

depart

low rank

their mother's

behind, daughters cannot. In her study, no daughter born to a low-ranking

mother managed

to

for local resources

produce

is

a single surviving offspring.

born to

intense, a daughter

When

a high-status

competition

mother

is

the

right sex in the right place at that time.^^

among

Recall that infants have a

But

life.

sex"

—

if

2

that

5^

the baboons Jeanne

Altmann studied

-percent chance of dying during each of the

baby

is

a

daughter born to

a

at

first

high-ranking mother

Amboseli,

two years of

—

the "right

the baby's survival chances go up twofold, and are higher than survival

chances for a son born to

breed sooner.

a

mother of the same

On average, mothers who get the

status.

Such daughters

also

sex right contribute an extra

half-grand-offspring to the next generation. Mothers at Amboseli produce no

more than seven vive.

Given

how

offspring in their lives, of little

these

which on average only two

baboon mothers have

show

to

sur-

for a lifetime spent

producing and carrying babies, such bonuses add up. Generation after generation, cumulative reproductive advantages mean that

mothers

in these matrilineal systems

compete

than the isolated copulations males fight over.

A

for

male

more enduring

who

stakes

hitches his repro-

ductive star to a successful matriline by siring a daughter in one, secures his ticket to posterity. Similarly,

if

a male's

parents benefit from son production.

mate

Lowborn

is

a subordinate female,

sons, like

both

poor country boys,

strike out for distant opportunities, leaving natal disadvantages behind. But in

some cercopithecine monkeys

like

macaques, there

is

another reason for sub-

ordinate mothers to bias toward sons. Females from dominant matrilines maliciously harass daughters born to competing mothers, sending a not so

"We may tolerate your sons for a time, but your daughters who will be permanent residents are not welcome." These bullies inflict much wear and tear on low-ranking mothers, especially those carrying subtle message:

—

daughters. Silk hypothesized that such penalties imposed upon low-ranking

mothers who produce daughters has led to selection on subordinate mothers to cither avoid conceiving, or avoid gestating, daughters.

n AU C H T

E

R

OR SONS?

S

Yet even this sophisticated calcukis

is

ALL

IT

D

N D

P H

V.

not the whole story.

S

335^

When

environ-

mental conditions change, the mother macaque or baboon pulls out

new

a

rule book.

.

.

.

and the "Wrong" Sex

Year alter

daughters are a pects. Yet

Shall

liability to

document

researchers elsewhere

at all.

the "Right"

that in habitats like

One

Amboseli,

low-ranking mothers. Sons offer the best pros-

baboon and macaque populations, no found

Become

year the evidence grows stronger

different

patterns.

In

some

maternal rank on sex ratios

effect of

is

Others exhibit the mirror-image of the Amboseli pattern, with

high-ranking mothers overproducing sons, low-ranking ones daughters, just asTrivers andWillard predicted. Different teams of researchers were reporting different patterns, each

group suspecting the others must be getting

assumed

statistically significant differences

it

wrong. Those

that the other

two groups were

infected bv "sex-ratio fever" and in their theoretical delirium

patterns in what was only In

up

in

1

99

1,

random

Carel van Schaik and

I

were among the primatologists swept as the "wild,

What if, we wondered, the researchers

monkeys were changing the

were imagining

variation.

what we jokingly referred to

research."

who found no

rules?

We

wild world of sex-ratio

weren't wrong. What

noticed, for example, that

it

if

the

was the

macaque and baboon populations from wide-open habitats with plenty of food and

room

for expansion that

were

least likely to

conform to the

"Amboseli pattern." Outright reversals of that pattern (with high-ranking

mothers overproducing sons, low-ranking ones daughters) were most often reported in large outdoor breeding colonies where the combination of ample

food and space contributed to very high birth all, is

what breeding colonies are for.) This

rates.

is

(Producing babies, after

when

it

occurred to us that

under ecological conditions conducive to rapid population growth, the

dif-

ferences in male and female reproductive potential so critical to the logic of the Trivers-Willard hypothesis

become

relevant.

At

this point, a

mother's

determination of the optimal sex of offspring for her circumstances does a flip-flop.

We reasoned that in rapidly

expanding populations, where both high- and

low-ranking females can successfully breed, the greater reproductive potential

of sons born to mothers in good condition takes priority over the endur-

ing value of advantageous maternal rank.

Under

the arduous conditions at

MOTHERS AND ALLOMOTHERS

33^

Amboseli, matrilineal access to scarce resources

is

the mother's top priority.

But in high-growth populations, monkey mothers march to a different drummer, depending on whether the most important factor hmiting the breeding success of their offspring will be access to resources or access to mates.

What Keeps Human Sex Ratios Nearly Equal? The existence in animals, especially other primates, of heretofore undreamedof capacities to adjust their production of sons versus daughters in adaptive

ways

raises

an awkward question. Given long-standing biases in favor of a

particular sex,

who

why

desired sex?

The

Mother Nature), If it is

why

hasn't natural selection led to subsets of

existing system it is

is

not only cruel (which

wasteful (which

not relevant to

is

is).

on mothers to

possible for selection to act

bias sex ratios at birth,

stop with a paltry six extra sons per hundred daughters? In populations

where from time immemorial parents have discriminated

why

human mothers

adjust to variable local conditions by automatically producing the

don't

we see sex ratios at birth much wasted effort: all

against daughters,

in the vicinity of 200: 100? This

save parents

would

the energy, the opportunity costs, the

time and risk of a pregnancy to produce a baby her parents won't even keep.

Why,

then, are

human

sex ratios at birth so nearly equal, roughly ^i percent

male, 49 percent female?

When

biologists are asked

tively close to parity,

more

why

sex ratios consistently hover conserva-

not they will invoke "Fisher's principle

likely than

of the sex ratio." This time-honored axiom of population genetics explains

why

roughly equal numbers of the two sexes are produced

species of birds and

mammals.

In the

1

daughters; and so long as outbreeding prevails (that sisters, as fig

wasps do); and so long

same opportunity to breed

(a big

if,

as

so

many

930s, British biostatistician Sir Ronald

Fisher reasoned that so long as producing sons costs the

with

among

it

is,

same

as

producing

brothers don't breed

as all individuals

have roughly the

turns out); then parents should allo-

cate equal investment in sons and daughters.

Imagine a population

in

which certain parents

specialize in

one or the

other sex. Let's say most mothers produced sons. As offspring mature, they will

breed

in a

lopsided world, top-heavy with males. Too bad for the sex in

excess. Although every scarce female will get to breed, only a

of males will manage

to.

Too bad

also for the parents that

random subset

overproduced sons.

DAUGHTERS OR SONS?

IT

ALL DEPENDS

337

because, on average, son-producers will be penalized by having fewer grandchildren. The will

mother lucky enough to produce daughters, on the other hand,

be rewarded by disproportionately more grandchildren

—

at least

tem-

porarily.

Over time,

natural selection should favor parents that produce the rare

sex, with the predictable

outcome

—

sex ratio should gravitate back to favor the

pendulum swinging

first

Once again, the son-producers. And so it goes,

a glut

of daughters.

one direction, then the other, favoring

first

daughter-producers, then son-specialists. The outcome, according to Fisher, is

a

population with

more or

Fisher's principle

is

less

equal numbers of sons and daughters.

why

the conventional explanation for

wildly skewed

sex ratios evolve only under special conditions. But such special conditions

turn out to be not so unusual. Supposedly, Fisher's principle explains

most human sex slightly

more

ratios are only as mildly

sons are born on average

is

skewed

as

they are.

that males are

why

The reasons

more

vulnerable

(both in utero and in infancy) to dying before the end of parental investment; thus,

bv producing

slightly

more of them,

parents are merely equalizing

investment in sons and daughters. Yet other animals Fisherian equality

—baboons and macaques,

when one

for

or the other sex costs

example less

—

deviate from

or provides a bigger

reproductive payoff. Why don't humans? It is

possible, of course, that the

gone undetected. For example,

if

phenomenon occurs but

has

somehow

parents biasing toward sons were

lumped

with those biasing toward daughters, the average sex ratio would come out ^0-^0. Indeed, deviations from the expected, approximately equal, sex ratios at birth are sometimes noted.

'^^

human

Occasionally groups surface with

spectacularly high sex ratios that cannot be attributed to differential neglect

or infanticide. These

may

timing of conception.

'^^

(or

may

not) have to do with customs that affect the

Furthermore, every so often geneticists stumble on a

rare pedigree, such as the English family that for ten generations

daughters in 32 of 3^ births, or the

produced

French family that produced exclusively

daughters (72 of them) over three generations. Yet these could be explained as

chance occurrences. Massive screening has unearthed only a handful of deviant cases, and none

so extreme, nor so precisely calibrated to reproductive possibilities, as the

wildlv biased sex ratios readily located

among wasps, wood lemmings, war-

MOTHERS AND ALLOMOTHERS

338

and spider monkeys. Overall, deviations from the standard human sex

biers,

ratio of

tary

1

1

00

girls are rare,

from George Williams, who wrote

find

I

02 to 106 boys per

it

evolutionary theory.

mination are

.

is left

trivial at best."^^

in sampling, or else the

sex ratios might be adaptive

all

right,

theory could be wrong.

but parents postpone their

—

have long done.

Much

evidence points to

(as in

the coypu),

birth, in line

about

human mothers

how much money

Each year

litters

consciously choose sons and daughters

after

with parental evaluation of what the repercussions will be for

are probably similar

ications, like

differ-

wasps), or differential retention of mostly female

long-term family goals. The underlying psychology

—

many Asian families Humans con-

of innate mechanisms that bias production of sons or daughters

conception

comes

as

this third possibility.

same posterity problems other animals do, but resolve them

ently. Instead

(as in

commen-

from random sex deter-

adjustments in parental investment until after birth

at

puzzled

to chance] seems to contradict

Instead, deviations

.

.

There could be an error

front the

a

passage:

rather mysterious that adaptive control of progeny seems not

to have evolved. [That this matter

Or human

prompting

now famous

in a

—

when modern American

to spend

on toys

although not the outparents

make

choices

for their children, or certain

med-

growth hormones. in the

United

States, parents

spend 60 percent more on toys for

boys (Legos and G.I. Joes) than on toys for

girls (disproportionately dolls).

Parents are twice as likely to treat a growth

hormone inadequacy

in a daughter. Part of their calculation

invest

more

in sons than daughters,

is

surely not just

son as

in a

whether they wish to

but which sex they feel will benefit more

from the intervention. Height, to take one example,

is

a far

more important

predictor of success (including salaries and marriage options) for sons than

it

""^^

is

for daughters.

Reassessing the Rajput Case

No

research on biased sex ratios in birds or

anthropologist Mildred Trivers and

Dickemann

first

mammals had been done when

encountered the logic

scant attention to the idea that there might be innate that

laid

Willard in their 1973 paper. Social scientists at that

enhanced inclusive

fitness

human

out by

time paid

predispositions

and the long-term survival of family

lines.

DAUGHTERS OR SONS? Devaluation of daughters was viewed

IT

ALL DEPENDS

339

purely cultural construct.

as a

assumed to be the outcome of free-floating minds spinning

It

was

infinitely variable

webs of meaning out of locally received traditions. As

anthropologists were concerned, the ideology of son

far as cultural

preference along with the custom of paying dowries to marry off daughters sufficed to explain female infanticide.

What

other reasons could there be?Yet

Dickemann was struck by how well the patterning of son preference in the north Indian case conformed to predictions of an evolutionary model that applied to animals generally. Trivers andWillard proposed that parents in sons, those that logic

were disadvantaged, daughters. They even

would be found

marry up the

in socially stratified

social scale,

upper end of the

end of the

scale

good condition should prefer

scale

human

specified that this

where women

societies,

whenever the "reproductive success of a male

exceeds his

sister's,

exceeds her brother's.

male whose socioeconomic

status

is

A

while that of a female

at the

at the

lower

tendency for the female to marry

a

higher than hers will, other things being

equal, tend to bring about such a correlation." Trivers and Willard's logic

even explained the most puzzling feature of daughter slaying in the Rajput case

—why

spring.

the

most

By contrast,

elite families

sub-elites

daughters in one of these process.

The poorest

None

were

elite

left

likely to kill half of their off-

paying exorbitant dowries to place

households, impoverishing their sons in the

who really did not have enough resources to ones who welcomed daughters and did not kill

subcastes,

feed their children, were the them."'

were the most

of this

made

sense unless one accepted the assumption that

parents were not counting offspring but looking further

down

toward grandchildren and beyond, toward the survival of a family

the line,

line.

Reversals of Fortune Leaving Daughters Preferred Eliminating daughters at the top of the hierarchy produces a vacuum sucking a shortage at the

bottom.

Families don't pay dowries to place daughters in families with the

same or

up marriageable

girls

from below, and creating

lower status than their own. They demand payment for them instead. At the

bottom of the heap, sons whose price

remain

commodity

celibate. Far

from

families cannot

cough up the required

calamities, daughters are the

bride-

most valuable

low-status families possess.

Referring to a daughter as a commodity will strike narily callous. But

we

many

are not talking about postindustrial

as extraordi-

Western popula-

— MOTHERS AND ALLOMOTHERS

34°

tions that for generations have release, freed

hved

in an

from concern about famines. Continued

ents and their children rarely depends

much food

unprecedented

state of ecological

survival of such par-

on choices mothers make about how

to allocate to one child versus another. But not

all

fortunate. Daughters not only offered the only prospect for in

many

cases they provided the only possibility at

all

mothers are so

upward

mobility,

of continued survival of

a family line.

world where drought and famine are recurring hazards, the

In parts of the

landless and dispossessed invariably have the worst chance of

through.

Under such harsh circumstances

spring of mothers arable land."

who marry

Hypergamy

it

(girls

marrying up)

is

Nor can

not it

a fluke.

It

was

a long-

be denied that decisions

have genetic outcomes.

Centuries of hypergamous mating have

breadcrumbs through the

left a trail

of genetic markers, like

forest of the Indian caste system,

different paths followed by the spring.

it

into families with access to resources, like

standing necessity for lineage survival. leading to

making

the likeliest survivors will be off-

two sexes

as

documenting the

they married and produced

An examination of genetic traits carried in mitochondrial

found in somatic and egg

from mother to

cells

offspring,

but not in sperm), which

showed

is

off-

DNA (DNA

transmitted only

that these mother-transmitted traits are

spread widely beyond traditional caste boundaries. For centuries, they have

been carried by brides and concubines moving up into higher- caste families.

By

Y chromosome,

passed from father to son on the transmitted

traits

they originated.

^"^

as

world by marrying

are less mobile. Father-

remain localized, rarely spreading beyond the caste where This

may be one

reason

why male

ble to extinction than those carried by mothers.

viewed

in the

contrast, paternally transmitted markers, traits

traits are

more

vulnera-

Thus do customs previously

purely cultural have profound demographic and genetic conse-

quences, as well as deep roots in

human

motivations and their decision rules

regarding children.

Human Nature and Human History The

earliest

evidence for sex-biased infanticide derives from the

baby skeletons

—

all less

DNA

of

than two days old and without apparent defect

excavated from the sewer of an ancient brothel

southern coast of modern

Israel.

in

Roman Ashkelon on

the

Fourteen of the nineteen victims of what

DAUGHTKRS OR SONS?

IF

ALL DEPENDS

archaeologists suspected was infanticide were male.

mothers were

their

If

341

indeed prostitutes, one assumes they came from the lowest rank of society: daughters hut not sons of these

among

sons

sessed

is

elites

mirrored by

a pattern that

women would

a preference for daughters

Daughter preference can

persists.

still

A preference for among the dispos-

have value.

still

be docu-

mented today amon^ Hungarian Gypsies and other disadvantaged groups. Consider what happened with the

late

1980s

fall

communism. Across

of

eastern Europe, economies and social services were disrupted, leading to an

unwanted pregnancies. Not

surprisingly, the inci-

dence of neonaticide has increased, but with an unusual

twist. Prior to 1990,

increase in both misery and

sons and daughters were about equally likely to be killed. After

1

990, Slova-

kian researcher Peter Sykora documents that the victims are disproportionately

male

—

2

1

of 27 in the neonaticides in his sample.

^^

Large chunks of Western history can be understood only by paying attention to such patterns.

Human

fates

can be read as artifacts of differential

treatment of offspring by their parents.

Which

sons inherited land and con-

tinued dynasties, which departed instead to colonize offspring vents),

Nowhere and

were predestined to

live

out their

lives in

which daughters were dowered and sent is

this

point better

social historian

made

new

worlds.

monasteries (or in con-

off to distant

kingdoms.

than in the writing of the archaeologist

James Boone.

Using medieval Portuguese genealogies, Boone traced the

and daughters among both the

who

Which

elites

—

fates

royalty and landed gentry

of sons

—and

those

served them, bureaucrats and soldiers, over a two-hundred-year period

(from 1380 to 1^80). Dukes and counts

at the highest social

ranks

left

more

surviving legitimate offspring (4.7 offspring on average, with no rehable

counts for illegitimates) than did cavaleiros and military

men below them

(2.3 legitimate children on average). For both sexes, firstborn offspring fared better. Later-born sons fought in the

away longer, and were more born sons, who

often

Crusades farther from home, stayed

likely to die in far-off places like India than first-

went no

farther than

Morocco and soon returned

to

marry and take over family holdings. Redundant daughters were

similarly banished, not to distant lands, but to

convents. Italian novelist Alessandro this

arch

Manzoni provided an apt description of

predestined claustration in his description of the proud Milanese patri-

who "destined

all

the younger children of either sex to the cloister, so as

MOTHERS AND ALLOMOTHERS

342

to leave the family fortune intact for the eldest son,

whose function

it

was to

perpetuate the family." This practice brought great unhappiness to younger offspring of both sexes. In his 1827 epic / promessi sposi

(The Betrothed), Manzoni sums up the

plight of a later-born daughter:

Still

hidden in her mother's

been irrevocably it

was to be

womb

settled. All that

that of a

Among

.

.

her state in

had already

life

remained to be decided was whether

monk or a nun,

but not her consent was required.

daughters

.

a decision for

which her presence

^^

Boone's medieval Portuguese, between 10 and 40 percent of

at

any given time were cloistered in convents. Elite daughters

married produced an average of 3.7 children, about the same (3.3) of surviving children left by sub-elite

moved up

the social scale

cess of daughters

when

Rajputs

—

the reverse was true. When

how

significantly

this situation

whom

of

who

number had

they married. Overall, the reproductive suc-

born to lower-ranking

families

brothers, while at the top of the hierarchy

to simulate

women, many

as the

—

was higher than as

among

the north Indian

Boone fed these data

in the third generation

computer

into his

would play out through time,

more grandchildren

that of their

produced

elites

through sons than

daughters, while lower ranks did better with daughters than sons.

Among "The Despised Ones" It

was reversals of fortune such

pologist Lee

study

is

as these that attracted the notice

Cronk when he went

to

of anthro-

Kenya to study the Mukogodo. Cronk's

unusual, because he specifically focused on those on the lowest rungs

of the local ladder.

The Mukogodo

are

former foragers pressured by economic necessity to

attach themselves as a disadvantaged "subcaste" to Masai pastoralists, adopt-

ing Masai language and values but never achieving equal status. Locally, the

name Mukogodo means "the despised ones" or, more literally, "poor scum." As is typical among pastoralists, the Masai prefer sons. The Mukogodo, who emulate them, claim to as well. But the actual behavior of Mukogodo mothers and the sex every 100

ratio of their offspring (there are about 67 little boys for

girls) tell a different story.

ters longer than sons,

Mukogodo mothers

breast-feed daugh-

and are more inclined to pay to take

a sick

daughter

DAU G H T

H

R

S

OR SONS?

ALL

11

D

N D

H F L

S

^4.3

than a sick son to the medical chnic. Partly for this reason, daughters are healthier and

Out

more

likely to survive than sons.

ol this strange

union of two cultures has emerged

marriage svstem structured along the

lines

rigidlv stratified clans of precolonial Rajasthan:

with daughters preferred over sons

Dickemann

women

many Mukogodo men, with

identified in the

flow up the hierarchy,

all.

With

so

daughter.

It is

not possible to

below

that of

for sure

which

is

know

mothers value more, the material benefits daughters bring, counted stock, or the grandchildren; but

two were so intertwined

as to

social

many Mukogodo

sons growing old wifeless, their average completed fertility

Mukogodo

up the

to Masai

smaller herds of livestock to draw on for

bride-price, have difficulty obtaining wives at

the average

many Muko-

the bottom. Because so

at

godo women become primary or secondary wives scale,

hypergamous

a

my

guess

is

make them

in live-

that over evolutionary time the

inseparable so far as a mother's

internalized preferences for different offspring are concerned.

Economics of Daughter Preference Outright daughter preference

Among

the disadvantaged.

is

unusual, but not necessarily confined to

the matrilineal Tonga people of southern Zaire,

daughters are essential for perpetuating the basimukoa, or matrilineage. The

more prosperous

the matrilineage, the

more

pressure to bear daughters.

surprisinglv, there are two cries of joy at the birth of a

bov.Too many sons, and the mother comes

baby

in for criticism

girl,

from

the point, males die in childhood at far higher rates than females.

twins die

at five

is

neglected, and

island of its

come

likely to die.

Same-sex male

to prefer daughters because is

with

a

long tradition of son

women

have found a special

the case with daughters born on the

Cheju Do, off the coast of South Korea. Cheju

W'omen abalone

Do

dence of these

Do

is

renowned

divers, called haeyno. Because this occupation

learns she

respect, Cheju

Of recorded

twins of mixed

living in areas

for themselves. This

well paid, daughters provide

Cheju

to

alive.

Sometimes parents, even those economic niche

More

times the rate of singletons, suggesting that parents do not go

out of their way to keep them

preference,

more

kin.

When

births, only 92 boys are reported for every 100 girls.

sexes are born, the boy

Not

only one for a

is

more

security than sons.

pregnant, she prays for a

girl.

When

a

is

for

relatively

woman on

Financial indepen-

women has also led to the highest divorce rate in Korea. In this Do has come to resemble some Western countries where fam-

MOTHERS AND ALLOMOTHERS

344 ilies

are in transition

new worlds where women mean they

between long-standing

legal protections along

patriarchal traditions and brave

with economic opportunities for

can afford to survive and rear a family with or without a

male provider.

Fine-Tuning Family Configurations Parents can be remarkably specific in their requirements for certain offspring sets. There are

which

leaves

lingers In

on

time-honored traditions specifying which sex

empty-handed or marries out with

a

stays or inherits,

dowry instead, which child

as a celibate spinster baby-sitting for the designated heir.

many

areas of Asia, the ideal family

one or two daughters. Thus,

is

composed of two

to four sons and

should not surprise us to occasionally

it

encounter "missing boys" along with

all

the missing girls

—

not in such

albeit

vast

numbers. Anthropologist G.William Skinner was among the

dict

and document

just such a pattern to missing children. In his

first

to pre-

most recent

study of census data from China's lower Yangtze region. Skinner and co-

worker Yuan Jianhua documented birth-order daughters, but also families that already

mostly higher-

1.2 million missing girls,

some 60,000 missing

boys, mostly from

had several sons.

Culturally mediated parental preferences can play out with chilling predictability. Studies

of child survival

Bangladesh make

clear that

at risk,

it

it is

among

Punjab and

villagers in the

in

not just daughters in these families that are

but daughters with one or more older

one

sisters. In

village in

Bangladesh, such daughters have a 90-percent higher chance of dying before the end of childhood than do girls without any older

luck of being born after two or

more older brothers

sister.

A boy with the bad

has a 40 -percent greater

chance of dying than an only son does.

Parental

commitment

to offspring can

and birth order conform to demonstrate islanders

on

this

do.

They

No wonder

norm. Among the

was sociobiologist Paul Turke,

Ifaluk Atoll.

tive than sons.

a desired

depend on how nearly the

in

first

fieldwork

child's sex

to empirically

among

Pacific

Daughters among these fisherfolk are more produc-

also help parents to rear

younger

daughters are preferred. Parents

figuration, producing a daughter

first

and then

siblings

who

more than sons

achieve the ideal con-

a son,

were better

off

and

DAUGHTERS OR SONS? reared

more

surviving offspring than those

Overall, mothers

who

bore

a

whose

daughter early

hijjher lifetime reproductive success than

ALL DEPENDS

IT

in their

daughter

initial

may be taken

was male.

reproductive career had

women who

bore

a

son

^^

first.

such mild preference for

In patriarchal societies in saturated habitats,

an

firstborn child

345^

to extremes.

Among

eighteenth- and

nineteenth-century farmers on the Nobi plain of Japan, the ideal pattern of "first a girl

but

it

then a boy" has a name: ichihime

nitaro.

Sons are the preferred sex,

they can, parents arrange things so as to have a

primary

to help rear the

heir, to

make

sure he

is

little

allomother on hand

as healthy

and good

as

he can

Parents were not above loading the demographic dice in an astounding

be.

gamble. Those young enough to be confident of plenty more chances to try for a "jackpot" configuration

happened to be born hime

nitaro.

births and

with

thus enhancing the odds of achieving the ideal

Thereafter, parents in

—

as possible

first,

might eliminate even the much desired son

if

—

he

ichi-

infanticide to space

to achieve as nearly

an ideal configuration of well-spaced, gender-balanced offspring

a fully qualified firstborn

Clearly, the

to retire.

Tokugawa Japan used

conditions were sufficiently auspicious

if

son coming of age just

as his father

"mania for sons" was never so simple

as

was ready

an across-the-

board preference for male children, solvable by an across-the-board biasing of the sex

ratio.

Why Humans Bias Investment After Birth Humans,

like

other animals, use flexible "decision rules" to bias investment

toward daughters under some conditions, toward sons under others. But unlike a

mother wasp, who

sizes

up demographic prospects and then com-

mits herself to producing mostly daughters or mostly sons, humans with very

few exceptions leave the matter open

until after birth.

Then they

evaluate

contingencies like birth order, offspring quality, available assistance, even inheritance prospects. Given the importance of history and narily flexible

ments

in

human breeding systems

which they

live

and

are,

how

how

extraordi-

variable the environ-

can be, parents with innate propensities to produce

one or the other sex would have been wrong

Where environmental

as often as

they were right.

^^

conditions, marriage and residence patterns, or

laws can change on short notice, the better part of evolutionary valor

postpone irrevocable decisions

till

the

last

feasible

is

to

moment. Conscious

strategists constantly update information about local prospects for sons ver-

sus daughters. Chronic tensions

between maternal and

patrilineal interests

MOTHERS AND ALLOMOTHERS

34^

new

are resolved quite differently as

subsistence opportunities

become

others close, as daughters once of no use suddenly

open up while

net assets, and so

on. Unlike other creatures with pressing reasons to bias parental investment

prior to birth, the sheer variability of the

of

precommitment

human

Furthermore, unlike other mammals, the

ill-advised.

human

sheer duration of parental investment in the

forms tances

it

can take

—means

—

condition makes that degree

and the myriad

case,

food, educational costs, marriage payments, inheri-

that parents have

many ways and myriad opportunities to bias

investment in different offspring.

Imagine

a

mother

in unusually

good condition who somehow biased pro-

duction toward a daughter in preparation for a nice matrilocal

life,

and then

found herself captured by some warlike, patriarchal tribe where only sons

were valued. Her physiologically based "decision" would have been

a mistake.

Far better to pursue the Fisherian course of equal investment prior to birth,

and then fine-tune investment

and daughters

in sons

after birth,

responding

to local cues and customs.

Biologically Based Behaviors Are Changeable Faced with constraints, parents readily value some offspring over others. This is

the bad news. The

cific

sex preferences

good news

—

such

as a

is

that

nowhere

mania for sons

in the

—

spread as son preference happens to be, there

human psyche

engraved

is

in

are spe-

DNA. As wide-

nothing to indicate that

it

represents an innate or universal preference on the part of mothers or fathers.

ters

There

is

no all-purpose psychoemotional

and sons are concerned.

however,

it

able as sons

may

—

In societies

straitjacket

with strong patriarchal traditions,

take special circumstances for daughters to

especially

if

where daugh-

become

as desir-

parents expect to have only one child.

Sex of offspring has been a long-standing concern for Westerners, too.

Even those who claim they "don't have

a preference" find that they

do when

pressed to imagine a situation in which they will have only one child. Instead

of infanticide, however, Western parents have adjusted parental investment

through time by designating some sons for the church, some later-born daughters to

mind that

become

"spinster aunts" (the fate

for her). In the United States,

married

it

women had rights to own

George

Eliot's family

had

in

has been only in the last century or so

property

in their

own name, and

only

since the Married Women's Property Acts passed in England and the United States in the latter part of the nineteenth century that daughters

began to

D A

Fig.

I

3. 4

woman

11

c;

1-;

at

—were

R

S

C)

R

S

O N

S

?

11

ALL

from poor and low-status families

L P

in

northern India

1-;

N D

H7

S

—

like this

In

north India today, however,

men

even the meanest and most poorly paid jobs, such that discrimination against

fill

daughters

creeping

is

D

buffered from discrimination both by the "bride-price" they com-

marriage and by the wages they were able to earn.

increasingly

down

possessed once enjoved.

inherit

1

Traditionally daughters

road worker

manded

H

the social scale, erasing

much

of the protection daughters of the dis-

(Sarah BlaJJer HrJj/Ambro-Photo)

on an equal footing with

today are actually somewhat

their brothers. Protected

more

by law, daughters

likely than sons to finish college,

and are

beginning to have athletic and career opportunities equivalent to those long

open to

sons. For

many

one-child couples, daughters are actually the sex of

choice. But these are very recent transformations,

ments

—

fragile

ones

at

that— following as

ing biases favoring sons.

still

virtually experi-

they do on the heels of long-stand-

MOTHERS AND ALLOMOTHERS

348

Fig.

1

3

.

J

Only

in the past

had educational and

women

few decades have Western

are collegiate varsity rowers, evidently as

of their femininity.

women

in countries like the

athletic opportunities equivalent to those available to

No

United States

men. These young

proud of their strength and competitiveness

one knows yet how such novel

social

experiments will pan out.

as

(Courtesy of

Davidjoffe)

Western folklore about sex determination could philosopher Anaxagoras believed that the that

by tying off the weaker

totle

recommended

(left

one) a

left

man

fill

volumes. The Greek

and the right testes differed, so

increased the odds of a son. Aris-

facing north during sexual intercourse, because he

believed a cold southern wind would induce conception of daughters. For the

more

literal-minded,

homespun recommendations

for siring sons prescribed

wearing boots to bed.

Not

all

of this

is

ancient history. Eschewing such folklore,

the 1960s turned to Dr.

Landrum

Shettles,

who

New Yorkers

prescribed a regimen of

vinegar douches to privilege X-bearing sperm, a douche of baking

promote the fortunes of Y-bearers.

West Coast counterpart,

Shettles

in

was followed

in the

1

powder 980s by

to

his

physiologist Ronald Ericsson, founder of Gametrics

Ltd. of Sausalito, California. Ericsson promised parents sex selection using a special technique to separate faster Y-bearing

X-bearing ones.

He

sperm from the more

sluggish

advertised his central premise with vanity license plates

DAUGHTERS OR SONS? on

read "X or Y." There was even a brief period

his car that

Americans could go to

a

349

when North

drugstore and pick up a "Gender choice child selec-

tion kit" for $49.9^, complete with itoring vaginal

ALL DEPENDS

IT

thermometer and paraphernalia

for

mon-

mucus, to determine precisely the moment for conceiving

When

son or daughter.

the U.S.

Food and Drug Administration decided

a

that

claims implied by pink and blue advertising on the box were not substantiated, the kits

were pulled

widely available

off store shelves. Today, prenatal sex testing

West. Anyone determined to use

in the

is

for sex selection

it

can manage to do so without breaking any laws.

This chapter began with sex-selective infanticide in China. to the distress this stark topic generates. All the analysis.

For humans are, above

abandon

self-interest for the

Humans do not that

easily,

all,

I

am

not

immune

more reason for dispassionate

resourceful creatures. They do not readily

common

good, or for someone

else's

good.

and without good cause, abandon the nepotistic urges

brought us from a paltry ten thousand souls a few hundred thousand

on Earth

years ago to the six billion

whether humans have free

from the It is

daily

the

will (and if so,

how

employ

to

it) is

far

removed

concerns of most humans.

common

humanity of the parents that

or cultural differences. Those diatribes

today. Philosophizing about topics like

who would rush to

would do well to maintain some

is

at stake here,

not ethnic

Beijing to deliver passionate

historical perspective.

While Chi-

nese infanticide rates have declined dramatically since the nineteenth century,

during that same period rates of child abuse, neglect, and infanticide

have sk>Tocketed in countries like the United States, although sex of the spring has relatively Infanticide in

little

China

is

to

do with

already illegal. Since 1987, laws against disclosing

who might

the sex of a fetus to parents

abortion

make Chinese laws

such laws in the West.

off-

it.

It is

subsequently practice sex-selective

related to sex-selective abortion tougher than

hard to see, therefore, what sense there would

be to additional legislation making preferential female infanticide or sexselective abortion more illegal in

to be

more

China than

effective than prohibitions.

it

already

The most

is.

Incentives are liable

effective

remedy may be

widely available contraception for birth spacing combined with educational

35^0

MOTHERS AND ALLOMOTHERS

and employment opportunities that create attractive futures for daughters, including scholarships and job opportunities that will benefit their families.

Countries convinced that mandatory birth control

term welfare of

their people

daughters -only families

is

essential for the long-

might want to consider special vouchers for

—good

for extra grandchildren.

4

Old Tradeoffs,

New What Jury

Contexts humankind

hostile to

First ledfrom Nature's

Her innocent

And

sense by

babe denied

so a

-LuigiTansillo,

from "La

path thefemale mind,

.

.

its

.

fashion's law repressed,

mother's breast? by William Roscoe

Balia," translated

in

i

798

Throughout human history, and long before, mothers have been making tradeoffs

between

quality and quantity,

effort in line with their

own

managing reproductive

stage, condition, and current

life

circumstances. As a result, infancy has not always been the

arms-of-love tableau

neck

many

of us imagine.

warm,

safe-in-the-

was, instead, a perilous bottle-

It

human gene pool had to pass ample documentation as to how tight a

that each individual contributor to the

through. Historical records provide

squeeze that sometimes was.

Of

2

1

,000 births registered in Paris in 1780, only g percent of them were

nursed by their

own

mothers.

It is

a riveting statistic that has

terize an era, France's "heyday of wet-nursing."'

dence of maternal indifference on

a

come

to charac-

The numbers provide

evi-

massive scale and today are often held up

as the prime exhibit in the case against the existence of maternal instincts in

the

human

species.

But

I

don't think that's what they actually prove.

These much-cited numbers derive from Lieutenant-General CharlesPierre LeNoir, a pohce official

whose job

it

was to monitor the

referral

bureaus used by working parents to locate wet nurses. LeNoir was also responsible for investigating complaints about wet nurses

who

failed to live

up to the terms of their contracts, as well as registering the disappearance of infants lost in the shuffle.

Of

the 20,000 babies nursed by

women

other than their mothers, the

luckiest 2^ percent were born to propertied parents

dren directly with wet nurses. Often such

elites

or other contacts to find acceptable candidates. 3SI

who

would

Some

placed their chil-

rely

on rural tenants

of the wet nurses, nan-

— a

MOTHERS AND ALLOMOTHERS

35^2

would

nies hired to lactate as well as caretake,

live

with the family under

maternal supervision. The unluckiest i^ percent of babies were delegated to

homes as described in chapter 2 It was up to these institutions locate someone to feed them, if they could. The remaining wet-nursed babies were mostly born to the middle class foundling

i

artisans, shopkeepers, or traders.

.

These were the "Bourgeoisie de

Paris,"

to

but

often only barely. Within this social class, a mother's salary or her unpaid labor was critical for the family's economic well-being. ^Typically, such moth-

were neither unmarried nor

ers

They

destitute.

relied

on professional

inter-

mediaries to find wet nurses for their babies. Hence the edge to the feminist

query raised by philosopher Elisabeth Badinter ity.

If

such

a thing as

maternal instinct

mothers be so unfeeling

exists,

Mother Love: Myth and Real-

in

how

could so

newborns

as to ship their

many thousands

off to

of

be suckled by an

unknown woman?

"Discretionary" Distancing Twentieth- century debates over the existence of maternal instinct focused on

such "discretionary" delegation of care.

It

was not the desperate mothers,

who arguably had no choice, that attracted notice, but the bourgeois mothers who presumably could afford to keep their babies near them and yet did

—

not. Greuze's painting of the farewell kiss (figure 14. 1)

outside the house. In large French

cities, a

shows what went on

middleman, called

a meneur,

would

What happened inside the home, or inside people's clear. An account by an eighteenth-century Frenchwoman

pick up the newborn. heads, was less disciple of

Rousseau

—

—

offers a glimpse. The writer,

Jeanne-Marie Phlipon de

Roland, has just visited an acquaintance who, though hopeful of a male

heir,

had given birth to another daughter. "Mme. D'Eu gave birth yesterday

noon

to a girl,"

Madame Roland

Her husband it,

a

.

.

is

wrote.

completely ashamed of

.The poor baby was sucking

room far removed from

was to nurse

it.

The

the baptism over, so the

The husband seems

its

father

its

it;

she

fingers

is

in a foul

in a great

mood

over

and drinking cow's milk

mother, waiting for the hired

was

little

at

in

woman who

rush to have the ceremony of

creature could be sent to the village.

.

.

.

to be deliberately structuring this situation to mini-

mize the mother's contact with her baby

—

in a

"room

far

removed."

It

was

a

OLD

Fig.

14.

1

La privation

sensible

depicts the pickup of a

wet nurse effects

T R A D

on children, vet

mother

,

N

i:

W

C

()

N T

H

X T

S

3^3

(The Painful Deprnation) by Jean-Baptistc Grcuze (1725

newborn by an

in the country. Little

focal points: the

K () F F S

itinerant entrepreneur

will transport the

1805)

baby to

a

of the vast literature on this topic deals with the psychological

their distress

must have been on the

artist's

kissing her baby goodbye; and, below,

(Courtesy ofBibliotheque Sationale, Pans)

who

two

mind. The painting has two

.saucer-eyed, fearful children.

MOTHERS AND ALLOMOTHERS

3 5^4

procedure that allowed few opportunities for infant cues to

elicit

nurturing

emotions, thus inhibiting formation of any bonds between mother and infant.

Absence of maternal responses under these conditions innate potentials of the

mammal

us

tells

little

about

in question.

Once out the door, the baby might find her wet nurse waiting in the menems cart, ready to hold her and feed her during the long, rough trip back to the

wet nurse's rural home. Otherwise only the meneur would show up,

leading a horse with baskets strapped to

back. Instances of babies lost

its

along the way occasionally surfaced in police reports for Lyons and Paris. For

who reached their destination, it was still less than certain that the woman waiting there would have sufficient milk. No wonder peasants who

babies

heard a church bell ring simply shrugged, "It's nothing, a

little

Parisian died!"^

Propaganda About Hired "Killers" Eighteenth- and nineteenth-century authorities

became

increasingly con-

cerned. They were worried about the high levels of infant mortality and population decline, as well as "public morality" (that

the sight of

women

Reformers, tion, likewise

on wet-nursing and

who had

had

they were distressed by

working outside the home). References to "natural law"

and the "sacred duty" of mothers abound drafting legislation

is,

testimony before committees

in

infant

abandonment.

a stake in romanticizing instinctive

a vested interest in identifying the use of a

the worst possible motivations.

became convenient

It

parental choices into one category

—

wet-nursing

to

—and

maternal devo-

wet nurse with

lump

a

range of

wide

to identify a

range of intentions under one motive: infanticide. Such propaganda was especially rife

by the time France belatedly passed the Roussel Law of

which was designed to protect

infants

from the worst excesses

i

874,

of wet-

nursing.

Medical doctors called

in to testify as

derous intentions of mothers

who

expert witnesses stressed the mur-

women

hired other

to nurse their babies.

French reformer Dr. Alexander Mayer described the practice of "abandoning, a

few hours

after

its

birth, a cherished being,

desired, to a coarse peasant ter

woman whom one

whose coming was ardently

has never seen,

and morality one does not know," condemning the practice

Parisian mothers, he contended,

were sending babies

whose characas "barbaric."

off to distant

wet

nurses "with the desire of not seeing them again."

The notion

that wet-nursing

must be

a disguised,

nonprosccutable form

OLD

T R A D

F

O

F F S

N

,

F

W

C

()

N T

F

X T

S

^ .t^'

Fig. 14. 2

Library,

de Nourrices

'^

^:

Father brings his infant to consult a recommandaresse, a

wet nurse. Le Bureau

iss

(The Wet Nurse Office),

woman who

tor a fee procures a

Paris, 18 16. (Counesj of Wellcome

Institute

London)

of infanticide, with wet nurses serving as contract killers,

propaganda and was quickly absorbed into angelmaker was

common

slang for

logic appears to be that any

is

worse than

attitude persists today

parlance. In England,

was extended to include

then does not carry the fetus to term, or infant at any cost,

effective

wet nurse; the German equivalent was

Engelmacherin. In France,Jaiseuse d'ange

The underlying

common

made

who

woman who after birth

just unnatural; she

among many who oppose

is

abortionists.

gets pregnant and

does not care for the

murderous.^ (This same

reproductive choice.)

'

MOTHERS AND ALLOMOTHERS

3^6 In

I

86^, Dr. Mayer correctly prophesized that "The whole thing

good sense and morality

revolting to

that in

twenty years people will refuse

to believe [wet-nursing] ever happened."^ Today, scholars

tend to follow Dr. Mayer's lead.

"It

who

wet nurse the parents hired was

sional killer.

.

Wet

."

.

unwanted

book

Infanticide,

and

"a professional feeder

nurses, proclaims another

whom

"were surrogates upon

recall this era

must have been common knowledge,"

writes twentieth-century psychoanalyst Maria Piers in her that the

so

is

a profes-

modern commentator,

parents could depend for a swift demise for

children."'

absence of other forms of birth control, women's maternal

In the

responses were heavily influenced by an amalgam of old and

mammalian decision

rules for dealing with tradeoffs

new

rules.

Old

between subsistence and

reproduction were reinforced by a conscious pragmatism on the part of

mothers. For example, she lose her job?

If

if

she continued to care for a particular infant, would

how would

she lost her job,

she and her family survive?

On

the other hand, could she improve her lot (the nest egg she might accrue, the better

home

she might provide),

brance by the infant? In

if

only she were free from current encum-

few mothers were seeking to

fact,

Many, however, were trying to reduce the

would take on

their well-being

heavy hand of fathers

who

kill

their babies.

born inopportunely

toll infants

and future prospects. Add to that equation the

were,

among

other things, eager to resume conju-

gal relations.

Propaganda about maternal intentions notwithstanding, allomaternal sharing of milk must have

first

women coop-

occurred among foragers where

erated to keep each other's babies from fretting. Wet-nursing in this earlier context

tented, not

provided a means for individuals to keep infants

kill

them.

How

might

this first

from more complex,

stratified societies?

We

that

cannot hope to

became enmeshed

in

we know about understand how

an intricate

traffic in

mother's milk, or evaluate what the wet-nursing era does or does not

about human "maternal Mother's milk, with

primates,

from

on

a

it

her.'"

special

we

is

rare for a

When

milk

is

us

start at the beginning.

mother

Among

other

to let another female's offspring nurse

provided by allomothers,

short-term, opportunistic

tell

immunoloaical and nutritional properties,

been too valuable to share indiscriminately.

always

has

instinct," unless its

much

and con-

voluntary sharing of milk have

been transformed into the commercialized networks

tens of thousands of mothers

alive

basis. Alternatively,

it

is

volunteered by kin

an older infant, the

mon-

OLD TRADEOFFS, NEW CONTEXTS key equivalent of

a

toddler, might take the initiative, latching

related female's nipples and being tolerated.'^ Such suckling a

35^7

on

more

is

to a

nearly

quick pick-me-up, tiding a youngster over, than a primary source of

nutrition.

A

look

at

or cowives lar

ethnographic accounts of mothers and their daughters,

who

sisters,

proffer breast milk to one another's offspring reveals a simi-

pattern of casual reciprocity, opportunistically offered and received.

Efe net-hunters in the Ituri Forest to the fisherfolk of the

Andaman

From

Islands,

allomaternal suckling was a mutually beneficial courtesy extended by coresi-

dent

women

—

neighbors, and blood kin.'^

affines,

How Flexible Lactation Is Evidence that such casual wet-nursing was ever an important part of tocene

lifestyles

is

purely circumstantial. Nevertheless, several features of

woman's biology improved the odds been

available.

So

far,

If

birth at the in

women,

mothers

as in

who

this

would

in

most primates,

is

is

the mys-

to synchronize ovulation with

women

living together gave

facilitate reciprocal suckling.

But lactation

extraordinarily flexible anyway. This

is

why

as

soon

as they recover.

Milk supply builds

response to infant demand, and lactation can be sustained almost indef-

initely until either

(This

woman

humans

stop lactating for a time (as during illness) can resume and

begin rebuilding their milk supply

up

identified for

synchrony of ovulation meant that

same time,

would have

that lactating allomothers

pheromone

the only

terious substance that causes one

another.

Pleis-

is

mother or

infant shuts

down production through

how novelist Jane Austen came to be the

weaning.

seventh child in her family to

suckle from the same wet nurse. )'^ In a pinch, lactation can

be induced without an allomother ever becoming

pregnant. Adoptive mothers

—

eighty

have lactated. But

—

girls as

this

young

as eight,

took more than

grandmothers

a miracle. Breasts

as old as

have to be

kneaded and massaged past many women's endurance, and nipples sucked

(some

women use baby

animals) long enough to trigger endogenous produc-

tion of prolactin and oxytocin.

'^

In allomothers able to

produce milk, there

no colostrum, but otherwise the composition of induced milk

is

is

adequate to

sustain infant growth.

Anthropologists have not paid there

is

a telling pattern in the

India, Africa, Indonesia,

much

attention to induced lactation. Yet

dozen or so accounts that

exist.

Whether from

North or South America, when induced

lactation

is

:

MOTHERS AND ALLOMOTHERS

3^8

mentioned, the milk provider

is

most often an old woman,

ing orphaned or fostered grandchildren.

^'^

Besides being

usually

more

one nurs-

willing and

not otherwise engaged in reproductive pursuits, grandmothers are ideal in

woman who has already lactated lactation successfully than a woman who

another respect. For physiological reasons, a is

three times

more

induce

likely to

has never borne a child.

Coerced Wet-Nursing Among those foragers and horticulturalists who practice wet-nursing, women voluntarily offer their breasts as a favor to another woman's child. Even when disputes erupt over who stays in camp and who goes off to forage,

the benefits are so obviously reciprocal that matters resolve them-

selves.

More

until there

make

exploitative forms of nonreciprocal wet-nursing could not arise

was one

class

of mothers able to compel lower-ranking mothers to

their breasts available.

There are multiple precedents for coerced wet-nursing

in other

mam-

mals, especially those with cooperative breeding systems (discussed in chapter 4).

The behaviors involved

are neither very specialized nor unusual. Take

the pack of wild dogs in which the dominant female killed

pups

in a

subordinate female's

litter.

all

but one of the

As the subordinate continued to suckle

her lone surviving pup, the dominant mother's ten pups, already larger than the lone survivor, took over her teats.

stunted and,

when

the pack

moved,

fell

The wet

nurse's last

pup remained

behind and would have died had the

observers not rescued him.^^

But

as to

when in human prehistory one mother first appropriated the milk

of another, no one has offered even a guess. By the third millennium B.C.

it

occurred to a Sumerian mother (the wife of Shulgi, ruler of Ur) while singing

when he grows

her son to sleep to promise the child a wife son

—complete

with a wet nurse

him;

The nursemaid joyous of heart

will sing to

The nursemaid joyous of heart

will suckle him.

In the

up, and then a

time of Homer,

in the eighth

.

.

.

century B.C., some wellborn sons

(like

prince Odysseus) were suckled by servants, while others in the same population

were nursed by

their

own

mothers.

OLD TRADKOFFS, NEW CONTEXTS Some wet

3^9

nurses were themselves from privileged backgrounds, their

tus further elevated

by contact with small scions.

nurses were recruited from the harems of the pharaoh's senior ingenious

way

on the guest

tomb

to

officials

(an

to elicit loyalty), and these allomothers subsequently appeared for royal funeral feasts.

lists

honor

sta-

wet

In ancient Egypt,

his

wet nurse.

The

^

Egypt was permitted to use the

was accorded wet nurses

child

title

Around 1330 B.C., King Tut built a of one royal wet nurse from ancient

"milk-sister to the king." Similar respect

and the Near

East.^^ In

Arab

cultures. Islamic law provides for three kinds of kinship: by blood, by

mar-

riage,

the

in India, China, Japan,

and by the happenstance of two individuals having sucked milk from

same woman. Less fortunate wet nurses were effectively slaves with wretched options.

Dozens of

texts and

good wet nurse. nant or

still

manuals survive

Virtually

own

nursing her

telling parents

what to look

advise against selecting a

all

infant.

woman who

for in a is

preg-

Given that wet nurses are often not well

nourished, there was a legitimate concern that the nurse might not be able to

make enough milk

for

implications, parents

birth and

two

infants.

were advised

whose milk was

still

Without so much

to find a

is

comment on

the

wet nurse who had recently given

"new." Thus do the manuals display a stark dis-

regard for the well-being of the wet nurse's pensable baby

as a

own

Her seemingly

infant.

assumed to have died, been weaned

very early,

dis-

or been

farmed out to another woman, possibly to be fed something other than mother's milk. "Pap," a gruel mixture of water and ground meal used in "drynursing,"

The his

was usually

lethal for

newborns.

fifteenth-century correspondence

between an

Italian

merchant and

wife chronicles that enterprising woman's efforts to find a suitable wet

nurse for one of her husband's

whose owTi

infant

seems

her disappointment notes that about

clients. ^^

She has her eye on a particular slave

likely to die. The

when

merchant's wife makes no secret of

the slave's baby survives. Historian Richard Trexler

3 o percent of infants sent to foundling

period of the Renaissance were the offspring of slaves,

homes during this whose owners had

other uses for their milk.

The Wet Nurses Of

all

the protagonists in these transactions,

we know

least

about the wet

nurses themselves. Whether slaves or just destitute peasants, the price of con-

— MOTHERS AND ALLOMOTHERS

360

tinued survival was providing milk to unrelated offspring their

own. Some wet nurses may have been country

girls

at the

expense of

hoping to earn a

dowry and then marry and reproduce

in earnest.

quite attached to their charges. Yet few

would have been permitted contact

with their charges after weaning. We logical

Many no doubt became

know almost nothing about the

trauma these ruptured attachments caused

infants

psycho-

and their care-

takers.

The demographic consequences, however,

are

known. Lactational sup-

pression of ovulation delayed the wet nurse's next conception. Yet this long interval infants.

between

Only

births

was not

offset

own

by increased survival of her

rarely did her circumstances improve, permitting her to offset

early losses by producing healthier offspring later. For her, wet-nursing

losing proposition

all

was

a

around.

There are hints that

in spite of the hopelessness of their position,

wet

nurses sometimes tried, with varying success, to subvert a system heavily

own

From Moses' mother to the Russian women who bribed foundling home personnel, some mothers managed to get themselves paid to nurse their own babies. Wherever they

biased against mothers nursing their

children.

could, mothers strategized to improve their

lot.

Rarely could they succeed.

Nevertheless, substitution of one baby for another

topsy-turvy merriment in Gilbert and Sullivan in ancient

Mesopotamia

High

Code of Hammurabi

taken seriously enough

(i

700

B.C.). If a

was

wet nurse

High Survival

times onward, wet nurses

could be found in

was taken

much

so, "they shall cut off her breast."^^

Fertility Plus

From medieval

the source of

to merit dire punishment. Switching babies

specifically prohibited in the

was caught doing

—was

—

elite

—

paid, indentured, enslaved

households in Europe, Asia, and the Near East. Care

to select a nonpregnant nurse with a healthy supply of milk. Living

in aristocratic households, closely supervised, infants

nurses had about the same survival rates

nursed by their

own mothers.

For

a

nursed by such wet

—sometimes

baby born

in

better

—

as infants

Lieutenant LeNoir's sample

from eighteenth-century France, survival chances were around 80 percent both for the tiny fraction nursed by their

good fortune to be wet-nursed

own mothers and

in their parents'

those with the

home.

Far from increasing infant mortality, wet nurses situated in privileged

homes permitted

elites to

bypass a normal

mammalian

constraint.

By com-

Prior to World

Fig. 14.3

War

hospitals in the United States

II,

still

hired wet nurses to feed pre-

mature babies. The wet nurse was allowed to continue nursing her own of

mind and because

let-down reflex that made tors calculated that

infant,

both for her peace

stimulation of one nipple by the sucking of the stronger baby produced a it

easier for the

weaker "preeinic" to obtain milk. Hospital administra-

wet nurses provided two to three hundred ounces of milk

salary of eight dollars a

week.

'

(Coumsj ofSjndics of Cambridge Unncmty

in

exchange for a

Library)

mandeering the milk of other women, ehte wives became pregnant again

much sooner without

subjecting their infants to higher mortaHty.

cumvented the tradeoff between "quantity" and "quahty" of

some

infants (especially

been weaned produce by their For

elites,

they were daughters,

early so their

a son)

own

if

cir-

otherwise have

mothers could get pregnant again hopefully to

were wet-nursed

longer than they

would have been breast-fed

mothers.

wet-nursing meant high

survival. In a not atypical case,

gave birth to her

first

ued reproducing

for thirty

when

who might

They

care. In fact,

fertility plus

high probability of infant

one eighteenth- century

British duchess

who

child at age sixteen, a year after her marriage, contin-

she was forty-six.

more

years, until her twenty-first child

Eight surviving offspring

was born

—which would be — was

a

record-breaking level of reproductive success for a hunter-gatherer

merely

average for

women

in

her circle. Typically, wives gave birth almost

MOTHERS AND ALLOMOTHERS

362

Fig.

14.4

Once

tives for hiring

Renowned

the use of

wet nurses became an established custom, mothers had various incen-

them. Gabrielle d'Estrees bore Henri IV of France three children out of wedlock.

for her beauty, detested for the wealth

and influence

it

brought her, she might have

achieved her ambition to see one of her sons succeed to the throne of France had she not died the age of twenty-six.

Her

decision to use a wet nurse

production of plentiful heirs.

More

preoccupation with machinations youthful-looking breasts. Even

likely,

at

related to the

her choice was dictated by convenience, her ambitious

at court,

more than

may or may not have been

and her desire to preserve compact, symmetrical,

for

most women, vanity was relevant

to a courtesan's

self-interest. (Photographic Girau Jon; courtesy of Music ConJc, Chantillj)

annually for the

first

decade of marriage, slowing to

a

more gradual pace

the second. In isolated pockets of Europe, rapid production of many at

short intervals continued to be the

norm

for

children

into the nineteenth century.

Fine-Tuning Parental Investment The longer

a

mother nursed her baby, the more

Mothers could

safely

wean

early only

when water

likely

it

was to survive.

did not cause dysentery.

OLD TRADEOFFS, NEW CONTEXTS

363

and where alternatives to breast milk were nutritious and palatable. But unless an observer (the

is

right there counting "time

way primatologists

ally occurs.

hood

do),

that the infant

Consider

a

tine families.

still

rarely possible to

it's

With wet nurses

on the nipple" and "time off"

it is.

When payment

know when weaning stopped so did the

had access to breast milk.

remarkable study of the intimate

From household

lives

of Renaissance Floren-

diaries, called ricordanze, historian Christiane

Klapisch-Zuber determined that one family out of three was more have a son nursed

in

casa

—

more

When

likely to

infants

likely to

the costlier, safer arrangement preferred by

wet nurse was supervised by the

fifteenth-century elites. This in-house

mother.

actu-

likeli-

were sent to wet nurses away from home, they were

— 69

be daughters

percent of daughters born, compared with

££ percent of sons, and mostly these were later-born, younger sons, "heirs to spare."

and

Even then, parents paid more so on average than

a half longer

their sons

their daughters.

would be nursed

a

month

^^

How Could Love, If "Natural " Be Discriminatory? "How

could

it

be that love,

were indeed natural and spontaneous, would

if it

be directed toward one child more than another?" asked Elisabeth Badinter

How

with her usual crisp logic.

could a mother care assiduously for a

born son and then "send the younger children away unequal treatment of progeny with genetic determinism,

is

for

only a problem for those

who assume

This, of course,

sharing genes by

is

true

common

if

many years?"^^Yet, who equate biology

that irrespective of maternal age or

condition, or of the viability or even sex of her progeny,

same, an invariant phenotype

first-

all

mothers are the

MOTHER.

the invariant constant (the 5^0-percent chance of

descent)

is all

that matters. But in the pragmatic

and not-at-all-nice domain of Mother Nature, mothers evolved to factor costs (which, in the

human

case, can range

in

from mother's age or physical

condition to a conscious awareness of future costs) as well as to factor in benefits (for

example,

a social milieu that offers sons better opportunities

than

daughters). Evolutionarily, the simplest cial

way

to explain maternal behavior

is

as a spe-

case of Hamilton's rule (see above, page 63) to explain altruistic acts

between related

individuals. Applied in this context, Hamilton's rule

much about genes

(after

all,

no one has any idea what

of genes, or what mechanisms are involved) as

it is

is

going on

is

not so

at the level

about predicting

when

MOTHERS AND ALLOMOTHERS

364

one individual should incur ton's rule

is

on behalf of another. At

a cost

a formally organized

metaphor

for

how

economy of maternal emotions, with C being

the

being the benefit to the recipient, and

r

C