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Table of contents :
List of Tables
List of Figures
Introduction to Volume 9
Chapter I. Introduction: The Research Problem and Methods
The Research Problem
The Research Method
Chapter 2. Theoretical Perspectives on Changes in the Subsistence and Settlement Systems
The Rise of Sedentism
The Rise of Agriculture
Consequences of the Rise of Agriculture and Sedentism
Sedentism and Health
Subsistence and Health
Chapter 3. Studies of Health and Agriculture in Prehistoric Populations
The Concept of Health
Paleopathology Studies of Subsistence Change
Review of Paleopathology Studies
Chapter 4. Archaeology of the Valley of Oaxaca
Description of the Valley of Oaxaca
The Chronology of the Prehispanic Valley of Oaxaca
San Sebastian Abasolo
Barrio del Rosario Huitzo
Fabrica San Jose
San Jose Mogote
Santo Domingo Tomaltepec
The Agricultural Potential of the Valley of Oaxaca
Temporal Trends in Subsistence
Temporal Trends in Settlement Patterns and Population Size
Social and Political Organization in the Valley of Oaxaca
Trade Networks and External Contact
Chapter 5. Materials and Methods: Hypotheses, Skeletal Health Markers, the Sample and Analytical Techniques
Skeletal Stress Markers
Nonspecific Stress Markers
Specific Stress Markers
Degenerative Joint Disease
Additional Health Markers
The Oaxaca Skeletal Samples
Chapter 6. Results
Summary of General Health Markers
Statistical Power Analysis
Analyses with Classic and Postclassic Groups Pooled
Chapter 7. Discussion and Conclusions
Comparison of Skeletal Stress Marker Frequencies
Interpretation of the Oaxaca Stress Marker Frequencies
Agriculture and Health
Appendix 1: Burial List
Appendix 2: Metrics
Appendix 3: Dental Pathology
Appendix 4: Skeletal Pathology
PREHISTORY AND HUMAN ECOLOGY OF THE VALLEY OF OAXACA Kent V. Flannery, General Editor Volume I The Use of Land and Water Resources in the Past and Present Valley of Oaxaca, Mexico, by Anne V. T. Kirkby. Memoirs of the Museum of Anthropology, University of Michigan, No.5. 1973. Volume 2 Sociopolitical Aspects of Canal Irrigation in the Valley of Oaxaca, by Susan H. Lees. Memoirs of the Museum of Anthropology, University of Michigan, No.6. 1973. Volume 3 Formative Mesoamerican Exchange Networks with Special Reference to the Valley of Oaxaca, by Jane W. Pires-Ferreira. Memoirs of the Museum of Anthropology, University of Michigan, No.7. 1975. Volume 4 Fabrica San Jose and Middle Formative Society in the Valley of Oaxaca, by Robert D. Drennan. Memoirs of the Museum of Anthropology, University of Michigan, No.8. 1975. Volume 5 Part 1. The Vegetational History of the Oaxaca Valley, by C. Earle Smith, Jr. Part 2. Zapotec Plant Knowledge: Classification, Uses and Communication about Plants in Mit/a, Oaxaca, Mexico, by Ellen Messer. Memoirs of the Museum of Anthropology, University of Michigan, No. 10. 1978. Volume 6 Excavations at Santo Domingo Tomaltepec: Evolution of a Formative Community in the Valley of Oaxaca, Mexico, by Michael E. Whalen. Memoirs of the Museum of Anthropology, University of Michigan, No. 12. 1981. Volume 7 Monte Alban's Hinterland, Part 1: The Prehispanic Settlement Patterns of the Central and Southern Parts of the Valley of Oaxaca, Mexico, by Richard E. Blanton, Stephen Kowalewski, Gary Feinman, and Jill Appel. Memoirs of the Museum of Anthropology, University of Michigan, No. 15. 1982. Volume 8 Chipped Stone Tools in Formative Oaxaca, Mexico: Their Procurement, Production and Use, by William 1. Parry. Memoirs of the Museum of Anthropology, University of Michigan, No. 20. 1987. Volume 9 Agricultural Intensification and Prehistoric Health in the Valley of Oaxaca, Mexico, by Denise C. Hodges. Memoirs of the Museum of Anthropology, University of Michigan, No. 22. 1989.
Related Volumes Flannery, Kent V. 1986 Guila Naquitz: Archaic Foraging and Early Agriculture in Oaxaca, Mexico, New York: Academic Press. Kowalewski, Stephen A., Gary M. Feinman, Laura Finsten, Richard E. Blanton, and Linda M. Nicholas 1989 Monte Alban's Hinterland, Part ff: Prehispanic Settlement Patterns in Tlacolula, Etla, and Ocotlan, the Valley of Oaxaca, Mexico. Memoirs of the Museum of Anthropology, University of Michigan, No. 23 (2 volumes).
MEMOIRS OF THE MUSEUM OF ANTHROPOLOGY UNIVERSITY OF MICHIGAN NUMBER 22
PREHISTORY AND HUMAN ECOLOGY OF THE VALLEY OF OAXACA Kent V. Flannery, General Editor Volume 9
AGRICULTURAL INTENSIFICATION AND PREHISTORIC HEALTH IN THE VALLEY OF OAXACA, MEXICO
by Denise C. Hodges
ANN ARBOR 1989
© 1989 by The Regents of The Univeristy of Michigan The Museum of Anthropology All rights reserved Printed in the United States of America ISBN 978-0-915703-16-6 (paper) ISBN 978-1-951538-04-0 (ebook) Library of Congress Cataloging-in-Publication Data Hodges, Denise C. Agricultural intensification and prehistoric health in the Valley of Oaxaca, Mexico/by Denise C. Hodges. p. cm.-(Prehistory and human ecology of the Valley of Oaxaca; v. 9) (Memoirs of the Museum of Anthropology, University of Michigan; no. 22) Bibliography: p. ISBN 0-915703-16-5 I. Indians of Mexico-Oaxaca Valley-Agriculture-Health aspects. 2. Indians of Mexico-Oaxaca Valley-Health and hygiene. 3. Indians of Mexico-Oaxaca Valley-Antiquities. 4. Oaxaca Valley (Mexico) Antiquities. 5. Mexico-Antiquities. I. Title. II. Series. III. Series: Memoirs of the Museum of Anthropology, University of Michigan; no. 22. GN2.M52 no. 22 [F1219. 1.0ll] 306 s-dcl9 [614.4'272'74] 88-38162 CIP
TABLE OF CONTENTS List of Tables ................................................................................................................... vii List of Figures .................................................................................................................. vii Acknowledgments .............................................................................................................. ix Xl Introduction to Volume 9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHAPTER I.
INTRODUCTION: THE RESEARCH PROBLEM AND METHODS .............................................. . The Research Problem ........................................................................................ . The Research Method ........................................................................................ . THEORETICAL PERSPECTIVES ON CHANGES IN THE SUBSISTENCE AND SETTLEMENT SYSTEMS ................ . The Rise of Sedentism ........................................................................................ . The Rise of Agriculture ....................................................................................... . Consequences of the Rise of Agriculture and Sedentism ............................................................ . Sedentism and Health ........................................................................................ . Subsistence and Health ....................................................................................... . STUDIES OF HEALTH AND AGRICULTURE IN PREHISTORIC POPULATIONS ................ . The Concept of Health ........................................................................................ Paleopathology Studies of Subsistence Change .................................................................... Methodological Issues ........................................................................................ Review of Paleopathology Studies ............................................................................... Summary ...................................................................................................
. . . . .
ARCHAEOLOGY OF THE VALLEY OF OAXACA ................................................................. . Description of the Valley of Oaxaca ............................................................................. . The Chronology of the Prehispanic Valley of Oaxaca ............................................................... . Archaeological Sites ......................................................................................... . San Sebastian Abasolo ...................................................................................... . Barrio del Rosario Huitzo ................................................................................... . Caballito Blanco ........................................................................................... . Dainzu .................................................................................................. . FP LEH Caries A>P DJD A=P Harris lines Child growth Por. hyper.
A=P A=P A>P A=P A=P
A>P A=P A>P A>P
Nubia Ohio A>P A>P A>P
P>A A>P A>P A = PNIA = IA
Geo. = Georgia Coast (Larsen 1982, 1984) Dick = Dickson Mounds (Goodman, Lallo, Armelagos and Rose 1984; Lallo 1973) Kent. = Kentucky (Cassidy 1984) Ill. = Illinois River valley (Cook 1979, 1984) Mex. = Chihuahua, Mexico (Corruccini 1983; Weaver 1981) Nubia = Sudanese Nubia (Martin et al. 1984) Ohio = Ohio River valley (Perzigian, Tench, and Braun 1984) Infect. = frequency of periosteal lesions LEH = linear enamel hypoplasia Caries = dental caries DJD = degenerative joint disease Child growth = retardation of growth Por. hyper. = porotic hyperostosis A = agriculturalists P = preagriculturalists NIA = nonintensive agriculturalists IA = intensive agriculturalists
generalize about health and agricultural development from these studies. The comparability of the data is further compromised by the fact that control for sex and age differences in the skeletal samples was exercised sporadically. The occurrence of some stress markers is related to the age and sex of the individual. For example, degenerative joint disease is more common in older adults than in young adults, and dental caries tends to be more frequent among females than males in numerous prehistoric populations (Larsen 1983). Without control for sex and age, several alternative explanations for the results are possible. Despite these difficulties, some general trends in the skeletal stress markers can be stated. It is evident that the agricultural populations tend to display higher frequencies of periosteal lesions, a marker of an infectious condition, than do the preagricultural groups (Lallo 1973; Larsen 1982; Perzigian, Tench, and Braun 1984). No significant difference in the frequency of periosteal lesions between preagriculturalists and agriculturalists were found by Cassidy (1980) and Weaver (1981). The lack of a difference in these studies may be due to the fact that the agriculturalists and pre agriculturalists in these studies were both sedentary. In the studies with significant periosteal lesion differences, the samples differ both in terms of subsistence and settlement patterns. In general, the frequency of individuals with infectious lesions appears to increase with changes in subsistence and settlement patterns. Enamel hypoplasias are generalized markers indicative of a growth disturbance. Only four of the studies examined frequencies of hypoplasia, and three of these found a significant temporal increase (Goodman et al. 1980; Cook 1984; Perzigian et al. 1984); no difference was observed in the other study (Cassidy 1980). The frequency of severe hypoplastic lesions was, however, significantly greater in the agricultural group in Cassidy's (1980) study. It appears that the frequency of individuals with growth disturbances increases with agricultural dependency and sedentary settlements. The frequency of Harris lines was found to be low among agriculturalists in two studies (Cook 1979; McHenry 1968), but did not differ between agriculturalists and nonagriculturalists at Dickson Mounds or Kentucky (Cassidy 1980; Lallo 1973). The interpretation of Harris lines presents a problem even when there are significant differences in frequencies. The problem with analyzing Harris lines is that the lines can be resorbed over time through normal bone maintenance. In fact, in a study of Harris lines in a modem population there were no lines that persisted for more than ten years (Gindhart 1969). Adult frequencies of Harris lines will not give an accurate record of growth disturbances during childhood. The meaning of the decrease in the frequency of Harris lines observed in the studies is unclear.
AGRICUUURAL INTENSIFICArION AND PREHISTORIC HEAIIH IN OAXACA
The temporal trend of an increase in dental caries with the shift to an agricultural diet is well known (Larsen 1983; Turner 1979). The increase is attributable to an increase in the consumption of grains, such as maize, that are rich in carbohydrates and are cariogenic. Only one of five studies did not find a significant increase in the frequency of caries (Dickel, Shulz, and McHenry 1984). The authors ofthe latter study suggest that the level of carbohydrate consumption did not differ in their samples, rather the preagricultural groups relied heavily on carbohydrate-rich foods (Dickel, Shulz, and McHenry 1984). In three of four studies the frequency of porotic hyperostosis and cribra orbitalia was higher in the agricultural sample (Cassidy 1980; Cook 1979; Goodman, Lallo, Armelagos, and Rose 1984). The fourth study, in which no difference was found, compared two agricultural samples (Weaver 1981). Porotic hyperostosis and cribra orbitalia are most often associated with an iron deficiency anemia in childhood (Stuart-Macadam 1985). Cereal grains contain phosphates and phytate, substances which appear to interfere with the absorption of iron in the human body (Pike and Brown 1984). On this basis alone, a trend toward higher frequencies of iron deficiency anemia would be expected with a shift to cereal diets. It appears that the frequency of iron deficiency anemia, and thus porotic hyperostosis, increases with the shift to agriculture, but the possibility that this increase is due to sedentarization cannot be ruled out. Iron deficiency anemia may also be caused by parasitic infections which may be more common in sedentary villages then among hunter-gatherers. In the three studies in which sexual dimorphism was examined, no trend was associated with the shift to agriculture (Benfer 1984; Lallo 1973; Larsen 1982). Larsen (1982) indicates that a significant increase in postcranial size occurred with the agricultural shift on the Georgia Coast; however, a reanalysis of the data found few of the measures of sexual dimorphism to be significantly different (Relethford and Hodges 1985). Among living popUlations, the degree of sexual dimorphism has been shown to increase with improved nutritional status (Tobias 1975). If sexual dimorphism did not change with the agricultural shift, then the interpretation that follows is that nutrition remained at a comparable level. If there is a temporal trend in degenerative joint disease associated with agricultural development, it is not clearly established by these studies. A significantly higher frequency of degenerative lesions was found among the agriculturalists in the Dickson Mounds population and in the Illinois Valley (Lallo 1973; Pickering 1984). The frequency of degenerative lesions was not significantly different among agriculturalists on the Georgia Coast (Larsen 1982) or in Kentucky (Cassidy 1984). It has been suggested that agricultural tasks such as hoeing and harvesting produce a constant strain on the arms and spine
(Cockburn, Duncan, and Riddle 1979). On the other hand, hunting is considered an activity that is unlikely to produce degenerative joint disease. Further, it is argued that while gathering can be laborious work, hunter-gatherers are known from studies of living groups to work for only a few hours of the day, thus lessening their exposure to stress (Cockburn, Duncan, and Riddle 1979). Such an interpretation of subsistence activities assumes that agriculturalists work their fields every day and that their work is very grueling. This interpretation does not consider the possibility that agriculturalists often plant only one or two crops a year and that every day may not necessarily entail doing hard labor in the field. At present, conclusive data to support an argument for a temporal trend of degenerative joint disease in either direction are lacking. In two of the studies a significant reduction in childhood growth in agricultural groups has been observed (Cook 1979; Lallo 1973). These findings suggest that health problems, either nutritional or disease related, were faced by children in agricultural groups. It would be interesting to know if this reduction in child growth is found in other populations that have shifted to an agricultural economy. Clearly more studies on this aspect of health in prehistoric populations are needed. All of the studies reviewed above are from the New World except for the Nubian study (Martin et al. 1984). This does not reflect an absence of interest in the paleopathology of Old World populations, but rather a lack of rigorous studies designed to examine the transition to agriculture. Most of the regions covered in Table 3.1 represent secondary centers of agricultural development, rather than primary centers where crops were originally domesticated. Whether the effects of agricultural development on health differ between primary and secondary centers is not demonstrable given the studies done thus far. The analysis of health in the Valley of Oaxaca, a primary center of agricultural development, should help to clarify this question. To summarize, biological effects from changes in the subsistence system have been observed on the skeletal remains of several populations. A few temporal trends in skeletal stress markers have been observed, but since they are based on anything from two to six studies, they are considered suggestive rather than definitive. With the shift to agriculture, significant increases have been observed in the frequencies of infectious lesions, enamel hypoplasia, dental caries, porotic hyperostosis, and child growth retardation. The magnitude of sexual dimorphism does not appear to change with the shift to agriculture. These trends are believed to be related to a shift to agriculture; however, they may also reflect changes in settlement patterns. The effects of agricultural development and changes in settlement patterns may not always be separable. Additional studies such as this one will help to clarify the trends and their association with agriculture.
The Archaeology of the Valley of Oaxaca DESCRIPTION OF THE VALLEY OF OAXACA
floodplain along the Rios Salado and Atoyac. The low alluvium is restricted in area and was not formed until after A.D. 1500 (Kirkby 1973). Thus the zones of importance to prehistoric populations would have been the mountain, the piedmont, and the high alluvium zones. The present day vegetation of the valley differs from the original plant cover. In fact, very few remnants of the original vegetation still. exist in the valley. The vegetation zones in the prehistoric period have been reconstructed by C. Earle Smith, Jr. (1978). In prehistoric times the region above 1700 m was most probably covered by an oak-pine forest (Smith 1978). Below 1700 m, the primary vegetation covering the valley would have been a thorn-scrub-cactus forest. Along the banks of the Rios Atoyac and Salado there would have been a mesophytic forest, probably predominated by willows. Between the me sophy tic forest and the thom-scrub-cactus forest would have been a relatively small mesquite forest. The mesquite forest present in the valley today has a high concentration of prickly pear, which was eaten as far back as preceramic times. The reconstruction of prehistoric vegetation gives us some idea of what types of plants might have been present. Obviously, the presence of certain edible plants does not necessarily mean that they were utilized as food, but it can give a picture of the variety of possible food substances; many Oaxaca sites have produced abundant remains of food plants. While the vegetation differs considerably within the different zones of the valley, all the zones could easily have been reached by the prehistoric inhabitants. The Valley of Oaxaca is environmentally diverse, but it does present a regionally homogeneous unit for examining the intensification of agriculture.
The Valley of Oaxaca is located in the southern highlands of Mexico in the State of Oaxaca (Figure 4.1). Its geographical location has been described in earlier volumes of this same series (Kirkby 1973, Smith 1978), to which the reader is referred for details. The valley is naturally divided into three arms by the Rios Atoyac and Salado. The northern sector is referred to as the Etla arm, the eastern sector as the Tlacolula arm, and the southern sector as the Zaachila or Valle Grande arm. Virtually the entire valley (including the surrounding piedmont and lower mountain slopes) has been intensively surveyed. Survey results from the Valle Grande and Central Valley are published and those from the Etla and Tlacolula arms are in manuscript* (Blanton et al. 1982). The locations of the archaeological sites in the valley from which human skeletal remains have been examined are shown in Figure 4.2. The physiography of the valley has been subdivided into four distinct zones: the mountain zone, the piedmont, the high alluvium, and the low alluvium (Kirkby 1973). The mountain zone begins at roughly 2000 meters and consists of steep slopes and narrow ridges. As a result of its poor soils, steep slopes, and the threat of frost, the mountain zone is not used extensively for agriculture today, nor was it used extensively for agriculture prehistorically. The piedmont zone is an area of transition from the mountain zone to the high alluvium. The lower reaches of the piedmont have deeper, less stony soils than the mountain zone and are more suitable for agriculture (Kirkby 1973). The piedmont zone is traversed by perennial streams flowing down from the mountains that can be diverted for irrigation. The piedmont zone is used today for agriculture and was also used prehistorically for agriculture. The valley floor is located primarily within the high alluvium zone (Kirkby 1973). Soils in the high alluvium are more than a meter deep and are well suited for agriculture. Today most of the farming in the valley occurs in the high alluvium zone, which was heavily utilized prehistorically as well. The low alluvium zone consists of the contemporary
THE CHRONOLOGY OF THE PREHISPANIC VALLEY OF OAXACA The chronological sequence for the Valley of Oaxaca is based on the stratigraphy of chipped stone and ceramic assemblages associated with radiocarbon dates. The occupation of Monte Alban, Oaxaca's first great urban center, has been divided by Caso, Bernal, and Acosta (1967) into five periods
*University of Michigan Museum of Anthropology Memoir. No. 23. Now in print.
AGRICUIIURAL INTENSIFICATION AND PREHISTORIC HEAIIH IN OAXACA
... . . .........
. I .. \.
:. :...... . . . ~~: . ~' ..
... • 0° • :
L -_ _LI_ _~'_ _~I
Figure 4.1. Location of the Valley of Oaxaca, Mexico.
ARCHAEOLOGY OF THE VALLEY OF OAXACA
1. 2. 3. 4. 5. 6. 7.
8. 9. 10. 11. 12. 13. 14. 15.
HUITZO SAN JOSE MOGOTE TIERRAS LARGAS MONTE ALBAN OAXACA , CITY DAINZU LAMBITYECO
YAGUL MITLA ZAACHILA SAN SEBASTIAN ABASOLO BRAWBEHL CABALLITO BLANCO FABRICA SAN JOSE SANTO DOMINGO TOMALTEPEC
CENTRAL AREA TLACOLULA ARM
Figure 4.2 Location of archaeological sites in the Valley of Oaxaca.
AGRICUlIURAL INTENSIFICJJION AND PREHISTORIC HEALTH IN OAXACA
(Monte Alban I-V) which run from 500 B.C. to the Spanish Conquest. The earlier prehistory of the valley has been divided by the University of Michigan project into four Archaic (preceramic) phases and five Formative (pottery-bearing) phases running from approximately 8000 B.C. to 500 B.C. (Flannery, Marcus, and Kowalewski 1981). The chronological sequence of the valley is outlined in Table 4.1. Almost nothing is known of the Paleoindian period in Oaxaca (Flannery and Spores 1983). The Archaic period, from approximately 8000 to 2000 B.C., is known from three cave sites (Guila Naquitz, Cueva Blanca, and Martinez Rock Shelter) and one open air site (Gheo-Shih), all located at the eastern end of the Tlacolula arm of the valley. During the Archaic, the valley was inhabited by foragers who hunted deer, peccary, rabbits, quail, and doves, and who gathered maguey hearts, acorns, pinon nuts, cactus fruits, and native vegetables (Flannery and Spores 1983). While no human skeletal remains have been recovered from the Archaic period in the valley, it was an important period in terms of the origin and early development of agriculture. Nevertheless, the study of health and agriculture in the valley is limited at this time to the intensification of agriculture, rather than its origins. Cucurbit seeds, Zea pollen, and small runner beans have been found on Naquitz phase living floors at Guila Naquitz (Flannery 1986). The next phase, Jfcaras, is known from GheoShih, which produced no organic remains but can be dated by TABLE 4.1 Chronology of the Etla Arm of the Valley of Oaxaca, Showing Time Periods Used in This Study Date
European Contact Monte Alban V
A.D. 950 Monte Alban IV
A.D. 700 Monte Alban I1Ib A.D. 450 Monte Alban IlIa A.D. 200 Monte Alban II
Late Monte Alban I
100 B.C. 300 B.C. 500 B.C.
E~ly Moo" Alb'" I } Rosano
700 B.C. Guadalupe 850 B.C. San Jose 1150B.C. Tierras Largas
1400 B.C. SOURCES: Flannery, Marcus, and Kowalewski 1981:91-92; Drennan 1983.
its projectile point typology and by its place in the Archaic pollen sequence. Zea pollen grains were recovered from GheoShih, dating to a period when primitive maize is known from the Tehuacan Valley (MacNeish 1964). The next phase, Blanca, is known from Cueva Blanca living floors C and 0, and is considered coeval with the early to middle Abejas phase in the neighboring Tehuacan Valley. Flannery, Marcus, and Kowalewski suggest that "by the time of the Abejas phase in the Tehuacan Valley (3400-2300 B.C.) and the Blanca phase in the Valley of Oaxaca (3295-2800 B.C.), domesticated com was probably as widespread in the area as Coxcatlan projectile points" (1981:63). The Archaic period was followed by the Early Formative, which included the first ceramic complex. Espiridion is the oldest such complex in the Valley of Oaxaca and resembles the Purron complex in the Tehuacan Valley (Flannery, Marcus, and Kowalewski 1981). It was followed by the Tierras Largas phase (1400-1150 B.C.). Tierras Largas sites have been found throughout the valley, and generally are small hamlets of less than 3 ha in area (ibid.), occupied by sedentary people cultivating maize, beans, squash, and avocados. Tierras Largas phase burials have been excavated at the sites of Tierras Largas and San Jose Mogote. The San Jose phase (l150-850 B.C.) followed. San Jose sites are located throughout the valley and are of approximately the same size as Tierras Largas phase sites, except for the type site of San Jose Mogote, which grew markedly to cover almost 70 ha. The San Jose phase also saw the emergence of relative differences in social rank among individuals. Skeletal remains from this phase have been excavated at the sites of Santo Domingo TomaJtepec, San Sebastian Abasolo, San Jose Mogote, and Tierras Largas. The Middle Formative period has been divided into two phases, the Guadalupe phase, 850-700(?) B.C., and the Rosario phase, 700(?) to 500 B.C. (ibid.). The Guadalupe phase was originally based on ceramics from Huitzo and may not have extended throughout the whole valley, remaining instead a local development in the EtIa and Central regions. Skeletal remains from the Guadalupe phase were excavated at Fabrica San Jose, San Jose Mogote, Barrio del Rosario Huitzo, and Tierras Largas. Rosario was the last phase prior to the founding of the urban center of Monte Alban, which occurred around 500 B.C. The Rosario phase, unlike the Guadalupe phase, seems to have been present throughout the valley. The pottery, art, and architectural styles of the Rosario phase evolved into the Monte Alban I styles (ibid.). Sites which have yielded Rosario burials include Fabrica San Jose, Barrio del Rosario Huitzo, San Jose Mogote, and Tierras Largas. The Late Formative period includes the Monte Alban Early I (Ia) and Late I (Ie) periods, and extends from 500 to 200 B.C.
ARCHAEOLOGY OF THE VALLEY OF OAXACA
(Blanton and Kowalewski 1981). While a third phase, Ib, was defined at the site of Monte Alban (Caso, Bernal, and Acosta 1967), it has not been identified in surface surveys of the valley, and following Blanton's work, Period I has been divided into la and Ie (Blanton et al. 1982; Drennan 1983). In the Late Formative, a regional political system centered at Monte Alban was established (Blanton et al. 1982). Skeletal remains from Monte Alban la and Ic have been excavated at Santo Domingo Tomaltepec, Fabrica San Jose, Monte Alban, Barrio del Rosario Huitzo, San Sebastian Abasolo, San Jose Mogote, and Tierras Largas. The Terminal Formative period in the valley is called Monte Alban II, 200 B.C.-A.D. 200 (Drennan 1983). The Main Plaza of Monte Alban was constructed during this period. Period II was marked by a decrease in site numbers, but an increase in mean site size, in the Valle Grande and Central areas relative to Monte Alban Ic (Blanton and Kowalewski 1981). Skeletal remains from Monte Alban II have been excavated from Monte Alban, Tierras Largas, San Jose Mogote, Brawbehl, Caballito Blanco, and Fabrica San Jose. The Classic period begins with the Monte Alban IlIa period, A.D. 200-450, designated the Early Classic (Drennan 1983). Caso, Bernal, and Acosta (1967) spoke of a Transici6n II-IlIa period at Monte Alban, but it has not been possible to identify such a period throughout the valley. In the Late Classic period, Monte Alban I1Ib (A.D. 450-600), the site of Monte Alban achieved its maximum size of twenty to thirty thousand occupants (Blanton and Kowalewski 1981; Drennan 1983). Skeletal remains from Monte Alban IlIa have been recovered at the sites of Monte Alban, Fabrica San Jose, and San Jose Mogote. The succeeding Monte Alban IV period, A.D. 600-950, was characterized by the disbanding of the regional political system centered at Monte Alban (Blanton and Kowalewski 1981; Drennan 1983). Period IV was initially thought to have witnessed the abandonment of Monte Alban, but it now appears that only the Main Plaza was abandoned, not the whole site. The work of Paddock and his colleagues at the site of Lambityeco has led them to believe that they can distinguish the ceramics of Period IV from those of Period IIIb (Paddock 1978; Paddock, Mogor, and Lind 1968). Blanton and his colleagues (1982) have also argued that they can distinguish Period Illb from Period IV in surface ceramic collections. Caso, Bernal, and Acosta (1967), however, did not feel that Period IIIb and Period IV ceramics could be distinguished from one another using collections from Monte Alban itself. The archaeological problems of distinguishing between Periods IIIb and IV are beyond the scope of my research. Since the Monte Alban IV skeletal remains used in this project are from Lambityeco and Yagul, and have been radiocarbon dated to approximately A.D. 700-750, problems with the ceramic chronology are avoided.
The Postclassic period of Monte Alban V, A.D. 950-1500, saw an increase in population size in the valley (Blanton and Kowalewski 1981; Drennan 1983). No valleywide regional political organization was present. Instead the valley appears to have been ruled by small local units until the Spanish Conquest. Skeletal remains from Monte Alban V have been recovered from numerous sites, including Monte Alban, Santo Domingo Tomaltepec, Fabrica San Jose, San Jose Mogote, Barrio del Rosario Huitzo, Zaachila, Tierras Largas, Yagul, and the Mitla Fortress. ARCHAEOLOGICAL SITES For this project, nearly all of the known prehistoric human skeletal remains from sites within the Valley of Oaxaca were examined. Time constraints prevented the observation of skeletal remains from royal tombs at Monte Alban, and a small portion of the remains from the sites of Yagul and Caballito Blanco. The absence of these few remains should not invalidate the findings. The archaeological sites from which human skeletal remains were examined are described briefly below. San Sebastian Abasolo Abasolo was a small hamlet in the Tlacolula arm of the valley. The Abasolo ruins are located 15 km east of Oaxaca City. The site is adjacent to the humid floodplain in an area where well irrigation is still practiced today. The site has a San Jose phase occupation of 1 to 2 ha, and was also occupied in Monte Alban Ic and V (Drennan and Flannery 1983; Flannery 1983a). Skeletal remains from the site are from the San Jose phase and Monte Alban Ic. Barrio del Rosario Huitzo Barrio del Rosario Huitzo is located in the northern section of the Etla arm of the valley, along an intermittent tributary, about 250 m from the Rio Atoyac. During the Guadalupe phase the site was apparently a small civic-ceremonial center, based on the presence of public buildings and mound construction (Flannery and Marcus 1983b). Burials from Huitzo date from the Guadalupe and Rosario phases, and Monte Alban la and V. Caballito Blanco The site of Caballito Blanco is located in the Tlacolula arm of the valley on a volcanic mesa 300 m from the site of Yagul. Thus far the site appears to have been occupied during Monte Alban II (Paddock 1983a). Of interest at Caballito Blanco is building 0, an arrowhead-shaped building resembling Building J in the Main Plaza at Monte Alban. Two infant burials dated to Monte Alban II were examined from the site.
AGRICULTURAL INTENSIFICJf['ION AND PREHISTORIC HEALTH IN OAXACA
The site of Dainzu is located approximately 20 km east of Oaxaca City in the Tlacolula arm. Excavations were carried out at the site by Bernal, who uncovered a series of monuments with figures described as ball players (Bernal 1967). The monuments date to Monte Alban II (Marcus 1983a). A Monte Alban III occupation is also evident at the site (Kowalewski 1983a). The exact phase associations of the burials from Dainzu have not yet been reported.
The Mitla fortress lies 2 km west of the modem town of Mitla near the eastern end of the Tlacolula arm. The site was constructed and used in Monte Alban v. A single burial excavated by W. Bittler on the fortress was examined for this project and dates to Period V (Javier Urcid, personal communication).
Fdbrica San Jose
The site of Fabrica San Jose is located in the Etla arm of the valley. It is in the piedmont zone, adjacent to the high alluvium, and very near to the mountains. Drennan's (1976) excavations at the site focused on the Early and Middle Formative periods, at which time the site was a small village covering less than 3 ha. Although the inhabitants were primarily farmers, evidence of salt making was found in some household units (Drennan 1976). The site was abandoned during Monte Alban la, but was reoccupied in Period II and abandoned again in IlIa. Occupation at the site after this seems to have been sporadic. Fabrica San Jose skeletal remains are from the Guadalupe and Rosario phases, and Monte Alban la, II, III, and V. Lambityeco (Yegiiih)
The site of Lambityeco is located in the Tlacolula arm of the valley about 2 km east of the town of Tlacolula. Here a larger archaeological zone referred to as Yegiiih covers over 75 ha and has been intermittently surveyed and excavated by the Universidad de los Americas and the Instituto de Estudios Oaxaquenos from 1961 to 1975. The term Lambityeco is used to refer to a smaller area of pure Monte Alban IV occupation within Yegiiih (Paddock 1983b:197). The largest zone of Yegiiih was occupied from the Rosario phase through to modem times. Radiocarbon dates ranging from A.D. 640 to 755 have been obtained from Lambityeco (Paddock 1983a). The skeletal remains from the site are all from Monte Alban IV and have been studied by Urcid (1983). Brawbehl
The site of Brawbehl is about 1 km west of Lambityeco, and may be part of the larger zone of Yegiiih (Paddock 1983a). Two burials from the site, Burials 69-10 and 69-13, were examined for this project; they have been radiocarbon dated to Monte Alban II (Drennan 1983:366).
San Jose Mogote
This site is located on a piedmont spur adjacent to the high alluvium zone in the Etla arm of the valley. It has so far been excavated for nine field seasons by Kent Flannery and Joyce Marcus (l983b). San Jose Mogote grew rapidly during the Early and Middle Formative, becoming the largest site in the valley prior to the founding of Monte Alban. Virtually abandoned during Monte Alban I, the site was made into a secondary administrative center during Monte Alban II and was sporadically occupied after that. Burials from San Jose Mogote date from the Tierras Largas, San Jose, Guadalupe, and Rosario phases, and from Monte Alban la, II, IlIa, and V. Monte Alban
Monte Alban is located atop a 400 meter hill in the center of the Valley of Oaxaca. It was founded in Monte Alban Ia (approximately 500 B.C.) and grew to cover 6.5 km by Period IIIb. Caso, Bernal, and Acosta (1967) were the first excavators at the site, which was mapped and intensively surface collected by Blanton in the 1970s (Blanton 1978). Although the site ceased to function as a regional capital by the end of Period IIIb, parts of the site continued to be occupied through Monte Alban V. The skeletal remains from Monte Alban examined for this project were excavated in 1972 and 1973 by Winter (1974). He excavated the residential terraces designated 634,635, and 636 in Blanton's survey, located north of the Main Plaza. These terraces are thought to have housed low to middle status families. The skeletal remains are from Monte Alban I, II, IlIa, IIIb, and V. Tierras Largas
Tierras Largas is located in the Etla arm of the valley, only 4.5 km from the Main Plaza at Monte Alban and 5 km from the modem city of Oaxaca de Juarez. The site is on a piedmont spur at the base of the hill of Atzompa, adjacent to the high alluvium zone (Winter 1972). Tierras Largas skeletal remains are from the Tierras Largas, San Jose, Guadalupe, and Rosario phases, and Monte Alban I, II, and V.
ARCHAEOLOGY OF THE VALLEY OF OAXACA
Santo Domingo Tomaltepec The site of Santo Domingo Tomaltepec is located in the piedmont zone of the Tlacolula arm of the valley. The site is small and fairly shallow, 2 ha in area and 0.5 to 2 m deep. It was mapped and test-excavated by Henry Wright in 1969 and 1972. In 1974, further excavations at Tomaltepec were undertaken by Michael Whalen (1981), concentrating on Formative deposits. One of the important findings of Whalen's work was a San Jose phase cemetery located outside the site's habitation area. Other burials from Tomaltepec date from Monte Alban la, Ic, and V. Yagul Yagul is 3 km to the east of Tlacolula and covers a kilometerlong volcanic tuff mesa which rises from the floor of the Valley of Oaxaca (Paddock 1983c:98). The site was excavated in the mid 1950s and early 1960s by Ignacio Bernal and John Paddock. Tombs of Monte Alban I style were uncovered at Yagul (Chadwick 1970), along with extensive architectural remains from Periods IV and V (Bernal and Gamio 1974; Paddock 1983a). The skeletal remains which I studied date to Monte Alban IV and V. Zaachila The ruins of Zaachila are located on a rocky islandlike rise in the flat alluvium of the Valle Grande arm. The site was occupied from the Early Formative through to the present day (Flannery 1983a). Part of the site was excavated in 1962 by Roberto Gallegos, including Tombs 1 and 2 (Gallegos 1963). Tombs 3 and 4 at Zaachila were excavated by Jorge Acosta in the early 1970s (Marcus Winter, personal communication). All four tombs are from Monte Alban V and provided skeletal remains examined for this study. Summary The skeletal remains examined in this project are from sites located in all three arms of the valley. While many of the sites were hamlets less than 3 ha in size, others were larger sites which probably had some administrative function. The remains date from the Tierras Largas phase of the Early Formative through Postclassic Monte Alban V. The biological aspects of the skeletal samples are discussed in the next chapter; the archaeological data from the sites on subsistence, settlement patterns, and social organization are discussed below.
THE AGRICULTURAL POTENTIAL OF THE VALLEY OF OAXACA Before discussing the effect of agricultural intensification in the valley on health, some discussion of the potential for agriculture in the valley is needed. The Valley of Oaxaca contains 700 km 2 of totally flat land and much larger zones of piedmont and mountain slopes. The agricultural potential of the valley is, however, offset by its semi-arid climate (Kirkby 1973). At meteorological stations in Oaxaca City and Tlacolula, the amount of moisture lost by evaporation during the year is greater than the amount of precipitation recorded (Smith 1978). Neither the Rio Salado nor the Rio Atoyac is used as a source of irrigation water today (Kirkby 1973). The perennial streams and tributaries from the mountains are the main sources of water for irrigation. The major determining factor in maize cultivation in this semi-arid region is moisture availability (Kirkby 1973). Agriculture is practiced today primarily in the high alluvium zone. The potential productivity of this zone varies throughout the valley. Kirkby (1973) recognizes two subregions within the high alluvium zone that have different potentials for agriculture. The southern Valle Grande area has a higher agricultural potential than do the northern Etla and Tlacolula areas. In the northern section of the valley, which includes the EtIa and Tlacolula arms, the alluvium is at a higher elevation and has a cooler climate. A ground frost is likely every year, with an average frost-free period of ten months (Kirkby 1973: 13). Agriculture in the Tlacolula arm is further hindered by the fact that it is the driest section of the valley (Smith 1978). In the southern high alluvium area, the elevation is lower and the climate is sufficiently warmer that ground frost has not been recorded (Kirkby 1973). Using the present patterns of land use and agricultural potential in the valley, Kirkby (1973) has examined agricultural potential, prehistoric settlement patterns, and population size. Since the population density of the valley today has been found to have a significant positive, linear relationship with corn yields, she assumes that the same relationship held in the past (Kirkby 1973). The potential corn yields, based on prehistoric corncob sizes from the Tehuacan Valley, were predicted for the Tierras Largas phase, the San Jose phase, Monte Alban I, and Monte Alban IIIb-IV. Kirkby (1973: 142-146) concludes that in general terms the changing patterns of population distribution and economic leadership through time are closely related to variations in agricultural resources around the Valley.... The number of inhabitants of the valley calculated on the basis of archaeological data (roughly 550 at 1300 B.C. and 3800 at 1000 B.C.) is always less than the number which it is calculated could have been supported by agriculture within the valley.
Since Kirkby's analysis of population and agricultural potential, more extensive settlement surveys of the Valley of Oaxaca
AGRICULIURAL INTENSIFICAf'ION AND PREHISTORIC HEALIH IN OAXACA
have been completed (Blanton et al. 1982). Kowalewski (1982), building on Kirkby's study, has reexamined the relationship between population potential and agriculture in the Valle Grande and central areas of the valley. He defines three types of land based on moisture availability. Type I land has a high water table and includes land that can be irrigated with a canal system; this land has the highest potential agricultural yields. Type II land has a marginal water table, but has good access to floodwater. The yields of Type II land will vary depending on the rainfall pattern. Type III lands have the lowest levels of available moisture, as the water table in these areas is low, and floodwaters are not received every year. Crops on Type III land are raised primarily by dry farming techniques. According to Kowalewski, Type I makes up 10.4% of the total arable land in the valley; Type II, 9.6%; and Type III, 79.9%. The potential population was calculated for the valley based on levels of maize consumption from ethnographic studies in the Valley of Oaxaca and from other locations in Mexico (Kowalewski 1982). The potential population is the number of people a specific area could support, based on the average consumption needs for an individual and estimates of maize yields per hectare. Kowalewski found that the potential population from Monte Alban Ia through Monte Alban V for the Valle Grande and Central zones increased linearly, and was well above the archaeological population estimates. The correlation between potential population size and the archaeological population size was not significant within any of the periods from Monte Alban Ia to V. This lack of correlation indicates that the estimated population size during these periods (Ia to V) was unrelated to the size of the population the valley could have supported. A strong association between site location and Type I and II land was found in each period. Although the quality of the land appears to be associated with site location, the lack of a relationship between potential population and actual population suggests a lack of population pressure in the valley. TEMPORAL TRENDS IN SUBSISTENCE The earliest evidence of prehistoric subsistence in the Valley of Oaxaca is from the Archaic, the period in which agriculture had its origins. Archaic subsistence evidence comes from a series of sites in the Tlacolula arm. The majority of the organic remains are from Guila Naquitz Cave (Flannery 1986), although pollen grains were recovered at Gheo-Shih (Flannery, Marcus, and Kowalewski 1981). The Archaic population of the valley hunted white-tail deer, peccary, cottontail rabbits, jackrabbits, quail, doves and other small animals. Cactus fruits, maguey hearts, acorns, pinon nuts, hackberry fruits and numerous other wild plants were collected by the Archaic inhabitants. In the Naquitz phase at Guila Naquitz Cave (8700-6700 B.C.), 14 seeds and peduncles of Cucurbita pepo and pollen
grains of Zea were uncovered. Small black runner beans were also found in these levels, but they belong to a species which has left no domestic descendants. In the adjacent Tehuacan Valley, 18 cobs of maize (Zea mays) were recovered from Coxcatlan Cave levels dated to 5050 B.C. (MacNeish 1964). Flannery has suggested that domesticated com was probably present in the Valley of Oaxaca during the Blanca pha5e (3295-2800 B.C.), on the basis of pollen evidence. Given the proximity of Tehuacan and the presence of Zea pollen in the Oaxaca Archaic, the assumption that maize was cultivated in Oaxaca by the Late Archaic seems reasonable. The earliest phase for which actual corncobs have been found is the Tierras Largas phase. Zea mays and teosinte have been found in Tierras Largas phase deposits at the sites of TomaJtepec and Tierras Largas (Whalen 1981; Winter 1972). At TomaJtepec, the common bean (Phaseolus vulgaris) was recovered along with teosinte, as well as avocados which may have been domesticated (Whalen 1981:31). Faunal remains from the Tierras Largas phase include white-tail deer, peccary, and cottontail rabbit (Whalen 1981). In the San Jose phase at Tomaltepec, maize was found in every feature that had appreciable levels of carbonized plant remains (Whalen 1981). Other plants also found in San Jose phase features include beans, teosinte, Chenopodium, and Amaranthus (Smith 1981). "Large quantities of animal bone recovered from early San Jose phase deposits at Tomaltepec show that hunting, especially of deer, continued to be an important element of the subsistence pattern" (Whalen 1981:60). Thus, subsistence in the Early Formative included domesticated crops such as maize, beans, and possibly avocados, while collecting of wild foods and hunting of animals continued to be important subsistence activities. In the Guadalupe and Rosario phases of the Middle Formative, cultivars which have been recovered in excavations include maize, beans, avocados, pumpkins, and chili peppers (Flannery, Marcus, and Kowalewski 1981). The remains of prickly pear and organ cactus fruits, acorns, hackberries, zapote, chipil, maguey, and fruit of the cuajilote were recovered along with domesticates in Guadalupe phase deposits (Flannery, Marcus, and Kowalewski 1981; Ford 1976). The faunal remains from the Rosario phase indicate that hunting was still of importance and that domestic dogs were eaten (Whalen 1981). Prior to the Late Formative period there is no evidence of canal irrigation systems. The earliest evidence of such irrigation comes from the southeastern flank of the site of Monte Alban and consists of a dam and canal over 2 km in length (Mason et al. 1977). The dam and canal have been dated to the Late Formative period based on sherds in the canal fill. The site of Hierve el Agua, located in the mountains east of Mitla, also contains evidence of a prehistoric water control system; a series of terraces and canals "fossilized" by travertine deposits were
ARCHAEOLOGY OF THE VALLEY OF OAXACA
found there (Flannery 1983c). Hierve el Agua was occupied from Monte Alban Ie (radiocarbon dated 420-310 B.C.) to V; usage of the canals probably began in Period Ie (Flannery 1983c:327). Prior to Monte Alban I, it seems that farming in the valley was accomplished primarily by dry farming and well irrigation rather than with canals (Flannery 1983c). The presence of canal irrigation in the Late Formative period suggests an intensification of agriculture, with maize probably forming a significant proportion of the diet. It has been suggested that agricultural practices were intensified beginning in Monte Alban Ia (Feinman, Blanton, and Kowalewski 1984). The intensification of agriculture may have involved an expansion of the area under cultivation and probably the planting and harvesting of a second crop (Feinman, Blanton, and Kowalewski 1984). Subsistence remains from the Late and Terminal Formative periods (Monte Alban la, Ie, and II) are few, as most of the excavations that have yielded subsistence data focused on the earlier periods. Late Formative corn, avocados, and ChenopodiumlAmaranthus have been recovered at Tomaltepec (1. Smith 1981). Hunting continued to contribute to subsistence in both the Late and Terminal Formative (Whalen 1981). It would seem that by the end of the Formative, subsistence was heavily dependent on the cultivation of maize, beans, avocados, chili peppers, squash and possibly other domesticates, but some reliance on wild plant foods and hunting continued. Very few subsistence data from the Classic period have been reported. Some data are available from Houston's (1983) study of flotation samples from Lambityeco, Dainzu, and terraces 634, 635, and 636 at Monte Alban. As Houston (1983) acknowledges, the samples are small and may not be representative, but they do give an indication of the kinds of plants that were being consumed. Botanical remains from Monte Alban IV at Lambityeco include maize, beans and fleshy fruits. The "remains of maize, common beans, black zapote, chenopod, and cactus fruit indicate a rich diet in a poor environment" at Lambityeco (Houston 1983:264). Zone A at Guila Naquitz also produced organic remains from Monte Alban IV that included acorns, susf, hackberries, maguey, prickly pear, mesquite, wild onions, maize, black twining beans, short bush beans, pumpkins, yellow chili peppers, white zapote, and avocados (Flannery and Smith 1983). A few general statements can be made about temporal trends in the subsistence base of the prehistoric population of the Oaxaca Valley. As with any prehistoric subsistence base, it is difficult to estimate the percentage of the diet made up of cultivars and the percentage from hunting and gathering. It is clear that in Oaxaca, agriculture was practiced by the Late Archaic period and appears to have increased in importance through the Formative period. The remains of canal irrigation systems in the Late Formative suggest that the practice of agri-
culture had intensified. It is suggested that agriculture in the Early and Middle Formative was nonintensive, while in the Late Formative, Classic and Postclassic periods intensive agriculture was practiced. Although maize appears to have been the main crop, numerous other domesticated plants were also cultivated. Hunting and gathering continued to contribute to the subsistence base in the Formative, Classic, and Postclassic periods. TEMPORAL TRENDS IN SETTLEMENT PATTERNS AND POPULATION SIZE As a result of Blanton's Valley of Oaxaca Settlement Pattern Project, temporal trends in settlement patterns for the valley have been established, albeit with the problems characteristic of any regional surface survey. The following discussion of settlement patterns and population estimates are based on survey data of the Valle Grande and Central areas (Blanton et al. 1982). Flannery (l983b) has speculated on population size in the Archaic period. He begins by assuming that Gheo-Shih was occupied by a macro band of 25 persons during the Jfcaras phase. If each arm of the valley had one macroband camp, then the population for the whole valley could have been 75 (Flannery 1983b:35). Since the Archaic period covers some 7,000 years and is known from only four sites in the valley, any population figures for this time period are highly speculative. Sometime between the Late Archaic and the Early Formative, the settlement pattern of the prehistoric popUlation of the valley shifted to a sedentary form. Villages first appear in the Valley of Oaxaca during the Espiridion phase of the Early Formative. From this time onward settlements were sedentary, although changes in the zonal location and density of sites are observed over time. Sites with Tierras Largas phase occupations have been reported from all three arms of the valley, with six sites known in the Etla arm and nine or ten from the Valle Grande and Central zones (Flannery 1983d). All the sites were small occupations of less than 3 ha, except for the site of San Jose Mogote which covered 7.8 ha. The population of the western valley (Etla, Central, and Valle Grande) during the Tierras Largas phase has been estimated at approximately 425 individuals (Flannery, Marcus, and Kowalewski 1981). The San Jose phase is marked by a substantial increase in population, especially at the site of San Jose Mogote which, including outlying barrios, grew to 70 ha with an estimated population of 700 individuals (Kowalewski, Fisch, and Flannery 1983). All other sites at this time were much smaller, under 3 ha in size. There were more than two dozen villages in the western valley (Etla, Central, and Valle Grande areas), 14 of them clustered significantly close to San Jose Mogote.
AGRICUIIURAL INTENSIFICJf['ION AND PREHISTORIC HEAIIH IN OAXACA
In the Early and Middle Formative, the Etla arm (containing the site of San Jose Mogote), appears to have been the demographic center of the valley (Flannery and Marcus 1983b). By the Rosario phase, San Jose Mogote had an estimated population of 1,000, and it served as the ceremonial center for an Etla arm population of 1,300 to 1,400 persons. The Central and Valle Grande areas had 25 villages with a total population below 1,000. Kowalewski (l983b:96) has estimated the average annual rate of population increase from 1400 B. C. to 500 B. C. at 0.1 to 0.4 percent. The Late Formative periods Monte Alban Ia and Ic are marked by population growth and an increase in occupation of marginal areas (Blanton et al. 1982:40). In Period la, twothirds of the increase occurred within a 20 km radius of Monte Alban (Blanton and Kowalewski 1981). Thirty km beyond Monte Alban, site densities essentially were unchanged from Rosario phase levels. The number of sites in the Valle Grande and Central regions increased from 103 in Period Ia to 307 in Period Ie. In Period I, the number of small settlements increased, as "isolated residences, hamlets, and tiny villages account for 89% of the settlements in the Etla and Central Valley areas" (Kowalewski 1983b:96). Much of the increase was the result of the concentration of population around Monte Alban. Kowalewski (1982), in his study of agriculture and population potential, estimated the prehistoric population of the Central and Valley Grande parts of the valley for Periods Ia through V. The population estimates presented below are from his Table 9-7 (ibid., 162), but are rounded to the nearest hundred. The population during Period Ia is estimated at 8,500 individuals (including Monte Alban itself, which had a population of 5,400), indicating a substantial increase from the preceding Rosario phase. The projected growth rate in Period Ia exceeds human reproductive capacity, which suggests some immigration into the areas so far surveyed (Blanton et al. 1982). Population continued to increase, as the Central and Valle Grande during Period Ie had a population estimate of 30,000, of which roughly 16,600 resided at Monte Alban. The Terminal Formative, Monte Alban II, is marked by a decline in population to 20,300 in the areas so far surveyed (Kowalewski 1982). The population at Monte Alban itself declined to 14,500. Most of the population decline tnat occurred in Period II was the result of population loss within 18 km of Monte Alban (Blanton et al. 1982). The Early Classic period, Monte Alban lIla, saw the population of the Central and Valle Grande areas reach 55,400 individuals, the highest estimate at any time in the western valley's prehistory (Kowalewski 1982). While the population of Monte Alban grew to approximately 16,600, it was not until the following IIlb period that the site reached its maximum size. In
Period IlIa, the area beyond 18 km from Monte Alban continued to grow, while the Central zone remained unchanged. The projected growth rate of Period IlIa exceeds human reproductive potential implying further immigration into the areas so far surveyed (Blanton et al. 1982). The population of the Central and Valle Grande areas declined in I1Ib to 42,600, but Monte Alban grew to its maximum size of 22,800. The Central area around Monte Alban saw an increase in population size and was occupied extensively. As in Monte Alban I, nearly 90% of the settlements were small hamlets and villages (Kowalewski 1983c). By Monte Alban IV, the site of Monte Alban had lost its role as a regional political center and its population fell to roughly 4,000 individuals (Blanton and Kowalewski 1981). Kowalewski (1982) has estimated the population of the Central and Valle Grande areas in Period IV at 28,400. He suggests that the decline of Monte Alban brought about a radical restructuring of the settlement system (Kowalewski 1983c). Problems with differentiating Period IIIb ceramics from those of Period IV prevent the emergence of a clear picture of Period IV settlement patterns. In Period V, the population of the Central and Valle Grande areas increased to roughly 50,600. Monte Alban appears to have been occupied by roughly 4700 individuals. The site never regained its former population size (Blanton and Kowalewski 1981). During Period V, there were "a series of apparent contrasts among subareas, with some parts of the valley showing nucleated centers and other parts mainly isolated residences and tiny hamlets" (Kowalewski 1983a:285). Settlements were highly dispersed, with 867 sites recorded in areas so far surveyed and an average site size of 3 ha (Blanton et al. 1982). To summarize, the earliest occupations in the Valley of Oaxaca are from the Archaic period. At that time, settlements were temporary sites occupied for up to several months by macro- or microbands. Towards the end of the Archaic period there was a shift to more permanent occupation of sites, which culminated in the small villages found in the Early Formative. From the Early Formative onward, settlement patterns in the Valley of Oaxaca were sedentary. The Etla arm of the valley had the highest density in the Early and Middle Formative, but with the founding of Monte Alban, the density became higher in the Central zone. The number of sites occupied and the concentration of sites varied throughout the Late Formative and Classic periods. During Periods Ia and II, the proportion of sites in the alluvium zone tended to be higher, while in Periods Ie and IlIa the proportion of sites in the piedmont was higher. The prehistory of the valley is characterized not by continuous population growth, but by fluctuations in population size. Population growth rates were low in the Early and Middle
ARCHAEOLOGY OF THE VALLEY OF OAXACA
Formative, but increased in the Late Formative and Classic periods. The changes in settlement patterns and population size have been connected to changes in the political organization of the valley.
regional political system with its capital at Monte Alban. Following the decline of Monte Alban in Period IV, the vaIley seems to have been divided up into a series of smaller, balkanized polities which were often at war with each other.
SOCIAL AND POLITICAL ORGANIZATION IN THE VALLEY OF OAXACA
Trade Networks and External Contact
Social Organization The social organization of the prehistoric population of the Valley of Oaxaca is perhaps best examined using data from residential units and burial practices. Excavations at several sites in the valley have focused on the Formative period and provide information on social organization. These sites include Tierras Largas (Winter 1972), Fabrica San Jose (Drennan 1976), Tomaltepec (Whalen 1981), San Jose Mogote, Abasolo, and Huitzo (Flannery and Marcus 1983b). In the Tierras Largas phase there is no evidence of social ranking to be found in either household patterns or burials. Tierras Largas phase society appears to have been egalitarian. Evidence of social ranking does appear in the succeeding San Jose phase. Social differentiation in the San Jose phase took the fonn of a continuum from relatively higher to relatively lower status without a true division into social classes such as took place in later periods. [Flannery, Marcus, and Kowalewski 1981:71] Relatively higher status seems to have been reflected in greater access to non local products, relatively greater access to deer meat, greater involvement in ornament production, and a residence more elaborate than the average, although not beyond the construction capacity of a single family. [Flannery and Marcus 1983b:63]
In the Middle Formative the trend toward increasing social differentiation continued. The nonrandom distribution of ceramics, ornaments of bone, stone, shell, and mica distinguish relatively higher status from relatively lower status households in the Middle Formative at Fabrica San Jose (Drennan 1976). Status differences in households goods and burial offerings were also evident at other sites including Tomaltepec and San Jose Mogote (Flannery and Marcus 1983b; Whalen 1981). By Monte Alban II, palaces and royal tombs at places like Monte Alban and San Jose Mogote indicate the stratification of society into an upper stratum of royalty and nobility and a lower stratum of commoners. Genealogical monuments of Monte Alban IIIb and IV document royal descent. By the Postclassic (Monte Alban V), there are elaborate palaces and elite tombs at sites like Yagul and Mitla, and Spanish documents of the sixteenth century describe a highly stratified Zapotec society (Flannery and Marcus 1983a). During the growth of Monte Alban from Period I to IIIb, the entire Valley of Oaxaca seems to have been integrated into one
It is evident that the inhabitants of the VaIley of Oaxaca were in contact with neighboring populations since the Archaic period. Wobst (1974), using computer simulations, has demonstrated that a minimum population of 175 to 475 individuals is needed to have an effective breeding population, that is, a population with a sufficient number of mates. Given the population estimate of 75-150 individuals for the valley in the Archaic, "obviously, the local groups of all these valleys [Oaxaca, Nochixtlan, and Tehuacan] had to remain in sufficient contact with each other to exchange mates" (Flannery 1983b:36). Interregional contact between Tehuacan and Oaxaca is suggested by the presence in Oaxaca sites of projectile points of types found more commonly in the Tehuacan Valley. In the Early and Middle Formative periods, evidence for interregional contact comes from analyses of obsidian, magnetite, shell, and other trade items (Pires-Ferreira 1975). SheIls from both the Pacific coast and Atlantic watershed were recovered at Early and Middle Formative sites in Oaxaca, indicating contact with those regions. Obsidian source data indicate that the VaIley of Oaxaca was in contact with populations in the eastern part of Puebla, the Teotihuacan Valley, and the state of Michoacan. The source for some small magnetite mirrors found in Veracruz and Morelos have been located in the Valley of Oaxaca, indicating contact between these regions. Evidence from both within and outside of the valley indicate that interregional contact continued through the Classic periods. At the urban center of Teotihuacan, a 100 x 150 m residential area was found to contain Oaxaca style ceramics (Paddock 1983d). The pottery found in this area, the so-called "Oaxaca barrio," is identical to pottery from sites in Oaxaca that date to the Transici6n II-III period. The pottery was made, however, with local Teotihuacan clays, and the buildings of the barrio were typical Teotihuacan apartment complexes (ibid.). There is also evidence that Teotihuacanos visited the Valley of Oaxaca, as they are depicted on a number of monuments at Monte Alban (Marcus 1983b). Contact with Teotihuacan in the Classic Period may have affected the prevalence of infectious diseases in Oaxaca. The population of Teotihuacan at its height in A. D. 600 is estimated between 125,000 and 200,000 (Rene Millon, quoted by Flannery and Marcus 1983e). With the urban population of Teotihuacan, its surrounding area, and the addition of other populations with which it was in contact, it may be possible
AGRICUIIURAL INTENSIFICATION AND PREHISTORIC HEAIIH IN OAXACA
that a population size large enough to support infectious diseases was reached. Storey (1985) has examined the mortality profile of one apartment complex at Teotihuacan and found mortality patterns similar to those of pre-industrial cities in the Old World. Infectious diseases are known to have been a significant health problem in Old World cities. The Teotihuacan mortality profile suggests that infectious diseases, although thought to be less common in New World populations, may well have existed and persisted via interregional contact.
After the decline of Monte Alban in Period IV, the Oaxaca population continued to have contact with outside populations, including the Mixtecs and the Aztecs. It is possible that the contact population size continued to be large enough to support the pathogens of infectious diseases. It is not clear at this time, however, how often contact was made, nor are the actual urban population sizes well established. It is possible that contact with Teotihuacan between 150 B.C. and A.D. 600 may have resulted in increasing infectious disease problems that continued into the Postclassic.
Materials and Methods HYPOTHESES, SKELETAL HEALTH MARKERS, THE SAMPLE AND ANALYTICAL TECHNIQUES Based on the temporal trends in subsistence, settlement patterns, and population size described in the preceding chapter, and the findings of previous paleo pathology studies, four hypotheses about health and agricultural intensification are proposed. The first three predict an increase in the levels of infectious problems, nutritional problems, and general health problems with the intensification of agriculture. The fourth hypothesis, stated as a null hypothesis for reasons discussed earlier, predicts no change in degenerative joint disease. The hypotheses and the basis of their formulation are discussed below. The hypotheses will be tested by examining the temporal frequencies of stress markers among skeletal samples from the Valley of Oaxaca. The markers that were examined are described, along with the criteria used in scoring them. The Oaxaca skeletal samples, their representativeness and temporal distribution are discussed along with the techniques used to analyze the data.
rare or nonexistent until the development of urban centers (Armelagos and Dewey 1970; Black 1975; Cockburn 1963). Human populations were not large enough, or did not have sufficiently high densities, for the pathogens of infectious diseases to be maintained continuously in the host population until urbanization occurred. Although it is unlikely that the population of the Valley of Oaxaca ever reached the size necessary to support acute infectious diseases, its increasing size and density may have contributed to an increase in other infectious problems such as parasitic infections. The archaeological record indicates that a substantial increase in population size and density occurred in the Late Formative period followed by minor fluctuations in the succeeding periods. The periods with higher population size and density were also the periods of intensive agriculture. This hypothesis has been stated as a directional prediction based on the findings of previous studies. Following the standard conventions of hypothesis testing, the null hypothesis of no change in the frequency of individuals with infectious problems is tested. The frequencies of periosteal reactions, lesions which are indicative of an infectious condition, are used to test the hypothesis. If the frequencies of periosteal reactions are higher among the intensive agriculturalists, the null hypothesis will be rejected.
HYPOTHESIS I THE INCREASING SIZE AND DENSITY OF THE VALLEY'S POPULATION OVER TIME RESULTED IN AN INCREASE IN THE FREQUENCY OF INDIVIDUALS AFFLICTED BY INFECTIOUS AGENTS.
There are two reasons to predict an increase in infectious problems. One reason is that previous studies of health and agricultural development in prehistoric North America have consistently found significantly higher frequencies of infectious lesions in agricultural samples than in preagricultural samples (Cook 1979; Lallo, Armelagos, and Rose 1978; Larsen 1982; Perzigian, Tench, and Braun 1984). It appears that the shift to agriculture results in a higher frequency of infectious disease problems, and it is suggested that an increase in infectious problems may also occur with the intensification of agriculture. Secondly, other studies have shown infectious disease to be
HYPOTHESIS II A GENERAL DECLINE IN HEALTH WAS ASSOCIATED WITH THE INTENSIFICATION OF AGRICULTURE.
This hypothesis predicts an increase in all health problems with agricultural intensification, including infectious diseases. While the presence of infectious conditions can be identified on skeletal remains by a specific marker (periosteal reactions), general health problems are assessed using a variety of nonspecific markers. This hypothesis is based on skeletal studies of health and
AGRICULIURAL INTENSIFICATION AND PREHISTORIC HEAU'H IN OAXACA
agriculture which have found significant increases with the development of agriculture in the frequencies of nonspecific health markers, for example, enamel hypoplasia, and other dental pathologies (Cassidy 1984; Cook 1979; Goodman, Armelagos, and Rose 1980; Perzigian, Tench, and Braun 1984). The general decline in health may be related to increasing nutritional and infectious problems, or to the synergistic interaction of the two factors. Even if the frequency of nutritional problems and the frequency of infectious problems are found not to have increased with agricultural intensification, the presence of both health problems may have resulted in a decline in health as individuals would have been more susceptible to stressors. As with Hypothesis I, the null hypothesis of no change in general health is the hypothesis tested. The hypothesis is tested by examining the frequency of general health markers including enamel hypoplasia, dental caries, dental abscesses, periodontal disease, dental calculus, and hypercementosis. HYPOTHESIS III
growth retardation, which reflects nutritional status, has also been found to be significantly higher among prehistoric agriculturalists than among preagriculturalists (Cook 1979; Lallo 1973). This hypothesis is tested by examining the frequency of individuals with porotic hyperostosis, a skeletal lesion indicative of iron deficiency anemia. The frequency of porotic hyperostosis gives some indication of problems with iron metabolism. Other measures for assessing nutritional status, such as child growth patterns and the magnitude of sexual dimorphism, could not be examined in the Oaxaca series due to the fragmentary condition of the remains. Hypothesis III cannot be tested as fully as desired, but the frequency of porotic hyperostosis will give some indication of dietary problems. The rate of dental wear is examined in conjunction with the third hypothesis. The rate of dental wear reflects on a broad scale the types of foods in the diet and the food preparation technology (Smith 1983). An examination of the rate of wear in the Oaxaca series will provide a rough indicator of dietary change, or change in food preparation techniques.
THE INTENSIFICATION OF AGRICULTURE RESULTED IN AN INCREASE IN NUTRITIONAL HEALTH PROBLEMS.
HYPOTHESIS IV THE INTENSIFICATION OF AGRICULTURE DID NOT AFFECT THE
This hypothesis is a corollary of the second hypothesis, which proposes a general decline in health. The prediction of increasing nutritional problems is stated in a separate hypothesis because it is possible, to a certain extent, to isolate evidence of nutritional problems from general health problems. Prehistoric nutrition levels can be assessed by examining specific stress markers, such as porotic hyperostosis, and by other parameters (Martin et al. 1985). The assumption underlying this hypothesis is that the intensification of agriculture results in higher yields of agricultural products, thus the percentage of agricultural products in the diet is expected to increase. Diets composed of a few staples are less likely to provide all the essential nutrients than are diets based on a variety of foods. Specific nutritional deficiency diseases have been associated with agricultural diets based on a single staple, such as beriberi with rice-based diets and pellagra with corn diets (Yudkin 1969). If the diet of the Oaxaca population was focused on agricultural products, then an increase in nutritional problems would be expected. Previous skeletal studies of the relationship between health and agriculture provide a basis from which the hypothesis of increasing nutritional problems is proposed. Th~se studies have found significant increases in the frequencies of skeletal pathologies related to nutrition, such as porotic hyperostosis, in comparing agricultural to preagricultural skeletal samples (Cassidy 1984; Cook 1979; Lallo 1973). Evidence of child
FREQUENCY OF DEGENERATIVE JOINT DISEASE.
Only the null hypothesis is stated here, as there is no firm basis for arguing for an increase or decrease in degenerative lesions. No change in the frequency of degenerative lesions has been observed in two paleopathology studies (Cassidy 1984; Larsen 1982), while two other studies have found a significant increase in the frequency of the lesions (Lallo 1973; Pickering 1984). Due to the limited number of paleopathology studies of the frequency of degenerative lesions and agricultural development, and to contradictory results, a direction of change cannot be predicted. The null hypothesis of no change in degenerative lesions is tested by examining the frequency of individuals with degenerative changes in the major body joints-the elbow, shoulder, hip, and knee-and in the vertebral column. SKELETAL STRESS MARKERS Several recent reviews have been written on the use of skeletal stress markers for assessing nutritional status of prehistoric populations (Goodman Martin, Armelagos, and Clark 1984; Huss-Ashmore, Goodman, and Armelagos 1982; Martin, Goodman, and Armelagos 1985). Most of the markers utilized in this project are discussed at varying lengths in these reviews. Given the recent summaries, the etiology and expression of stress markers are reviewed only briefly here.
MATERIALS AND METHODS
NONSPECIFIC STRESS MARKERS Nonspecific stress markers are markers with more than one possible etiology. The presence of the marker indicates a health problem, but the cause of the problem cannot be ascertained from the marker alone. Enamel hypoplasia, for example, has been associated with dietary deficiencies, infectious diseases, enteropathies, congenital defects, and nephropathies (Pindborg 1982). In clinical cases the etiology can be determined from the case history of the individual, but such information is not available for prehistoric samples. Markers such as enamel hypoplasia provide a measure of general stresses which are severe enough to affect the skeletal system. Nonspecific stress markers examined in this project include enamel hypoplasia, and a series of dental pathologies: periapical abscesses, calculus, dental caries, dental wear rates, and hypercementosis. The presence of the latter dental markers are related to oral health practices, and in varying degrees, to dietary practices. Enamel Hypoplasia Description Enamel hypoplasia is a developmental defect of enamel formation (Pindborg 1970). The defect is a transverse depression consisting of a linear groove which may be marked by small pits, or consists of an array of pits. The defect is a result of a metabolic disruption in the cells that produce enamel, the ameloblasts (Kreshover 1960). The disruption of amelogenesis causes an arrest in the formation of enamel, and if the ameloblasts do not recover from the metabolic disturbance, this can result in the death of the ameloblast (Samat and Schour 1941). The arrest and destruction of ameloblasts produces the enamel hypoplasia, a defect in enamel thickness (Rose, Condon, and Goodman 1985). Enamel hypoplasia can result from both systemic and local factors (Pindborg 1982). Local factors that have been associated with enamel hypoplasias include trauma, surgery, electric bums, and irradiation (Pindborg 1982). Systemic factors that have been implicated in hypoplasia formation include infectious diseases, nutritional deficiencies (including vitamin, protein, and mineral deficiencies), enteropathies, congenital conditions, nephropathies, and premature birth (Pir::dborg 1982). It is not possible, however, to determine the etiology of a defect from its appearance. Although the precise etiology of enamel hypoplasia cannot be ascertained, enamel hypoplasias are indicative of a period of physiological disruption. Their presence indicates not only the occurrence of a stressor, but also a response from the host
(Rose, Condon, and Goodman 1985). The fact that amelogenesis was resumed after the stress episode ended indicates an effective response by the host's resistance. The presence of the hypoplasia indicates that enamel formation was resumed. The size of the defect, however, does not necessarily indicate the severity of the stress: "At present there is no evidence that the severity of a metabolic disturbance affects the magnitude (depth and width of involvement) of a hypoplastic lesion" (Rose, Condon, and Goodman 1985:286). From the location of an enamel hypoplasia, the age of the individual at the time of the growth-disrupting stress can be estimated, since the rate of tooth formation is known. The age at the time of stress is estimated using standards for tooth formation from modem populations (Samat and Schour 1941). The chronology of tooth formation of modem populations can be used in determining the developmental age at stress from enamel hypoplasias in prehistoric populations (Goodman, Armelagos, and Rose 1980; Swardstedt 1966). Hypoplasias are valuable nonspecific markers of stress in prehistoric populations as they are relatively permanent markers. Unlike other indicators of systemic physiological disruptions (e.g. Harris lines), enamel hypoplasias are not lost during normal skeletal maintenance. Hypoplasias are permanent markers lost from the record only by attrition of the enamel or loss of the tooth. Hypoplasias have the additional advantage of detection by occurring on the hardest tissue of the skeleton, enamel, which is the part most likely to be preserved. Further, enamel hypoplasias can be observed macroscopically and do not require specialized equipment or preparation of specimens. The analysis of enamel hypoplasias in skeletal series requires the use of age-specific rates or age-adjusted rates (Rose, Condon, and Goodman 1985). In several studies the mean age at death of individuals with enamel hypoplasia has been reported to be lower than the mean age at death of individuals without the defect (Cook 1981; Swardstedt 1966). The use of age-specific rates in comparing samples will alleviate any effects of differential mortality associated with hypoplasias. Scoring All deciduous and permanent teeth were examined for enamel hypoplasias. Enamel hypoplasias were identified by the presence of linear depressions or pits observable with the naked eye. The number of enamel hypoplasias were recorded for each tooth on which the enamel surface could be examined. The few cases where the enamel surface could not be observed due to calculus deposits, or for some other reason, were excluded from the analysis. The distance of the hypoplasia from the cemento-enamel junction was measured when possible. The distance was converted into a developmental age at stress based
AGRICUUURAL INTENSIFICAFION AND PREHISTORIC HEAUH IN OAXACA
on the tooth formation chronology chart published by Goodman and colleagues (Goodman, Armelagos, and Rose 1980:520). Age-at-stress estimates were made into half-year age intervals ranging from birth to 7 years of age. Periapical Abscesses Description A periapical abscess is an acute inflammation of the soft tissues adjacent to the root of a tooth. The inflammation of periapical tissues can lead to the destruction of the alveolar bone at the apex of the tooth. Periapical abscesses can be caused by infections that accompany periodontal disease and dental caries, and have been associated with tooth trauma and severe attrition (Shafer, Hines, and Levy 1983). Periapical abscesses in the maxilla can also be associated with sinus infections in the maxilla. Abscesses are formed when an inflammation of the pulp cavity spreads to the periapical tissues. The inflammation can result in pus formation and eventually lead to tissue necrosis. In skeletal remains, periapical abscesses are evident from alveolar bone destruction in the periapical region. An abscess indicates that an inflammatory condition had been present.
formation while carbohydates, calcium, and vitamin A appear to promote calculus formation (Stanton 1969). Calculus deposits develop and are retained in the mouth as a result of failure to remove plaque. With the practice of good oral hygiene the amount of calculus deposits in the mouth will be minimal. When oral hygiene is poor, the variation in the amount and rate of calculus formation can be considerable (Ramfjord and Ash 1979). While the occurrence of calculus may be considered beneficial, in that it may protect the enamel surface from cavitation (Hillson 1979), calculus can irritate the gingival tissues, leading to gingivitis or periodontitis (Shafer, Hines, and Levy 1983). The accumulation of calculus indicates poor oral hygiene practices which can lead to additional oral health problems. Scoring The teeth of all individuals were examined for calculus deposits. Each tooth was scored for the presence or absence of calculus. When calculus was present, a score from 1 to 3 was recorded for the amount of calculus present. A score of 1 was given for a small band of calculus, a score of 2 for more extensive deposits covering less than half of the crown, and a score of 3 for calculus which covered half or more of the crown.
Scoring The alveoli were examined for evidence of periapical abscesses. The alveolar bone adjacent to each tooth apex was scored for the presence or absence of an abscess. When an abscess was present, the severity of the abscess was scored on a scale from 1 to 3 based on the extent of bone destruction. An abscess was scored 1 when the area of bone loss was limited to a few millimeters in diameter. A score of 2 was given when the area of bone destruction covered roughly 3 to 5 millimeters, a moderate amount of loss. A score of 3 was given to marked bone destruction in which an area greater than 5 millimeters was lost. Dental Calculus Description Dental calculus or tartar "is attached dental plaque which has undergone mineralization" (Shafer, Hines, and Levy 1983:768). The formation of calculus is preceded by the formation of plaque, a mucinous film containing microorganisms (Ramfjord and Ash 1979). The actual process by which dental plaque is mineralized and its causal factors are not understood, but theories have suggested that it may be related to changes in the pH of the saliva or plaque (Ramfjord and Ash 1979). Dietary studies have suggested that ascorbic acid inhibits calculus
Periodontal Disease Description Periodontal disease is an infectious disease of the periodontium that is divided into four categories of pathological involvement (Shafer, Hines, and Levy 1983). Only the inflammatory category which includes gingivitis and periodontitis is of concern here. Gingivitis is an inflammation of the gingiva. When the alveolar bone is infected, the condition is referred to as periodontitis. Periodontitis, as with other infectious diseases, is a result of interactions among the host periodontal tissues, bacteria, and nutrient materials (Grigsby and Sabiston 1976). Clarke and Carey (1985:691) have argued that "it is more likely that the host response is the factor that determines when the disease is active or in remission, with periods of social stress or illness determining the balance in the hostparasite relationship of the gingiva." The pathogenic factors associated with periodontitis include local factors such as calculus, microorganisms, food impaction, and poor oral hygiene (Shafer, Hines, and Levy 1983). Systemic factors can also be involved in the etiology of periodontitis, including nutritional deficiencies such as ascorbic acid deficiency and protein deficiency (Ortner and Putschar 1981; Shafer, Hines, and Levy 1983). Periodontitis is identifiable in skeletal remains as the loss of
MJfI'ERIALS AND METHODS
alveolar bone. When alveolar bone is resorbed, the distance from the bone crest to the cemento-enamel junction increases. However, incidences of continuous tooth eruption, antemortem tooth loss, and dental caries can also result in alveolar bone resorption. "If there is alveolar resorption but little or no evidence of caries or tooth loss, a diagnosis of periodontal disease is appropriate" (Ortner and Putschar 1981:443). The presence of periodontal disease in a skeletal series will be indicative of oral health problems, including poor oral hygiene. Whether the loss of bone is due to local factors or systemic factors can not be determined from the skeletal remains. When periodontal disease is observed in conjunction with calculus, it is reasonable to assume that the calculus provided the irritation that led to the inflammation (Ortner and Putschar 1981). If the periodontal disease is not found in conjunction with calculus, then the etiology cannot be determined and, quite likely, the condition is due to poor oral health practices. Scoring When a tooth was found intact in the alveolar bone, the alveolus and tooth were examined for bone resorption. A tooth was scored as positive for periodontal disease when the alveolar crest had resorbed a few millimeters below the cervical line. The amount of resorption was scored on a scale of 1 to 3 with a score of 1 given when not all of the cervical third of the root was exposed. A score of 2 was given when the cervical third of the root was exposed as well as a small portion of the middle third of the root. The condition in which all of the cervical and middle thirds were exposed was given a score of 3. Hypercementosis Description Hypercementosis is excessive formation of secondary cementum on root surfaces (Shafer, Hines, and Levy 1983). The build-up of cementum may be limited to the apex or can extend over most of the root surface. Hypercementosis has been associated with: (1) supraeruption of a tooth due to the loss of an antagonist, (2) inflammation, usually from a periapical infection, (3) tooth repair initiated by occlusal or root trauma, and (4) osteitis deformans, also known as Paget's disease (Goaz and White 1982; Shafer, Hines, and Levy 1983). In the case of supraeruption of a tooth, the formation of cementum occurs usually around the apex, but can extend further up the root. In inflammation cases, the cementum generally is formed some distance from the inflammation, rather than adjacent to the inflammation. In cases of tooth repair, the formation of cementum is generally not excessive. In Paget's disease a generalized
hypercementosis is observed with excessive amounts of cementum formed. Hypercementosis is clinically a fairly innocuous condition which requires treatment for the primary cause only (Shafer, Hines, and Levy 1983). The presence of hypercementosis does indicate an oral health problem such as an infection, trauma, or supraeruption of a tooth. Hypercementosis has not been examined extensively in skeletal popUlations, perhaps because it can require radiographs of the dentition if the teeth are not loose (Patterson 1984). The study of hypercementosis is feasible, however, in series where the teeth are no longer intact. The frequency of hypercementosis can be used as a reflection of general oral health problems. Scoring All teeth on which the roots could be observed were examined for hypercementosis. The presence or absence of hypercementosis was recorded for these teeth. No attempt was made to categorize the location of the cementum formation or the amount of cementum formed. Dental Caries Description Dental caries is an infectious disease initiated by microbial activity which results in the progressive destruction of the enamel (Pindborg 1970). Caries are formed by the action of bacteria that inhabit dental plaque and flourish on decaying food particles. Streptococcus mutans is the primary type of bacteria involved in caries formation (Bierman 1979; Krasse 1985; Shafer et al. 1983). While the presence of bacteria is an essential component of caries formation, the type and texture of foods in the diet also influence caries formation. Carbohydrate-rich foods are highly associated with caries formation, particularly foods with sugars, such as sucrose and fructose (Bierman 1979; Newbrun 1982). The texture of food is an important cariogenic factor in that sticky foods tend to remain on the tooth surface, increasing the probability of caries formation (Bierman 1979; Naylor 1984). Gruels and porridges, which are sticky, tend to be more cariogenic than raw foods. The frequency of food consumption and food preparation techniques can also affect the cariogenicity of foods (Naylor 1984; Newbrun 1982). Certain surfaces of dental enamel are more susceptible to caries formation than are others. The occlusal surface, for example, contains fissures and pits where food particles can become trapped, providing a breeding ground for bacteria. Moore and Corbett (l971, 1973) examined the frequency and location of dental caries in ancient British populations and found that the most common location before extensive attrition
AGRICUIIURAL INTENSIFICJfI'ION AND PREHISTORIC HEAIIH IN OAXACA
had occurred was on the occlusal surface. In older individuals with more extensive dental attrition, the most frequent location of caries was at the cemento-enamel junction (Moore and Corbett 1971, 1973). Scoring Every tooth was examined for evidence of dental caries. When present, the caries was recorded according to its severity and location. Small pits were scored l. Larger pits, which involved less than a quarter of the crown, were scored 2. Caries, which involved from a quarter to half of the tooth crown, were scored 3. When more than half of the crown was involved the severity score was 4. The location of the caries on the tooth was recorded when possible. The categories of locations recorded were: occlusal, buccal, mesial, distal, and lingual. Dental Attrition Description Dental attrition is the wearing away of enamel on the occlusal surface thereby exposing the dentin and pulp cavity. The amount of dental attrition observed on an individual is in part related to the age of the individual: the greater the dentin exposure, the older the person (Lovejoy 1985; Miles 1958, 1962). The rate at which the tooth is worn away is related to both the diet and the food preparation technology (Smith 1983). In order to compare the rate of attrition between skeletal samples, age must be controlled by comparing groups of similar ages. An alternative method is to examine the rate of wear as determined by differences in the amount of wear on adjacent teeth (Scott 1979a; Smith 1972). By comparing the rate of wear the measure of attrition is kept independent of age. The rate of dental attrition can be closely tied to diet and food preparation techniques. Scoring Several different systems have been proposed for measuring the degree of dental attrition (Lovejoy 1985; Molnar 1971; Scott 1979b; Smith 1983). The system proposed by Scott (1979b) is applicable to the molars only and thus is of limited use in examining wear in the whole dentition. Smith's (1983) system represents an expansion of Molnar's (1971) system, with 8 levels of wear as opposed to Molnar's 6 levels. In this project, Smith's (1983) 8-grade system was used to score the amount of attrition, and Molnar's (1971) system was employed for measuring the direction of wear. The teeth of the Oaxaca remains were scored for the degree of attrition and for the direction of attrition in the mesial-distal and buccal-lingual planes. The difference in the degree of attrition between the Ml and M2 is used as a measure of the rate of wear.
SPECIFIC STRESS MARKERS Porotic Hyperostosis Description Porotic hyperostosis refers to bony lesions found on the cranium (Mensforth et al. 1978). The lesions generally occur on the supraorbital plate and pericranial surfaces of the parietals, occipital, and frontal (Mensforth et al. 1978). The lesions of porotic hyperostosis exhibit a coral or sievelike porosity with marginal hypervascularity. Over the past century a variety of different terms have been used to describe these lesions, including cribra cranii, symmetrical osteoporosis, and spongy hyperostosis (Steinbock 1976). Presently the term porotic hyperostosis is used most frequently. Armelagos (1967) has suggested that there are three types of porotic hyperostosis: cribra orbitalia, osteoporotic pitting, and spongy hyperostosis. Cribra orbitalia refers to pitting in the roof of the orbits. Osteoporotic pitting is the presence of pits on the external surface of the cranium. Spongy hyperostosis is the formation of osteophytes on the external surface of the cranium and the expansion of the diploe (Carlson, Armelagos, and VanGerven 1974). Armelagos's (1967) description and terminology for porotic hyperostosis is used here. The lesions of porotic hyperostosis indicate that a thickening or expansion of the diploe and thinning of the subperiosteal table has occurred (Angel 1966). Pressure from the hematopoietic marrow, probably from an increased production of red blood cells, would produce the thickening of the diploe which is characteristic of porotic hyperostosis (EI-Najjar et al. 1976). The diploic expansion suggests a hematological etiology for the lesions. Several different etiologies have been suggested for the manifestations of porotic hyperostosis, including congenital hemolytic anemias, iron deficiency anemia, cyanotic congenital heart disease, and polycythemia vera in childhood (Steinbock 1976). The last two disorders are quite rare and thus unlikely explanations for the fairly frequent occurrence of porotic hyperostosis in prehistoric populations. The lesions are generally considered indicative of anemia, either an iron deficiency or a congenital hemolytic anemia (Martin, Goodman, and Armelagos 1985; Mensforth et al. 1978; Stuart-Macadam 1985). Congenital hemolytic anemias such as thalassemia and sicklecell anemia are associated primarily with Old World populations. Presently no evidence exists for Pre-Columbian congenital anemias in the New World (El-Najjar et al. 1976). The presence of porotic hyperostosis in prehistoric populations in the New World is thus considered an indication of iron deficiency anemia (EI-Najjar et al. 1975; Lallo, Armelagos, and Mensforth 1977; Lanzkowsky 1977; Mensforth et al. 1978).
MMERIALS AND METHODS
The presence of porotic hyperostosis usually indicates an iron deficiency anemia, but the specific etiology of the anemia may not always be determinable. Iron deficiency anemia may result from hookworm infections, or from the synergistic interaction of malnutrition and infections (Scrimshaw, Taylor, and Gordon 1968), as well as from low iron intake. It may also result from interference in iron absorption. Iron absorption is hampered by the presence of elements that form insoluble complexes with the iron. Phosphates, and probably phytate, are examples of elements that interfere with iron absorption (Pike and Brown 1984). In living popUlations, iron deficiency anemia is more prevalent among women than men due to iron loss from menses, pregnancy, and lactation (Pike and Brown 1984). Sex differences in the frequency of porotic hyperostosis have been observed in skeletal samples, although the differences are not always significant (Stuart-Macadam 1985). Iron deficiency is also common during infancy and adolescence when the growth rate is accelerated (Pike and Brown 1984). Studies of porotic hyperostosis in skeletal samples have consistently found significantly higher frequencies of the pathology in the subadult segment than in the adult segment (Stuart-Macadam 1985). Stuart-Macadam has argued that the cranial lesions observed in adults are actually remnants of a childhood anemia which did not necessarily persist into adulthood. Clinical studies have shown that cranial lesions associated with anemia are usually formed in young children, but can be retained as adults (StuartMacadam 1985). The outer table in adults is not as responsive to pressure as is the crania of children; thus in adults, anemia is less likely to produce cranial changes (Stuart-Macadam 1985). Additionally, increased production of red blood cells as a response to anemia can be achieved through several pathways apart from marrow expansion. In pathology studies of prehistoric populations, the frequency of porotic hyperostosis among adults is often taken to be indicative of childhood anemias rather than an adult episode. The interpretation of porotic hyperostosis in skeletal series from the Valley of Oaxaca is approached with caution, as the valley is located within the geographical distribution of the hookworm Necator american us (Faust, Beaver, and lung 1975). Given the lack of dramatic climatological shifts in the past 2,000 years in the valley, it seems likely that the hookworm was a menace prehistorically. Hookworm infections arise from contact with contaminated soils (Faust, Beaver, and lung 1975), which may be expected to increase with increasing population density. If population density increased with agricultural intensification, then an increase in the frequency of porotic hyperostosis may be due in part to hookworm infections. The frequency of porotic hyperostosis in the valley may be
related not only to hookworm infections, but to iron absorption problems also. The diet of the skeletal populations examined here is one based on maize, a food substance that contains phosphate and phytic acid which interfere with iron absorption. If agricultural intensification results in an increased dietary reliance on maize, then an increase in porotic hyperostosis would be expected. Scoring The skeletal remains were examined for porotic hyperostosis. The orbital lesions of cribra orbitalia were scored separately from the vault lesions of osteoporotic pitting. Cribra orbitalia was scored as present or absent, and when lesions were present they were further scored according to their extent. Slight cases were characterized by fine, small foramina. Moderate cases were identified by the presence of larger foramina linked together, and severe cases were those with more extensive foramina including expansion outside of the normal contour. In cases where only one orbit was present the score for cribra orbitalia was based on that orbit. The same criteria were used to score the occurrence of osteoporotic pitting on the vault. Periosteal Reactions Description Periosteal reactions are infectious lesions that occur on the periosteal surface of bone (Ortner and Putschar 1981). The lesions are formed as a result of an inflammation of the periosteum. When the periosteum is infected, the membrane is lifted away from the bone surface. Osteoblastic activity is then initiated on the inner layer of the periosteum and new woven bone is formed. The woven bone may eventually be incorporated into the cortex. Periosteal reactions are recognized on dry bone by the presence of new bone formation on the cortex. Periosteal reactions are associated with specific disease syndromes such as syphilis and tuberculosis (Ortner and Putschar 1981). The differential diagnosis of infectious diseases is difficult in dry bone specimens, however, because various diseases result in the formation of periosteal reactions. Additionally, infections and malnutrition tend to be associated with one and other, and interact in a synergistic manner (Scrimshaw, Taylor, and Gordon 1968). The inflammation indicated by periosteal lesions may have been induced, or exacerbated by, malnutrition and poor hygiene (Steinbock 1976). While the specific cause of a lesion can rarely be determined, periosteal reactions are specific markers in that they indicate the presence of an infectious agent.
AGRICUIIURAL INTENSIFICATION AND PREHISTORIC HEAIIH IN OAXACA
The Oaxaca skeletal remains were examined for periosteal reactions. Periosteal reactions were recorded for all of the major bones of the axial skeleton, the cranium, and mandible. Only those individuals for which a significant proportion of the bone was present (estimated to be over one-third of the bone) were scored. When lesions were observed, the location of the reaction was recorded along with a severity measure based on the relative amount of bone formed. A score of 1 was given when a slight amount of bone had been formed. A score of 2 was given when a moderate level of new bone was evident. Scores of 3 and 4 were recorded when more extensive bone formation was indicated. Degenerative Joint Disease Description
Degenerative joint disease is detectable in dry bone by the presence of osteophytes, and by lytic destruction of the articular surfaces, both in the peripheral synovial joints and the joints of the spine (Jurmain 1978; Steinbock 1976). The development of bony changes is preceded by a slow destruction of the articular cartilage (Ortner and Putschar 1981). The etiology of degenerative joint disease appears to be related to systemic factors such as age and sex, and stress factors such as trauma, diet, and biomechanical stress (Jurmain 1977; Kellgren 1961; Pickering 1984). Pickering (1984), in a study of skeletal remains from the Illinois River valley, found that the size of the joint was not correlated with the presence of degenerative lesions. According to Jurmain, (1977:364) "given enough time, the cumulative effects of biological aging and other systemic agents will eventually produce some degenerative disease in all joints, but the crucial factor determining expression of degenerative disease in severe form at an early age is the presence of chronic, severe functional stress." The frequency and pattern of degenerative lesions in young adults will reflect functional stress and the activity patterns of a society (Pickering 1984). There are three types of bony lesions associated with degenerative joint disease: osteophytes or marginal lipping, lytic destruction of the articular surfaces, and eburnation (Steinbock 1976). The osteophytes have been associated with moderately advanced cases and are evident generally before eburnation occurs (Steinbock 1976). Eburnation is associated with advanced cases in which the cartilage has been eroded away. Scoring
The major body and spinal joints were all examined for evidence of degenerative lesions. A detailed scoring system for the knee, hip, elbow, and shoulder joints has been developed by Jurmain (1975) and was used to score degenerative lesions
in the Oaxaca remains. For each joint a series of locations within the joint were examined for degenerative changes. For the knee joint, eight locations were examined on the proximal tibia, six on the distal femur, and three on the patella. In the hip, six locations were examined on the femur and four on the innominate. In the elbow, seven locations were examined on the humerus, six on the ulna, and three on the radius. In the shoulder, four locations were scored on the scapula and three on the humerus. In each joint the left and right sides were scored separately. The location points were examined for osteophyte development on the marginal surfaces, and for lytic lesions and eburnation on the articular surfaces. The scoring system is described in greater detail by Jurmain (1975). The vertebral column was also examined for degenerative joint disease. The vertebrae were scored for osteophytosis on the margins of the body. A score of 1 was given when a few osteophytes were present. A score of 2 was given when a moderate level of osteophytes had developed. When bony spurs or bridges were present the vertebra was scored as a 3. When the body had joined with the adjacent body or the joint was ankylosed, a score of 4 was given. Destruction of the superior and inferior articular surfaces was also recorded. When slight exostosis was present a score of I was given. Scores of 2 were given when a moderate level of exostosis was evident and was accompanied by slight destruction of the articular surface. More severe developments of exostosis and lytic destruction were scored 3. When the joint was fused, the vertebra was scored 4. Additional Health Markers
Measures of long-bone length and diameters were also taken to assess childhood growth patterns and adult sexual dimorphism. However, the skeletal remains frequently were too incomplete, particularly in regard to the metaphyseal and epiphyseal regions of the long bones. As a result, the data are insufficient to determine growth patterns, or to permit statistical analysis. THE OAXACA SKELETAL SAMPLES A regional approach to the analysis of skeletal remains is one in which a series of skeletal collections from different locations within a region are pooled for analysis. Some justification for the pooling of skeletal series from different sites is required other than pooling merely to increase the sample size. The use of a regional approach in the analysis of the prehistoric population of the Valley of Oaxaca can be justified on several levels. First, the individuals residing in the three arms of the valley appear to have been in contact with each other. It seems likely that individuals would have had to seek marriage partners from neighboring villages, as many excavated sites were
MATERIALS AND METHODS
quite small, with probably no more than a hundred inhabitants. As a result of this interaction, the population of the valley should have been fairly homogeneous in genetic makeup. A study of the skeletal remains from the site of Monte Alban found no significant differences in nonmetric traits between high- and low-status groups, which suggests that the population was biologically homogeneous (Wilkinson and Norelli 1981). The assumption of biological similarity within the pooled skeletal series underlies this analysis. The use of a regional approach is also justified on the basis of environmental homogeneity. The valley is a tightly circumscribed area surrounded by mountainous terrain. It does contain several physiographic zones, but all of these zones are accessible from any location in the valley. Climatic conditions vary only slightly. It is nearly ideal for a regional approach as it is a small, circumscribed area with a biologically homogeneous popUlation. The representativeness of the Oaxaca skeletal samples is difficult to ascertain. Only a few reports exist on the excavation of the skeletal remains. Burials from the Early and Middle Formative periods have been found primarily in association with residential structures in small cemeteries at San Jose Mogote and Tierras Largas and in a larger San Jose phase cemetery at Tomaltepec (Drennan 1976; Flannery and Marcus 1983b; Whalen 1981; Winter 1972). The San Jose phase cemetery at Tomaltepec did not include the remains of children, which suggests an age bias in the Tomaltepec sample (Whalen 1981). Child burials from the San Jose phase were recovered at other sites, however, so that the regional sample does not have the same bias. In general, the Early and Middle Formative periods are represented by a sizeable sample and are more likely to be representative than are the samples from later periods, since the valley's population was smaller in Formative times. The Classic and Postclassic samples are more problematic. They are definitely not representative of the whole population. The Classic period was characterized by several status levels, with the higher levels represented by the individuals interred in the elaborate tombs of Monte Alban. I was not able to examine these high-status individuals. The Monte Alban remains I examined are from households which have been identified as low status (Winter 1974). The rest of the Classic period remains are from outlying villages, and were probably also of lower status; thus, the remains examined from the Classic period are biased toward the lower status segments of the society. However, since the largest segment of the population was probably the lower status level, the sample is not substantially biased in representing the population. The remains from the Postclassic periods are primarily from the sites of Lambityeco, Zaachila, and Yagul. The Lambityeco remains are from what has been identified as an elite residential
area (Lind and Urcid 1983). The Zaachila and Yagul remains are all from tombs. The tombs probably included individuals of very high status who may have been accompanied by individuals who were slaves or retainers. The series may not be representative of the site's whole population, but may be representative of several segments of that population. In summary, a regional approach is justified on the grounds of genetic and environmental similarity among the samples. Further, the approach is appropriate in that the population of the valley was essentially a single popUlation. The sites in the valley were not isolated units; there was interaction among the inhabitants of the various sites. Additionally, a regional sample will give a better representation of the health pattern of the whole population than would a sample from a single site. ANALYTICAL TESTS The distribution of subadult and adult individuals according to temporal phase associations is shown in Table 5.1. It is evident that the numbers of individuals in each phase are too small for us to compare frequencies of skeletal markers across 14 phase groups. In order to facilitate comparisons, the phases were pooled into larger temporal groups. The skeletal samples from the Tierras Largas phase through the Rosario phase were pooled into one group, herein referred to as the Formative group. These individuals are pooled because they are all from phases in which agriculture was probably nonintensive (Fein-
TABLE 5.1 Distribution of Individuals by Temporal Phase
Males Tierras Largas San Jose Guadalupe Rosario Rosario-Ia MAla MAIe MA Ie-II MAIl MA II-IlIa MA IlIa MA IIIb MA IIIb-IV MA IV MAV Total
Adults, Sex Unknown
2 29 13 7 3 4 5 I 10 6 5 3 I 18 45 152
8 28 10 9 I I 9 2 9 2 3 2 I 14 43 142
0 15 10 II I I 13 I 8 I 3 3 0 26 13 106
I 22 4 2 I 3 5 0 5 I I 0 1 8 11 65
52 36 63
55 29 57
36 31 39
29 16 19
Total 11 94 37 29 6 9 32 4 32 10 12 8 3 66 112 465
172 112 178
Pooled Samples' Formative Classic Postclassic
'Individuals from Rosario·Ia are included in the Fonnative pooled sample. Individuals from MA I1Ib-IV were not included in the pooled samples.
AGRICUIIURAL INTENSIFICATION AND PREHISTORIC HEAIIH IN OAXACA
man, Blanton, and Kowalewski 1984). Further, the population in these phases was small and the density was low (Flannery, Marcus, and Kowalewski 1981). The individuals from Monte Alban la through IIIb were pooled into a group referred to as the Classic group (Monte Alban I and II are not considered Classic in a chronological sense, so the term is one of convenience only). The justification for pooling these samples is that they all represent periods of intensive agriculture. The intensification of agriculture is believed to have begun in la (Feinman, Blanton, and Kowalewski 1984) and to have continued through IIIb. The population in these periods was much larger than it was during the time of the Formative group, and had a higher density also. The remains from Monte Alban IV and V were pooled into a single group, referred to as the Postclassic group. The practice of agriculture by this group is also believed to have been intensive. Periods IV and V were not pooled with the Classic group because they were periods characterized by local political units, rather than a major regional system centered at Monte Alban. It is possible that this change in the political system may have affected health levels, and thus the Postclassic group was kept separate from the Classic group. The age and sex distribution of the three temporal groups is shown in the lower portion of Table 5. 1. The sample sizes in the tests of stress marker frequencies are lower than the values presented in the table, as most of the remains were fragmentary. The numbers in the table represent a maximum sample size. The sex and age of the individuals were estimated using standard, gross morphological markers (Bass 1979; Ubelaker 1978). The sex of adult individuals was based on the appearance of dimorphic markers on the innominates and the cranium (Bass 1979). In cases where the sex markers were not observable, the sex of the individuals was estimated from the general robusticity of the remains. It was not possible to determine the sex of all individuals; individuals for which the sex could not be estimated are included in Table 5.1 under the heading of Adults, Sex Unknown. The adults of unknown sex were included in the analyses when the male and female samples were pooled. The age of subadult individuals was estimated by the stage of dental development (Ubelaker 1978). When the dentition was not present, the length of the long bones were used to estimate the age of the individual (Bass 1979). The age of adult individuals was usually estimated from the condition of the pubic symphysis (Bass 1979; Todd 1920). Due to the fragmentary state of many individuals, age could not always be estimated from the pubis. In these cases, age was estimated from the level of dental attrition (Miles 1962). Individuals aged by the degree of dental attrition were assigned to broad, IO-year age categories.
The null forms of the four hypotheses were tested by comparing frequencies of markers among the three temporal groups. Comparisons were first made between the sexes to determine if the frequency of a marker differed by sex. When no difference was found, the male and female groups were pooled to form an adult group. In a few cases where the significance of the sex difference could not be determined, the assumption is made that sex differences were not substantial, and the male and female groups were pooled. Adults of all ages were included in the comparisons of stress markers, except for the analysis of degenerative joint disease. Of the adult individuals whose ages were estimated, 30% were between the ages of 17 and 24 years, 39% between 25 and 39 years, 20% between 40 and 49 years, and 11% were considered to have been 50 or older. In the analysis of degenerative disease only adults aged 17 to 50 years old were included in the samples. The numbers of subadults in the samples were too small to examine temporal differences in markers by age groups. The subadult individuals aged from birth to 17 years were pooled for analysis. Since the data are all measured on an ordinal scale, the test for frequency differences among the temporal groups were made using nonparametric statistics, primarily the chi-square test (Siegel 1956). The chi-square test compares the frequency of individuals affected in two or more samples and determines whether the frequencies of the samples differ (Siegel 1956). In cases where the expected cell frequency is less than 10, Yates correction for continuity is used (Snedecor and Cochran 1980). The chi-square test does not require that the samples be normally distributed, but does require that the observations be independent of one another. If a sample is made up of individuals who lived at the same time, the samples will not be independent for some health measures, since when one person in a population has a disease, the other family members and neighbors may contract the condition from the infected individual. This sort of "contagion" probably does not create a serious problem for the analysis of the Oaxaca data for two reasons. The first reason is that the samples from the archaeological sites have few individuals from the same time period, with the exception of cemeteries at San Jose Mogote and Tomaltepec, and even then it cannot be determined if the individuals actuaIIy lived coevally. The samples used in the analyses are regional samples spanning several centuries, which lessens the probability that the individuals in the sample would have lived coevally. Second, many of the markers examined are not caused by contagious diseases. Although it is not possible to document that the individuals in the samples are independent observations, it is reasonable to assume that the problems which may emanate from the lack of complete independence do not invalidate the use of chi-square in analyzing the samples.
MIfI'ERIALS AND METHODS
When no statistical difference is found among or between samples there are two possible explanations. One is that the phenomenon under investigation is not present. The other explanation is that the phenomenon exists, but that the sample size was too small or otherwise inappropriate. The latter explanation can be eliminated in cases where no statistical difference is found by performing a power analysis of the statistical test: "The power of a statistical test of a null hypothesis is the probability that it will lead to the rejection of the null hypothesis, i. e., the probability that it will result in the conclusion that the phenomenon exists" (Cohen 1969:4). The power value can range from 0 to 1.0, with the higher values indicating a higher probability of rejecting the null hypothesis when the phenomenon is present. The phenomenon in this study is a temporal difference in the frequency of stress markers. Low power values indicate that even if the phenomenon exists, the probability of concluding that the phenomenon is present, or rejecting the null hypothesis, is low. A power value of 0.80 is considered desirable, as it indicates a 0.05 probability of falsely rejecting a null hypothesis and a 0.20 probability of
accepting a false null hypothesis (Cohen 1969). Conventionally, falsely rejecting a null hypothesis is considered to be a more serious error than accepting a false null hypothesis. The power of the tests will indicate the probability that a significant difference among the samples would have been found given the size of the samples, the level of significance chosen for the test, and the size of the effect that can reasonably be expected based on other studies. The power of the chisquare tests of the hypotheses is determined in this study using the power tables provided by Cohen (1969). The size effect is "some specific nonzero value in the population. The larger this value, the greater the degree to which the phenomenon under study is manifested" (Cohen 1969: 10). A medium size effect, in which the magnitude of the expected difference is of a medium size, is used to determine the power of the test. A medium effect is chosen rather than a small effect, as it would be less likely to result from random sampling error than would a small effect. The significance level used in all the statistical tests is alpha = 0.05.
Results HYPOTHESIS I THE INCREASING SIZE AND DENSITY OF THE VALLEY'S PopuLATION OVER TIME RESULTED IN AN INCREASE IN THE FREQUENCY OF INDIVIDUALS AFFLICTED BY INFECTIOUS AGENTS.
The null hypothesis of no change in the frequency of individuals with infectious conditions was tested by examining the frequencies of periosteal reactions. Periosteal reactions were recorded for the major bones of the axial skeleton, the cranium, and mandible. In the case of paired bones such as the femur an individual was scored as afflicted for the bone when a rea;tion had been observed on either the left or right side. The frequencies of males with periosteal reactions on the lower limb, upper limb, and nonlimb bones are shown in Table 6.1. * Four of the nine bones show a temporal pattern of increasing frequency, and the remaining five bones show fluctuating temporal patterns. The number of individuals with an afflicted bone is often small, in many cases too small for testing temporal patterns. In all cases where the temporal pattern can be tested (femur, fibula, and clavicle), no significant differences are found. The frequencies of periosteal reactions on the lower limb, upper limb, and nonlimb bones of the females are shown in Table 6.2. Two of the nine bones show temporal patterns of increasing frequency, one a pattern of declining frequency, and the remaining six show fluctuating patterns. The temporal differences can be tested on only two bones, the tibia and fibula. In neither case do the frequencies of the temporal groups differ significantly. The male and female periosteal reaction frequencies were compared within the temporal groups to determine if the frequency of individuals afflicted differs between the sexes. Only the frequencies of the femur, tibia, and fibula can be tested as the sample sizes of the other bones are too small. No signifi-
cant differences between the sexes are observed on the femur, tibia and fibula. The frequencies of periosteal reactions on all adults are shown in Table 6.3. Even though the significance of frequency differences between males and females cannot be determined for all the bones, the frequencies in the males and females were pooled. Only one of the seven elements tested has a significant temporal difference: the reaction frequencies on the femur show a significant temporal increase. The frequencies of periosteal reactions on nine major bones among subadults less than six years old are presented in Table 6.4. The frequencies of periosteal reactions in subadults aged 6 to 17 years old are presented in Table 6.5. The number of individuals afflicted in the 0 to 5 year group and in the 6 to 17 year group are too small to test for temporal patterns; thus, all of the subadults were pooled. The frequencies of all sub adults aged from birth to 17 years are shown in Table 6.6. Even when the subadults were pooled, valid chi-square tests can be per. formed on only two bones, the femur and tibia. The reaction frequencies of the temporal groups do not differ significantly on either the femur or tibia. To summarize, a few significant changes in the frequency of periosteal reactions can be observed on the bones examined. While a trend of increasing frequency from the Formative to Postclassic group is present, in some cases its significance cannot be determined, and in others the trend is not statistically significant. The overall temporal pattern of periosteal reaction frequencies suggests that the null hypothesis should not be rejected. HYPOTHESIS II A GENERAL DECLINE IN HEALTH WAS ASSOCIATED WITH THE INTENSIFICATION OF AGRICULTURE.
The hypothesis was tested by examining a series of general health markers: enamel hypoplasia, dental caries, dental abcesses, periodontal disease, dental calculus, and hypercementosis.
*Tables 6.1-6.38 will be found at the end of the chapter.
AGRICUUURAL INTENSIFICIITION AND PREHISTORIC HEAUH IN OAXACA
Enamel Hypoplasia The frequencies of adult individuals with at least one tooth displaying an enamel hypoplasia are shown in Table 6.7. The males show a temporal decline in the frequency of enamel hypoplasia, but the trend is not significant. The female pattern differs from the male, as the frequency increases from the Formative to the Classic but declines in the Postclassic. The temporal trend among females is not, however, significant. When the frequencies of affected males and females are compared within the temporal groups, no significant sex difference is found in the Formative, Classic or Postclassic groups (p > O.OS). Since the male and female frequencies do not differ significantly, the sexes were pooled to test for temporal differences among all adults. The frequencies of all adults with enamel hypoplasia do not differ significantly among the temporal groups (Table 6.7). The frequencies of subadult individuals with enamel hypoplasia on the permanent dentition are shown in the lower portion of Table 6.7. The sample sizes are too small to test for temporal differences within the three age groups (O-S, 6-11, and 12-16 years). When the age groups are pooled the numbers are still too small for testing. Previous studies (Goodman and Armelagos 1985a, 1985b) have suggested that the susceptibility of different tooth types to enamel hypoplasia formation is not equal. This finding implies that differences, or the lack of differences, among samples in the frequency of hypoplasia may be due to the types of teeth present in the samples. Thus, further temporal comparisons based on a single tooth type were made to control for differential susceptibility. The teeth most susceptible to hypoplasia formation, the mandibular canines and maxillary central incisors (Goodman and Armelagos 1985b), were selected for further study. The frequencies of individuals with hypoplasia on the left and right mandibular canines are shown in Table 6.8. The frequency of individuals with afflicted left canines does not differ between the sexes (p > O.OS) in the Formative, Classic or Postclassic groups, nor do the frequencies on the right canine. The frequencies of affected males, females, and pooled adults do not differ significantly among the temporal samples . on either the left or right canine. The frequencies of individuals with hypoplasia on the left and right maxillary central incisors are shown in Table 6.9. The numbers of afflicted teeth are too small to test for frequency differences between the sexes in the Classic and Postclassic groups. No sex differences are found on either the left or right incisors in the Formative group (p > O.OS). The frequencies of males with an affected left or right incisor do not differ significantly among the temporal groups. The frequencies of the females cannot be tested for differences among the temporal
groups due to small sample sizes. The pooled adult frequencies do not differ significantly on either the left or right incisors among the temporal groups. The frequencies of subadults with permanent mandibular canines and maxillary central incisors were low. When all the subadults were pooled, the numbers were too small to allow us to discern a temporal pattern or test for temporal differences. The results thus far indicate no significant temporal differences in the frequency of individuals with enamel hypoplasia, whether all the teeth are considered, or whether only the mandibular canines and maxillary central incisors are considered. While the frequency of individuals with enamel hypoplasia does not differ, the timing of the stress that produced the hypoplasia may vary among the groups. To examine the timing of the enamel hypoplasia-producing stress the chronological distributions of the hypoplasias are examined. In determining the distribution of enamel hypoplasias, only individuals in which the distance of the hypoplasia from the cemento-enamel junction could be measured were included. Age-at-stress estimates were made based on the hypoplasia distance (using the methodology in Goodman et al. 1980), in half-year age intervals ranging from birth to 7 years of age. The inclusion of an individual into an age interval required the presence of one hypoplasia within the age range of the interval. The chronological distributions of enamel hypoplasia episodes among the males are shown in Table 6.10. The sample sizes were determined by the number of individuals with observable tooth surfaces that formed during the age interval. The differences among the temporal groups are presented visually by the bar graph in Figure 6.1. In the Formative the median age interval is the 3 to 3. S year interval, in the Classic the median is the 3.S to 4 year interval, and in the Postclassic the median is the 3 to 3.S year interval. The differences in the distributions were tested with the median test which determines whether independent groups could have been drawn from the same population, or from populations with equivalent medians (Siegel 19S6). The distributions of the temporal groups do not differ significantly (p > O.OS) among the males. The differences in the frequencies of individuals afflicted at each age interval among the temporal groups were tested with a chi-square test. Among the males, significant differences are found at the 3 to 3.S year and 4 to 4.S year intervals (Table 6.10). At both intervals the Formative has the highest frequency, while the lowest frequency is in the Classic for the 3 to 3.S year interval and in the Postclassic for the 4 to 4.S year interval. The differences at intervals 3 to 3.S and 4 to 4.S years indicate that a significantly higher percentage of the male population in the Formative group experienced a growth disruption during those intervals than in the other temporal groups. The chronological distributions of enamel hypoplasia episodes among the females are shown in Table 6.1l. A graphical
display of the distributions is presented in Figure 6.2. The median age interval of each distribution is the same for all the temporal groups: the 3.5 to 4 year interval. The distributions of enamel hypoplasias do not differ significantly (p > 0.05) among the temporal groups. The results of the test of temporal differences in the percentage of female individuals afflicted during an age interval are included in Table 6.11. A significant difference is found among the females at the 3 to 3.5 year interval. In this interval the highest percentage of afflicted individuals occurs in the Postclassic followed by the Formative and Classic groups. The chronological distributions of the males and females in each temporal group were tested for differences between the sexes. The chronological distribution of hypoplasia episodes does not differ significantly (p > 0.05) between males and females in any of the three temporal groups. The distributions of the males and females were thus pooled, and the pooled distributions are shown in Table 6.12. The median of the Formative distribution is the 3 to 3.5 year interval, and in both the Classic and Postclassic groups the distribution median is the 3.5 to 4 year interval. A bar graph of the hypoplasia distributions in the adult samples is shown in Figure 6.3. The chronological distributions do not differ significantly (p > 0.05) among the temporal groups. The significance of the temporal differences in the frequency of adult individuals affected during an age interval are shown in Table 6.12. Significant differences among the temporal groups are observed at the 3 to 3.5 year interval only. At the 3 to 3.5 year interval the highest frequency is in the Formative group, 67.7%, followed by the Postclassic with 60.2%, and the Classic frequency of 31.4%. A more conservative approach to determining the chronological distribution of hypoplasia in a sample has been used in other studies (Goodman, Armelagos, and Rose 1980, 1984). The conservative approach scores an age interval as afflicted when the individual has at least two different teeth with hypoplasias measured to that interval. This approach was also used on the Oaxaca samples, and the frequencies of individuals with matched hypoplasias (present on two or more teeth) are shown in Table 6.13 for males, in Table 6.14 for females, and in Table 6.15 for all adults. As with the unmatched hypoplasias, the distributions of the males and females within the temporal groups do not differ significantly (p > 0.05). The differences in the distributions of matched hypoplasias among the temporal groups do not differ significantly among the males, females, or all the adults (Tables 6.13-6.15). The distribution of the matched hypoplasias were compared with the distribution of the unmatched hypoplasias within the temporal groups. The results of the median tests used to compare the matched and unmatched distributions are shown in Table 6.16. No significant differences are observed among the
male, female, or pooled adult samples. Since no differences are observed between the matched and unmatched distributions, and the sample sizes in the matched distributions are small, no further analyses of the matched distributions were performed. The chronological distribution of enamel hypoplasias among the subadults was not examined due to the small number of individuals on which enamel hypoplasias can be measured. In summary, no temporal differences in the distribution of hypoplasias can be found. A few significant differences in the number of individuals afflicted during a half-year age interval were identified in the samples. The differences show a fluctuating temporal pattern; none of the intervals with an increasing temporal frequency are found to be statistically significant. Dental Caries The frequency of dental caries was analyzed by first examining the frequency of individuals with dental caries and then the frequency of teeth afflicted. The two approaches were taken since the frequency of caries is reported in the literature both by tooth and by individual. Since the susceptibility of teeth to caries formation differs between the anterior and posterior teeth (Shafer, Hines, and Levy 1983), the anterior and posterior teeth were analyzed separately. The frequencies of individuals with dental caries are shown in Table 6.17. It is evident that the frequency of individuals with carious posterior teeth is higher than the frequency of individuals with carious anterior teeth. The frequency of affected males and females does not differ significantly (p > 0.05) in the Formative, Classic or Postclassic groups. Since no significant difference in caries frequency is observed between the sexes, the males and females were pooled. No significant differences in the frequency of individuals with caries in the posterior teeth are found among the temporal samples of males, females, or all adults. No significant differences are found in the anterior teeth in the males or pooled adult samples; the temporal differences in the anterior teeth cannot be tested in the females. The subadult sample sizes are too small for testing the significance of the temporal differences. The frequencies of teeth afflicted with dental caries are shown in Table 6.18. The frequency of carious posterior teeth in males is significantly higher than the frequency in females in the Formative (p > 0.05), but the frequencies of carious anterior teeth do not differ. The frequencies in males and females in the Classic and Postclassic do not differ significantly in the posterior or anterior teeth. The male and female samples were not pooled, since a significant sex difference is present in the Formative group. The frequency difference among the temporal groups in males with carious teeth is not significant for the anterior teeth, but is significant for the posterior teeth.
AGRICULIURAL INTENSIFICAJ'JON AND PREHISTORIC HEALIH IN OAXACA
100 90 80
II Classic fIJ Postclassic
50 40 30 20 10 0
0.0 - 0.5 - 1.0 - 1.5 - 2.0 - 2.5 - 3.0 - 3.5 - 4.0 - 4.5 - 5.0 - 5.5 - 6.0 - 6.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Developmental Age (years) Figure 6.1. Chronological distributions of enamel hypoplasia episodes among males.
100 90 80 70 60 Percent
II Classic mTiI Postclassic
40 30 20 10 0 0.0 - 0.5 - 1.0 - 1.5 - 2.0 - 2.5 - 3.0 - 3.5 - 4.0 - 4.5 5.0 - 5.5 - 6.0 - 6.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 -5.0 5.5 6.0 6.5 7.0 Developmental Age (years) Figure 6.2. Chronological distributions of enamel hypoplasia episodes among females.
50 40 30 20 10 0 0.0 - 0.5 - 1.0 - 1.5 - 2.0 - 2.5 - 3.0 - 3.5 - 4.0 - 4.5 - 5.0 - 5.5 - 6.0 - 6.5 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Developmental Age (years) Figure 6.3. Chronological distributions of enamel hypoplasia episodes among all adults.
Additional chi-square tests indicate that the frequency of the Formative group is significantly higher than the Postclassic's frequency, while the Classic group does not differ significantly from the others. The differences among the temporal samples of females in carious anterior and posterior teeth are not significant (p > 0.05). The temporal pattern of the subadults cannot be tested for the anterior teeth, but in the posterior teeth there is a significant difference. The frequency of carious teeth increases from the Formative to the Classic, but decreases in the Postclassic. The severity scores of the caries were examined to determine if severity varied independently of the number of teeth afflicted. The severity of a caries was scored on a scale from 1 to 4. The distributions of caries across the four severity levels are shown in Table 6.19. In all three groups, the most frequent score was 2, which is a lesion larger than a pit, but with less than one-quarter of the crown destroyed. The caries severity distributions do not differ significantly among the males. The female temporal groups cannot be tested due to the small number of caries with high severity scores. The locations of the caries were recorded as occlusal, buccal, mesial, distal, or lingual. The distributions of the caries by location are shown in Table 6.20. The categories of mesial and distal, and buccal and lingual were pooled to test for temporal differences. The males show a significant temporal difference in the location of dental caries, with the Formative group showing a higher frequency of occlusal caries. The females also differ significantly in the distribution of caries locations. The
frequency of occlusal caries is higher in both the Formative and Postclassic than in the Classic group. In summary, the frequencies of individuals with dental caries do not differ significantly among the Formative, Classic, and Postclassic samples for either males or females. The frequency of male individuals afflicted is significantly higher than the female frequency in the Formative group, but no sex difference is found in the Classic or Postclassic groups. The frequency of teeth afflicted shows a significant temporal decline in the posterior dentition of males, but does not differ significantly among the females. No significant frequency differences in carious teeth are observed among males and females, except for the posterior dentition in the Formative. The male frequency in the Formative is higher than the female frequency. No significant differences in the severity of the caries are observed. The location of caries does differ significantly among both the males and the females. The frequency of occlusal caries is higher in the Formative and Postclassic than in the Classic, with the frequency of mesial-distal caries higher in the Classic. Periapical Abscesses
The frequencies of teeth with periapical abscesses in the maxilla and mandible are shown in Table 6.21. The maxilla and mandible were examined separately, as abscesses are more likely to be observed on the maxilla than on the mandible due
AGRICUIIURAL INTENSIFICAI'ION AND PREHISTORIC HEAIIH IN OAXACA
to the alveolar bone being thinner on the maxilla (Patterson 1984). The thinner alveolar bone makes it more likely for the bony destruction of the abscess to be evident. The frequencies of abscesses are all low, but are higher in the maxilla than mandible. The frequencies of abscesses in the male samples do not differ significantly among the temporal groups in the maxilla; the number of abscesses is too small to test the temporal differences in the mandible. The frequencies of abscesses in the maxilla and mandible of the females do not differ significantly among the temporal groups. The number of teeth with abscesses in the mandible and maxilla in the Formative groups does not differ significantly between the sexes. In the Postclassic group there is no sex difference in the frequencies of maxillary abscesses. The significance of the sex differences in the Classic group, and in the mandibular teeth of the Postclassic group, cannot be determined. The male and female groups were pooled, however, for further analysis. Among the pooled adult sample the frequency of abscesses in the maxilla and mandible do not differ significantly among the three temporal groups. The severity scores of the abscesses were compared across temporal groups for possible differences. The distributions of the abscesses cannot be tested in either the male or female groups due to small sample sizes. When the male and female samples are pooled, there is no significant difference in the severity scores across temporal groups (Table 6.22). The data on dental abscesses indicate a low frequency of affected teeth. No temporal differences in the frequency of abscesses can be found among the males, females or pooled adult sample. The significance of the temporal differences in severity scores cannot be determined for the males or females; however, when the sexes are pooled there is no association between the distribution of severity scores and temporal groups. Dental Calculus The frequencies of anterior and posterior teeth with dental calculus in the maxilla and mandible are shown in Table 6.23. The teeth are subdivided into anterior and posterior groups in the maxilla and mandible, because the anterior teeth of the mandible and the posterior teeth of the maxilla are 'more prone to the development of calculus deposits due to their proximity to salivary gland ducts (Shafer, Hines, and Levy 1983). In all groups, the male frequencies are higher than the female frequencies, but the differences are significant only in the anterior teeth of the maxilla in the Postclassic group, the anterior teeth of the mandible in the Formative, and the posterior teeth of the mandible for all three groups (p > 0.05). Given these sex
differences in frequencies, the male and female groups cannot be pooled. Four of the eight comparisons of temporal groups show significant differences (Table 6.23). The temporal pattern of an increase in the frequency of calculus is significant in the anterior teeth of the maxilla in both males and females, and in the anterior teeth of the mandible of both males and females. The remaining comparisons show no significant temporal trends. The severity scores of the calculus deposits were compared to determine if the temporal groups differ in the severity (size) of the calculus deposit. The distribution of the severity scores is shown in Table 6.24. The most frequent score among both males and females is a 1, which indicates a small deposit. The severity distributions of the male samples differ significantly, with the Classic group having a higher percentage of teeth with small calculus deposits (score of 1) than the Formative and Postclassic groups. The distributions of the females do not differ significantly. Periodontal Disease The frequencies of teeth with evidence of periodontal disease are shown in Table 6.25. The male frequencies are significantly higher than the female frequencies in each of the temporal groups (p > 0.001). The significant sex difference in the frequency of periodontal disease precludes the pooling of male and female groups. The temporal trends among the male and female samples all show highly significant declines in the frequency of teeth afflicted (Table 6.25). The distributions of severity scores of periodontal disease are shown in Table 6.26. The severity scores are compared across the temporal groups to determine if severity level is associated with temporal group. The distributions of the male samples show a significant association between severity scores and temporal groups. The percentage of teeth assigned a score of 1 is substantially higher in the Postclassic group than in either the Formative or Classic group. The percentages of those assigned a score of 2 are substantially higher in the Formative and Classic groups than in the Postclassic. The distributions of the females also differ significantly among the temporal groups. The distribution differences among the females have the same pattern as in the male sample: higher percentages of score 1 teeth are found in the Postclassic and Formative, while a higher percentage of score 2 teeth is found in the Classic. The periodontal disease data demonstrate that a significant decline in the frequency of the condition occurred over time among both the male and female samples. The severity of the lesions (amount of bone loss) is lower in the Postclassic group than in the Formative and Classic, both among males and females.
The frequencies of teeth with hypercementosis are shown in Table 6.27. The frequencies among the temporal groups of males do not differ significantly. The frequencies of hypercementosis in the female temporal groups are significantly different. The Formative and Postclassic frequencies are lower than the frequency of the Classic group. When the frequency of affected teeth is compared between the sexes, no significant differences are observed in the Formative, Classic, or Postclassic groups (p > O. OS). The frequencies of the male and female groups were pooled to form an adult group. In the pooled adult sample, the Classic group has a significantly higher frequency of teeth with hypercementosis than do the Formative or Postclassic group. SUMMARY OF GENERAL HEALTH MARKERS Overall, the markers used to test the second hypothesis show a lack of temporal differences. No significant temporal differences are found in the following categories: the frequency of enamel hypoplasia among males or females; the chronological distributions of enamel hypoplasia in males and females; the frequency of individuals with dental caries; male frequencies of carious anterior teeth; female frequencies of carious teeth; frequencies of periapical abscesses; male frequency of hypercementosis; and in the frequency of dental calculus on posterior teeth of the maxilla and mandible (both sexes). Significant temporal increases are observed in the frequencies of dental calculus on the anterior teeth of the maxilla and mandible both among males and females. Significant temporal declines are observed in the frequency of male individuals with enamel hypoplasia defects at age interval 4 to 4.S years, the frequency of periodontal disease, and the frequency of carious posterior teeth among males. Significant fluctuating patterns are observed in the female and adult hypercementosis frequencies, male individuals with enamel hypoplasia defects in the 3 to 3.S year interval, females with enamel hypoplasia defects at 3 to 3.S years, and adults with enamel hypoplasia at ages 3 to 3.S. Although the results of the tests of different markers are not in complete agreement, on the whole they indicate that the null hypothesis should not be rejected. HYPOTHESIS III THE INTENSIFICATION OF AGRICULTURE RESULTED IN AN INCREASE IN NUTRITIONAL HEALTH PROBLEMS.
The third hypothesis was tested by examining the frequency of porotic hyperostosis. The frequency of porotic hyperostosis gives an indication of iron metabolism problems only. Unfortunately, other measures of nutritional status, such as growth
patterns, cannot be analyzed in the Oaxaca series. I:I0wever, enamel hypoplasia, which is used in testing HypotheSIS II, can also be used in testing Hypothesis III since it is an indicator of growth disruptions that may be related to nutritional problems. Additionally, the rate of dental wear is a rough indicato~ of changes in diet and food preparation technology. An eXamI?ation of the rate of wear was made to determine if the underlymg . assumption of dietary change is supported. The frequencies of cribra orbitalia and porotic hyperostOSIS were examined to determine if the frequency of iron deficiency anemia changes with agricultural intensification. The fr~ quency of adult individuals with cribra orbitalia is shown m Table 6.28. The highest frequencies among males and females occur in the Postclassic; the lowest frequencies are observed in the Classic groups. The female frequencies are higher than the male though the number of individuals afflicted is too small to test the significance of this difference. The assumption was made that the male and female frequencies do not differ significantly and the frequencies were pooled. The numbers of individuals with cribra orbitalia are too small to test the temporal patterns among the male and female subsamples. A significant temporal difference is not observed among the pooled adult sample. The frequencies of subadult individuals with cribra orbitalia are shown in the lower portion of Table 6.28. The three age groups were pooled to test for temporal differences, as. the sample sizes within the age groups are too small for testI~g. The combined frequencies show a decline from the Formative to the Classic of 3.3 percent which is followed by an increase of 10 percent in the Postclassic, but the trend is not significant. Porotic hyperostosis of the pericranial vault was scored separately from cribra orbitalia. The frequencies of adults with porotic hyperostosis are shown in Table 6.29. As with cribra orbitalia, the number of individuals afflicted was too small to test for sex differences within temporal groups. The number of individuals was also too small to test for temporal differences in the male and female samples. Assuming no difference in the frequency between the sexes, the male and female frequencies were pooled. No significant temporal difference was found among the pooled adults. The frequency of subadults with porotic hyperostosis (osteoporotic pitting) is shown in the lower portion of Table ~.2~. Porotic hyperostosis was not observed among the subadult mdIviduals in the Formative group. The absence of the lesion in the Formative precludes any test for temporal differences. The lesion was observed on individuals in the Classic and Postclassic groups with higher frequencies in the Postclassic in the 0 to Sand 11 to 17 year groups. The number of individuals affected is too small in the Classic group to allow a test of whether this frequency is statistically significant.
AGRICUIIURAL INTENSIFICATION AND PREHISTORIC HEAIIH IN OAXACA
The severity of the lesions of cribra orbitalia and porotic hyperostosis may have varied over time, even though the frequencies of the lesions do not. The Kruskal-Wallis one-way analysis of variance test determines whether k samples were drawn from the same population (Siegel 1956). A KruskalWallis one-way analysis of variance was performed to test whether the severity of the cribra orbitalia and porotic hyperostosis lesions varied over time. No significant differences in the distribution of severity scores were observed among the male, female, or pooled adult samples (p > 0.05), nor do the severity scores of the subadults differ significantly among the temporal groups (p > 0.05). The severity scores of porotic hyperostosis also do not differ among the temporal groups of subadults, males, females, or pooled adults (p > 0.05). To summarize, no significant temporal increase in the frequency of cribra orbitalia can be found among the adults or subadults. No significant temporal trend in porotic hyperostosis can be found among either the adults or subadults. The severity of both types of lesions also does not differ significantly among the temporal groups. The rate of dental wear was determined by subtracting the dental attrition score of the second molar from the score of the adjacent first molar. The mean rates of wear for adult males and females are shown in Table 6.30. The temporal differences in the mean rates of wear were tested using the Kruskal-Wallis one-way analysis of variance test. The only significant difference in the female samples is in the left quadrant of the mandible, in which the rate of wear decreases from the Formative through the Postclassic. Among the males, significant temporal differences are found in all quadrants except the left side of the mandible. In all cases, the mean rate of wear decreases from the Fonnative through the Postclassic. When the male and female groups are pooled, significant temporal differences can be observed in all but the left quadrant of the maxilla. The trend in the adult sample is a reduction in the rate of wear over time. The significant reduction in the rate of wear suggests that a change in dietary coarseness, or changes in food preparation techniques, occurred over time. The rate of wear data may lend indirect support for the assumption underlying the hypothesis that the diet changed with the intensification of agriculture. HYPOTHESIS IV THE INTENSIFICATION OF AGRICULTURE DID NOT AFFECT THE FREQUENCY OF DEGENERATIVE JOINT DISEASE.
The hypothesis, which was proposed as a null hypothesis, is tested by examining the frequency of degenerative lesions in the shoulder, elbow, hip, knee, and vertebral column joints. The remains were in such a fragmentary condition that rarely
were all the surfaces that form a joint present. The only effective approach to examining degenerative joint disease was to score a joint as afflicted when at least one of the locations on one of the bones forming the joint had evidence of a moderate level of lipping or lytic changes (a score of 2 or more in lurmain's  scoring system). Additionally, more than one location must have been scored in order for the joint to be recorded. For the vertebral joints, an individual was considered afflicted when more than one vertebra of the segment had a score of 2 or more, indicating at least a moderate fonnation of osteophytes and some erosive changes. The frequencies of individuals with afflicted synovial body and vertebral joints are shown in Table 6.31. The frequencies are of adult individuals aged between 17 and 50 years. Although limiting the samples to individuals in this age range greatly reduced the sample sizes, it helped to minimize the influence of normal age-related degenerative changes. Unfortunately, the frequency differences in degenerative lesions cannot be tested among the male and female groups. Even when the frequencies of the sexes are combined, the samples are still too small for statistical testing. The most common trend observed among the adult frequencies, however, is an increase in degenerative joint disease from the Formative to the Classic followed by a decline in the Postclassic. STATISTICAL POWER ANALYSIS In the statistical analyses presented above, the null hypotheses were not rejected. Before it can be concluded that there is no change in health over time, however, the power of the tests must be examined. A power analysis measures the probability that a null hypothesis was accepted falsely. The powers of the chi-square tests performed above were detennined using Cohen's (1969) power tables, and are presented in Table 6.32. For all the tests a significance level of 0.05 was used, and the expected size of the effect was a medium-sized difference. Conventionally, a power value of 0.80 is considered desirable, as it indicates a 0.05 probability of falsely rejecting a null hypothesis and a 0.20 chance of accepting a false null (Cohen 1969). An examination of the power values in Table 6.32 indicates that the power of the tests range considerably. The tests of dental pathologies, which have large sample sizes, have high power values indicating a high probability of rejecting a false null hypothesis when the effect size is of a medium magnitude. Even the test of dental pathologies which have small sample sizes, such as enamel hypoplasia and individuals with dental caries, have power values near .80 or above. The statistical tests of the dental pathologies, given their power values, suggest that the lack of a difference among the temporal groups is not due to a sample size problem. Even if the expected size of
the effect is small, 15 of the 22 tests of dental pathologies listed in Table 6.32 would still have power values higher than 0.80. In the tests of cribra orbitalia and periosteal reactions the power values of the tests of males and females are less than 0.80, but when the sexes are pooled the power of the tests increases to above the 0.80 level. The tests of pooled adults samples have sufficient power to detect an effect of a medium magnitude on the frequency of periosteal reactions and cribra orbitalia. The tests of degenerative lesions, on the other hand, have small sample sizes and low power values. ANALYSES WITH CLASSIC AND POSTCLASSIC GROUPS POOLED The analyses presented thus far were performed with three temporal groups, the Formative, Classic, and Postclassic. The decision was made to distinguish between the Classic and Postclassic groups even though they both represent periods of intensive agriculture because they differ in other cultural factors (social and political organization). Since the proposed hypotheses address the question of agricultural intensification and the three-group analyses found little evidence of a temporal trend, Classic and Postclassic groups were pooled. Remains from the sites of Dainzu and Yagul, for which phase associations were unknown, were included in the pooled sample because the excavations at the sites were of Classic and Postclassic deposits (Bernal 1967; Bernal and Gamio 1974). Only the frequencies of the markers were examined; the differences in severity scores were not reexamined. The frequencies of males, females, and adults with periosteal reactions on the limb bones are shown in Table 6.33. Among the males, a significant temporal increase in the frequency of individuals affected is observed on the femur and tibia. No significant change is evident between the frequencies on the fibula. Among the females, no significant temporal difference is observed on the femur, tibia, or fibula. When the sexes are pooled, the only significant temporal difference is on the femur, with a higher frequency among the intensive agriculturalists. The power values for the tests of periosteal reactions using an expected medium-sized effect are also included in Table 6.33. The power values for the male and female tests are slightly lower than the desirable 0.80 value, but the power values of the pooled adult tests are all above 0.80. In general, the power values of the tests are high, indicating confidence in the ability of the tests to have rejected the null hypothesis if a difference of a medium magnitude were present. The frequencies of both cribra orbitalia and porotic hyperostosis are shown in Table 6.34. The sample sizes of the male and female groups are too small to test for temporal differences in either cribra orbitalia or porotic hyperostosis. The pooled
adult groups, however, show no significant temporal difference in the frequency of either lesion. The subadult sample of individuals aged from birth to 17 years old show no significant (p > 0.05) temporal difference in the frequency of cribra orbitalia; the frequency of porotic hyperostosis cannot be tested. The power analysis of the cribra orbitalia and porotic hyperostosis tests are included in Table 6.34. The power values for the adult samples are quite high, greater than .95, indicating a high probability that the null hypothesis would have been rejected if a medium-sized effect been present. Given the high power value, the confidence in concluding that a medium-sized effect is not present, and in not rejecting the null hypothesis, is also high. The frequencies of individuals with enamel hypoplasia on the mandibular canines and on the maxillary central incisors are shown in Table 6.35. No significant temporal differences are found on either type of tooth in the samples of males or pooled adults. In the female samples, a significant increase is observed on the left canine, but no differences are found on the right canine or on the incisors. The power analysis of the tests of enamel hypoplasia are included in Table 6.35. The power value of the tests of the canines are higher than the tests of the incisors, and higher among the adult and male samples than among the female samples. The high power values indicate that there was a high probability of rejecting the null hypothesis if a medium effect had been present. The frequencies of individuals with dental caries in the posterior teeth and the frequency of carious posterior teeth are shown in Table 6.36. The frequency of individuals with caries does not differ temporally among the males, females, or adults. The frequency of carious teeth does not differ between the temporal groups of females or males. The frequency of teeth affected differs significantly between the sexes in the Formative group, precluding the pooling of the male and female frequen,?ies. The high power values (Table 6.36) support the conclusion that the samples do not differ (with an effect of a medium magnitude or larger) since the probability of rejecting the null hypotheses is high. The frequencies of teeth with periapical abscesses, periodontal disease, and hypercementosis are shown in Table 6.37. No significant differences are observed in the frequency of abscesses in the male, female, and adult samples. A significant temporal decline is observed in the periodontal frequencies of both males and females. The frequency of hypercementosis does not differ significantly between the male groups, but does show a significant increase in the female and adult samples. The frequencies of teeth with calculus are shown in Table 6.38. Significant temporal increases are observed among the males in the anterior teeth of both the maxilla and mandible, and among the posterior teeth of both jaws. The frequencies of
AGRICUIIURAL INTENSIFICAIION AND PREHISTORIC HEAIIH IN OAXACA
females also show a significant temporal increase in the anterior teeth of both jaws, but no differences are observed in the posterior teeth of either jaw. A few differences are evident between the results of these analyses and those in which the Classic and Postclassic groups were separated. The only significant difference that was found in the three-group comparison but not in the two-group comparison is in the male frequency of carious posterior teeth. In the two-group comparisons, significant differences that were
found but not observed in the three-group comparisons are the frequency of male individuals with periosteal reactions on the femur and tibia, a significant increase in the frequency of calculus in males on the posterior teeth of the maxilla and mandible, and a significant increase in the frequency of females with enamel hypoplasia on the left mandibular canine. Generally, the results of the two-group analyses are in agreement with the results of the three-group analyses.
TABLE 6.1 Frequency of Periosteal Reactions among Males
Formative N %
Classic N %
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
28 20 16 29 22 18 23 34 35
21 18 20 22 21 21 22 24 20
10.7 50.0 43.8 0.0 4.5 16.7 26.1 5.9 5.7
Postclassic N %
TABLE 6.3 Frequency of Periosteal Reactions among Adults
28.6 18 44.4 4.91 0.09 94.4 18 77.8 I' 50.0 24 37.5 0.27 0.88 9.1 26 15.4 I 38.1 25 16.0 I 28.6 24 12.5 I 40.9 22 45.5 1.17 0.57 8.3 40 12.5 I 0.0 32 3.1 I "In this table and the tables that follow, the "I" indicates that in the chi-square test more than 20% of the cells had expected frequencies of less than 5, which makes the chi-square test inappropriate (Seigel 1956).
Formative N %
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
68 48 46 60 47 36 42 70 68
Formative % N
Classic N %
Postclassic N %
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
33 24 26 27 23 17 18 30 28
19 17 IS 14 13 16 11 13 15
20 17 17 20 20 18 17 34 25
'See Table 6.1.
15.2 70.8 38.5 7.4 17.4 17.7 22.2 6.7 3.6
31.6 52.9 40.0 7.1 0.0 18.8 45.5 7.7 6.7
25.0 47.1 29.4 10.0 15.0 16.7 11.8 11.8 12.0
45 39 41 37 40 39 33 43 36
28.9 69.2 41.5 8.1 20.0 23.1 42.4 9.3 2.8
Postclassic N % 39 38 46 48 48 45 40 79 63
33.3 60.5 32.6 12.5 14.6 13.3 30.0 11.4 6.4
6.68 0.88 0.80
0.04 0.66 0.68
0.20 0.82 3.07 0.86
0.91 0.68 0.23 0.66
'See Table 6.1.
TABLE 6.4 Frequency of Periosteal Reactions among Children Less Than 6 Years Old
TABLE 6.2 Frequency of Periosteal Reactions among Females
11.8 60.4 39. I 3.3 14.9 16.7 23.8 5.7 4.4
Classic N %
1.60 0.13 I
Formative N %
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
13 14 7 11 10 8 8 13 8
'See Table 6.1.
15.4 71.4 0.0 0.0 20.0 0.0 0.0 30.8 25.0
Classic N % 10 7 4 9 7 7 8 9 9
20.0 42.9 25.0 11.1 0.0 14.3 0.0 22.2 22.2
PostcIassic N % 10 10 8 10 10 8 9 15 II
10.0 80.0 12.5 10.0 20.0 12.5 0.0 6.7 27.3
X2 I' I I
TABLE 6.8 Frequency of Individuals with One or More Enamel Hypoplasias on the Mandibular Canines
TABLE 6.5 Frequency of Periosteal Reactions among Children 6 to I7 Years Old Formative
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
10 7 8 6 5 4 5 10 13
40.0 42.9 12.5 0.0 40.0 25.0 0.0 0.0 0.0
3 5 2 5 5 6 5 4 7
66.7 80.0 50.0 20.0 20.0 0.0 0.0 25.0 0.0
16 16 19 19 19 18 15 17 15
31.3 75.0 42.1 15.8 15.8 5.6 20.0 17.7 26.7
Formative P Males left right Females left right Adults left right
I I I I I I I
'See Table 6.1.
TABLE 6.9 Frequency of Individuals with One or More Enamel Hypoplasias on the Maxillary Central Incisors
TABLE 6.6 Frequency of Periosteal Reactions among Children Less Than I7 Years Old Formative
Femur Tibia Fibula Humerus Ulna Radius Clavicle Cranium Mandible
23 21 15 17 15 12 13 23 21
26.1 61.9 6.7 0.0 26.7 8.3 0.0 17.4 9.5
13 12 6 14 12 13 13 13 16
30.8 58.3 33.3 14.3 8.3 7.7 0.0 23.1 12.5
26 26 27 29 29 26 24 32 26
23.1 76.9 33.3 13.8 17.2 7.7 12.5 12.5 26.9
0.02 0.88 I' I I
P 0.99 0.66
Males left right Females left right Adults left right
'See Table 6.1.
'See Table 6.1.
TABLE 6.10 Chronological Distributions of Enamel Hypoplasia Episodes Observed on One or More Teeth among Males
TABLE 6.7 Frequency of Individuals with One or More Permanent Teeth with an Enamel Hypoplasia Formative Males Females Adults 0-5 yrs. 6-11 yrs. 12-17 yrs. 0-17yrs. 'See Table 6.1.
42 39 100 4 6 15 25
73.8 71.8 70.0 50.0 50.0 80.0 68.0
31 20 61 2 6 2 10
67.7 80.0 73.8 100.0 83.3 100.0 90.0
48 31 91 2 10 9 21
62.5 1.28 77.4 0.18 69.2 0.39 100.0 fa 80.0 I I 77.8 81.0 I
p 0.53 0.91 0.83
Age Interval in Years
birth-0.5 0.5-1.0 1.0-1.5 1.5-2.0 2.0-2.5 2.5-3.0 3.0-3.5 3.5-4.0 4.0-4.5 4.5-5.0 5.0-5.5 5.5-6.0 6.0-6.5 6.5-7.0
39 40 40 40 41 42 43 43 43 43 43 43 41 38
2.6 0.0 2.5 5.0 34.2 47.6 79.1 53.5 58.1 18.6 16.3 4.7 7.3 0.0
23 23 23 23 25 25 26 26 26 26 26 26 26 25
0.0 4.4 8.7 13.0 8.0 48.0 19.2 42.3 42.3 19.2 3.9 3.9 3.9 4.0
39 42 42 42 43 43 43 43 43 43 43 43 43 36
Median test of distributions: X2 'See Table 6.1.
P Ia 2.6 0.0 I 0.0 I 11.9 I 25.6 4.36 0.12 25.6 4.19 0.13 51.2 23.85 ::J ......
.... .... J.J • ..} 12 0 18 0 5 0 10 27.3 11 50.0 4 31 25.8 0 18 0 17 25.0 4
24-3 24-4 24-5 24-7 24-8 24-9 24-10 24-12 1
2 1 8 28 10
HI0 87.5 29.6 100 96.9
92.9 91.3 100 100 57.1 66.7 80.0 100 100 60.0 60.0 60.0 9.1 100 60.0 25.0 100 66.7 100 100 88.9 0 70.4 100
10 8 27
8 27 2 1 8 4 3 2 14
1 9 1 5
5 5 5
23 6 20 21 21 5 3
Cal cuI us
100 100 100 100 75.0 7.4 100 100 33.3 100
100 0 100
Hl0 94.7 0 100 0 78.6
27 1 27
27 1 1 3 4 3 2 13
9 1 5 9
3 4 5 3 5
19 2 4 7 14
6 6 8
0 0 0 0 0 0
7.1 0 0 12.5 0 0
8 6 8
3 4 5 3 5
14 19 2 8 8 15
6 4 2 4
3 2 6 10 1 5 4 6
1 1 7
60.0 75.0 16.7 100 16.7 13 0 0
26 10 14 5 8 5 23 15 14 17 9
25.0 213.0 13.0 13 .3 0 23.5 22.2 0
0 0 9.1 3.9 20.0 35.7
20.0 25.0 3.7 25.0 0 10 8 27 4 32 16 2 1
28.6 17 .4 0 21.4 65.0 35.3 20.0 0 0 0 0 0 0 37.5 20.0 50.0 0 16.7 0 20.0 0 0 7.4 0 12.5 0 50.0 0 8.3
7 27 2
1 6 1 5
7 23 7 14 20 17 5 2 4 4 5 5
8 4 2 1 12
0 0 12.5
7 2 16
Hyper cementosi s
1 5 6 dec. 7-1 8 T. 3 T. 6
D D D D D D D
8 19 17 25 6 11 8 6
14 21 1 5 12 9 3
7.1 9.5 0 0 0 44.4 66.7
0 8.3 0 0 0 0 8.0 0 0 3.6 0 0 0 0
0 0 0 5.9 0
3.5 0 11.1 50.0
0'" 3.3 18.2 0 0 23.5 8.13 16.7 0 0 13
0 100 1013 50.0 100 100
10 1 15 5 12 8 2
13 13 0 16.7 0 0
Hl 6 15 5 12 9 3 0
13 0 11.1 13 50.13
46.2 0 0 0 0 0
0 100 91.7 100 100 100
100 100 100 100 96.7 0
6 3 5 9 3 4 16 24 21 25
8 9 2 5 6 32 5
16 Hl 24
213 6 18 13 313
0 0 0 0 0 0 0 0 13 0 0
6.3 0 0 0 0
5.0 0 0 0 0 0 0 0 20.0 13 0 0 0
6 1 5 7 3 4 16 24 21 25 13 28 7
16 9 9 2 5 6 32 6
8 16 10 25
20 6 18 13 31
26 6 21 16 30
29 z2 15 Z T. 2-1 18 Z T. 2-3 dec. 2 Z T. 2-3 perm. 7 Z T. 2-5 7 Z T. 2-7 32 Z T. 2-7-1 7 Z T. 2-8 17 Z T. 2-8-2 6 Z T. 2-8-4 3 Z T. 2-8-5 5 Z T. 2-9 12 Z T. 2-9-1 3 Z T. 2-9-2 4 Z T. 2-Hl 18 28 Z T. 2-11 Z T. 2-12 25 Z T. 2-13 25 Z T. 2-14 17 28 Z T. 2-15 Z T. 2-16 14 Z T. 3-2 1 Z T. 3-3 5 10 Z T. 3-6
31 34 35 36-1 36-2 36-3 dec. 36-3 perm. 37 39 42 43 46-1 46-2 49
TL TL TL
TL TL TL
TL TL TL TL TL
14 21 1 5 12
6 3 5 12 3 4 18 28 25 25 17 28 14 1 5 10
15 18 2 7 7 32 7
8 19 17 25 5 11
26 6 21 16 30
50.0 81.0 0 100 66.7 55.6 66 .7
93.1 20.0 27.8 0 0 0 43.8 42.9 11.8 100 33.3 0 75.0 33.3 50.0 11.1 60.7 0 0 35.3 53.6 78.6 100 80.13 10 .0
76.9 16.7 Hl0 56.3 11313 9.1 37.5 31.6 47.1 92.13 100 HHl 62.5 83.3
0 0 0 0 0
4 8 4
3 1 3
0 0 66.7
0 1 3 8 1
0 0 0 0 0
0 53.9 13 100
9.1 0 13 0
2 15 1 5 4 1 5 8
3 13 1 2
11 1 4 3
28.6 14.3 0 0 30.0 25.0 33.3
11 18 2 17 7 31 7 17 6 3 5 8 3 4 18 28 26 26 18 23 14 1 5 9 14 21 1 5 10 8 3
23.1 13 25.0 18.2 0 83.3
22.7 33.3 40.13 46.7 13 03 0
0 9.1 0 0 47.1 57.1 12.9 14 .3 11.8 0 0 0 75.0 33.3 0 66.7 35.7 11.5 0 13 30.4 42.9 0 20.0 0 17
11 8 6
19 13 24
22 6 213 15 30 11