Differential Persistence of Variation in Prehistoric Milling Tools from the Middle Rio Puerco Valley, New Mexico 9781407300108, 9781407330587

Table of contents :
Front Cover
Title Page
Copyright
ACKNOWLEDGMENTS
ABSTRACT
TABLE OF CONTENTS
LIST OF FIGURES
LIST OF TABLES
Chapter I. INTRODUCTION
Chapter II. BACKGROUND FOR RESEARCH
Chapter III. HYPOTHESIS
Chapter IV. METHODS AND PROCEDURES
Chapter V. RESULTS
Chapter VI. DISCUSSION
Chapter VII. CONCLUSIONS
Appendix A. ARTIFACT ANALYSIS DATA BY MANO USE SURFACE
Appendix B. SANDSTONE ARTIFACT DATA
Appendix C. VESICULAR BASALT ARTIFACT DATA
Appendix D. SITE TEMPORAL CLASSIFICATION
REFERENCES CITED

Citation preview

BAR  S1594  2007   MURRELL  

Differential Persistence of Variation in Prehistoric Milling Tools from the Middle Rio Puerco Valley, New Mexico

PREHISTORIC MILLING TOOLS FROM THE MIDDLE RIO PUERCO VALLEY

Jesse B. Murrell

BAR International Series 1594 B A R

2007

Differential Persistence of Variation in Prehistoric Milling Tools from the Middle Rio Puerco Valley, New Mexico Jesse B. Murrell

BAR International Series 1594 2007

Published in 2016 by BAR Publishing, Oxford BAR International Series 1594 Differential Persistence of Variation in Prehistoric Milling Tools from the Middle Rio Puerco Valley, New Mexico © J B Murrell and the Publisher 2007 The author's moral rights under the 1988 UK Copyright, Designs and Patents Act are hereby expressly asserted. All rights reserved. No part of this work may be copied, reproduced, stored, sold, distributed, scanned, saved in any form of digital format or transmitted in any form digitally, without the written permission of the Publisher. ISBN 9781407300108 paperback ISBN 9781407330587 e-format DOI https://doi.org/10.30861/9781407300108 A catalogue record for this book is available from the British Library

BAR Publishing is the trading name of British Archaeological Reports (Oxford) Ltd. British Archaeological Reports was first incorporated in 1974 to publish the BAR Series, International and British. In 1992 Hadrian Books Ltd became part of the BAR group. This volume was originally published by Archaeopress in conjunction with British Archaeological Reports (Oxford) Ltd / Hadrian Books Ltd, the Series principal publisher, in 2007. This present volume is published by BAR Publishing, 2016.

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ACKNOWLEDGMENTS

The completion of this research would not have been possible without the support of a number of people. I acknowledge Drs. Stephen Durand, Phillip Shelley, John Montgomery, Kathy Roler Durand, and Janet Frost of the Anthropology Department of Eastern New Mexico University (ENMU) for the sound advice and guidance they always provided. I thank each of them for the knowledge they shared in the classroom and during less formal discussions. I appreciate the work of Andre LaFond and the ENMU curation facility staff. They made the Rio Puerco Valley ground stone assemblage accessible for research. I thank Nancy Akins, Stephen Post, and Steven Lakatos of the Office of Archaeological Studies of the Museum of New Mexico for sparking my interest in ground stone analyses. I gratefully acknowledge Dr. Jonathan Damp and my colleagues at Zuni Cultural Resource Enterprise for their support. I thank James Smith and family, Mike Garcia, and Monica Enke for discussion and hospitality. Finally yet importantly, I greatly appreciate the support of my family.

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ABSTRACT

There is a long-standing interest in use efficiency and evolution in prehistoric ground stone tool research. A design and performance analysis conducted with replica tools examines a number of milling tool performance characteristics including use efficiency, ease of manufacture, and ease of maintenance as well as their interplay in the design process. This analysis shows that raw material and use surface area affect use efficiency. Milling tools that express efficiency enhancing traits have a positive impact on their user’s potential adaptedness. A paradigmatic artifact classification documents the variation in prehistoric manos from archaeological sites in the Middle Rio Puerco Valley of New Mexico. Temporal-frequency distributions track the differential persistence of variation. A number of artifact classes containing manos that are more efficient show a great degree of replicative success. These classes have temporal-frequency curves suggesting that natural selection favors their traits. Other classes show little replicative success and curves suggesting they are the product of stochastic processes or drift. Analysis shows historical correspondences between the replicative success of artifact classes and aspects of the selective environment including agricultural productivity and population trends. Some of these also suggest that milling efficiency enhancing traits are an adaptation, in other words, the product of natural selection.

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TABLE OF CONTENTS

ACKNOWLEDGEMENTS ................................................................................................................................................ iii ABSTRACT ..........................................................................................................................................................................v LIST OF FIGURES..............................................................................................................................................................ix LIST OF TABLES ...............................................................................................................................................................xi CHAPTER I: INTRODUCTION ..........................................................................................................................................1 Report Organization .........................................................................................................................................................2 CHAPTER II: BACKGROUND FOR RESEARCH.............................................................................................................3 Selectionist Archaeology..................................................................................................................................................3 Ground Stone Tool Research............................................................................................................................................4 Analogical Reasoning and the Use Efficiency Argument ................................................................................................7 The Rio Puerco Valley Project .........................................................................................................................................8 CHAPTER III: HYPOTHESIS .............................................................................................................................................9 CHAPTER IV: METHODS AND PROCEDURES............................................................................................................11 Design and Performance Analysis..................................................................................................................................11 Artifact Analysis.............................................................................................................................................................13 Mano Attribute Analysis ...........................................................................................................................................14 Artifact Classification................................................................................................................................................15 Temporal Classification of Artifacts .........................................................................................................................15 CHAPTER V: RESULTS....................................................................................................................................................17 Design and Performance Analysis..................................................................................................................................17 Artifact Analysis.............................................................................................................................................................32 CHAPTER VI: DISCUSSION ............................................................................................................................................43 CHAPTER VII: CONCLUSION.........................................................................................................................................47 Mano Variability and Aspects of the Selective Environment in Historical Perspective.................................................48 Aceramic ...................................................................................................................................................................49 Early Ceramic to A.D. 800 ........................................................................................................................................50 A.D. 800 to 900 .........................................................................................................................................................50 A.D. 900 to 1000 .......................................................................................................................................................50 A.D. 1000 to 1100 .....................................................................................................................................................50 A.D. 1100 to 1200 .....................................................................................................................................................50 A.D. 1200 to 1300 .....................................................................................................................................................50 Towards an Explanation of Mano Variability ................................................................................................................51 APPENDIX A: ARTIFACT ANALYSIS DATA BY MANO USE SURFACE ................................................................53 Variable and Value Labels .............................................................................................................................................55 APPENDIX B: SANDSTONE ARTIFACT DATA ...........................................................................................................65 APPENDIX C: VESICULAR BASALT ARTIFACT DATA ............................................................................................69 APPENDIX D: SITE TEMPORAL CLASSIFICATION ...................................................................................................73 REFERENCES CITED .......................................................................................................................................................79

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LIST OF FIGURES

Figure

Page

1. Hypothetical Temporal-Frequency Curves for Changes in Mano Use Surface Area (adapted from O’Brien and Holland 1992: Figure 1)...........................................................................................................................9 2. Location of Collection Areas......................................................................................................................................12 3. Use Surface Outline Forms.........................................................................................................................................15 4. Use Surface Longitudinal Cross-Section Forms.........................................................................................................15 5. Hypothetical Paradigmatic Classification for Manos .................................................................................................16 6. Large Vesicular Basalt Mano-Metate Set...................................................................................................................18 7. Large Sandstone Mano-Metate Set.............................................................................................................................19 8. Small Vesicular Basalt Mano-Metate Set...................................................................................................................20 9. Small Sandstone Mano-Metate Set.............................................................................................................................21 10. Peckingstones and Hammerstone Used to Manufacture Replica Mano-Metate Sets. ................................................22 11. Line Graph Depicting the Results of Pecking Experiment. ........................................................................................23 12. Boxplot Depicting Median, Interquartile Range, and Range of Values For Preform Weight Loss (g) During the Pecking Experiment............................................................................................................................24 13. Line Graph Depicting the Results of the Grinding Experiment..................................................................................25 14. Boxplot Depicting Median, Interquartile Range, Range of Values, and Outlier for Preform Weight Loss (g) During the Grinding Experiment..................................................................................................................26 15. Line Graph Depicting the Results of Fine Meal Production Experiment. ..................................................................28 16. Boxplot Depicting Median, Interquartile Range, Range of Values, and Outlier for the Weight of the Fine Meal (g) Produced on the Replica Mano-Metate Sets. .................................................................................29 17. Location of Archaeological Sites That Yielded the Analyzed Manos........................................................................33 18. Frequency Distribution of Use Surface Area Classes.................................................................................................34 19. Paradigmatic Artifact Classification...........................................................................................................................35 20. Temporal-Frequency Distribution of Sandstone Artifact Classes. .............................................................................36 21. Temporal-Frequency Distribution of Vesicular Basalt Artifact Classes.....................................................................36 22. Temporal-Frequency Distribution of Metamorphic and Non-vesicular Igneous Artifact Classes..............................37 23. Temporal-Frequency Distribution of Selected Artifact Classes. ................................................................................37

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Figure Page 24. Temporal-Frequency Distribution of Selected Artifact Classes. ................................................................................48 25. Precipitation Effectivenes Index and Annual Rainfall in the Middle Rio Puerco Valley Through Time (adapted from Durand and Baker 2003:Figure 9.7). .........................................................................................49 26. Mean Distance Between Sites and Number of Rooms in the Middle Rio Puerco Valley Through Time (adapted from Durand and Baker 2003:Figure 9.4). .........................................................................................49

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LIST OF TABLES

Table

Page

1. Sand Grain Size Ranges. ............................................................................................................................................14 2. Results of the Pecking Experiment.............................................................................................................................23 3. Descriptive Statistics for the Pecking Experiment......................................................................................................23 4. Results of the Grinding Experiment. ..........................................................................................................................25 5. Descriptive Statistics for the Grinding Experiment. ...................................................................................................25 6. Use Surface Attributes for the Replica Mano-Metate Sets. ........................................................................................27 7. Results of the Meal Production Experiment. ..............................................................................................................28 8. Descriptive Statistics for the Meal Production Experiment........................................................................................28 9. Summary of Total Weights (g) of Meal Produced During Experiment......................................................................30 10. Mano Weight Loss (g) During Meal Production Experiment.....................................................................................31 11. Site Frequency, Mano Frequency, and Mano Use Surface Frequency by Temporal Class. .......................................34 12. Mano Raw Material Class by Temporal Class Cross-Tabulation...............................................................................38 13. Mano Use Surface Area Central Tendency and Dispersion Statistics by Temporal Class. ........................................39 14. Sandstone Mano Texture by Temporal Class Cross-Tabulation. ...............................................................................39 15. Results of Sandstone Mano HCl Test by Temporal Class Cross-Tabulation. ............................................................40 16. Vesicular Basalt Mano Vesicle Count Central Tendency and Dispersion Statistics by Temporal Class. ..........................................................................................................................................................................40 17. Vesicular Basalt Mano Maximum Vesicle Diameter Central Tendency and Dispersion Statistics by Temporal Class......................................................................................................................................................41

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Chapter I INTRODUCTION

Scholars holding divergent theoretical perspectives (e.g., Basalla 1988:6; Diamond 1997:242; Dunnell 1989:42; Lyman et al. 1997:222; Lyman and O’Brien 2001:330; Pfaffenberger 1992:494, 495) agree that the commonsense notion that “necessity is the mother of invention” lacks explanatory weight when it comes to questions of technological change. Nelson (1932:111) explicitly brought the saying to bear on the origin and development of material culture (see Lyman et al. 1997:222; Lyman and O’Brien 2001:330). This notion implies that humans recognize necessity and with their intent to fulfill a need or overcome a problem drive technological change. Furthermore, Nelson (1932:107, 109, 119) argued that with developments in material culture man increasingly "isolates himself from direct contact with the raw natural world" resulting in a "nearly complete artificialization [sic] of existence.” Nelson would have us believe that humankind divorced itself from nature and natural processes with developments in material culture. These ideas leave one alternative; humans themselves are the impetus of technological change. Human intentions become the root of the matter.

The study of human history is incomplete without an examination of technological change. Archaeology is particularly well suited for such an examination because its record is composed of the material products of technological behavior. The great time depth of the archaeological record holds opportunities to investigate long-term change in these material products, namely artifacts, or material culture in general. Archaeology has the potential to be an historical science. This entails a working body of scientific theory and methodology. Evolutionary or selectionist archaeology offers such a working body. Evolution has been an anthropological concern since the late 19th century works of Louis Henry Morgan and Edward Burnett Tylor. The orthogenetic evolution inspired by these early authors held sway for nearly a century. Its foundation lies in the anthropological study of contemporary people; however, the time depth required to study evolutionary change exists in the archaeological record. Recognizing the potential of the archaeological record and without borrowing from anthropology, selectionist archaeology provides a theoretical framework that differs significantly from the cultural evolution of Morgan and Tylor. Selectionist archaeology is relatively new; in fact, in the mid 1990s it was referred to as an "emerging paradigm" (O'Brien and Holland 1995a:175), while cultural evolution enjoys a long history.

Explaining human technological change with human intent is vitalistic rather than scientific. Vitalism refers to finding cause in the subject of study rather than in a theoretical framework (Dunnell 1989:37). Rindos (1985:84) argued that appeals to human intent "have no place as explanation in a scientific study of human culture and cultural change. They are idealistic and inherently unverifiable. They merely restate the observation in new terms ('Why did X occur?' 'Because people chose X'). They provide an antitheory - a void that has the function of knowledge and conveys none.” Some selectionists relegated human intent to the role of proximate rather than ultimate cause (Dunnell 1989:37; Lyman and O'Brien 1998:618). Human intent may be one source of variation, but it is this variation rather than human intent that is important (O'Brien and Holland 1992:45, 1996:184; Lyman and O'Brien 1998:618). The root of the matter lies in the differential persistence of this variation and the selective environment. In bold terms, O'Brien and colleagues (O'Brien et al. 1994:268; O'Brien and Holland 1995b:158) commented, "Unlike the road to hell, the evolutionary pathway is not paved with good intentions.”

Nels Nelson (1932:103), a pioneer in Americanist archaeology, saw parallels between the process that guides material culture development and the process of “organic evolution” at work in the natural world. Unlike most modern biologists and paleobiologists, who account for “organic evolution” with the processes of natural selection and drift, Nelson (1932:114-117) appealed to an evolution resulting in "gradual improvement" and progression along a transformational series of "easy steps or stages.” Nelson, in rank with the cultural evolutionists, saw change as a transformational rather than a selective process (see Dunnell 1996b:32). This view is in accord with the evolution of Morgan and Tylor and was more akin to Spencerian social philosophy than Darwinian evolutionary science (see Dunnell 1996a:24-25; Dunnell 1996b:30-35). It foreshadowed the later work of White (1959), Steward (1955), and Sahlins and Service (1960), which influenced the "new" or processual archaeology.

Modern evolutionary theory is scientific; it is capable of generating testable models or hypotheses concerning the

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Differential Persistence of Variation in Prehistoric Milling Tools course of human history (Dunnell 1995:33-34). This research involves a testable statement derived from Darwinian evolutionary theory. It involves an examination of technological change in prehistoric milling tools from the Rio Puerco Valley of New Mexico. Milling tools, manos and metates in particular, were an integral part of Ancestral Puebloan food production technology.

summarizes the fundamental premises of selectionist archaeology and the history of ground stone tool research. It also provides a discussion concerning the role of analogical reasoning in this research and a brief discussion concerning the Rio Puerco Valley Project. Second, I offer a series of testable propositions and a core hypothesis drawn from Darwinian evolutionary theory. Third, I detail a methodology for data generation and analysis. Analysis involved a design and performance analysis of replica tools as well as a classification system for archaeological specimens. Lastly, I present results of the analyses followed by a discussion of the results framing them in the context of the selective environment.

Report Organization In the following, I outline the theory and method that I will apply in the examination of variation in these tools. First, I present a background for research. This chapter

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Chapter II BACKGROUND FOR RESEARCH

phenotype as all traits of an individual produced by the interaction of the genotype and the environment. These traits are both physical and behavioral. Environment refers to both the natural and the social environment. The phenotype is flexible. For instance, social learning may lead to the incorporation of a new technological behavior. Phenotypes comprise the pool of variation upon which natural selection may work.

This chapter presents a review of the key concepts of selectionist theory and the history of ground stone tool research. Themes common in both early and contemporary ground stone tool research include a concern with ethnographic analogy and tool use efficiency. I review the role of analogical reasoning in selected previous research and present its role in approaching questions of use efficiency as well as its theoretical underpinnings in my research. The chapter also includes a description of the Rio Puerco Valley Project and its basic objectives.

Transmission entails the transfer of information between individuals (O'Brien and Lyman 2000:406). This includes genetic information in the form of genes or cultural information in the form of ideas. Both genetic and cultural transmission is responsible for the human phenotype (Dunnell 1989:44). Genetic transmission is a one-way street; parents pass genetic information or genes to offspring. Cultural transmission has a more complex pathway. The transmission of cultural information may involve intragenerational transfer as well as intergenerational transfer between individuals that are not necessarily parent and offspring. Dunnell (1996b:51) contended, "that most of the behavioral component of the human phenotype is transmitted culturally, that is, learned extragenetically.” This has implications for the rate of cultural change (Teltser 1995:5). It may proceed more rapidly than the passing of generations (Dunnell 1996b:51; Leonard and Jones 1987:212).

Selectionist Archaeology Charles Darwin (1979 [1859]) preferred to call his theory "descent with modification" because the term evolution was already in use by Herbert Spencer. The somewhat unwieldy label yielded to Spencer's term, often clarified as Darwinian evolution. Darwinian evolution requires phenotypic variation, genetic or cultural transmission of variation, and differential persistence of variation (cf. Dunnell 1996a:25, 1996b:32; Leonard and Jones 1987:212; Leonard 2001:68). One must keep in mind that the generation of variation is independent from the process that leads to differential persistence of variation in successive states (Rindos 1985:70, 1996:156). This distinguishes the approach from Lamarkian evolution (sensu Dawkins 1999:296) with its notion that variation is directed toward adaptation. Dunnell (1996b:32) defines evolution as "a particular framework for explaining change as the differential persistence of variability.” Evolution is a transgenerational change in the phenotypic traits or trait states expressed within an aggregate of individuals resulting from natural selection or drift. Evolution is historical and contingency bound; in other words, it occurs over time and previous states condition it (O'Brien et al. 1998:487).

A distinction is made between "individuals who have reproductive success and the traits of those individuals which have only replicative success" (Leonard and Jones 1987:214). Cultural change via the differential persistence of variation is tied not only to differential reproductive success but also to the differential replicative success of the traits of individuals (Leonard and Jones 1987:212). The replicative success of a trait or trait state need not affect the reproductive success of the individual bearer of a trait. A trait or trait state that affects the reproductive success of individuals is functional and those that have no effect on reproductive success are stylistic (sensu Dunnell 1978:199). Using temporal-frequency distributions, archaeologists can monitor the differential replicative success of phenotypic traits of individuals over time at different scales (Leonard and Jones 1987:215).

A central premise of selectionist archaeology is that the material products of human technological behavior contained within the archaeological record are components of past human phenotypes (O'Brien and Holland 1995a:179; O'Brien et al. 1994:260-261; O'Brien et al. 1998:486). As Dunnell (1989:44) put it, "artifacts are the hard parts of the behavioral segment of phenotypes.” Leonard and Jones (1987:213) also spelled out this premise. Following biologist Ernst Mayr, they viewed the

Natural selection is a concept of great import to selectionist archaeology. Biologists have described natural

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Differential Persistence of Variation in Prehistoric Milling Tools Biologists and archaeologists realized that the term "adaptation" has multiple meanings (Burian 1992:7; Kirch 1980:103; VanPool 2002:15-17). O'Brien and Holland (1992:38) dealt with this problem by differentiating between adaptation, adaptations, and adaptedness. Adaptation is a transgenerational process that leads to the increased survivability or reproductive success of the members of a population. Adaptations are phenotypic traits or trait states that are the demonstrated product of natural selection. Adaptedness or fitness is the state of an individual relative to other individuals sharing the environment and resulting from its evolutionary history. Material culture can contribute to an understanding of adaptation and adaptedness. A performance analysis can help evaluate the contribution of a trait or trait state to an individual's potential adaptedness. As an example, consider a large mano use surface area as a trait state. Because the individual user, not the mano's use surface area, is the unit of reproduction, the analyst must view the artifact in terms of replicative success, which the researcher can monitor with temporal-frequency distributions and relate to the results of the performance analysis. A more efficient mano, a determination left to performance analysis, may increase the potential adaptedness of the user and it may have greater replicative success. To approach the question of why a more efficient mano may increase the potential adaptedness of the user, the analyst must examine the selective environment. Natural selection favors the more adapted individual, and in this scenario, the more efficient mano may become an adaptation in certain selective environments.

selection as a law, a principle, a force, a cause, and an agent (Hodge 1992:218). Rindos provided a rather different conceptual definition: Natural selection... is not a metaphysical force interposed between the organism and the environment, but is rather the summation of all of the relationships between the organism and the environment that affect the organism's reproductive success. In a sense, natural selection is part of the organism. Natural selection in this sense does not cause the changes that occur in populations over time. Rather it is the disparities present in organisms, which, over time, accumulate and allow us to describe the result as evolution. In other words, natural selection is not an external force determining which individuals are to survive, but a concept that (rather artificially) lumps together any and all events based on differential reproduction that cause change in the characteristics of a population over time. This change is what we call evolution [Rindos 1984:39, emphasis in the original]. By viewing natural selection as part of the organism rather than external to it, this conception presents a problem for scientific researchers attempting to find external causes in the theoretical framework rather than within the studied phenomena. Endler provided a concise definition of natural selection that works for selectionist archaeology (see Leonard 2002:226):

Ground Stone Tool Research "Natural selection" can be defined as a process that occurs if and only if these three conditions are present: the population has (a) variation among individuals in some attribute or trait (phenotypic variation); (b) a consistent relationship between that trait and mating ability, fertilizing ability, fertility, fecundity, and/or survivorship (fitness variation); and (c) a consistent relationship, for that trait, between parents and their offspring, which is at least partially independent of common environment effects (inheritance) [Endler 1992:220].

Prehistoric milling tools, which are the focus of this study, are usually included within a larger ground stone artifact category during analysis (e.g., Adams 1996). Ground stone artifact analysis took many different forms since early notable work (e.g., Bartlett 1933). There was much concern for the morphological and raw material analysis of artifacts (e.g., Lancaster 1983, 1984, 1986). A considerable amount of archaeological experimentation with replica tools, mainly, but not exclusively, manos and metates, was undertaken (e.g., Adams 1988, 1999; O'Brien 1994; Wright 1993; Zier 1981). There were several ethnographic and ethnoarchaeological studies focusing on the production or use of manos and metates (e.g., Bartlett 1933; Cook 1970; Hayden 1987; Horsfall 1987; Mauldin 1993, 1995) some of which concentrated on raw material procurement or quarrying (e.g. Aschmann 1949; Cook 1973). Archaeologists also showed an interest in the procurement of raw materials for milling tools (e.g., Huckell 1986; Schneider 1996) as well as the impacts that raw material scarcity has on ground stone technology (e.g., Stone 1994). Others emphasized that the composition of an archaeological assemblage has the

As Endler (1992:220) pointed out this definition also provides a definition of drift if condition (b) is not met. Traits or trait states that meet conditions (a), (b), and (c) are functional, that is they are subject to natural selection, and those that meet conditions (a) and (c) but fails to meet (b) are stylistic, that is they are subject to drift (sensu Dunnell 1978; Leonard 2002:227). If conceived of as an external "causal process" (Hodge 1992:218), natural selection provides a testable explanation of cultural change (O'Brien et al. 1998:486).

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Chapter II: Background for Research ethnographic observations of ground stone tool use to gain analytic insight into archaeological specimens (e.g., Adams 1993) as well as to test propositions arrived at through ethnographic information (e.g., Adams 1988). Many, if not most, of the ground stone tool experiments were geared toward an examination of use alteration (e.g. Adams 1988, 1989a, 1989b; O'Brien 1994; Wright 1993; Zier 1981).

potential to provide information regarding mobility and land use, particularly on the topic of site reuse (Nelson and Lippmeier 1993). Gleaning information on site function, occupation duration, and abandonment processes from ground stone assemblages was the focus of some (Schlanger 1991). Despite this diversity of approaches, the main body of ground stone research shows several common threads interlacing contemporary and earlier work.

E. B. Sayles (1983) set forth a staged temporal sequence, labeled the Cochise culture, for the Archaic period in southeastern Arizona. Sayles (1983:68) stated that grinding tools are the most distinctive artifacts of the Cochise culture. He believed these tools were more temporally diagnostic than Cochise flaked stone artifacts. He charted a developmental sequence of ground stone tool types including slab, shallow-basin, and deep-basin nether stones (Sayles 1983:77). Sayles (1983:78) contended that tools become more efficient and specialized in the Chiricahua stage and this reflects an increased dependence on grass seed, including primitive maize. Along these lines, he states that “the change in the shape and nature of the grinding surface of the nether stone and the accompanying change in the conformation of the handstone used with it documents the growing importance of grinding in the Cochise economy and the need for more efficient grinding equipment” (Sayles 1983:78). By the Early Pottery horizon, nether stones and handstones increased in size and the deep-basin nether stones replaced the shallow-basin nether stones. These changes were associated with “advances in the development of maize” (Sayles 1983:78). Like Bartlett, Sayles worked within a cultural evolutionary framework and was concerned with use efficiency, but also saw a relationship between variation in use efficiency and changes in maize.

Early research set the standard for a heavy reliance on ethnographic information in ground stone artifact analysis. In her pioneering analysis of several prehistoric milling tools from northeastern Arizona, Bartlett (1933) compared artifacts to contemporary Hopi examples. Considering statements like "metates of this type belong to a more primitive stage of culture" and "progress in milling stones took many hundreds of years to accomplish, yet each new step made the task easier or quicker", she also worked within a cultural evolutionary framework (Bartlett 1933:20, 29, emphasis added). Woodbury (1954) authored a classic analysis of ground and flaked stone artifacts from Awatovi and other prehistoric sites in the Jeddito district of northeastern Arizona. Stating, "(ethnographic) information is indispensable as a basis for the fullest and most meaningful interpretation of archaeological material" and that "interpretations must be cautious, particularly until they can rest on the firmer base of the observed details of the 'primitive' technologies still extant", Woodbury (1954:203) was unequivocal about the weighty role he envisioned for ethnographic information in archaeological interpretation. Both Bartlett and Woodbury had an interest in the study that would later be termed ethnoarchaeology. Their research strategy shows similarities to what the behavioral archaeologists later labeled Strategy 2 (Reid et al. 1995:210; Schiffer 1976:4-7). This strategy used contemporary material objects to infer past human behavior. Morris’ work (1990:182-183, 188-189) provided a more recent example of the reliance on ethnographic information in the interpretation of ground stone artifacts.

Other researchers commented on the relationship between changes in milling tool morphology and changes in the variety of corn that is available (e.g., Diehl 1996:105; Doebley and Bohrer 1980:212, 216, 218; Doebley and Bohrer 1983:32-35; Galinat and Gunnerson 1963:130131; Shelley 1980:112-113). The analysis of prehistoric milling tools and maize from Salmon Ruin suggested that the change from trough to slab metates, which occurs from the Chacoan occupation to the Mesa Verde occupation, co-occurs with changes in the dominant variety of corn (Doebley and Bohrer 1980: 212, 216, 218; Shelley 1980:112-113). Shelley (1980:113) stated that, “the variety of corn grown and processed by the Salmon inhabitants may be a major factor in explaining the variation in milling technology.” Diehl (1996) used multiple lines of evidence, including mano metric data and corn ubiquity data, to assess change in corn consumption through time in Mogollon pithouse villages. He noted that the onset of increased corn consumption and larger milling tools roughly coincides with the introduction of Maiz de Ocho, which has larger cobs and

Woodbury (1954:203) called for experiments to aid in archaeological interpretation, which is also in keeping with behavioral archaeology strategies to assist archaeological inference (Reid et al. 1995:210-212, Schiffer and Skibo 1995; Schiffer et al. 1994; Skibo 1992:18-28). It was not until the late 1980s and 1990s with the sustained experimental program of Adams (1988, 1989a, 1989b, 1993, 1994, 1999) that those interested in ground stone artifacts heeded this call to any great extent. Adams' research employed both ethnographic information and experiments. Adams used experiments to recreate

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Differential Persistence of Variation in Prehistoric Milling Tools involved a Bolivian villager. The woman used four manometate sets, which varied in size, to process two types of toasted and untoasted corn. Mauldin recorded the time it took to grind 1 kg of each type to meal. The results showed that there was an inverse relationship between use surface area and time spent grinding. That is, with an increase in the use surface areas of manos and metates, the amount of time spent grinding a set amount of corn decreased. There was no mention of morphological or material variability in the experimental tools, rendering it difficult to evaluate these results.

larger and softer kernels (Diehl 1996:105). The corn may have been better suited for meal production. Lancaster's analysis (1983, 1984, 1986) of ground stone artifacts from prehistoric sites in the Mimbres Valley of New Mexico generated a classification of manos and metates based on metric and morphological attributes. Functional differences between types were explored using raw material type, striation orientation, and metric data. The functional assessment suggested two tool classes. Onehand manos, basin metates, and grinding slabs were generalized tools used to process a variety of materials. Two-hand manos and trough metates comprised specialized tool kits used to process corn. Diachronic changes in the shape and metric attributes of artifacts, the relative frequency of tool classes, and the selection of raw material reflects a move toward increasingly efficient tools.

A series of experiments led Adams (1999:492-493) to conclude that, in general, mano and metate morphology, more specifically mano size, did not reflect agricultural dependence (see Hard 1986:105-125, 1990), but rather reflected processing techniques. She cautioned that any efficiency evaluation must also consider a variety of other factors including the material that is processed, toolstone textural variation, and tool user motor habits (Adams 1999:486-487). Morris (1990:188) also saw multiple factors contributing to the ability to process large amounts of corn. These included increases in use surface area, operating the mano with both hands, the use of vesicular basalt, and fatigue-reducing postural changes. Earlier, Lancaster (1983:85-86) argued that toolstone textural variation and multi-stage grinding techniques played a part along with use surface area in tool efficiency.

Lancaster (1983:77) defined efficiency as "an increase in the amount of corn ground per unit of time.” Lancaster's efficiency argument (1983:77-78) partly rested on the assumption of earlier researchers (Martin and Plog 1973:216-217; Plog 1974:139-142) that increases in effective use surface area increase efficiency. Lancaster (1983:78-82) attempted to bolster the argument by reference to an industrial experiment involving a pan mill used to crush dolomite. In this experiment, pan diameter and roller width combined with pressure comprised charge load. As pan diameter and roller width were increased, charge load decreased. The experiment demonstrated a positive relationship between charge load and the number of revolutions required to crush dolomite to a certain texture, that is, as the charge load decreased the required number of revolutions also decreased.

Recent analysis of metates from Paquime, which is a large prehistoric site with monumental architecture in the Casas Grandes region of northern Chihuahua, Mexico, assumed that metates produced by specialists would exhibit less variation than metates produced by non-specialists (VanPool and Leonard 2002:712). The researchers computed corrected coefficients of variation (CVs) for a number of metric attributes of two types of trough metate. Among these were total length, total width, trough length, and trough width. The researchers suggested that there is a relationship between some of these variables and the performance characteristics of the metate. Following the efficiency argument, they contend that trough length and width affect use efficiency. Lower corrected CVs in metric variables not heavily affected by use suggested that, compared to the producers of the smooth-cornered metates, the producers of the square-cornered metates might be relatively more specialized. The researchers then computed corrected CVs for the metric data generated by Lancaster (1983, 1984, 1986) for slab and through-trough metates from numerous sites in the Mimbres Valley. They compared the data, and again, the Paquime squarecornered metate displayed the lowest corrected CVs. VanPool and Leonard (2002:726) concluded that the specialization of the production of prestige goods, for example, copper bells and macaws, along with the specialization of utilitarian items, namely square-cornered metates, indicates, "Production specialization was a

Later researchers used the efficiency argument in a number of ways. Hard (1990:137-138) embraced the argument citing additional evidence of its plausibility from another experiment with a dolomite crushing pan mill (Lowrison 1974:179-180). Hard (1986:105-125, 1990) used ethnogaphic data reported by Murdock (1967), ethnographic photograph archives, manos analyzed during ethnographic field work, and manos from ethnographic collections housed in museum curation facilities to suggest that mano metric variation reflects prehistoric agricultural dependence. He did not break with tradition in ground stone analysis with his heavy reliance on ethnographic information. Hard and colleagues (Hard 1986:125-127; Hard et al. 1996) used mano metric data in concert with coprolite evidence, corn ubiquity data, and stable carbon isotope ratios in human remains to assess prehistoric agricultural dependence. Mauldin (1993:319-320, 1995:253-256) conducted an experiment to directly test the proposition that larger use surface areas are more efficient in terms of time spent to produce corn meal. This ethnoarchaeological experiment

6

Chapter II: Background for Research concerning the role of analogical reasoning in archaeology (e.g., Ascher 1961; Binford 1972a, 1972b, 1972c; Gould 1980:29-47; Stahl 1993; Wylie 2002). This literature has generated much debate.

fundamental organizing principle of the community.” In a separate work, VanPool (2001), working from a selectionist perspective, used the same data from the square-cornered Paquime metates to argue that the low corrected CVs indicate functional traits that are favored by natural selection (also see O'Brien and Lyman 2003:2021). He equated functional traits with performance characteristics, for instance, trough length and width measured use efficiency. Furthermore, VanPool (2001:136) argued that functional traits displayed limited variation because only a portion of the variation was selected for, namely the more efficient variants, and the majority was selected against, namely the less efficient variants, eventually dropping out of the pool of variation.

Selectionists, who view archaeology as an historical science, pointed out the importance of distinguishing between the immanent and configurational processes and properties of phenomena when drawing analogies (Lyman and O’Brien 1998:624; O’Brien et al. 1998:492-493; Wolverton and Lyman 2000). They built upon the distinction made by a paleontologist discussing historical science (Simpson 1963:24-25). Immanent characteristics are unchanging; they act in a uniform way throughout history. These are the properties of matter and energy as understood in chemistry, mechanics, and physics. Configurational characteristics are always in a state of change and contingent upon previous states. For instance, human behavioral processes are configurational. Simpson (1963:25) defined history as “configurational change through time.” He clarified this statement by asserting that the action of immanent properties and processes on and within particular configurations is important in determining history (Simpson 1963:29).

To conclude this section, I enumerate a number of themes in ground stone analysis. First, there is an interest in evolution. This is most apparent in the cultural evolutionism of Bartlett (1933) and the selectionist archaeology of VanPool (2001). Second, there is a longstanding interest in the application of ethnographic information to ground stone analysis. This is evident in early work of Bartlett (1933) and the contemporary work of Adams (1999). Third, there is also a long-standing interest in variation in use efficiency as indexed by mano and metate metric attributes. Researchers often assume that larger tools are more efficient. Some support the argument with analogy to pan milling experiments. Seldom have researchers interested in ground stone experimentation directly tested the argument. The focus on use efficiency occurs to the near exclusion of studies focusing on other performance characteristics such as ease of manufacture or maintenance. Finally, there has been a considerable amount of experimental work involving replica ground stone tools. The concern of most investigators is distinguishing use alteration signatures.

Wolverton and Lyman (2000:235-236) spelled out the differences between immanent and configurational analogies and argue that the failure to make this distinction in archaeology has led to confusion surrounding the role of analogical reasoning. The main part of this distinction is that immanent analogies rest upon timeless and spaceless chemical, mechanical, and physical laws, while configurational analogies rely on empirical generalizations, which are often treated as timeless and spaceless laws, but which, in fact, are time and space bound. The construction of a configurational analogy involves the generalization of:

Analogical Reasoning and the Use Efficiency Argument

multiple observations of a configuration created by known immanent processes… The generalization serves as the analog, which is subsequently extended in an attempt to identify the processes that created another particular configuration of unknown creation. The configurational analog relies on an empirical generalization that is based on repeated observations [Wolverton and Lyman 2000:235].

As commonly applied in ground stone analyses, the use efficiency argument claims that there is an inverse relationship between the use surface area of a milling tool and the amount of time spent producing a set amount of meal. Early appeals to similar arguments rested on the sole foundation of commonsense (e.g., Martin and Plog 1973:216-217; Plog 1974:139-142). Later, these appeals found basis in analogies drawn from experimental results. Researchers drew analogies from industrial experiments involving dolomite-crushing pan mills (Lancaster 1983:78-82; Hard 1990:137-138 citing Lowrison 1974:179-180). Other researchers drew analogies from an ethnoarchaeological experiment (Mauldin 1993:319-320, 1995:253-256) and a replication experiment (Adams 1999:484-493). In all of these works, explicit discussion of the theory supporting the use of analogical reasoning is lacking; however, there certainly is no lack of discussion

The construction of immanent analogies involves: using laws that apply in all times and places to understand a configuration of unknown creation. Such analogies do not rely on the extension of empirical generalizations based on configurational processes from known contexts. Rather, properties and processes that are nonhistorical – immanent – underpin the

7

Differential Persistence of Variation in Prehistoric Milling Tools immanent properties and processes act on and within during meal production. In an experimental context, a single tool user employing a consistent technique will control these configurational aspects to a degree. The individual tool user has achieved a certain level of skill. This tool user can consistently apply techniques involving posture, motor habits, adding material to tools, and collecting processed materials to name a few.

analogy. Physical, chemical, and/or mechanical properties that hold in all times and places are used to explain the unknown [Wolverton and Lyman 2000:236]. Behavioral analogies, which are commonly employed in archaeology, are “particular kinds of empirical generalizations” (Wolverton and Lyman 2000:237). Treating behavioral empirical generalizations as if they were immanent laws rather than merely configurational has led to much consternation over archaeological analogy (Wolverton and Lyman 2000:237). If archaeologists are to make sense of the past by observing the present, immanent analogies are key (cf. Lyman and O’Brien 1998:624; O’Brien et al. 1998:492). Failure to distinguish the two kinds of analogy and treating the two as “one analytical tool” will only lead to further confusion (Wolverton and Lyman 2000:237).

In ground stone analysis, the use efficiency argument first hinged on commonsense and then later hinged on analogical reasoning. I intend to evaluate the use efficiency argument with a performance analysis conducted with replica milling tools. These experiments may provide a source for an immanent analogy, which can shed light on the variation in an archaeological assemblage. Unlike Hard (1990), who moved from the immanent to the configurational realm when he equated the ability the process more meal with greater agricultural dependence, a behavioral condition, I will strictly employ immanent analogy. I engage analogical reasoning to understand how variation in the use surface area and the toolstone of prehistoric milling tools affects the amount of meal produced.

Hard’s (1990) argument that mano metric variation can be used to evaluate a prehistoric group’s relative degree of dependence on agriculture was steeped in analogical reasoning. Different kinds of analogies were drawn, but their differences remain unrecognized. The analogy that likens the formal properties of milling tools and pan mills appears to be an immanent analogy. The physical and mechanical properties and processes that ensure larger use surfaces require less time to crush a material to a certain particle size are immanent. In a different light, Hard (1990:140) found a correlation between metric variation observed within ethnographic mano assemblages and an ethnographic group’s dependence on agriculture. The contention that agriculturally dependent ethnographic groups used larger manos is an empirical generalization projected on to the archaeological past. Hard (1990:141148) went on to use archaeological mano metric data to assess a prehistoric group’s relative degree of agricultural dependence. The use of larger manos by more agriculturally dependent groups is a behavioral configuration. Hard (1990) drew a configurational analogy from ethnographic data and used it as if it were immanent to gain an understanding of archaeological data. This is simply the understanding of the present. Confusing the two kinds of analogy in this manner excludes the possibility of change and is inconsistent with an archaeology geared toward the examination of change through time.

The Rio Puerco Valley Project The Rio Puerco Valley Project was a large-scale project involving survey, testing, and excavation of archaeological sites in the middle Rio Puerco Valley of the East in northwestern New Mexico (Baker 2003:5). Cynthia Irwin-Williams of Eastern New Mexico University (ENMU) initiated the project in 1970 and it ran through 1981. The study area is located between Township 16 and 12 North and Range 4 and 1 West of the New Mexico Prime Meridian in Sandoval County. It is located approximately 72.4 km (45.0 mi) northwest of Albuquerque. The main thrust of the project was the investigation and explanation of change in Ancestral Puebloan culture from A.D. 600 to 1300 (Baker 2003:5; Irwin Williams 2003:1). During the course of the project researchers discovered and documented thousands of archaeological sites, conducted intensive excavations at Guadalupe Ruin, the center of a Chacoan era community, and conducted test excavations at over 100 sites, many of which were part of the Chacoan era community centered at Guadalupe Ruin. Baker and Durand (2003), Durand and Durand (2000), Pippin (1987), and several ENMU graduate theses (e.g., Giacobbe 1999) reported the results of the Rio Puerco Valley Project. This work is of primary importance in at least two regards. First, it provides a way to anchor in time any observed variation in the Rio Puerco Valley mano assemblage. Second, it allows a greater understanding of the selective environment in which any observed variation may occur. I detail these important aspects in later chapters of this report.

Immanent properties and processes work to guide the amount of meal produced on milling tools of varying sizes and varying materials. A performance analysis involving experiments with replica tools may allow a clearer picture of the immanent characteristics of meal production. The experiments can become a source for an immanent analogy. Of course, human behavior, specifically skill and technique, also plays a part in the amount of meal produced. This is an aspect of the configuration that

8

Chapter III HYPOTHESIS

Leonard (2001:73-75) entertained a set of "thought experiments" (sensu Binford 1985:583; Dawkins 1999:3) concerning technology, efficiency, and natural selection. He argued that the time and energy spent at some mundane daily task adds up over the lifetime and even slight advantages in terms of efficiency may allow one to spend more time or energy on reproduction or parental investment, which should increase reproductive success. In a more direct manner, but cautionary of a research focus restricted to what he terms “engineering fitness”, Rindos (1984:40) stated that one of the required conditions of Darwinian evolution is "those traits that increase the efficiency of the organism in the environment tend to increase reproductive success and will be selected for.”

The design and performance analysis with replica manos, metates, peckingstones, and a grinding slab will test the following propositions concerning use efficiency as well as ease of manufacture and maintenance: (1)

There is no relationship between raw material and ease of manufacture.

(2)

There is no relationship toolstone and use efficiency.

(3)

There is no relationship between use surface area and use efficiency.

(4)

There is no relationship between toolstone and ease of maintenance.

between

A trait or trait state that is under selection has a distinctive temporal-frequency curve (O’Brien and Holland 1992:4950, Figure 1, 1996:190, Figure 10.1; O’Brien et al. 1994:265). The curve shows a relatively rapid increase in frequency then a steady deceleration and leveling as the trait becomes prevalent in a population. After some time, there is a rapid fall off with change in the selective environment or with selection favoring a different trait or trait state. Traits or trait states that are not under selection drift with fluctuating frequency. Figure 1 illustrates

The results of the design and performance analysis will allow one to determine how different trait states, i.e., attribute states, affect use efficiency. If a mano performs well with respect to use efficiency, then it may have a positive effect on the tool user’s potential adaptedness in certain selective environments. I aim to track the replicative success of artifacts with trait states having a positive effect on use efficiency by plotting the temporalfrequency distributions of pertinent artifact classes.

Figure 1. Hypothetical Temporal-Frequency Curves for Changes in Mano Use Surface Area (adapted from O’Brien and Holland 1992:Figure 1).

9

Differential Persistence of Variation in Prehistoric Milling Tools hypothetical temporal-frequency curves for changes in mano use surface area. In this scenario, manos with use surface areas measuring between 0.1 and 100.0 cm2 fluctuate in frequency through time and never predominate, indicating they are a product of stochastic processes or drift. Early in the represented temporal range, manos with use surface areas measuring between 100.1 and 200.0 cm2 predominate, peak in frequency, and experience a rapid fall off with a change in the selective environment that favors the larger manos with use surface areas measuring between 200.1 and 300.0 cm2. The process of natural selection partially explains the rise and fall in frequency of the two larger mano classes, but explanation remains incomplete without an historical understanding of the selective environment. The results of previous archaeological research in the Rio Puerco Valley provide a greater understanding of this selective environment.

In the following chapters, I present and evaluate the temporal-frequency distributions of pertinent artifact classes. The connection between the replicative success of artifacts and the potential reproductive success of individual users lies in the selectionist conception of phenotype (O’Brien et al 1994:268). Behaviors and the material products of behavior are components of the phenotype. In this way, one can evaluate the notion that a material product of a technological behavior is a human adaptation. I derive the following hypothesis from Darwinian evolutionary theory: (5)

10

If Proposition (2) or (3) is rejected, then the temporal-frequency distribution of the efficiency enhancing trait state will show that at some point in time it was subject to natural selection, in other words, it was an adaptation.

Chapter IV METHODS AND PROCEDURES

and smaller mesa tops in the vicinity. I manufactured one large and one small set from each material. The large vesicular basalt and sandstone sets are comparable in size, as are the small vesicular basalt and sandstone sets. The replica manos have a flat to slightly convex use surface in longitudinal cross-section and the metates have a flat to slightly convex transverse cross-section. In terms of traditional ground stone typology, the replicas are slab milling tools.

This chapter presents the techniques employed during the course of this investigation. I lay out the methods and procedures used during the design and performance analysis as well as the artifact analysis. The chapter details a methodology for data collection and artifact classification. Design and Performance Analysis O'Brien and his colleagues (1994:261) provided insight for conducting a design and performance analysis. Design analysis, which may involve experimentation, investigates the design and manufacture of a material item. Performance analysis involves experiments aimed toward understanding how well a material item functions in a specific activity. In other words, the concern is an understanding of the item's performance characteristics. Selectionists share the concern for performance characteristics with behavioral archaeologists (O'Brien et al. 1994:261; O'Brien et al. 1998:488; Schiffer and Skibo 1995:235, 1997:30; Schiffer et al. 1994:199; Skibo and Schiffer 2001). Schiffer and Skibo (1995:235) defined a performance characteristic as “the behavioral capabilities that an artifact must possess in order to fulfill its function in a specific activity.” The milling tool performance characteristics examined in the following experiments include use efficiency, ease of manufacture, and ease of maintenance.

An experimental run consisted of grinding corn on a mano-metate set for 10 minutes. I conducted 10 experimental runs with each set. I used dried, wholekernel, feed corn produced by Oñate Mills of Albuquerque, New Mexico. The corn appeared to be of the dent variety. I separated the resulting meal into a coarse and fine fraction by passing it through a flour crank-sifter. I weighed the fractions resulting from each experimental run. I suspected that tool material loss would contribute to these weights; therefore, I weighed the tools before and after each experiment and the difference in tool weight was subtracted from the fine meal weight because no larger pieces of material were observed in the coarse fractions. I measured milling tool efficiency as the amount of meal produced per unit of time. Evaluation of Propositions (1), (2), and (4) involved an experiment aimed at providing insight into raw material selection. Raw material selection is an aspect of the design process. Raw material selection may affect multiple performance characteristics including ease of manufacture, use efficiency, and ease of maintenance. Most likely, a single raw material will not simultaneously optimize all of these performance characteristics. The design process may involve compromise (Schiffer and Skibo 1995:236). Horsfall (1987:334), whose focus was milling tools, saw this in terms of a “conflict of (design) constraints.” She stated that, “there is never a ‘best’ solution to any problem. Instead the problem solution, as reflected in the particular artifact, represents a satisfactory response to a total set of particular constraints, or to a particular context, and there usually is more than one possible satisfactory solution” (Horsfall 1987:334). Compromise among “design constraints” is a likely source of the variation that one may observe in an archaeological assemblage. The design analysis clarified these conflicts and compromises and the performance analysis explored their effect on use efficiency.

The evaluation of Propositions (2) and (3) involved an experiment geared toward the investigation of use efficiency. As discussed in the Background for Research chapter, ground stone analysts have either assumed or lent some support to the idea that use surface area and raw material have performance-related consequences. The experiment conducted to test Proposition (2) and (3) involved grinding corn to meal on four replica manometate sets. I collected the sandstone and vesicular basalt for these sets from the Rio Puerco Valley. Collection areas contained talus materials located directly below a primary or exposed bedrock source. All collection areas were located near the valley bottom. Figure 2 presents the location of the collection areas. The sandstone from both collection areas appears to be from the lower portion of the Cretaceous-aged Gallup Formation. The vesicular basalt is from Plio-Pleistocene basalt flows that cap Mesa Chivato

11

Differential Persistence of Variation in Prehistoric Milling Tools

R3W #

T15N

#

$ Adapted from the following USGS 7.5 minute 1:24000 quadrangle maps: Guadalupe, NM 1995 (35107-E2) and Cabezon Peak, NM 1961, Photorevised 1989 (35107-E1)

N

#

Sandstone

$

Vesicular Basalt

%

0

0.5 0

0.5

1 Miles 1 Kilometers

Figure 2. Location of Collection Areas.

12

NEW MEXICO

Chapter IV: Methods and Procedures study of human adaptedness and adaptation. If a tool performs well with respect to some performance characteristic, then it may have a positive effect on the tool user’s potential adaptedness in certain selective environments.

I tested Proposition (1) during the manufacture of the four replica manos. Ground stone analysts have noted that evidence of initial shaping during manufacture can include pecking, grinding, and flaking (e.g., Adams 1996:3). Because lithic tools are a product of a subtractive technology, I measured ease of manufacture as the amount of material removed by pecking or grinding per unit of time, but I certainly realize that this is not the only conceivable measure. I alternately pecked each large mano preform to manufacture manos of comparable size. I used a single chert peckingstone. Replication experiments have hinted at the efficacy of chert pecking stones in shaping ground stone tools (Pond 1930:75, 81). Fieldworkers commonly find pecking stones of siliceous material in association with milling tools or milling tool facilities in archaeological contexts (e.g., Murrell 2004:122, 126, Figure 7.1, Table 7.6). The duration of each pecking episode was 10 minutes. I monitored material removal by weighing the preform after each episode of pecking. I ran each experiment 10 times.

Artifact Analysis Archaeologists studying the evolution of technology must remember that, as Dunnell (1995:34) stated, “Evolution explains variation. Consequently, the archaeological record has to be described as variation.” Traditional types, for example one-hand and two-hand manos, obscure variation because they are often essentialist constructs. From an essentialist perspective, things are similar because they share essential properties (Lyman et al. 1997:4). They approximate an ideal and variation is noise. From a materialist perspective, the focus is uniqueness and variation. Mayr (1994) characterized these ontological differences as typological thinking and population thinking, respectively. He stated, “For the typologist, the type (eidos) is real and the variation an illusion, while for the populationist the type (average) is an abstraction and only variation is real” (Mayr 1994:158). Mayr (1977:325, 1994:157-158) believed that Darwin’s replacement of typological thinking with population thinking is one of his greatest scientific contributions and among “the most drastic conceptual revolutions in Western thought.” By embracing Darwinian evolutionary theory and a materialist ontology, archaeology becomes an historical science capable of tracking change in archaeological phenomena through time rather than just measuring difference between phenomena (Lyman et al. 1997:4).

To further evaluate Proposition (1), I alternately ground each small mano perform on a sandstone slab to produce usable manos of comparable size. I wet the preform and slab to facilitate grinding. Replication experiments have suggested that the use of water is beneficial in maintaining a rough surface on sandstone slabs used to shape ground stone tools (Pond 1930:77). I monitored material removal in the same manner, and again, I conducted 10 10-minute experimental runs. Flaking posed difficult control issues because the amount of material removal is partly dependent on the location of the point of impact, among many other factors. I offer only subjective observations regarding flaking in the evaluation of Proposition (1).

Ground stone analysts commonly set up a strict dichotomy for mano classification and a strict trichotomy for metate classification. For instance, a mano is a one-hand or twohand type, and a metate is a basin, trough, or slab type. This practice obscures considerable variation. The analyst may see the types as having an empirical existence rather than as a unit imposed on the variation in the empirical world for the purposes of measuring that variation. In this instance, the focus is on the variation between types rather than the total range of variation. The analyst is pursuing a typological thinking that I attempted to avoid in the following analysis. This discussion also points to the distinction between empirical and theoretical units (Dunnell 1986:151-153). The attributes I monitored are theoretical units informed by design and performance analyses and chosen to measure the differential persistence of functional variation through time. The standard one-hand and two-hand mano dichotomy often involves empirical units. In other words, the researcher sees one-hand and two-hand manos as having an empirical existence with discrete functions. For instance, the researcher views one-hand manos as generalized tools used to process a variety of materials, while two-hand

Proposition (4) was partly tested during the previously described pecking experiment. Ground stone analysts have often commented that mano and metates may exhibit pecking across the use surface (Adams 1996:3; Woodbury 1954:54). This is the result of maintenance aimed at sharpening or roughening the use surface to make it more effective during the grinding process. I contend that one measure of the ease of maintenance is the amount of material removed by pecking per unit of time. Proposition (4) was also partially evaluated during the meal production experiments. I assume that more durable milling tools require less maintenance. Tool weights taken after each grinding episode allow one to approximate tool weight loss, which may provide insight into tool durability. An understanding of mano and metate design and performance characteristics was the aim of these experiments. The experiments were an initial step in a

13

Differential Persistence of Variation in Prehistoric Milling Tools sand grains cemented by silica, carbonates, iron oxide, or clay. The sandstone of numerous geologic formations is available in the Middle Rio Puerco Valley; however, it is unlikely that all contain sandstone suitable for milling tools. Quartzite or metaquartzite is a metamorphic rock primarily composed of quartz. It is the result of a metamorphism involving heat and pressure of rock originally formed in a sedimentary context, usually sandstone. Quartzite is available from terrace gravels in the valley (Brett 2003:Tables 7.2 and 7.3).

manos were parts of specialized tool kits used to process corn. Mano Attribute Analysis I collected attribute-level data during a macroscopic examination and measurement of all whole manos recovered from intensively excavated sites, tested sites, and sites with mapped surface collections during the Rio Puerco Valley Project. Manos have at least one use surface and display evidence of manufacturing by flaking, pecking, grinding, or some combination of these techniques along tool edges or non-use surfaces, or manos display evidence of maintenance in the form of pecking across a use surface. A mano’s use surface is the area that contacted the metate during use. It often appears as a faceted area, which may also exhibit striations, produced by material removal during use. In short, a mano is a formal handstone exhibiting evidence of manufacture and/or maintenance.

To monitor variation within vesicular basalt and sandstone, I made observations on a number of attributes that may affect mano performance characteristics. I made all observations in the central portion of the mano’s use surface. With the aid of an Amstrat American/Canadian Stratigraphic card, I measured sandstone texture. Table 1 presents grain size ranges. I conducted a Hydrochloric (HCl) acid effervescence test to evaluate the sandstonecementing matrix. I diluted the acid with distilled water to produce a five percent solution. I dispensed the solution with a dropper. If there was some degree of effervescence, I used several drops and only recorded the last reaction to ensure that the cementing matrix produced the reaction rather than a surface accumulation of carbonates. Manos that showed some degree of effervescence most likely contain carbonates in the cementing matrix, while those that showed no effervescence most likely contain a silicacementing matrix. The sandstone with silica cement is more durable relative to those with carbonate cement. For the vesicular basalt manos, I placed the stratigraphic card on the central portion of the use surface and counted the number of vesicles in a 5 cm transect. I also measured the maximum diameter of the largest vesicle in this transect to the nearest tenth of a centimeter. These measurements may provide an index to vesicular basalt surface texture.

Raw Material Attributes. The raw materials most likely represented in the mano assemblage include basalt, vesicular basalt, sandstone, and quartzite. Basalt is a dark colored, fine-grained, volcanic igneous rock. The matrix may include phenocrysts. These are usually dark colored minerals. Basalt originates from massive lava flows. Vesicular basalt forms when trapped gases expand during the cooling process. This leaves open vesicles or cavities in the material. Plio-Pleistocene-aged basalts occur as flow remnants that cap Mesa Prieta and Mesa Chivato, which are landforms that bound the Rio Puerco Valley (Nials 2003:29-30). Basalt is a constituent of the terrace gravels occurring within the valley. Sources also include plugs, dikes, and sills exposed in the valley (Brett 2003:140). Sandstone is sedimentary rock consisting of

Table 1. Sand Grain Size Ranges. Wentworth Class Coarse Sand Medium Sand Fine Sand

Size Range (mm) 0.500-1.000 0.250-0.500 0.125-0.250

Manufacturing and Maintenance Attributes. I recorded the presence or absence of manufacturing flaking, pecking, and grinding as well as maintenance pecking. Flaking appears as negative flake scars or remnant negative flake scars. Pecking appears as profuse, small, basin-shaped areas of material removal. On vesicular basalt, pecking is more difficult to identify, but often appears as areas of subtle step fracturing of the material between vesicles. Grinding appears as faceted areas, which may also exhibit striations.

φ Scale 1 to 0 2 to 1 3 to 2

the number of use surfaces and whether they were adjacent or opposing surfaces. I also recorded use surface outline form and use surface longitudinal cross-section form. Figure 3 presents the outline forms and Figure 4 presents the longitudinal cross-section forms. Metric Attributes. I monitored a number of metric attributes including length, width, and thickness as well as use surface length and width. Length, width, and thickness are perpendicular maximum linear dimensions. I used large capacity calipers to take all measurements to the nearest tenth of a centimeter. After taking the use surface length and width measurements, I calculated the

Morphological Attributes. I documented several morphological attributes of mano use surfaces. I recorded

14

Chapter IV: Methods and Procedures approximate use surface area. For oval or elliptical-shaped use surfaces, area was calculated using the following equation: use surface area = (use surface length)(use surface width)(0.8). For subrectangular use surfaces, area was calculated using the following equation: use surface area = (use surface length)(use surface width)(0.9). I did not take use surface curvature or cross-section form into account in these calculations, again rendering them merely approximations.

Oval

Artifact Classification I constructed a paradigmatic classification (sensu Dunnell 1971) to examine change through time in certain functional aspects of prehistoric milling tools by tracking frequency changes in the resulting artifact classes. This purpose is in line with other studies that have employed paradigmatic classification (see O’Brien and Holland 1996:194). Several selectionists advocated the use of paradigmatic classification, in part, because it is successful in accommodating variation and it is adjustable; that is, the analyst can add or remove dimensions to serve different purposes (Jones et al. 1995:21; Leonard and Jones 1987:205-207; Lyman and O’Brien 2002:71-73; O’Brien and Holland 1996:194). Paradigmatic classification is a multidimensional array where each dimension is of equal importance. Each dimension encompasses a particular attribute and its various attribute states, which can also be termed modes. The intersections of dimensions generate artifact classes.

Elliptical

Subrectangular

Figure 3. Use Surface Outline Forms.

Figure 5 illustrates a hypothetical two-dimensional classification for manos. The dimensions are raw material and use surface area. Nine artifact classes result from the intersection of the dimensions. In this hypothetical classification, I set the use surface area modes in a completely arbitrary manner. In the following analysis, I explored the range of variation in this dimension with a histogram. I attempted to set the modes to correspond with modality observed in the histogram. To incorporate variation in raw material, such as textural variation, or morphological variation, I could add dimensions and expand this hypothetical classification. I used artifact classes derived in this manner to track artifact change through time with temporal-frequency distributions. The manos in the Rio Puerco Valley assemblage were amenable to temporal placement via spatial association with ceramic assemblages included in Durand and Hurst’s seriation (2003).

Slightly Convex

Convex, Ground Ends

Flat

Temporal Classification of Artifacts Mano Use Surface

A total of 238,115 pottery sherds from over one thousand tested and surveyed sites in the Rio Puerco Valley were subjected to a rough-sort typological analysis (Hurst 2003:55). Design styles, surface treatments and, in some instances, temper composition are the basis of the

Mano Outline

Figure 4. Use Surface Longitudinal Cross-section Forms.

15

Differential Persistence of Variation in Prehistoric Milling Tools

Use Surface Area B. 100.1-200.0 cm2

C. 200.1-300.0 cm2

1A

1B

1C

2A

2B

2C

3A

3B

3C

A. 0.1-100.0 cm

Raw Material

1. Sandstone

2. Vesicular basalt

3. Quartzite

2

Figure 5. Hypothetical Paradigmatic Artifact Classification. stone artifacts, from both excavated and surveyed sites. I merged the database generated during the mano attribute analysis and artifact classification with a database containing information about the seriation groups represented at each site. I keyed this merger to site number, and in a few instances to site subdivisions. In most cases, the ceramic analysts assigned multiple seriation groups to a single site. I constructed temporal classes that combined sequent seriation groups into classes with approximately 100-year time ranges. If a mano was associated with multiple temporal classes, then I observed that mano for each associated class. For occupations classified as Archaic and Basketmaker II on the basis of material remains other than ceramic artifacts, I classified the manos as Aceramic. For occupations lacking a seriation group assignment and classified as Basketmaker III and early Pueblo I by the analysts, I classified the manos as Early Ceramic to A.D. 800. I eliminated artifacts from Navajo affiliated occupations and those lacking seriation group information, or a definite or probable confidence level. I assigned each of the remaining artifacts to one or more of the following seven temporal classes representing the Archaic and Ancestral Puebloan occupation of the study area: Aceramic, Early Ceramic to A.D. 800, A.D. 800 to 900 (seriation groups 1-3), A.D. 900 to 1000 (seriation groups 4-8), A.D. 1000 to 1100 (seriation groups 9-11), A.D. 1100 to 1200 (seriation groups 12-14), and A.D. 1200 to 1300 (seriation groups 15-17).

classification. Hurst (2003) laid out the necessary conditions for type membership. A total of 5610 sherds from approximately 60 analytic proveniences in excavation units exposing stratified deposits at excavated and tested sites were seriated using multi-dimensional scaling (Durand and Hurst 2003:125-126, Table 6.5). The scaling scattergram was segmented using cluster analysis. Segmentation resulted in 17 seriation groups that were then given a mean ceramic date and date range using the few tree-ring and archaeomagnetic age determinations available from the project and supplemented by date ranges derived from tree-ring samples associated with pottery types reported by Breternitz (1966). Durand and Hurst (2003) and Hurst (2003) discussed the methodology and the resulting temporal framework, which ranges from approximately A.D. 800 to 1300 with seriation groups spanning approximately 40 years. Using data derived from the rough sort analysis, the analysts then placed the unexcavated sites in time by using a coefficient of similarity to compare the pottery collection from each site to the composite pottery profiles generated by the cluster analysis (Durand and Hurst 2003:119, 131-132). The analysts classified each site occupation represented by a particular seriation group as definite, probable, and possible (Durand and Hurst 2003:132). I used only definite and probable occupations in this research. This temporal framework allows researchers to place other aspects of material culture in time, including ground

16

Chapter V RESULTS

In an archaeological assemblage, milling tools often do not display evidence of all of these techniques. The use of one technique may obliterate the evidence of a technique used earlier in the manufacturing process. Often archaeological milling tools exhibit evidence of one or some combination of techniques. Less often, this evidence appears superimposed providing insight into the sequence of techniques used during the manufacturing process.

This chapter presents the results of the design and performance analysis as well as the artifact analysis. I provide the results of these analyses in narrative, graphic, and tabular form. I evaluate the testable propositions and the hypothesis. I discuss the implications of these results in this chapter and in the subsequent chapters. Design and Performance Analysis Experimental treatments of milling tool manufacture and maintenance are sorely lacking in the archaeological literature. Notable exceptions include the early replication work of Havlor Skavlem (Pond 1930), who dealt with ground stone tool manufacture, and the recent work of Wright (1993), who focused on milling tool use, but also showed concern for tool maintenance. To this point, the predominant concern of those conducting ground stone experimental studies has been use or use efficiency (e.g., Adams 1989b, 1993, 1999; Mauldin 1993) and use alteration signatures (e.g., Adams 1988, 1993; O’Brien 1994; Zier 1981). One of the explicit concerns of this research was milling tool manufacture and maintenance. In the following, I present the results of a design and performance analysis aimed toward an understanding of milling tool performance characteristics as well as their interplay in the design process and how they may affect potential human adaptedness. In addition to a concern with use efficiency, I also examined ease of manufacture and ease of maintenance.

To evaluate Propositions (1) through (4), I manufactured four replica mano-metate sets. Figures 6 through 9 illustrate these sets. Figure 10 depicts a hammerstone (d) and three peckingstones (a-c) that I used to manufacture these sets. In addition to these tools, I used an Estwing rock hammer during the manufacture of the vesicular basalt metates. I did not use the manufacture of these metates to evaluate the testable propositions. I used a single peckingstone (Figure 10c) during the experiment designed to evaluate Proposition (1). Proposition (1) asserts that there is no relationship between raw material and ease of manufacture. I offer only subjective observations concerning this proposition and the flaking technique. The amount of material removed per unit of time was the measure that made ease of manufacture operational. During flaking, material removal depended on the placement and force of impact administered by the manufacturer to the raw material or preform with a hammerstone. Successful material removal also depended upon platform configuration. The sandstone was easily flaked. The vesicles in vesicular basalt seemed to inhibit the fracture initiated by the hammerstone impact to some degree. Vesicular basalt flakes often appeared chunky and lacked easily identifiable flake morphology; however, I easily removed material by flaking. I recognized no glaring differences in the ease of flaking to manufacture between the two materials.

The milling tool manufacturing process involves flaking, pecking, and grinding techniques. Milling tools in archaeological assemblages often display evidence of these techniques. In the course of the manufacturing experiments, it became apparent that these techniques were best applied in a serial fashion at different points in the manufacturing sequence. Flaking a preform allows the manufacturer to remove more material relative to the other techniques. Using this technique, the manufacturer can begin to rough out the selected raw material into a more usable form. Some selected raw materials may not require the relatively large-scale material removal enabled by the flaking technique. The pecking technique allowed more controlled and finer shaping of the raw material or preform. The grinding technique enabled small-scale material removal and relatively more controlled and finer shaping of the preform. These are simply subjective observations made during the course of experimentation.

I conducted a pecking experiment to evaluate Proposition (1). After ten runs of the pecking experiment, I had manufactured two usable manos with comparable use surface areas. Table 2 presents the results and Table 3 offers central tendency and dispersion statistics for preform weight loss. Figure 11 provides a graphic display of the variation in preform weight loss over the course of the experiments. Figure 12 provides graphic display of the central tendency and dispersion statistics for the batches

17

Differential Persistence of Variation in Prehistoric Milling Tools

Figure 6. Large Vesicular Basalt Mano-Metate Set.

18

Chapter V: Results

Figure 7. Large Sandstone Mano-Metate Set.

19

Differential Persistence of Variation in Prehistoric Milling Tools

Figure 8. Small Vesicular Basalt Mano-Metate Set.

20

Chapter V: Results

Figure 9. Small Sandstone Mano-Metate Set.

21

Differential Persistence of Variation in Prehistoric Milling Tools

Figure 10. Peckingstones and Hammerstone Used to Manufacture Replica Mano-Metate Sets.

22

Chapter V: Results Table 2. Results of the Pecking Experiment.

Preform Weight (g)

Experimental Run 1 2 3 4 5 6 7 8 9 10

Sandstone 2490 2396 2357 2273 2218 2197 2146 2119 2100 2082

Vesicular Basalt 1908 1855 1833 1795 1759 1709 1676 1639 1608 1580

Preform Weight Loss (g)

Sandstone 83 94 39 84 55 21 51 27 19 18

Vesicular Basalt 45 53 22 38 36 50 33 37 31 28

Table 3. Descriptive Statistics for the Pecking Experiment. Sandstone Preform Weight Loss (g) 10.0 18.0 94.0 49.1 45.0 29.2 59.5

Statistic N Minimum Maximum Mean Median Standard Deviation Coefficient of Variation

Vesicular Basalt Preform Weight Loss (g) 10.0 22.0 53.0 37.3 36.5 9.7 26.0

100

Sandstone Preform

90 80

Weight Loss (g)

70 60 50 40 30 20

Vesicular Basalt Preform

10 0 1

2

3

4

5

6

7

8

Experimental Run

Figure 11. Line Graph Depicting the Results of Pecking Experiment.

23

9

10

Differential Persistence of Variation in Prehistoric Milling Tools

100 90 80

Weight Loss

70 60 50 40 30 20 10

Sandstone Preform

Vesicular Basalt Preform

Figure 12. Boxplot Depicting Median, Interquartile Range, and Range of Values for Preform Weight Loss (g) During the Pecking Experiment. manos by pecking. Material inconsistencies influence variation in the amount of material that can be removed by pecking per unit of time.

of weight loss values. Cursory examination of these tables and figures showed that there is a greater range of variation in weight loss for the sandstone preform. Differences in sandstone cementation or, more likely, the weathering of the cementing matrix, may partially account for this relatively wide range. Some areas of the sandstone preform seemed more friable and it seemed easier to remove material in these areas. Figure 12 shows that the sandstone preform range of weight loss values subsumes the vesicular basalt preform range of values. A comparison of the means presented in Table 3 showed that, on average, I removed more material from the sandstone per 10-minute pecking episode. I conducted a two-tailed T-test to evaluate the observed differences in mean weight loss. The null hypothesis stated that the mean weight loss for the sandstone and the vesicular basalt performs is equal. With a confidence interval set at 0.05 and with equal variances not assumed, the null hypothesis stands (t=1.213, df=10.965, p=0.251). Proposition (1) also stands. The experimental results suggested that there is no significant difference between the ease of manufacturing sandstone and vesicular basalt

To further evaluate Proposition (1), I conducted a grinding experiment with sandstone and vesicular basalt preforms. I used a wet sandstone slab to shape the preforms. After ten experimental runs, I had manufactured two usable manos with comparable use surface areas. Table 4 presents the results and Table 5 offers central tendency and dispersion statistics for preform weight loss. Figure 13 provides a graphic display of the variation in preform weight loss over the course of the experiments. Figure 14 provides graphic display of the central tendency and dispersion statistics for the batches of weight loss values. A comparison of the means presented in Table 5 showed that, on average, I removed more material from the sandstone preform per 10-minute grinding episode. I conducted a two-tailed T-test to evaluate the observed differences in mean weight loss. I removed the outlier, which is evident in Figure 14, from the vesicular basalt batch of values. The null hypothesis stated that the mean

24

Chapter V: Results Table 4. Results of the Grinding Experiment. Experimental Run 1 2 3 4 5 6 7 8 9 10

Preform Weight (g)

Sandstone 1733 1707 1681 1659 1642 1622 1595 1570 1545 1523

Vesicular Basalt 1070 1059 1051 1045 1039 1032 1022 1015 1008 999

Preform Weight Loss (g)

Sandstone 27 26 26 22 17 20 27 25 25 22

Vesicular Basalt 18 11 8 6 6 7 10 7 7 9

Table 5. Descriptive Statistics for the Grinding Experiment. Sandstone Preform Weight Loss (g) 10.0 17.0 27.0 23.7 25.0 3.3 13.9

Statistic N Minimum Maximum Mean Median Standard Deviation Coefficient of Variation

Vesicular Basalt Preform Weight Loss (g) 10.0 6.0 18.0 8.9 7.5 3.6 40.4

30

Sandstone Preform

25

Weight Loss (g)

20

15

10

5

Vesicular Basalt Preform 0 1

2

3

4

5

6

7

8

Experimental Run

Figure 13. Line Graph Depicting the Results of the Grinding Experiment.

25

9

10

Differential Persistence of Variation in Prehistoric Milling Tools

30

Weight Loss

25

20

15

10

5

Sandstone Preform

Vesicular Basalt Preform

Figure 14. Boxplot Depicting Median, Interquartile Range, Range of Values, and Outlier for Preform Weight Loss (g) During the Grinding Experiment. There were notable differences in the ease of manufacturing sandstone and vesicular basalt manos by grinding, which allows only small-scale material removal. Sandstone manos were easier than vesicular basalt manos to manufacture by grinding on a sandstone slab. Overall, it appears that sandstone manos were only slightly easier to manufacture. This was most apparent when it came to small-scale material removal by grinding. There was little difference in ease of manufacture when it came to largerscale material removal by flaking and pecking. These conclusions partially rest on the statistical comparison of mean weight loss. I must caution that the mean statistic is an abstraction. The underlying variation is what is real.

weight loss for the sandstone and the vesicular basalt performs is equal. With a confidence interval set at 0.05 and with equal variances not assumed, the null hypothesis was rejected (t=13.095, df=13.948, p