Primate and Human Evolution

Primate and Human Evolution provides a synthesis of the evolution and adaptive significance of human anatomical, physiological, and behavioral traits. Using paleontology and modern human variation and biology, it compares hominid traits to those of other catarrhine primates both living and extinct, presenting a new hominization model that does not depend solely on global climate change, but on predictable trends observed in catarrhines. Dealing with the origins of hominid tool use and tool manufacture, it compares tool behavior in other animals and incorporates information from the earliest archeological record. Examining the use of non-human primates and other mammals in modeling the origins of early human social behavior, Susan Cachel argues that human intelligence does not arise from complex social interactions, but from attentiveness to the natural world. This book will be a rich source of inspiration for all those interested in the evolution of all primates, including ourselves.

SUSAN CACHEL is Associate Professor of Physical Anthropology at Rutgers University. She is a member of the Rutgers Center for Human Evolutionary Studies, and is an instructor and researcher at the Koobi Fora Field School in Kenya.

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Cambridge Studies in Biological and Evolutionary Anthropology

Series editors

HUMAN ECOLOGY
C. G. Nicholas Mascie-Taylor, University of Cambridge
Michael A. Little, State University of New York, Binghamton
GENETICS
Kenneth M. Weiss, Pennsylvania State University
HUMAN EVOLUTION
Robert A. Foley, University of Cambridge
Nina G. Jablonski, California Academy of Science
PRIMATOLOGY
Karen B. Strier, University of Wisconsin, Madison

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Primate and Human Evolution

Susan Cachel

Department of Anthropology Rutgers University

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CAMBRIDGE UNIVERSITY PRESS
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Cambridge University Press
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Published in the United States of America by Cambridge University Press, New York

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© Cambridge University Press 2006

This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements,
no reproduction of any part may take place without
the written permission of Cambridge University Press.

First published 2006

Printed in the United Kingdom at the University Press, Cambridge

A catalog record for this publication is available from the British Library

ISBN-13 978-0-521-82942-7 hardback
ISBN-10 0-521-82942-9 hardback

Cambridge University Press has no responsibility for the persistence or accuracy of URLs for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

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I dedicate this book to my parents, Henry Cachel and Leokadia Piotrowska Cachel.

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Contents

		Preface	page xv
		Acknowledgments	xvii
1.		Introduction	1
		The primate order	1
		Ape and monkey bias	11
		Evolution before natural selection	13
		1858–1859: The advent of natural selection theory	15
		Essentialism versus population-thinking	20
		1863: Thomas Henry Huxley and the place of humans in nature	22
2.		A brief history of primatology and human evolution	26
		Introduction	26
		Antiquity and the Middle Ages	30
		The Renaissance to the late eighteenth century	32
		The nineteenth century	36
		The early twentieth century	37
		The “new” physical anthropology	43
		1959 – annus mirabilis	44
		The baboon renaissance	50
		Sociobiology and behavioral ecology	53
3.		The catarrhine fossil record	56
		The geological time scale	56
		Major features of primate evolution	56
		The shape and pattern of primate evolution	57
		The early catarrhine primates	62
		Hominoid systematics	64
		The Miocene hominoid radiation	65
		Community structure and competition between primate species	70
		The end of the hominoid radiation and the rise of the cercopithecoids	73
		Climate change in the late Miocene and the first hominids	76
4.		Primate speciation and extinction	81
		Primate speciation and extinction in the geological past	81
		Speciation in modern primates	86
		Extinction in modern primates	94
5.		Anatomical primatology	107
		Introduction	107
		Phylogeny and cladistic methodology	107
		Adaptation and the “adaptationist program”	115
		Studying adaptation	117
		The functional morphology of fossil species	119
		Ontogeny and anatomical genomics	124
		Phenotypic variability	126
6.		Captive studies of non-human primates	128
		Introduction	128
		The influence of captivity on behavior	128
		Harry Harlow’s research	130
		An inventory of abnormal captive behaviors	130
		Biomedical primatology	137
7.		What can non-human primate anatomy, physiology, and development reveal about human evolution?	141
		The catarrhine substrate	141
8.		Natural history intelligence and human evolution	146
		Introduction	146
		Ideas on the origins of hominid intelligence	150
		Hominid attention to natural history	155
		Animal behavior and artificial intelligence	157
		Natural history intelligence	159
		Problems with the social cognition model	163
		Further primatological evidence against social cognition as a generator of intelligence	167
		Brain mechanisms underlying natural history intelligence	171
		Other tests of the social cognition theory	179
		Natural history intelligence over the course of human evolution	180
		Conclusions	182
9.		Why be social? – the advantages and disadvantages of social life	185
		Why be social?	185
		How to become social	188
		Explanations of primate social complexity	194
		What is the catarrhine substrate for sociality?	194
10.		Evolution and behavior	196
		Proximate and ultimate factors in behavioral evolution	196
		Factors limiting population size	197
		Diet and foraging behavior	198
		Cultural traditions	199
		Phylogenetic inertia and phylogenetic constraint	201
11.		The implications of body size for evolutionary ecology	203
		Introduction	203
		Measuring body size in fossil species	208
		Body size and paleocommunity reconstructions	209
		Body size and behavior	213
		The all-too-familiar use of sexual dimorphism to infer sociality in fossil species	215
		Reversible body size changes in individuals	218
		Size and shape changes: adaptation and plasticity	220
		Population-level differences in body size	231
		What can be inferred from body size in fossil species?	236
		The sweating response, body shape, and heat adaptation	239
		The evolution of body size in primates	245
		Conclusions	248
12.		The nature of the fossil record	252
		Does the fossil record faithfully record past events?	252
		Decimation and recovery from extinction	259
		Rates of evolutionary change	262
		Time-averaging	265
		Taphonomy and experimental studies	266
13.		The bipedal breakthrough	271
		Introduction	271
		Ape models for bipedal origins	271
		Behavior and morphology	276
		Bipedal efficiency	277
		Paleoenvironment	280
		Bipedal origins	280
		Lessons from Oreopithecus	288
		A mixture of morphologies	290
14.		The hominid radiation	292
		The earliest hominids	292
		Plio-Pleistocene hominids	293
		The single-species hypothesis	293
		Sympatry and multiple hominid niches	298
		Sexual dimorphism and niche structure	303
		The origin of genus Homo	305
		Hominid dispersion from sub-Saharan Africa	306
		Asian ape-men: Early ideas about hominid origins in Asia	306
		The origins of anatomically modern humans	308
		Genetic variation in modern humans	310
15.		Modeling human evolution	311
		Baboon models	311
		Referential and conceptual models	313
		A “composite mammal” model	314
16.		Archeological evidence and models of human evolution	317
		Human antiquity	317
		Recognition that the archeological record is not coeval with the human paleontological record	321
		Bone modification and inferences of hominid behavior	329
		Climatic events and the archeological record	331
		“Man the Hunter” and the new physical anthropology	333
		Food, food-sharing, and division of labor	336
		Pair-bonding	340
		Taphonomy and the nature of “sites”	343
		The hominization process	344
17.		What does evolutionary anthropology reveal about human evolution?	351
		Phenotypic change and “contemporary evolution”	351
		Body size and shape changes	353
		What factors are responsible for the origin of generalized species?	361
		Tool behavior and technology	366
		Language	369
		Early hominid sociality	371
18.		Final thoughts on primate and human evolution	382
		Speciation, extinction, and other evolutionary processes	382
		Terrestrial life and bipedality	384
		Tool behavior	385
		Intelligence	386
		Complex sociality	387
		References	389
		Index	452

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Preface

This book is not intended to be an introductory textbook in physical anthropology, although it addresses most of the topics found in such texts. Many of the ideas developed here were originally presented to Rutgers University students in advanced undergraduate or graduate courses or in colloquia in the Rutgers Department of Anthropology or in the Rutgers graduate interdepartmental Quaternary Studies Seminar.

   The focus of this book is the fundamental relationship between humans and other Old World higher primates. Many books have been written about primate behavioral ecology, and a mountain of books have been written about human evolution. However, fewer volumes deal with both human and non-human primates, and those that do so tend to emphasize the behavioral continuity between human and non-human. I will take a different approach here, because I will emphasize profound discontinuity between human and non-human primate cognition and sociality. I will also introduce evidence from Plio-Pleistocene archeology. Archeology is the description and interpretation of human behavior gleaned from the material residues of that behavior, and the spatial and temporal context of these residues. Thus, archeology contributes a line of evidence about the behavioral component of the human phenotype that is independent from inferences of behavior based on human paleontology and functional anatomy.

   The strong evolutionary relationship that unites all Old World higher primates is reflected in the existence of the taxonomic category Catarrhini, which includes humans, Old World monkeys, lesser apes, and great apes. In this book I emphasize that an understanding of the strong evolutionary coherence of catarrhine primates can illuminate a number of problems in human evolutionary history, such as the advent of bipedalism, factors affected by body size or sexual dimorphism, speciation, species richness, and extinction. However, while emphasizing the anatomical and physiological coherence of catarrhine primates, I also emphasize the behavioral distinctiveness of living and fossil humans. In particular, I will argue that the behavioral ecology of living non-human primates yields no special insight into the origins of human intelligence, tool behavior, or sociality. In this sense, I am an apostate from primatology.

   Yet, how can one study the origins of intelligence, tool behavior, or sociality without invoking the evidence of the behavior and ecology of living non-human primates? The earliest archeological record reveals important clues about human attentiveness to the natural world and human ability to manipulate the natural world. I introduce a new model of hominization, with a distinctive type of attentiveness to the natural world being a major trigger for hominization. Climatic change is usually invoked as an important or crucial factor in human evolution, but here I downplay environmental change as a major factor in hominization. Attentiveness to the natural world influences higher cognitive functions. Rudiments of this change in cognition already appear at the beginning of the hominization process, rather than being a late arrival that culminates with the appearance of modern humans. The origins of human sociality can be inferred from a broad comparative base of mammalian social organization, creating a “composite mammal” model, rather than one relying solely on the behavioral ecology of the living chimpanzee species. Studying the forces of natural selection that mold differences in sociality among mammals allows one to speculate about selection pressures that molded early hominid sociality.

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Acknowledgments

Several colleagues read drafts of this book, and commented on portions of it. These are Drs. John W. K. Harris (Rutgers University), Ryne Palombit (Rutgers University), Carmel Schrire (Rutgers University), and Matt Sponheimer (University of Colorado at Boulder). Any errors that remain are my own. Dr. Robert J. Blumenschine, Director of the Center for Human Evolutionary Studies in the Department of Anthropology, Rutgers University, provided funds for manuscript preparation and wrangled up new computer hardware when technical difficulties arose. Dr. Emma Mbua, Head of the Division of Paleontology, National Museums of Kenya, Nairobi, granted me access to fossil human and non-human primate material. Drs. Phillip V. Tobias and Ronald J. Clarke, University of the Witwatersrand Medical School, Johannesburg, and Dr. Francis Thackeray, Transvaal Museum, Pretoria, granted me access to fossil human material, and Ron Clarke and Dr. Katherine Kuman invited me to explore several of the major South African sites. Ms. Purity Kiura (Rutgers University) provided me with photos taken during her thesis research on living humans in northern Kenya. During the course of our routine work together teaching in the Koobi Fora Field School, John (Jack) Harris also took me to all of the major and many of the minor paleoanthropological sites in the Koobi Fora region, east of Lake Turkana in northern Kenya. Because Jack was involved with many of the original excavations, and because his students continue to locate and excavate sites in this area, he is a fount of information about the discovery, analysis, and interpretation of Plio-Pleistocene paleoanthropological material in the Turkana Basin.