Agustin Fuentes Biological Anthropology Concepts and Connections, 2nd Edition 2011

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Biological Anthropology: Concepts and Connections


Biological Anthropology: Concepts and Connections

S E CO N D E D IT IO N

Agustn FuentesUniversity of Notre Dame

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Published by McGraw-Hill, an imprint of The McGraw-Hill Companies, Inc., 1221 Avenue of the Americas, New York, NY 10020. Copyright 2012, 2007. All rights reserved. No part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written consent of The McGraw-Hill Companies, Inc., including, but not limited to, in any network or other electronic storage or transmission, or broadcast for distance learning. This book is printed on acid-free paper. 1 2 3 4 5 6 7 8 9 0 QVR / QVR 9 8 7 6 5 4 3 2 1 ISBN: 978-0-07-811700-8 MHID: 0-07-811700-3 Sponsoring Editor: Gina Boedeker Marketing Manager: Patrick Brown Developmental Editor: Craig Leonard Production Editor: Rachel J. Castillo Manuscript Editor: Jan Fehler Design Manager: Cassandra Chu Text Designer: Jenny El-Shamy Cover Designer: Linda Beaupr Photo Research Manager: Brian Pecko Buyer: Tandra Jorgensen Composition: 9/13 ITC Bookman Light, Aptara, Inc. Printing: 45# New Era Matte Plus, Quad/Graphics Vice President Editorial: Michael Ryan Editorial Director: William R. Glass Director of Development: Nancy Crochiere Cover: Adult footprint from the trail of fossilized hominid footprints discovered in volcanic ash at Laetoli, Tanzania in 1978: John Reader/Photo Researchers, Inc.; Modern human walking on beach: Steve Mason/Getty Images. Credits: The credits section for this book begins on page 363 and is considered an extension of the copyright page. Library of Congress Cataloging-in-Publication Data Fuentes, Agustn. Biological anthropology : concepts and connections / Agustin Fuentes.2nd ed. p. cm. Rev. ed. of: / Core concepts in biological anthropology / Agustin Fuentes. c2007. Includes bibliographical references and index. ISBN-13: 978-0-07-811700-8 (alk. paper) ISBN-10: 0-07-811700-3 (alk. paper) 1. Physical anthropology. I. Fuentes, Agustin. Core concepts in biological anthropology. II. Title. GN51.F83 2011 599.9dc22 2010045902 The Internet addresses listed in the text were accurate at the time of publication. The inclusion of a website does not indicate an endorsement by the authors or McGraw-Hill, and McGraw-Hill does not guarantee the accuracy of the information presented at these sites.

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This book is dedicated to three amazing teachers: my parents, Victor Fuentes and Elizabeth Fuentes, and my graduate mentor, Phyllis Dolhinow. The book itself is the result of all the students who sat through my lectures, asked questions, and pushed me to really, really think about what we teach and how we teach it. Because of them, I also dedicate this book to all who love the quest for knowledge and ask their teachers and themselves for more.


Brief Contents

PREFACE

xvi xxi

ABOUT THE AUTHOR

Introduction

3

Chapter 1 Introduction to Evolutionary Fact and Theory Chapter 2 Basics of Human Biology

13

45

Chapter 3 Introduction to Genetics and Genomics Chapter 4 Modern Evolutionary Theory Chapter 5 Primate Behavioral Ecology Chapter 6 Early Primate Evolution Chapter 7 Early Hominin Evolution

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95

119

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Chapter 8 Plio-Pleistocene Hominins and the Genus Homo Chapter 9 The Rise of Modern Humans

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257

Chapter 10 Human Biological Diversity in Context

297

Chapter 11 The Present and Future of Human EvolutionCREDITS GLOSSARY INDEX 370 363 366

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Contents

PREFACE xvi ABOUT THE AUTHOR xxi

Introduction FAQs For Biological Anthropology 3 How Old Is the Planet and What Organisms Have Lived on It Over That Time? 3 If Life on Our Planet Has Changed So Much Over Time, What About the Planet Itself? 6 Have Humans Changed? 6 Where Did Modern Science Come From? 7 Where Is Uzbekistan? 8 Chapter 1 Introduction to Evolutionary Fact and Theory 13

Anthropology Is the Study of Human and Nonhuman Primates 15 Anthropology Is a Scientic Discipline 16 Critical Thinking Is the Systematic Assessment of Information 16 The Scientic Method Is a Way of Testing Ideas About the World Around UsConnections: Thats a Fact, Jack . . . Or Is It? 19

18

Scientic Investigation Is a Collaborative Process 21 Evolutionary Theory Is the Cornerstone of Anthropology Evolution Is Both Fact and Theory 22Connections: Making a Monkey Out of You? 22

22

Early Explanations of Life Were Both Philosophical and Religious 23 The Scientic Revolution Opened the Door to Systematic Study of the World 25 Evolutionary Thought Emerged From Scientic Collaboration 26 Charles Darwin Proposed Natural Selection as the Mechanism of Evolution 31Connections: Can You Understand Evolution and Be Religious? 39

What We Know/Questions That Remain Summary 40 Critical Thinking 41 Resources 42 References 43 Chapter 2 Basics of Human Biology The Place of Human Beings in Nature Where Do Humans Fit In? 47

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45 47

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Connections: Why Do Monkeys Look Like Little People and Our Dogs Understand Us? 47

How Are Relationships Among Organisms Determined? Human Morphology: The Bodys Form and Structure 49 Tissues Cover Us and Bind Us Together 49 The Skeleton: Our Basic Form 50 The Musculature Interacts With the Skeleton 55Connections: My Bones Ache 55

48

All Mammals Share Common Skeletal Structures 55 Human Physiology: The Systems of the Body 57 The Circulatory and Respiratory Systems Transport Nutrients and More 57 The Nervous System and Brain Control the Actions of the Body and Assess the Organisms Surroundings 58 The Endocrine System Regulates and Communicates Hormonal Information Throughout the Body 60 The Digestive System Processes Nutrients 61 The Reproductive System Enables Us to Produce Ospring 62Connections: Whoa, Where Did That Come From? The Fascinating Development of Human Genitals 64

All of These Systems (and More) Are Interconnected What We Know/Questions That Remain 65 Summary 66 Critical Thinking 66 Resources 67 Chapter 3 Introduction to Genetics and GenomicsConnections: GeneWhat Is in a Word? 71

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69 70

Heredity Is the Passing of Genetic Information From Generation to Generation DNA Is the Molecule of Heredity 72 DNA Is Found in Cells 72 DNA Has a Specic Structure 73 DNA Has Three Main Functions 74Connections: Why It Is Important to Understand What DNA Does 82

Mendels Basic Model of Inheritance 82 Traits Are Passed From Generation to Generation 82 Mendels Work Continues to Inform Current Knowledge 84 The Relationship Between Genes and Traits Is Complex 85 Four Ways Genes Produce Traits 86 Are There Specic Genes for Certain Diseases? 87 Most DNA Doesnt Appear to Do Anything! 87 Does DNA Cause Certain Behaviors? 88Connections: My Genes Made Me Do It! 88

Population Genetics Helps Us Understand Evolution What We Know/Questions That Remain 90 Summary 91 Critical Thinking 91 Resources 92 References 93

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Contents

Chapter 4 Modern Evolutionary Theory

95

Evolutionary Change Occurs In Populations In Four Ways 96 Mutations Are Changes in the DNA 98 Gene Flow Is the Movement of Alleles Within and Between Populations 99 Genetic Drift Is a Change in Allele Frequency Across Generations Due to Random Factors 100 Current Concepts of Natural Selection Involve an Understanding of Genetics 101Connections: Survival of the Fittest? Not Really 104

The Four Core Processes Do Not Explain All Change 105 Speciation Is the Process by Which New Species Arise 108 Species Can Be Dened in Many Ways 108Connections: Species, Schmeecies . . . I Know One When I See It and So Do They 109

Subspecies Are Divisions Within a Species 110 Phyletic Gradualism and Punctuated Equilibrium: Dierent Paces of Change 111 Similarities Can Result From Either Parallel or Convergent Evolution 112 Biodiversity in Evolution: Why We Should Care About Biological Variation 113Connections: Why Conserve Stuff Anyway? 114

What We Know/Questions That Remain Summary 115 Critical Thinking 116 Resources 117 References 117 Chapter 5 Primate Behavioral Ecology

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119 120

Comparative Primatology Provides Insights Into Modern Human Behavior The Living Primates Are Widespread and Diverse 120 Comparing the Primates Helps Us Understand Behavior 127Connections: Monkey See, Monkey Do, and Humans Too? 129

To Study Behavior, We Have to Measure It 129 Specic Methodologies Are Used to Measure Primate Behavior 129 A Behavior Can Be Viewed From Five Perspectives 130 Behavior and Genetics Are Interconnected 131 Behavioral Ecology Provides the Basis for Evolutionary Investigations of Behavior 132 Socioecological Pressures Aect Organisms in Five Areas 132 Success of a Behavioral Adaptation Is Measured in Terms of Energy Costs and Benets 133 Reality Is More Complex Than Suggested by Cost-Benet Analyses 135Connections: Are All Men Jerks? 136

General Behavior Patterns in the Living Primates 137 Mother-Infant Bonds Are the Core of Primate Societies 137 There Are a Few Primary Grouping Patterns in Primates 138 Aliation and Grooming Are Important in Primate Societies 138 Hierarchies and Dominance Help Structure Primate Societies 139

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Dispersal and Life History Patterns Are Important to Social Behavior 140 Cooperation and Conict Are Integral to Primate Societies 141 Social Organization in Two Nonhuman Primate Societies: Macaques and Chimpanzees 141 Macaques: A Widespread Primate Genus 141 Chimpanzees: Our Closest Relatives 146 Humans Are Also Primates, and Human Behavior Has an Evolutionary History 151 Social Organization and Behavior in Humans 152 Comparisons With Macaques 152 Comparisons With Chimpanzees 153 What Is Uniquely Human? 154Connections: Why We Never Shut Up 154

What We Know/Questions That Remain 155 Conserving the Nonhuman Primates Is a Critical Challenge Summary 156 Critical Thinking 157 Resources 158 References 158 Chapter 6 Early Primate Evolution 161

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Fossils Provide Direct Evidence of an Organisms Existence 162 Humans Are Members of the Order of Mammals Called Primates A Very Brief History of the Mammals 165Connections: Homiothermy is Cool! 167

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Primates Are Mammals With Specic Characteristics 167 The Fossil Primates 168 The Earliest Possible Primates Are Found in the Paleocene 168 Why Did Primates Evolve Out of Early Mammalian Groups? 170 True Primates Appear in the Eocene 171 Anthropoids (Simiiformes) Radiate in the Oligocene 173Connections: Why Care About 30-Million-Year-Old Dead Primates? 174

Hominoid Primates Radiate During the MioceneConnections: Ok, So Is Gigantopithecus Bigfoot?

176181

Nonhominoid Anthropoid Primates Radiate During the Pliocene and Pleistocene 182 Evolutionary Relationships Among These Fossil Primates Are a Matter of Debate 182 What We Know/Questions That Remain 184 Summary 184 Critical Thinking 185 Resources 185 References 186 Chapter 7 Early Hominin Evolution 189191

Connections: Why Walking on Two Legs Makes Birth Painful for Mom

Classication of Hominids/Hominins Is a Subject of Debate Early Hominins Evolved Primarily in East Africa 195 Early Possible Hominins 196

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Hominins of the Middle and Late Pliocene Were Bipedal and Sexually Dimorphic 200Connections: Big Guys With Small Teeth Rock! 203

Were There Early Hominins in Southern Africa? 205 Evolutionary Relationships Are Unclear 205 Fossils Give Us Clues About Early Hominin Behavior 206 Habitat: Where They Lived 207 Diet: What Did They Eat, and How Did They Get It? 207 Tools: Did They Use Bone, Wood, or Stone Tools? 207 Social Life: How Did They Live Together? 208 The Bipedalism That Wasnt 208Connections: Hyenas, Wolves, and Saber-Toothed Cats, Oh My! 209

The Evolution of Bipedality Has Several Possible Explanations What We Know/Questions That Remain 211 Summary 212 Critical Thinking 213 Resources 213 References 214 Chapter 8 Plio-Pleistocene Hominins and the Genus Homo

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217

Changes at the Late Pliocene-Pleistocene Boundary 219 The Robust Hominins Had Unique Cranial and Dental Anatomy 220 The Genus Paranthropus: Hominins With Massive Chewing Adaptations 220 Robust Hominin Behavior 225 The Gracile Hominins Shared Characteristics With Both Earlier and Later Groups 226 Genus Australopithecus: Three Plio-Pleistocene Forms 226 Are These Australopithecines Ancestral to Humans? 230 Early Homo: A New Genus Emerges 231Connections: Where Is the Missing Link? 232

Gracile Hominin Behavior and the Advent of Biocultural Evolution The Genus Homo Diversies: The First Humans 237 A Classication Debate: One Genus but How Many Species? 238 Physical Characteristics of H. erectus 240 Geographic Distribution of H. erectus 241Connections: Is that You Frodo? Ardi? 243

235

When Did Hominins Expand Beyond Africa? 245 Why Did Hominins Expand Beyond Africa? 246 H. erectus Material Culture and the Expansion of the Biocultural Evolution 246Connections: Whats the Deal With Fire? 250

What We Know/Questions That Remain Summary 252 Critical Thinking 253 Resources 253 References 254 Chapter 9 The Rise of Modern Humans

251

257

Archaic Homo Sapiens and the Changing Speed of Innovation 259 The Oldest Archaic Human Fossils Are Found in Africa 259

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Archaic Human Fossils Are Found Across Eurasia 261 Archaic Humans Are Found in China but Not in Southeast Asia Is Homo heidelbergensis a True Species? 264 The Neanderthals Were Not as Dierent as First Thought, but They Were Dierent 264Connections: Im No Neanderthal! 266

262

Material Culture of the Archaic Humans 267 Increased Complexity in Tool Use and Hunting 267 Dietary and Behavior Changes Associated With New Tool Kits 268 Social Patterns: High Levels of Communal Cooperation 269 Postmortem Modication of Bodies 270 Why Did the Neanderthals Disappear? 270 The Appearance of Anatomically Modern Homo sapiens 272 Anatomically Modern Humans Are Dened Morphologically, Not Behaviorally 272 The Earliest Anatomically Modern Fossils Are Found in Africa 273 The Eurasian Record Demonstrates the Spread of Modern Humans 274 Material Culture Becomes Very Complex With the Appearance of Modern Humans 277 Blades and Associated Industries Revolutionized the Human Tool Kit 277 Changing Technologies and Behavioral Patterns Aected Diet 279 Modern Humans Used Art and Symbols 279Connections: Art for Arts Sake? 281 282

Burial of the Dead Was Ubiquitous and Postmortem Modication Common 282Connections: Why We Love Our Dogs (At Least Some of Us Do)

Current Human Patterns Began to Emerge 20,000 Years Ago 283 The Origin of Modern Humans Is a Matter of Debate 283 The Case for a Recent African Origin 284 The Case for Multiregional Evolution 287 The Case for Multiple Dispersals 288 As Usual, Reality Is Not This Clear 289 What We Know/Questions That Remain 290 These Models Inuence the Way We Think About Human Dierences Summary 291 Critical Thinking 292 Resources 293 References 293 Chapter 10 Human Biological Diversity in Context 297

291

A Basic Summary of Human Evolution: The Origin of Behavioral and Biological Diversity 299 Humans Have Long Exhibited Biological Diversity 300 A Visible but Misunderstood Variation: Skin Color 301Connections: Everyone Tans! But Skin Color is Still Culturally Defined 302

Another Visible Dierence: Body Shape and Size 305 A Cornerstone of Variation Research: Skull MorphologyConnections: Skulls Are Us? 307

307

Sex Dierences Are Seen in the Skeletal and Soft Tissue of Humans 309 The Impact of Disease Environments: Variation in the Human Immune System 311xiv Contents

Blood Groups Vary Within and Across Populations 312 Most Genetic Variation Is Found Within Populations 314 Human Biological Diversity Is Best Explained Using a Biocultural Approach 315 Natural Selection and Human Cultural Behavior 316 Examples of Selection and Adaptation in Human Variation 317 Race Is A Very Poor Way to Describe Variation In Homo Sapiens Sapiens 321 What Is the Evidence Regarding Biological Races in Humans? 322Connections: Is High Blood Pressure a Black Thing? 324

There Is a Scientic Study of Human Biological Variation 325 Why Does the Notion of Biological Race Persist? 326 A Very Brief History of Racism 326 Modern Notions Are Also Due to a Lack of Context 328 What We Know/Questions That Remain 331 Summary 332 Critical Thinking 332 Resources 333 References 334 Chapter 11 The Present and Future of Human Evolution How Do We Study Human Behavioral Evolution? 338 337

Sociobiology 338 Human Behavioral Ecology (HBE) 339 Evolutionary Psychology (EP) 339 Dual-Inheritance Theory (DIT) 340 Biocultural Approaches to Studying Modern Humans 341 A Modern Approach to Studying the Evolution (Past and Future) of Human Behavior 341 Humans Are Still Evolving 343 Diseases and Modern Humans 343Connections: Can Evolutionary Perspectives Be Applied to Modern Medicine? 346

Cultural Patterns Inuence Morphology 348 Culture, Evolution, and the Future: Where Are We Headed? 352 Human Densities and Global Population Are Dramatically Dierent Today Genetic Manipulation Can Inuence Our Evolution 356Connections: Where Is That Banana From? 357

352

Some of Our Behavior Reects Adaptations 357 Understanding Biological Anthropology and Understanding Ourselves What We Know/Questions That Remain 359 Summary 359 Critical Thinking 360 Resources 360 References 361CREDITS GLOSSARY INDEX 370 363 366

358

Contents

xv

Preface

Do your students struggle with complex concepts like genetics and evolution? Do they have difculty seeing the relevance of biological anthropology to their lives? If so, I have written this text for you.

How this book will help you . . .I am a rm believer in the incredible importance of anthropology in our everyday lives. Yet, in speaking with colleagues around the country and reading McGrawHills research, Ive learned that instructors greatest frustrations in teaching introductory biological anthropology are helping students understand certain key concepts (i.e., genetics, evolution) andperhaps even more importantlymaking them see the relevance of this course material to their lives.

. . . by helping your studentsBiological anthropology classes are packed with information that is directly relevant to all of us and should be both interesting and exciting. Biological anthropologists are making exciting discoveries that change the way we view ourselves today, our understanding of our past, and our future as a species. Yet students often walk away from their textbooks with no understanding of how the information they have just read applies to their lives. Thats why, in this book, Ive introduced the theme of Connections.

. . . connect the concepts to their livesThis text directly speaks to students and relates the concepts of biological anthropology to their lives. It does so in several ways:

Connections boxesSeveral times in each Chapter, I include a Connections feature that directly shows students the relevance of the particular topic being discussed to them and their everyday lives. For example, in Chapter 5, we explore whether male aggression is an evolutionary trait; in Chapter 7, why bipedality made childbirth more difcult; and in Chapter 9, why humans feel a special connection to dogs.

Chapter-opening storiesIn addition, each chapter begins with an example, taken from the headlines, of an important question biological anthropologists have asked or answered:

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How do steroids affect athletes (Chapter 2)? What do discoveries about primate culture tell us about what makes humans unique (Chapter 8)? What is race and what is it not? (Chapter 10)?

Connecting students to related informationCallouts in the margin show students other places in the text a topic is covered, allowing the student either to review material that they have already studied or read more about a topic that interests them.

Understanding key conceptsBy focusing on the key concepts and presenting them in a straightforward manner, this text encourages students to think about, assess, and use the information presented, not just memorize it and recite it back on a test. Several aspects of this text are designed to help students deal with challenging concepts: The Introduction, set up as a series of FAQs (How old is the planet? Have humans changed over time? Where does modern science come from?) presents background information students need but do not always have access to. Chapter 2: Basics of Human Biology contains a review of human anatomy and biology, a chapter unique among introductory texts but extremely important to students understanding of human evolution and variation. Key terms, dened in the margin where they are introduced, help students with new vocabulary and provide an easy review for exams.

The importance of critical thinking and the scientic processTo understand science, students must understand how scientists develop new knowledge, how new knowledge is determined to be valid, and what remains to be discovered. They need to understand how biological anthropologists do science. This is a key concern of this book. Scientic Discovery. The Introduction and early chapters focus on the process of discoverynot just what we know, but how we know it. I explore how scientic discovery builds on earlier knowledge. So, for example, I dont just tell the student about Darwins theory of natural selection; I explain how Darwin built on earlier knowledge to form a unied and cohesive explanation for how life evolved. In addition, at the end of each chapter, students nd a unique criticalthinking feature, What We Know/Questions That Remain. This feature summarizes key knowledge presented in the chapter and highlights the most important questions that remain to be answered. It will help students see that science is an ongoing process and that our current state of knowledge is subject to change. Most importantly, it demonstrates the exciting nature of ongoing research in biological anthropology. Critical Thinking Questions at the end of each chapter ask the student to analyze and synthesize material rather than just memorize it.

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Focus on humanitys place in the natural world. As a biological anthropologist and primatologist, I focus on humans as a part of the primate order. My goal is to give students a wide perspective on what it means to be human and to help them think critically about important issues that face all of humanity. Chapter 5 discusses human behavioral ecology in the context of primate behavior. Chapters 7 through 9 present an overview of human evolution in the context of the evolution of the entire primate order. Chapter 11 explains that humans are still evolving and speculates on what this means for global ecology.

How is this book organized?This book is organized into an Introduction and 11 chapters. The Introduction, as described above, presents crucial background information set up as an engaging series of FAQs. Chapters 1 through 4 introduce students to the eld of anthropology, the science of biological anthropology, Darwinian evolution, human biology, and the modern evolutionary synthesis. Chapter 5 is a uniquely fascinating introduction to primate behavioral ecology, written from the point of view of a working primatologist. Chapters 6 through 9 survey human evolution from the earliest mammals through Homo sapiens. Chapter 10 surveys human variation. Chapter 11 puts it all together by speculating on how humans are continuing to evolve. Biological anthropology is a dynamic, fast-changing eld, and its discoveries about genetics, human evolution, and human variation are vitally relevant to students lives. I hope that students reading this book will come to understand the relevance of these concepts and become as excited to learn about biological anthropology as I am to teach it.

SupplementsFor the instructorThe books online learning center at www.mhhe.com/fuentes2e provides a multitude of password-protected instructor resources including an Instructors Manual, Testbank, Computerized Testbank, and PowerPoint slides.

For the studentThe Online Learning Center (www.mhhe.com/fuentes2e) also provides a wealth of study tools for the student, including chapter outlines, chapter summaries, and chapter quizzes with feedback and instructor reporting.

McGraw-Hill Higher Education and Blackboard have teamed up!What does this mean for you? 1. Your life simplied. Now you and your students can access McGraw-Hill Connect and Create right from within your Blackboard courseall with one single sign-on. No more logging in to multiple applications.

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Preface

2. Deep integration of content and tools. In addition to single sign-on, you get deep integration of McGraw-Hill content and content engines right in Blackboard. Whether youre choosing a book for your course or building Connect assignments, all the tools you need are right there: inside Blackboard. 3. Seamless Gradebooks. Tired of keeping multiple gradebooks and manually synchronizing grades into Blackboard? When a student completes an integrated Connect assignment, the grade for that assignment automatically (and instantly) feeds your Blackboard grade center. 4. A solution for everyone. Whether your institution is already using Blackboard or you just want to try it on your own, we have a solution for you. McGraw-Hill and Blackboard can now offer you easy access to industryleading technology and content, whether your campus hosts it or we do. Be sure to ask your local McGraw-Hill representative for details.

CreateCraft your teaching resources to match the way you teach! With McGraw-Hill Create, www.mcgrawhillcreate.com, you can easily rearrange chapters, combine material from other content sources, and quickly upload content you have written, like your course syllabus or teaching notes. Find the content you need in Create by searching through thousands of leading McGraw-Hill textbooks. Arrange your book to t your teaching style. Create even allows you to personalize your books appearance by selecting the cover and adding your name, school, and course information. Order a Create book and youll receive a complimentary print review copy in 35 business days or a complimentary electronic review copy (eComp) via email in about one hour. Go to www.mcgrawhillcreate.com today and register. Experience how McGraw-Hill Create empowers you to teach your students your way.

CourseSmart e-TextbookThis text is available as an eTextbook at www.CourseSmart.com. At CourseSmart your students can take advantage of signicant savings off the cost of a print textbook, reduce their impact on the environment, and gain access to powerful web tools for learning. CourseSmart eTextbooks can be viewed online or downloaded to a computer. The eTextbooks allow students to do full text searches, add highlighting and notes, and share notes with classmates. CourseSmart has the largest selection of eTextbooks available anywhere. Visit www. CourseSmart.com to learn more and to try a sample chapter.

TegrityTegrity Campus is a service that makes class time available all the time by automatically capturing every lecture in a searchable format for students to review when they study and complete assignments. With a simple one-click start and stop process, you capture all computer screens and corresponding audio. Students replay any part of any class with easy-to-use browser-based viewing on a PC or Mac. Educators know that the more students can see, hear, and experience class resources, the better they learn. With Tegrity Campus, students quickly recall key moments by using Tegrity Campuss unique search feature. This search helps students efciently nd what they need, when they need it, across an entire semester of class recordings. Help turn all your students study time into learning moments immediately supported by your lecture.

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AcknowledgmentsMany reviewers provided useful feedback throughout the process of developing and producing this book. The following faculty members reviewed all or part of the manuscript; their comments were extremely helpful and are deeply appreciated: Annalisa Alvrus, Mesa Community College Eric Anderson, Yakima Valley Community College Robert Anemone, Western Mich UnivKalamazoo Diana Ayers-Darling, Mohawk Valley Community College Dale Borders, Grand Valley State University Ben Campbell, University of WisconsinMilwaukee Judith Corr, Grand Valley State University Fabian Crespo, Univ of LouisvilleLouisville Annlee Dolan, San Joaquin Delta Comm CLG William Doonan, Sacramento City College Arthur Durband, Texas Tech University Phyllisa Eisentraut, Santa Barbara City College Eva Garrett, Lehman College Samantha Hens, CA State Univ Sacramento Kathryn Hicks, Univ of Memphis Madeleine Hinkes, San Diego Mesa College Douglas Kemper, University of Cincinnati Andrew Kramer, Univ of TennesseeKnoxville Kenneth Lewis, Michigan State University Andrew J. Marshall, University of California John McDermott, Fullerton College Joan Miller, San Diego State University Robert Paine, Texas Tech University Bruce Pierini, Sacramento City College Michael Pilakowski, Butte College Aimee Preziosi, West Los Angeles College Robert Quinlan, Washington State UnivPullman Melissa Remis, Purdue University Donna Ricca, South Puget Sound Community College Kathleen Rizzo, Univ of IllinoisChicago Anne Titelbaum, Tulane University Elizabeth Weiss, San Jose State University Barbara Wheeler, Santa Rosa Junior College James Stewart, Columbus State Comm Coll Daniel Temple, Univ of MissouriColumbia William Whitehead, Ripon College Many, many people at McGraw-Hill have made this book possible, but I only have space to thank a few of them. Developmental Editor Craig Leonard and Sponsoring Editor Gina Boedeker shepherded me through much of this project, and the book owes a substantial part of its inception to Janet Beatty and Michael Park. Rachel Castillo supervised production, and Robin Mouat produced the truly spectacular illustration program. Devi Snively provided a wide array of technical assistance and moral support throughout the process and Audrey the wonder dog provided unwavering support during the creative process.

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About the Author

Agustn Fuentes completed a BA in Zoology and Anthropology and an MA and PhD in Anthropology at the University of California, Berkeley. He conducted his dissertation eldwork in the remote Mentaiwai islands of Indonesia and has worked throughout Southeast Asia, North Africa, and the Southern Iberian Peninsula. Dr. Fuentes rst taught Introduction to Biological Anthropology in the fall of 1995 at UC Berkeley. In 1996 he joined the department of Anthropology at Central Washington University (CWU), where he founded and directed the interdisciplinary undergraduate Primate Behavior and Ecology program. At CWU, Dr. Fuentes began working intensively with undergraduate students on original research, and between 1998 and 2002 he collaborated with Universitas Udayana in Bali, Indonesia, to run summer eld projects involving over 80 undergraduates from 9 different countries. Since 2002 Dr. Fuentes has been in the Department of Anthropology at the University of Notre Dame where he is a professor of Anthropology. His research and teaching interests include the evolution of cooperation and social complexity in humans, the evolution of social organization, conict negotiation across primates, and reproductive behavior and ecology. His current research projects include human-monkey interactions in Asia and Gibraltar and assessing the roles of cooperation, social complexity, and patterns of peace in human evolution. He is also interested in issues of disease, inequity, and resilience. Dr. Fuentes is committed to an integrated holistic anthropological approach. He has published over 50 articles, 17 book chapters, 4 edited volumes, and 2 single-authored books.

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Introduction

FAQs for biological anthropologyBecause I teach biological anthropology, I know that students sometimes take this course without some useful background information about science. As a result, they have a lot of questions. Therefore, in this section, Ill answer the most common of these questions. Youll nd this information, along with the illustrations in this section, useful throughout this course.

How Old Is the Planet and What Organisms Have Lived on It over That Time?Before we begin discussion about human biological evolution, we need to provide a backdrop to give us context. Lets quickly run through the last 4.5 billion years of the planets geological and biological history to give us a little perspective on the relative context of humankind. The history of this planet is divided into eras, which are divided into periods, which are further divided into epochs (Figure I.1). The majority of the earths history is in the Proterozoic era. The Proterozoic began with the formation of the earth, approximately 4.5 billion years ago, and ended with the rst major diversication of life-forms, approximately 600 million years ago. It is in this era that we nd the rst hints of life on this planet: tiny fossilized impressions suggesting clusters or chains of linked cells resembling todays blue-green algae and bacteria (prokaryotic cells, or cells that do not contain a nucleus). From about 3.51.5 billion years ago, these are the only kinds of fossils we nd. So, prokaryotes were the only organisms on the planet for the rst 2 billion years of life. Starting around 1.21.5 billion years ago, life-forms became slightly more diverse. We begin to nd evidence of eukaryotic cells (cells that have a nucleus, like those of all animals and plants). By 1 billion years ago, we nd indirect evidence (fossilized burrowing tracks and fecal pellets) of multicellular organisms. Between 1 billion and 570 million years ago, we see a diversication of types of fossil organisms; however, all life is still very small and conned to limited habitats in the oceans.

3

Era Cenozoic

Period (epochs)

Beginning of period (millions of years ago)

Biological features The genus Homo evolved toward the end of period First hominoids First anthropoids Early prosimians at beginning of period

Pleistogene (Pleistocene and Holocene) 1.8 Neogene (Miocene and Pliocene) 23.0

Paleogene (Paleocene and Oligiocene) 65.5

Cretaceous 145.5

First placental mammals

Mesozoic

Jurassic 199.6 Triassic 251.0 Permian 299.0

First flowering plants; first mammals and birds

Carboniferous 359.2 Paleozoic

First coniferous trees; first reptiles and insects

Devonian 416.0 Silurian Ordovician 443.7

First amphibians and land plants; first bony fish First fish with jaws First vertebrates, armored fish without jaws

488.3

Cambrian 542.0

Invertebrate fossils, molluscs, crustaceans, Echinodermata

Proterozoic

First fossilized animals and plants; protozoa, sponges, corals, and algae Precambrian First fossil bacteria

3000

FIGURE I.1The geological time scale shows the sequence of appearance of the major forms of life on earth.

4

Introduction

The next geologic era, the Paleozoic, began around 540 million years ago. The rst period of the Paleozoic era, the Cambrian, shows the rst major example of an adaptive radiation (expansion by a single group of organisms into a diverse array of forms) that we see in the fossil record. At the start of this period we see an explosion of forms moving into a wide array of new niches, or habitats and lifeways, in the oceans. From the basic structures of organisms in the late Precambrian, we see a multitude of variants arise as organisms exploit new oceanic environments and ways of making a living. By the end of the Cambrian period, we have the rst precursors for many modern animal lineages. Throughout the rest of the Paleozoic we see an array of new forms arising from existing varieties. In the Ordovician we see a great expansion in complex multicellular organisms, including the rst shes (jawless shes). By the beginning of the Silurian we nd fossils of jawed shes, which suggests a radical change in the cycle of life (that is, the appearance of active chewing). These are the rst active vertebrate predators. These earliest jawed sh have no bones, only cartilage, and at least one lineage of these early Silurian sh is ancestral to modern sharks and rays. By the middle of the Silurian, bony sh show up in the fossil record and diversify into at least two main groups: the lobe-nned and the ray-nned shes. The currently favored hypothesis is that one or more lineages of lobenned shes gave rise to the rst land vertebrates (the amphibians). The rst fossils of land plants show up during this period. By the end of the Devonian, we have evidence of land animals (insects), complex land plant formations (like swamps), and a huge array of life-forms in the seas. From the rest of the Paleozoic we nd a growing number of fossils of land animals, especially in coastal areas, where the early amphibians (which looked very much like slightly modied lobe-nned sh) gradually changed into a wide array of amphibian forms and early reptiles. During the last period of the Paleozoic (the Permian), there was a broad radiation of reptilian forms, including a group called the therapsids, or mammal-like reptiles (the reptile group that mammals are hypothesized to be most closely related to). The Mesozoic era began around 250 million years ago. By the early Mesozoic, reptiles had undergone a broad and dramatic adaptive radiation. Freed from the water by two crucial adaptationsself-contained eggs and skin that resists drying outreptiles spread across the land environments and adapted to a broad spectrum of habitats. During this era the best-known reptile group, the dinosaurs, make up a large portion of the fossil remains. It is also during the Mesozoic that the rst mammals show up (Figure I.2). These mostly small, probably nocturnal, insect-eating mammals are found throughout the era, but do not make their grand adaptive radiation until the Cenozoic. The Mesozoic was the age of reptiles. The Cenozoic, which began around 65 million years ago, is the age of mammals and birds. After an enormous extinction event at the Mesozoic-Cenozoic boundary, mammals and birds began to diversify, lling many of the niches left vacant by the extinctions. The Cenozoic period is very important in the history of primates (and therefore humans) and is covered in detail in chapter 6.

FIGURE I.2An artists conception of an early mammal, Hadrocodium wui. Its skull was found in 195-million-year-old sediments in China; the paper clip is included to show the animals size.

adaptive radiation expansion by a single group of organisms into a diverse array of forms

FAQs for Biological Anthropology

5

FIGURE I.3Model of the earths interior, showing the layers. This demonstrates the earths crust oating on the liquid mantle.

PANGEA

More than 200 million years ago

If Life on Our Planet Has Changed So Much Over Time, What About the Planet Itself?During the time that life on earth has been changing, so has the surface of the planet. The process of plate tectonics drives the phenomenon of continental drift. Plate tectonics results from the continental plates oating on a layer of mantle (magma, or molten rock, like lava) (Figure I.3). Currents in the magma move the plates in a number of different ways. Sometimes magma pushes up between plates and solidies, pushing them apart (spreading). When plates meet, one can overlap the other, driving it down into the magma (subduction). Plates can move against one another, pushing the earth up and creating mountain ranges (collision). If we look at the model of continental movement over just the last 200 million years, we can see that the earths surface has changed dramatically over time (Figure I.4). Understanding that the earth and life on it have changed over the last 4.5 billion years is an important basic concept. You will notice throughout this book that change over time is a recurring notion in biological anthropology.

LAURASIA

GONDWANA

180 million years ago

65 million years ago

Have Humans Changed?Yes, absolutely, humans have changed. Change over time in humans is pretty much the core of biological anthropology. So, thinking about change on a slightly smaller scale than 4.5 billion years, lets turn to another basic set of information that well be expanding upon throughout this bookthe history of humans and their immediate ancestors over the last 6 million years. Figure I.5 is a time line of human history over the last 6 million years. This time line is just a brief outline to get you to start thinking about names, places, and dates in human evolution. Well be discussing each of the names and types of human or humanlike organisms in detail in chapters 6 through 11. Notice, however, that during most of the time that our species has been evolving, more

Present

FIGURE I.4Continental drift. The continents took on their present relative positions only about 35 million years ago. The forces of plate tectonics continue to reshape the crust.

6

Introduction

0 Homo floresiensis Homo neanderthalensis Homo sapiens sapiens (us) Homo sapiens (archaic) Homo heidelbergensis 1 Homo antecessor ?

Modern humans

Humans, but not modern humans Homo erectus Paranthropus boisei

Homo ergaster 2 Paranthropus robustus

Australopithecus sediba Humanlike relatives Homo rudolfensis

Homo habilis Million years ago Australopithecus garhi Paranthropus aethiopicus 3 Australopithecus africanus Australopithecus bahrelghazalia Kenyanthropus platyops Australopithecus afarensis 4 Australopithecus anamensis Early possible ancestors

Ardipithecus ramidus ramidus 5

Ardipithecus ramidus kaddaba Orrorin tugenensis

6

Sahelanthropus tchadensis

FIGURE I.5An evolutionary time line of human history. In this book we will explain what these dierent organisms are and how they might be related to us.

than one humanlike species existed side by side. While trends and patterns are evident in the history of human evolution, there is not an inevitable trajectory. Knowing this may help you realize that our species is just one of many on this planet that evolved by lling (and modifying) a specic niche.

plate tectonics process by which the earths crustal plates move independently of one another, resulting in continental drift continental drift theory that the present conguration of continents results from the movement of the earths crust

Where Did Modern Science Come From?All of the information weve just reviewed and all that we will be introducing is primarily the product of a process we call science. What we call modern


7

science developed over the last 5 or 6 centuries and is largely what Francis Bacon called for in 1605: a collaboration between inductive methodologies (drawing conclusions from extant facts) and experimental methodologies (testing hypotheses and making observations). This contrasts with the a priori methods used before this time, wherein thinkers went from cause to effect, basing their reasoning on beliefs or assumptions rather than experience or testable observations. The hallmark of modern scientic knowledge is its falsiability, not its veriability; that is, science can prove things 100% false but not 100% true. To be falsiable, statements must be capable of being subjected to tests that might result in their refutation. So scientic information emerges from series of observations, refutations, and hypotheses supported by rigorous testing. In this book we focus on scientic information and processes that relate to understanding our bodies and our biological history. It is important to realize that all our current knowledge rests on past discoveries and collaborations. For example, our understanding of the cells that make up our bodies has developed over 350 years. It began in 1665, when Robert Hooke rst described cells. In 1683, Anton van Leeuwenhoek used his early microscopes to examine blood and sperm cells. In 1883, August Weismann recognized the role of gametes (germ-cells, or egg and sperm). In 1902, Emil Fischer proposed that proteins (the building blocks of our cells) are made up of naturally occurring amino acids, and in 1926, J. Haldane described the complex internal structures of cells and their permeable membranes. All of these elements laid the groundwork for Erwin Chargaffs 1950 discovery of the composition of DNA and James Watson and Francis Cricks 1953 model of the structure of DNA. Similarly, our understandings of the basic patterns in our solar system and galaxy started with Johannes Keplers and Galileo Galileis observations and proposals in the early 1600s. These in turn supported Nicolaus Copernicuss notions about the motion of planets and the sun as the center of the solar system. By 1704, Isaac Newton had published accounts of his ideas on gravity, optics, and particulate light; and approximately 200 years later, Albert Einstein began publishing his ideas about the energy source of the sun and the relationships among matter, mass, and light. In 1929, Edwin Hubble published his observations that all galaxies were moving away from each other. Today all of their proposals, plus many others, are integrated in our understanding of the motion of the earth and all other celestial bodies. Even such seemingly minor scientic events as the discoveries that resulted in the production of the rst electric refrigerator and the invention of the television tube (both in 1923) have had a great impact on our ability to conduct laboratory work and write it up. (Freezers and computers are now ubiquitous in laboratories worldwide.) Modern science comes from a specic set of methodologies and a continuous history of investigation, collaboration, and refutation. Understanding that our knowledge is based on prior knowledge, and is subject to change, is important for assessing the information presented in this text. In chapter 1, you will see how the theory of evolution developed out of investigations carried out over several centuries by numerous scientists in a number of different elds.

Where Is Uzbekistan?A major piece of any college students baseline education (regardless of your major) is a grasp of the geography of the planet. You are 1 of over 6 billion

8

Introduction

humans currently residing on earth; as a citizen of this planet you need to know where you and your neighbors live. Also, in this course you will be learning about discoveries that have taken place all over the world. Figure I.6 shows a current (as of the time this book was written) world map. With these few basic bits of information under your belt, you are now ready to move on to the study of biological anthropology.


9

160 8010

140

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40

0

GREENLAND (DENMARK)

U.S.60

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UNITE

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STATES

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M

Tropic of Cancer20

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MAURITCAPE VERDE

COLOMBIA0

Equator

ECUADOR

GUYANA SURINAME FRENCH GUIANA (FR) VENEZUELA

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A R G E N T I N A

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CHILE0 0 300 Miles 300 Kilometers

THE BAHAMAS

URUGUAY

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MEXICO JAMAIC A BELIZE HAITI

DOMINICAN REPUBLIC PUERTO RICO

GUATEMALA EL SALVADOR10

ST. KITTS AND NEVIS ANTIGUA AND BARBUDA CARIBBEAN HONDURAS DOMINICA SEA 60 MARTINIQUE ST. LUCIA ST. VINCENT AND THE GRENADINES Antarctic Circle BARBADOS NICARAGUA GRENADA TRINIDAD AND TOBAGO COLOMBIA VENEZUELA

SOUTH PACIFIC OCEAN

SOUTH ATLANTIC OCEAN

GAMB

GUIN BISS10

Antarctic Circle

ATLACOSTA RICA PANAMA

OC0 0

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1000 1000 2000

2000 Miles 3000 Kilometers

Scale: 1 to 125,000,000

0

150

FIGURE I.6The world today. Can you nd Uzbekistan?

10

Introduction

0

BA LTI

NORTH SEA55

C SE

SWEDEN

A

NORWAY

20

ESTONIA

0

100 Miles

0 100 KilometersLATVIA LITHUANIA BELARUS RUSSIA

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NETHERLANDS

RUSSIA

GERMANY BELGIUM LUXEMBOURG

POLAND UKRAINE

CZECH REPUBLIC SLOVAKIA

FRANCE

LIECHTENSTEINAUSTRIA

MOLDOVA HUNGARY ROMANIA

SWITZERLANDSLOVENIA

CROATIA

MONACO

SAN BOSNIAMARINO HERZEGOVINA

SERBIA and MONTENEGRO)BULGARIA

BLACK SEA

ITALY40 20 0 20 40 60 8040

100

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ALBANIA

MACEDONIA

160

AND ARK)

GREECE

80

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ARCTIC OCEANArctic Circle

M

E DIT E R R

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ICELAND UNITED KINGDOM

SW ED

NORWAY

EN

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MALTA

FINLAND

R

U

S

S

I

A

60

IRELANDFRANCE ANDORRA

KAZAKSTAN UZBEKISTAN TURKEY TUNISIACYPRUS LEBANON ISRAEL

MONGOLIA KYRGYZSTAN TAJIKISTAN C H I N A NEPAL BHUTAN MYANMAR (BURMA) NORTH KOREA SOUTH KOREA JAPAN

PORTUGAL

SPAIN

TURKMENISTAN SYRIA IRAQ JORDAN BAHRAIN SAUDI ARABIA

NORTH PACIFIC OCEAN

40

MOROCCO ALGERIA LIBYA

EGYPT

AFGHANISTAN IRAN KUWAIT QATAR PAKISTAN

Tropic of Cancer

AN

MAURITANIA

MALI

NIGER CHAD NIGERIA

ERITREA SUDAN

APE RDE

YE M

EN

OM

UNITED ARAB EMIRATES

INDIA BANGLADESH THAILAND LAOS VIETNAM

TAIWAN

20

PHILIPPINESPALAU

UGANDA ETHIOPIA CAMEROON CENTRAL AFRICAN REPUBLIC SO TOM AND PRNCIPE EQUATORIAL GUINEA GABON CONGO REPUBLIC RWANDA DEM. REP. OF THE CONGO ANGOLA ZAMBIA

DJIBOUTI SOMALIAEquator

MARSHALL ISLANDS MICRONESIA NAURU

SRI LANKAMALDIVES

CAMBODIA (KAMPUCHEA )

BRUNEI MALAYSIA I N D O N E S I A

KIRIB

KENYA BURUNDI TANZANIA

SINGAPORE

0

I AT

SEYCHELLES MALAWI COMOROS MOZAMBIQUE

PAPUA NEW GUINEA

SOLOMON ISLANDS

INDIAN OCEANTropic of Capricorn

TUVALU

EAST TIMOR

VANUATU

FIJI20

NAMIBIA BOTSWANA SOUTH AFRICA

MADAGASCAR MAURITIUS

AUSTRALIA

ZIMBABWE SWAZILAND LESOTHO

MAURITANIA MALI

NEW ZEALAND

40

SENEGAL GAMBIA GUINEABISSAU GUINEA0

NIGER

0 0

100 Miles 100 Kilometers

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CASPIAN RUSSIA60

BURKINA FASO

SEA

BENINBLACK

Antarctic CircleGEORGIA

ATLANTIC OCEAN

SIERRA LEONE LIBERIA

IVORY COAST

GHANA

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SEA80

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40

0 0

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300 Miles

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TOGO

TURKEY AZERBAIJAN IRAN


11

C H A P T E R

1

Introduction to Evolutionary Fact and TheoryThis chapter addresses these questions:

What is anthropology, and what do its four subfields cover? What is science, and how does it work?

Is evolution a fact or a theory? Where do our ideas about evolution come from? Why is the theory of evolution significant, and why is it so misunderstood?

1

I

n 1925 the theory of evolution went on trial in the United States. A Tennessee court casethe famous Scopes Monkey Trialwas the arena for a debate about whether evolution could be taught in the public schools. The case had all the elements of high drama, including great speakers, impassioned arguments, and a county courthouse packed with spectators and journalists in 100-degree heat (Figure 1.1). On trial was John T. Scopes, a 24-year-old science teacher who admitted teaching evolution in the local high school, in violation of state law. The American Civil Liberties Union wanted to test the constitutionality of that law, and Scopes agreed to be their test case. Tennessee, like many states of that time, had passed a law against teaching evolutionspecically, against teaching any theory that denies the story of divine creation of man as taught in the biblebecause it was viewed as a threat to the American way of life. The theory of evolution was popularly believed to suggest that humans were descended from monkeys, a notion considered both ridiculous and blasphemous. The prosecuting attorney, William Jennings Bryan, even called the case a contest between evolution and Christianity and portrayed the defense lawyer, Clarence Darrow, as the greatest atheist . . . in the United States. Bryan had had a career in national politics, having served as secretary of state under Woodrow Wilson and having run for the presidency himself three times. In recent years he had joined the tent revival movement, touring the country as a ery evangelical preacher. Darrow, the nations most prominent defense attorney, wanted to challenge what he saw as

FIGURE 1.1The Scopes trial. Clarence Darrow, the lead defense attorney, is leaning on the desk at the center of this photo; William Jennings Bryan is behind him (light jacket). The high-stakes nature of this trial is palpable.

provincial resistance to progress and scientic ideas. He also wanted to show that the theory of evolution did not inherently conict with the teachings of Christianity. Darrow had several experts lined up to explain evolution and show how it was compatible with biblical teachings, but the judge would not allow him to put them on the stand. Undeterred, Darrow asked Bryan himself to take the stand. Darrow then asked Bryan a series of questions aimed at exploring how a literal interpretation of the Bible could be reconciled with the laws of nature and with known facts about the earth and its peoples. Bryan started o gamely but soon became entangled in inconsistencies and absurdities; ultimately, he was revealed to be a man who had given little thought to any ideas that diered from what he had been taught as a child. The cause he represented was similarly tarnished. The trial ended with Scopes being convicted of breaking the law against teaching evolution and ned $100. The verdict was overturned a year later, but only on a technicality, so the law remained on the books. The Tennessee law was nally repealed in 1967, and in 1968 the U.S. Supreme Court declared such state laws unconstitutional. The Scopes trial was dramatized (and partly ctionalized) in the mid-1950s in the play Inherit the Wind, by Jerome Lawrence and Robert E. Lee. Since then, the play has been performed innumerable times in countries around the world and has appeared as both a Hollywood lm and a television movie. With the Scopes trial more than 80 years in the past, the theory of evolutionan extremely well supported theory accepted by virtually all scientists in every country of the worldnow enjoys a secure place in public school curricula, right? Wrong! In 2000, Kansas revised its statewide science standards to exclude all mention of evolution or any matters relating to the age of the earth or the universe, and in 2005 the Kansas board of education rewrote the denition of science. By 2007, state courts had overturned the board of educations revisions, but the battle continues in Kansas even today. In 2004, Ohio moved to label the discussion of evolution as only one theory among many in explaining life on this planet. As of 2010, some states continue to revise their standards to include topics related to biological and geological change

14

CHAPTER 1

Introduction to Evolutionary Fact and Theory

over time without mentioning the word evolution. Still other states place disclaimer stickers on all science textbooks that deal with evolution, stating that evolution is a controversial theory presented by some scientists. A recent study found that about one third of the states have science standards that, by omitting or distorting evolution, are shortchanging students and making it dicult for them to understand how science works (Lerner, 2000). What is it about the theory of evolution that makes its detractors so angry and uncomfortable? Does it claim that people are descended from apes or monkeys? Does it try to disprove the Bible or make it impossible for people to hold religious beliefs? Is there an irreconcilable conict between evolutionary perspectives and religious views and values? As you will see in this chapter, the answer to these last three questions is no. Evolution is a core principal of the sciences and is at the heart of anthropology. It is also one of the most widely misunderstood sets of ideas in our culture today. This chapter will help you understand what the theory of evolution asserts, how it emerged from the thinking of many scientists over time, and what skills and methods are required in order to understand and investigate scientic issues.

Anthropology is the study of human and nonhuman primatesThe word anthropology comes from two Greek roots: anthropos, meaning human, and logia, meaning studythus, the study of humans. We can expand this denition by looking at the mission statement of the American Anthropological Association. The societys mission is to advance anthropology as the discipline that studies humans and nonhuman primates in all their aspects, through archaeological, biological, ethnological and linguistic research, and to foster the use of anthropological knowledge in addressing human problems. From this mission statement we can see, then, that anthropology is the study of humans (us) and our closest biological relatives (other members of the order Primatesmonkeys, apes, and prosimians). Anthropology is divided into four subelds, or areas of investigation: archaeology, biological anthropology, cultural anthropology, and linguistic anthropology. Anthropologists in all these subelds are committed to ensuring that the knowledge they acquire is made available to nonanthropologists and is applied to issues facing humanity. What areas of study are included in the four subelds of anthropology? Archaeology is the study of the material past of humans: what the people of the past made, how they lived, and how they modied their environment, as evidenced by the material clues they left behind. Biological anthropology (also called physical anthropology) focuses on the biological facets of the human species, past and present, along with those of our closest relatives, the nonhuman primates (monkeys, apes, and prosimians). Cultural anthropology is the study of that extremely complex entity we call human culture: the patterns of behavior we exhibit in our families, relationships, religions, laws, moral codes, songs, art, business, and everyday interactions. The main tools of the cultural anthropologist are ethnographya study of a specic culture and ethnologythe comparative study of cultures around the world. Linguistic anthropology is the study of language, its origins, construction, and uses. Although we divide anthropological investigations into four subdisciplines, they are not actually separate lines of inquiry; in fact, they are all intertwined. Anthropologists take a holistic approach in their study of humans, considering evidence from all four subelds (Figure 1.2). It is only by investigating all

anthropology the study of all aspects of the human experience Primates mammalian order to which humans belong archaeology the study of the patterns of behavior and the material record of humans who lived in the past biological anthropology the study of the biological and biocultural facets of humans and their relatives cultural anthropology the study of human culture in all of its complexity culture patterns of behavior human societies exhibit in their families, relationships, religions, laws, moral codes, songs, art, business, and everyday interactions ethnography the focused study of a culture or aspects of a culture ethnology the comparative study of many cultures linguistic anthropology the study of language, its structure, function, and evolution holistic approach the practice of drawing on all subdisciplines of anthropology, as well as other disciplines, to attempt to answer questions about humans

Anthropology is the Study of Human and Nonhuman Primates

15

Cultural anthropology

Linguistic anthropology

FIGURE 1.2The four subelds of anthropology. They integrate to form the holistic approach.

these aspects that anthropologists have any hope of unraveling the complex, marvelous, and ongoing story of humankind. Anthropologists also take a comparative approach in their work. They rely on specic studies to generate a large amount of information on one subject, and then they compare data and results across many studies, cultures, or populations. In this way they hope to understand, for example, the amazing array of similarities and differences we see in the human species and to determine which characteristics are universal to the human species and which are unique to particular groups or societies. Anthropologists work collaboratively with other anthropologists and researchers and try to tackle questions at both the local and the global levels. Anthropologists also take a historical approach, keeping in mind the contributions and insights of previous scholars in their elds and applying them to their own work. And they are well aware that all people, themselves included, see the world through the lens of their own culture. They strive, if not for objectivityan impossible goalat least for vigilance against cultural and personal bias as they observe and study human beings of other times and places. In this book we focus on biological anthropology, but you will see the other subelds in evidence throughout the discussions and examples. Biological anthropology itself can be divided into a number of subcategories. Probably the best known is paleoanthropology, the study of the fossils (the material evidence for past life) and fossil environments of past humans and nonhuman primates. Other biological anthropologists focus on the interconnections between human biological variation (such as differences in height, weight, and genetic makeup across different populations) and physiology, anatomy, disease, and demography. Still others look at the biological basis of behavior and how aspects of culture can be inuenced by biology and ecology (the interrelationships between living organisms and their environments). Finally, there are those who focus their studies on nonhuman primate species; they use the comparative approach to understand what is common to all primates, what is common to some primates, and what may be unique to humans.

Biological anthropology

Archaeology

Anthropology is a scientic disciplineAs a scientic discipline, anthropology shares certain characteristics with the other sciences. First, it requires that practitioners, students and professionals alike, use critical thinking, a certain way of approaching and thinking about information. Second, it makes use of the scientic method, a particular way of making observations, gathering data, and testing hypotheses. And nally, it operates through collaboration, a way of working together and building on the scientic work done by others. As you will see, critical thinking, the scientic method, and collaboration are recurring themes in anthropology, and they are three key themes in this book. We consider each of them in more detail in the next sections.

comparative approach the practice of comparing features across entities/cultures/ organisms to elucidate similarities and dierences paleoanthropology the study of fossil humans and human relatives fossil material evidence of past life on this planet ecology interrelationships between living organisms and their environments

Critical Thinking Is the Systematic Assessment of InformationPeople today are bombarded with information via the media, the Internet, and even college classes; in fact, we may be said to suffer from information overload. As educated people living in a democratic society, we need to think about what we read and hear rather than accept everything at face value. In other words, we need to think critically.

16

CHAPTER 1


critical thinking Critical thinking means active participation in the learning process. It taking control of information means taking control of the information presented to you and examining it. presented to you and examinIt means asking, Where did this information come from? What part of this ing it information consists of facts, or veriable, observable truths? What ideas and fact conclusions are being derived from those facts? What reasoning processes and a veriable, observable truth assumptions were used to reach these conclusions; are they logical, or do they involve inconsistencies and false assumptions? In what form are the ideas and conclusions presented: Are they dogmatic assertions, or are they clear statements backed with logical arguments? Are nonfactual elements presented as facts? Does the person presenting the information have something to gain (or lose) by convincing you to accept a certain viewpoint? What are the implications of the conclusions for different groups of people or for society in general? Lets take a current example of this critical thinking questioning CONNECTIONS process. Some researchers today believe that there are inherent (or biologically based) differences in intelligence between the groups we See chapter 10, pages 321330, for (in the United States) refer to as Asian, Black, and White. What further detail on race and racism. facts are provided to support this statement? Some standardized

tests (such as the SAT) and some IQ tests show different average scores for these three groups. From these facts, these researchers conclude that there are inherent differences in intelligence among the three groups. What reasoning processes and assumptions lie behind these conclusions? The researchers make at least two assumptions: that the three groups are biologically distinct and that the tests actually measure innate cognitive abilities (intelligence). They then argue that the differences among the groups can best be explained as biologically based. Is this reasoning process logical, or are there inconsistencies and false assumptions? The conclusions are based on false assumptions. For one thing, as we will see in chapter 10, the human species cannot currently be divided into large, biologically dened subunits (races or subspecies) labeled Asian, Black, and White. For another, exactly what aspects of biology are measured by standardized tests is not clear (although something is denitely being measured, because people vary individually in their scores). Do the researchers conclusions have any implications for the groups in question or for society in general? Yes: If differences in test scores are primarily biological in origin, then social, educational, or economically based programs will have minimal impact on improving the lower-end test scores. However, if these differences are not primarily biological, such programs may be effective. These two possibilities have signicant economic, social, and political implications, and thus individuals making claims about this issue may have social, economic, and political motives. To evaluate complex arguments and issues like this one, you need to use your critical thinking skills. You also need relevant information. In chapter 10 we deal in much more depth with issues related to race, behavior, and human biological variation. Throughout the book we provide a substantial amount of information that you can use to critically examine a number of hotspot issues related to human variation. Beyond what you read here, you have access to nearly limitless information at the library, in other classes, and on the Internet. If a particular topic intrigues you, by all means search beyond the introductory information given here and pursue it through the suggested readings and websites, recommendations from your instructor, and even eld trips to natural history museums or archaeological sites. Part of the goal of this book is to help you hone your critical thinking skills and build

Anthropology is a Scientic Discipline

17

up your knowledge base so you can more easily distinguish opinion from fact, wishful thinking from valid argument, and traditional belief from scientic practice.

The Scientic Method Is a Way of Testing Ideas about the World Around UsBiological anthropology is an area of study that gathers information by a specic methodology: the scientic method. The scientic method is a way of asking questions about ourselves and the world around us, and all scientists use it. In general the scientic method is very simple: You observe a fact (a veriable, observable truth), construct a hypothesis (a testable explanation for the observed facts), and you then test that hypothesis. If your test demonstrates that your hypothesis is wrong (refutes it), you go back to the drawing board and try another hypothesis (and test it). If the test does not refute your hypothesis (in other words, supports it), you retest. If the tests you perform continue to support your hypothesis, then, as a serious scientist, you try to present or publish the results so that others will perform the same tests and/ or examine your tests to conrm that the hypothesis is correct. If a set of hypotheses is supported again and again by multiple researchers, we call it a theory. This process is the scientic method, and this sequence of activities observe hypothesize test support or refute retestis the basic pattern of science (Figure 1.3). Notice that when you use this methodology, you cannot prove yourself right; you can only prove yourself wrong. The test portion is designed as a refutation tool, not a proving right tool. This characteristic is what makes science different from all other modes of investigating human beings and the world around us (such as philosophical inquiries and religious doctrines). In fact, proving themselves wrong is exactly what scientists do. Every now and then they come up with a strongly supported hypothesis or even a really robust theory, one that consists of a set of supported hypotheses that all interconnect and act as a powerful tool for explaining natural phenomena. However, they do not produce the truth. What scientists do is take an enormous array of possible truths and reduce them to a few probable truths. This basic method is relatively straightforward, but in practice scientic inquiry does not usually begin with pure observation. Because there are already so many supported hypotheses out there explaining so many observations, much of scientic investigation is now driven primarily by hypothesis testing rather than observation gathering. That is, most scientists use the hypothetical-deductive approach: testing a hypothesis as a rst step rather

hypothesis a testable explanation for the observed facts theory a set of supported hypotheses

STOP

& THINK

Is this what you think of when you hear the word science? If not, is that a problem?

Support

New hypothesis

Observe

Hypothesize

Retest

Test

Refute

Support

Theory

FIGURE 1.3The scientic method. Note that the process is circular rather than linear.

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CONNECTIONSThats a Fact, Jack . . . Or Is It?People on television and the internet are always throwing around the word fact, but those facts are not the same as science facts. A fact in a court case is a reasonably supported idea, observation, or statement. In everyday use, fact means something that someone believes is true or at least reliable. Wikipedia (many students favorite source) denes a fact as a pragmatic truth, a statement that can, at least in theory, be checked and conrmed. For scientists this is not enough. It does not matter what you believe in theory; it matters what is observable and veriable. Scientic facts are veriable truths, and there are very few of them. Facts can be readily observed and replicated again and again by anyone. For example, if I hold up a pen and let go of it in New York, Buenos Aires, Cairo, or Beijing it will drop. Anyone who repeats this will nd the same result as long as they are standing on the surface (more or less) of the planet. Now, most of you would say that gravity is the fact behind the pen dropping. But gravity is not the fact; the fact is that the pen will drop, plain and simple. Gravity is a theory (a supported set of hypotheses) for why the fact (the pen drops) occurs. This is an important difference between scientic facts and popular facts. Popular facts are usually not scientic facts and therefore should not be given the same weight in thinking about the world. Popular facts are often ideas, opinions, or hypotheses and theories posing as facts. Think about this . . . what was the last thing you called a fact? Is it an observable, veriable truth, or something else?

than making baseline observations and constructing hypotheses based on them. Their sequence is based on existing knowledge: They construct a hypothesis, test it, nd it supported or refuted, and retest it. Still other scientists take theories and continue to test aspects or components of them (theory hypothesize test support or refute aspects of theory modify theory). In sum, researchers today are gathering baseline observations, creating hypotheses, testing new or existing hypotheses, and assessing and modifying theories. This is science at its core. Although the scientic method has built-in mechanisms to ensure that it is as objective and bias free as possible, it does not exist in a vacuum. Humans are culturally complex beings, and science is always inuenced by personal and cultural factors. Cultural factors and historical issues inuence, among other things, the kinds of questions being asked and even how observations are conducted and reported. For example, before the 1970s most research on primates suggested that primate societies were male dominated and that males displayed most of the important behaviors; females appeared to play very minor roles in social interactions. Beginning in the 1970s, new studies began to appear that showed a great deal of complexity and variation in female behavior (Strier, 1984; Strum & Fedigan, 2000). What had happened? Before the 1970s, most American and European primatologists (scientists who study primates) were men, but in the late primatologist researcher who studies primates 1960s and early 1970s, women began going into primatology (indeed, into all areas of academic and professional life). These female researchers women like Phyllis Dolhinow, Linda Fedigan, and Jane Goodall, to name just a fewlooked at primate society differently and asked CONNECTIONS different questions (Figure 1.4). With more women observing primate behavior and gathering data, a different picture of primate See chapter 5, pages 137151, for more details about primate lives. society began to emerge. In fact, a dramatic shift occurred in how female primates and primate societies were portrayed. The male


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FIGURE 1.4The focus on female primates revealed a great deal of complexity in social networks and spotlighted the social development of the young. Here we see two adult female long-tailed macaques (Macaca fascicularis) and their infants engaged in the sharing of close social space.

paradigm predominant ways of thinking about ideas

primatologists working in the eld before the 1970s were not deliberately distorting their observations; they simply had certain prior ideas about what male and female roles should be, and they had been trained to ask questions primarily about male primates. Their research reected their cultural background and their training. They were practicing the scientic method, but the scope of behavior they observed and the types of hypotheses they proposed were limited by their experience and culture. Different elds of science (and all elds in which knowledge is acquired and assessed) also have varying paradigms, or predominant ways of thinking about ideas. Because people are educated within these paradigms, their questions and interpretations are inuenced and directed by their training (as you are inuenced by the way this book is written and the way your instructor delivers the information in the classroom). A main paradigm of biological anthropology is evolution by natural selection. For example, when biological anthropologists examine a given fossil, the questions they ask are usually related to how the patterns and processes of evolution have impacted the form and function of the fossil in question. Technology and innovation alter the realm of possible investigations and inuence what kinds of observations can be made and how they can be assessed. As an example, consider what could be investigated before and after the development of the telescope, the microscope, or even the computer. Despite these inuences, the scientic method does provide the foundation for research and theory that we can accept with a reasonable degree of certainty. The foundation provided by the scientic method has allowed for the enormous leaps in knowledge that have given us vaccines and antibiotics, long-lasting and safely preserved foods, air travel, personal computers, and a multitude of other scientic and technological innovations.

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A note of caution: Many people think of science as a belief system or a body of truth rather than a methodology. Why do television advertisements frequently proclaim 9 out of 10 doctors prefer a given product? Because doctors are considered men and women of science and therefore thought to possess expert opinions on any subject that might be thought of as having a scientic basis (like pain relievers or toothpaste). If we think of science as a body of truth or a belief systemthe truth as validated by expertsthen whatever the experts prefer or like the most is important. But if by science we mean a methodology, the preference of scientists is irrelevant; the only information that matters is the outcome of tests and experiments and the assessment of hypotheses and observations. Because science is a methodology, not a belief system, it doesnt matter what doctors or scientists think or like about a product. As students and active learners, you need to remember that science is a methodology and not a system of expert validation. Scientists frequently disagree, and this disagreement is a good thing. Researchers with differing backgrounds and orientations are going to look at data in different ways and ask different types of questions giving various types of answers. These variations are benecial to the practice of science because the more questions asked, the more observations made, and the more tests conducted, the more knowledge we gain and the better directed our investigations are. Resolving disagreements by observing, hypothesizing, testing, and retesting is science; resolving disagreements by expert opinion is not. Science is a unique and valuable way to ask questions about ourselves and the world around us. It differs from other systems in two important ways: First, it is self-correcting; second, it does not provide ultimate truths. If your question is a moral, ethical, religious, spiritual, or otherwise philosophical one, such as Why are we here? Is there a supreme being? or Why does evil exist? do not look to the scientic method for an answer. Rather, turn to your family, friends, counselor, clergyperson, or spiritual advisor. Such questions are better debated, discussed, and answered in these contexts than in the realm of science.

STOP

& THINK

Should we care what experts think? Who decides who an expert is?

Scientic Investigation Is a Collaborative ProcessCollaboration, or working together, is central to scientic inquiry. Scientists collaborate by performing experiments and observations together and by using the published results of other scientists work. Collaboration allows scientists to maximize the quality of tests and data and, importantly, to get multiple views on every issue. Working collaboratively has special signicance today, when we have such a huge amount of information about the living and nonliving forms on our planet. For example, consider the study of human ancestry. To ask relevant and effective scientic questions about human fossils, we need people capable of working in the elds of anatomy, anthropology, biology, chemistry, climatology, ecology, geology, paleontology, and zoology, among others. If we want to get into further depth, we will also need people competent in the elds of evolutionary biology and physics. Nor can we forget that to conduct research we need money and permits from federal and local governments; so we also need individuals who speak different languages and who understand communication, economics, and political science. In short, it is impossible for a single individual to do extensive and effective research today; too much knowledge is required to answer even one simple question. Scientists have always collaborated on scientic investigations. Remember that humans do not really live that long and research can take enormous amounts of time and effort. Many scientists have conducted research that was


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not used in their lifetimes but was vital to the work of future generations. Gregor Mendel, for example, spent his life conducting experiments on plants to reveal the mechanisms of inheritance. In his lifetime, his work was relatively unknown. After his death, his ndings provided the basis for the modern study of genetics. Thus, when we talk about scientic collaboration, we do not always mean that the collaborators worked directly with one another; rather, scientists used previous ndings in their own research or thinking. This is why publishing and presenting information is so important. Data are useless if no one sees them; hypotheses are useless if no one hears or reads them. Today, most academic scientists present their work at professional meetings and publish their research in journals. Every piece of information adds to the overall knowledge base, and everyones work contributes something at one point or another. Probably the most important example of scientic collaboration discussed in this book is that which resulted in Charles Darwins publication of On the Origin of Species. As you will see later in this chapter, Darwins ideas did not originate solely with him; rather he was able to formulate them because of the body of knowledge that existed at the time he lived combined with his own life experiences. This collaborative experience primed him to synthesize an enormous amount of information into a comprehensive theory of evolution, one that has held up to this day.

Evolutionary theory is the cornerstone of anthropologyEvolution Is Both Fact and TheoryEvolution is biological change across generations. It is a factthat is, it is an observable, veriable truththat life on this planet has changed over time. By examining fossils, by doing biochemical analyses of humans and other organisms, and by studying the geology of the planet, we can see that change has occurred over time. That is the fact of evolution. The theory of evolution is a set of hypotheses that explain how the change occurs. This theory is an explanation, a proposed mechanism, for change, and it is testable and thus

CONNECTIONSMaking a Monkey Out of You?We do not come from monkeys. This is one of the most common misconceptions of evolutionary ideas and, if you think about it, is really silly. Monkeys and humans are both around today . . . one cannot come from the other. Monkeys, you, and I share a common ancestor (about 35 million years ago or so; see chapter 6) that was neither a human nor a monkey. Life has changed a lot throughout the history of this planet and many forms gave rise to many others, but those forms that exist now cannot be the ancestors to other forms that also exist now. Evolutionary relationships between ancestors and descendant species are like a tree. Consider whatever is alive now to be like the very tips of all the tiwigs extending from the branches of the tree. The ancestors are the places along the branches leading back to the trunk, the trunk itself, and even the roots. Some twigs are close to each other, and thus share the ancestors of the branch they both come off of (like humans and chimpanzees), others are more distant and only share the trunk of the tree in common (like humans and mushrooms). So monkeys cannot be our ancestors, but they can be close branches on the tree of life.

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scientic. Currently, the theory of evolution is well supported by repeated testing. Evolution, then, is both a fact and a theory. The fact is that the earth and things on it have changed over time, and the theory is an explanation for how those changes have occurred. We know that life has changed and continues to change. Biological anthropology studies the mechanisms of that change and how we have come to understand them at the beginning of the 21st century. To see how we arrived at our current theoretical understandings, we need to look back at the ideas and innovations that gave rise to our current concepts, as well as the cultural context in which they arose.

STOP

& THINK

When most people talk or think about evolution, are they using evolution the fact or evolution the theory?

Early Explanations of Life Were Both Philosophical and ReligiousAll human societies classify the components of the world around them and have explanations for how things came to be and how they work on a dayto-day level. All have origin storiesmyths about how the world was created. The Judeo-Christian-Islamic creation stories, in combination with ancient Greek and Roman philosophies, have greatly inuenced the European natural sciences from which we derive our current ideas about evolution.

The Greek and Roman LegacyAn important idea in Greek and Roman philosophy was the Scalae Natura, or Great Chain of Being. This idea dates back to classical Greece and the philosopher Aristotle (~384322 BCE) or even earlier, and until the 18th or 19th century, it represented the established order of life for most Western cultures. In essence, this notion is that all forms of life on the planet can be ranked in order from the most important to the least important (Figure 1.5). Early forms of this idea place gods and demigods at the top; human males next; then elephants, dolphins, and human females; and then the entire panoply of life on earth (usually ending with the earthworm at or near the bottom). By the 18th century this concept was commonly held by Europeans with only slight modication: God at the top, angels below God, humans next, and then all the beasts of land, sea, and air. Although this notion may seem simplistic to us today, it inuenced how people saw the world for centuries. Such a linear ranking of organisms supports the beliefs that higher ranked forms are better than lower ranked forms and that humans are superior to other life-forms. The Greek and Roman philosophers also embedded the idea of essentialismthe notion of ideal typesin our philosophical heritage. This concept dictates that each organism has a true, ideal form and that all living representatives of that organism are slight deviations from the ideal type. This notion is important because it provides an explanation for the slight variations we see in different forms, even among members of the same species. Within this belief system, then, you would not ask scientic questions about why an ape, a human, and a monkey all have ve ngers and a prehensile thumb, for example; or why a dog and wolf are almost identical in

FIGURE 1.5The Scalae Natura, or Great Chain of Being, from a 1579 engraving. What species are seen as high ranking? Low ranking?

Evolutionary Theory is the Cornerstone of Anthropology

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every way; or why an ostrich has wings and cannot y while an eagle has wings and can. In this belief system the answers are selfCONNECTIONS evident: Apes and monkeys are degenerate

Agustin Fuentes Biological Anthropology Concepts and Connections, 2nd Edition 2011

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