Table Of Content0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page ii
Fifth Edition
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0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page i
HOW HUMANS EVOLVED
Fifth Edition
0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page iv
For Sam and Ruby
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0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page iii
HOW HUMANS
EVOLVED
Robert Boyd • Joan B. Silk
University of California, Los Angeles
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0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page v
ABOUT THE AUTHORS
ROBERT BOYDhaswrittenwidelyonevolutionarytheory,focus-
ingespeciallyontheevolutionofcooperationandtheroleofculture
inhumanevolution.HisbookCultureandtheEvolutionaryProcess
receivedtheJ.I.StaleyPrize.Hehasalsopublishednumerousarticles
inscientificjournalsandhaseditedvolumes.Heiscurrentlyco-chairof
theMacArthurPreferencesNetworkandProfessorofAnthropologyat
theUniversityofCalifornia,LosAngeles.
JOAN B. SILKhasconductedextensiveresearchonthesociallivesof
monkeysandapes,includingextendedfieldworkonchimpanzeesatGombe
StreamReserveinTanzania
andonbaboonsinKenyaand
Botswana.Sheisalsointer-
estedintheapplicationof
evolutionarythinkingto
humanbehavior.Shehaspub-
lishednumerousarticlesin
scientificjournalsandschol-
arlyeditedvolumes,andis
currentlyProfessorofAnthro-
pologyattheUniversityof
California,LosAngeles.
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0a_Front Matter [4p]:How Humans Evolved [5e] 10/31/08 4:45 PM Page vii
CONTENTS
Preface
xv
Prologue: Why Study Human Evolution?
xxi
Part One: How Evolution Works
Chapter 1: Adaptation byNatural Selection
2
Explaining Adaptation before Darwin 2
Darwin’s Theory of Adaptation 4
Darwin’s Postulates 5
An Example of Adaptation by Natural Selection 6
Individual Selection 11
The Evolution of Complex Adaptations 12
Why Small Variations Are Important 12
Why Intermediate Steps Are Favored by Selection 14
Rates of Evolutionary Change 17
Darwin’s Difficulties Explaining Variation 21
Chapter 2: Genetics
24
Mendelian Genetics 24
Cell Division and the Role of Chromosomes in Inheritance 26
Mitosis and Meiosis 27
Chromosomes and Mendel’s Experimental Results 28
Linkage and Recombination 32
BOX 2.1 MORE ON RECOMBINATION 34
Molecular Genetics 37
Genes Are DNA 38
Some Genes Code for Proteins 40
Regulatory Sequences Control Gene Expression 46
Not All DNA Carries a Message 49
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viii CONTENTS
Chapter 3: TheModern Synthesis
53
Population Genetics 53
Genes in Populations 54
How Random Mating and Sexual Reproduction Change
Genotypic Frequencies 55
BOX 3.1 GENOTYPIC FREQUENCIES AFTER TWO GENERATIONS OF
RANDOM MATING 59
How Natural Selection Changes Gene Frequencies 59
The Modern Synthesis 60
The Genetics of Continuous Variation 60
How Variation Is Maintained 64
Natural Selection and Behavior 68
Constraints on Adaptation 71
Correlated Characters 72
Disequilibrium 74
Genetic Drift 75
Local versus Optimal Adaptations 79
Other Constraints on Evolution 80
BOX 3.2 THE GEOMETRY OF AREA/VOLUME RATIOS 81
Chapter 4: Speciation and Phylogeny
85
What Are Species? 85
The Biological Species Concept 87
The Ecological Species Concept 88
The Origin of Species 91
Allopatric Speciation 91
Parapatric and Sympatric Speciation 95
The Tree of Life 96
Why Reconstruct Phylogenies? 99
BOX 4.1 THE ROLE OF PHYLOGENY IN THE COMPARATIVE METHOD 102
How to Reconstruct Phylogenies 103
Problems Due to Convergence 104
Problems Due to Ancestral Characters 105
Description:With its unique blend of evolutionary theory, population genetics and behavioral ecology, How Humans Evolved provides students with the most contemporary and complete introduction to physical anthropology available.Robert Boyd and Joan B. Silk’s modern presentation of genetics and observable behav
