GENETICS AND THE SEARCH FOR MODERN HUMAN ORIGINS
John H. Relethford
State University of New York College at Oneonta
Wiley-Liss
A John Wiley & Sons, Inc., Publication
New York, Chichester, Weinheim, Brisbane, Singapore, Toronto
2001
FROM THE BACK COVER
Researchers are increasingly turning to genetic data to help decipher the
origins of modern humanity. Did we arise as a new species in Africa
200,000 years ago and then replace human populations outside of Africa
(African replacement), or are we part of a single evolving lineage
extending back perhaps as far as two million years ago (multiregional
evolution)? Genetics and the Search for Modern Human Origins is an
introduction to the genetic evidence of modern human origins, including
what it can show us about prehistory, population size, and
migration. Weighing the various debates, the author argues for a
multiregional view that our recent origins are mostly, but not exclusively,
out of Africa.
Taking into consideration the ongoing debate over modern human origins,
this book offers a fascinating and educated look into the concepts,
methods, and interpretations of human origins without weighing down the
text with advanced mathematics or excessively technical language. John
Relethford, a highly acclaimed author, provides a clear and concise review
of how genetic data is used to study modern human origins.
Topics discussed in Genetics and the Search for Modern Human Origins include:
* Evolution and genetic history
* "Mitochondrial Eve"
* Genetic diversity and recent human evolution
* Genetic differences between human population
* Reconstructing ancient demography
* Neandertal DNA
* Summary of the genetic evidence
Genetics and the Search for Modern Human Origins is an engaging and
informative resource for anyone interested in genetics, evolution, and
human origins.
TABLE OF CONTENTS
1. Reflections of the Past 1
1.1 The Genetic History of the Human Species / 3
1.2 The Organization of this Book / 6
2. Evolution and Genetic History 10
2.1 The Genetic Code / 11
2.2 The Process of Inheritance / 12
2.2.1 Dominant Alleles / 14
2.2.2 Inheritance of Chromosomes / 15
2.3 Measures of Genetic Variation / 15
2.3.1 Red Blood Cell Blood Polymorphisms / 16
2.3.2 DNA Markers / 17
2.3.3 Mitochondrial DNA / 19
2.3.4 The Y Chromosome / 19
2.3.5 Complex Phenotypic Traits / 20
2.4 How Does Evolution Work? / 20
2.4.1 Mutation / 21
2.4.2 Natural Selection / 22
2.4.3 Genetic Drift / 24
2.4.4 Gene Flow / 28
2.4.5 Interaction of the Evolutionary Forces / 28
2.4.6 Microevolution and Macroevolution / 29
2.5 Genetics and History-Two Examples / 32
2.5.1 The Population History of Ireland / 32
2.5.2 The Ape-Human Split / 35
2.5.3 Different Approaches to Population History / 38
2.6 Summary 139
3. The Modern Human Origins Debate 41
3.1 Geologic Time / 42
3.2 Early Hominid Evolution / 43
3.3 Evolution of the Genus Homo / 45
3.3.1 Early Humans-Homo erectus / 46
3.3.2 "Archaic" Humans / 48
3.3.3 "Modern" Humans / 49
3.3.4 Lumpers and Splitters / 51
3.4 Models of Modern Human Origins / 54
3.4.1 The Mode of the Transition-Replacement or
Multiregional Evolution? / 55
3.4.2 The Location and Timing of the Transition-Africa or
Worldwide? / 61
3.4.3 Evolutionary Models / 62
3.5 Summary / 66
4. In Search of Our Common Ancestor 67
4.1 "Mitochondrial Eve" / 68
4.1.l Analyzing Mitochondrial DNA / 68
4.1.2 The Analyses / 75
4.1.3 The Debates-Where Did Eve Live? / 79
4.1.4 The Debates-When Did Eve Live? / 82
4.2 Coalescent Theory-When Did the Common Ancestor Live? / 83
4.2.1 Estimates of Coalescent Dates from Mitochondrial DNA
/ 85
4.2.2 Estimates of Coalescent Dates from Other Genes / 87
4.2.3 Coalescent Dates and Population Size / 88
4.3 Geography and Gene Trees-Where Did Our Ancestors Live? / 89
4.4 Summary I 91
4.5 Postscript / 93
5. Genetic Diversity and Recent Human Evolution 94
5.1 Genetic Diversity and Evolution / 95
5.2 Measuring Genetic Diversity / 97
5.3 The Geographic Distribution of Human Genetic Diversity / 101
5.4 Evolutionary Interpretations of African Genetic Diversity / 104
5.4.1 A Recent African Origin of Our Species? / 104
5.4.2 Regional Variation in Population Size? / 110
5.5 Summary / 117
6. Genetic Differences Between Human Populations 119
6.1 Genetic Distance and Evolution / 119
6.2 Levels of Genetic Differentiation / 122
6.3 The Pattern of Genetic Distances Between Populations / 127
6.4 Evolutionary Interpretations / 128
6.4.1 Do the Genetic Distances Reflect Phylogenetic
Branching? / 130
6.4.2 Do the Genetic Distances Reflect Differences in Gene
Flow? / 132
6.4.3 The Need to Consider Regional Differences in
Population Size/137
6.4.4 Estimating Ancient Migration / 141
6.5 Summary / 143
7. How Many Ancestors? 145
7.1 Different Concepts of Population Size / 146
7.2 Estimating Ancient Population Size / 149
7.2.1 Ecological Estimates of Census Size / 150
7.2.2 Genetic Estimates of Species Effective Size / 151
7.3 A Pleistocene Population Explosion? / 154
7.3.1 Gene Trees and Population Expansion / 154
7.3.2 Mismatch Distributions and Frequency Spectra / 156
7.3.3 Evidence of Expansion from Microsatellite DNA / 159
7.3.4 Estimating the Time of the Expansion / 161
7.3.5 What Happened Before the Expansion? / 164
7.4 Evolutionary Interpretations / 168
7.4.1 Evidence of Speciation and Replacement? / 168
7.4.2 Extinction and Recolonization of Local Populations?
/ 171
7.5 Summary / 176
8. Neandertal DNA 178
8.1 Studying Ancient DNA / 178
8.2 Discovery of Neandertal DNA / 179
8.2.1 The First Neandertal DNA Sequence (Feldhofer) / 179
8.2.2 The Second Neandertal DNA Sequence (Mezmaiskaya) / 180
8.3 Evolutionary Interpretations / 181
8.3.1 Variation within Neandertals / 182
8.3.2 Were Neandertals a Separate Species? / 183
8.3.3 Regional Affinities of Neandertal DNA / 186
8.3.4 Were Neandertals a Different Subspecies? / 190
8.4 Summary / 190
8.5 Postscript / 192
9. Putting the Pieces Together 194
9.1 Summary of the Genetic Evidence / 195
9.2 The Fossil Record-A Population Geneticist's View / 197
9.2.1 The Distribution of Archaic and Modern Fossils / 198
9.2.2 Similarity of Recent Moderns to Earlier Archaics and
Moderns / 199
9.2.3 Regional Continuity / 202
9.3 "Mostly Out of Africa" / 205
9.4 Issues and Future Directions / 210
Chapter Notes 212
Bibliography 232
Index 246
WHERE TO ORDER:
John Wiley & Sons, Inc.
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Somerset, NJ, 08875-1272 U.S.A.
Phone: 800-225-5945
Fax: 732-302-2300
Web site: www.wiley.com
Cost: $69.95 Hardcover (ISBN: 0471384135)
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