Preface ...................................................... xiii
SECTION 1: Background
1 Comprehending Human Biological Diversity ..................... 3
The Beginnings of Western Classification Systems ............. 3
Classifying the Diversity .................................... 4
A Shift in Racial Classifications ............................ 7
Polygenism ................................................... 9
More Measuring of Skulls and the Ideal Type ................. 11
Typological Approach ........................................ 11
Mendelian Genetics and Race ................................. 12
Questioning the Usefulness of the Race Concept .............. 13
A Genetic Definition of Race ................................ 14
Clines and Populations ...................................... 18
So, Where Are We Today? ..................................... 19
Chapter Summary ............................................. 20
Supplemental Resources ...................................... 21
2 The Genetic Basis of Human Variation ........................ 23
A Minimalist View of the Requirements for Inheritance via
DNA ......................................................... 23
Mitosis Produces Identical Nuclear DNA in Daughter
Cells .................................................... 23
Meiosis Produces Haploid Daughter Cells .................. 24
Human Chromosomes ........................................... 24
The Processes of Cell Division .............................. 27
Mitosis .................................................. 28
Meiosis .................................................. 30
DNA ......................................................... 31
The Molecular Composition of DNA ......................... 31
Replication .............................................. 32
Transcription ............................................ 33
Translation .............................................. 35
From Genotype to Phenotype .................................. 38
Dominance ................................................ 39
Mutation .................................................... 40
Substitutions ............................................ 40
Insertions and Deletions ................................. 40
Recombinations ........................................... 41
Translocations and Nondisjunctions ....................... 41
Mutation Frequencies ..................................... 43
Basic Transmission Genetics: The Mendelian Laws ............. 43
Mendel's First Law: Segregation of Alleles ............... 44
Mendel's Second Law: Independent Assortment of Alleles ... 44
Beyond Mendel ............................................... 46
Sex-Linked Inheritance ................................... 46
Mitochondrial DNA ........................................ 47
Explorations in diversity: Telomere Length and Aging ..... 48
What Is a Gene? ............................................. 48
Chapter Summary ............................................. 48
Supplemental Resources ...................................... 49
3 Population Genetics and Human Variation ...................... 50
Probability Theory .......................................... 50
Probability Rules ........................................ 50
Hardy-Weinberg Equilibrium .................................. 51
Allele Frequencies ....................................... 52
Expected Genotype Frequencies ............................ 53
Why Is Hardy-Weinberg Equilibrium Important? ............. 56
How Can We Tell If a Population Is in Hardy-Weinberg
Equilibrium? ............................................. 57
Departures from Hardy-Weinberg Equilibrium .................. 58
Multiple-Locus Hardy-Weinberg Equilibrium ................ 58
Assortative Mating ....................................... 63
Inbreeding ............................................... 65
Evolutionary Forces ......................................... 68
Mutation ................................................. 68
Selection ................................................ 70
Drift .................................................... 76
Migration ................................................ 84
Combining Forces ......................................... 85
Chapter Summary ............................................. 87
Supplemental Resources ...................................... 88
SECTION 2: Variation in Genes, Simple Genetic Traits,
and DNA Markers
4 Blood Group Polymorphisms ................................... 91
Antigens, Antibodies, and the Immune System ................. 91
The Immune System ........................................ 91
Genetic Polymorphisms in the Blood .......................... 95
ABO, Hh (FUT1), Secretor (FUT2), and Lewis (FUT3) Systems ... 95
The ABO Histo-Blood Group System ......................... 95
Hh (FUT1) and Bombay .................................... 98
The Secretor System (FUT2) ............................... 99
The Lewis System (FUT3) .................................. 99
Explorations in diversity: Histo-Blood Groups and
Diet .................................................... 100
Geographical Distribution and Natural Selection of the
ABO Histo-Blood Group System ............................... 102
Cholera ................................................. 107
Syphilis (Treponemal Diseases) .......................... 107
Plague .................................................. 107
Smallpox ................................................ 108
Pathogen Receptors ...................................... 108
Blood Group Associations ................................ 111
Other Possible Selective Factors Molding the ABO
System .................................................. 112
The Rh System .............................................. 113
The Rh System and Selection ............................. 114
Explorations in diversity: Erythrocytes as Pathogen
Decoys .................................................. 117
The MNSs Blood Group System ................................ 117
The Duffy Blood Group System ............................... 120
Other Blood Groups ......................................... 121
Chapter Summary ............................................ 121
Supplemental Resources ..................................... 122
5 Plasma Proteins and Red Cell Enzymes ....................... 123
Detection of Genetic Polymorphisms ......................... 123
Some Plasma Proteins ....................................... 124
Haptoglobin (α2-globulins) .............................. 126
Transferrin ............................................. 127
Group-Specific Component or Vitamin D-Binding Protein ... 127
Immunoglobulins (Gm-Am and Km) .......................... 129
Apolipoproteins, β-Lipoproteins, and β2-Glycoproteins ... 131
Other Plasma Proteins ................................... 131
Explorations in diversity: Novel Ways to Explore Human
Variation and Evolution ................................. 132
Red Cell Enzymes ........................................... 133
Glucose-6-Phosphate Dehydrogenase ....................... 133
Other Enzyme Systems of Anthropological Interest ........ 137
Exploring Population Structure with Classical Markers ...... 138
Example 1: The Irish Travelers or Tinkers ............... 138
Example 2: The Origins of Indo-Europeans ................ 138
Chapter Summary ............................................ 142
Supplemental Resources ..................................... 142
6 Human Leukocyte Antigen Polymorphism ....................... 143
The Major Histocompatibility Complex ....................... 143
Location and Organization of the MHC ....................... 143
Linkage Disequilibrium ..................................... 146
HLA and Disease Associations ............................... 147
Explorations in diversity: HLA and Mate Choice? ......... 149
HLA and Population Diversity ............................... 150
Chapter Summary ............................................ 155
Supplemental Resources ..................................... 155
7 Human Hemoglobin Variants .................................. 157
Beginnings of Hemoglobin Research .......................... 157
The Hemoglobin Molecule and Hemoglobin Genes ............... 157
Hemoglobin Variants ........................................ 159
The Geographic Distribution of the Sickle Cell Allele ...... 161
How Resistance to Falciparum Malaria Works .............. 164
The Possibility of Differential Fertility .................. 165
Origin of the Sickle Cell Allele ........................... 165
Single-Mutation Theory .................................. 165
Multiple-Mutation Theory ................................ 167
Other Hemoglobinopathies ................................... 170
Hemoglobin E ............................................ 170
Hemoglobin С ............................................ 171
Other Hemoglobinopathies of Anthropological Interest .... 172
Thalassemias ............................................... 172
α-Thalassemias .......................................... 172
β-Thalassemias .......................................... 175
Thalassemia Haplotypes ..................................... 176
The Thalassemias and Natural Selection ..................... 177
Chapter Summary ............................................ 180
Supplemental Resources ..................................... 180
8 Milk, Taste, and Cerumen ................................... 182
Lactase Restriction and Persistence ........................ 182
Taste: Phenylthiocarbamide (6-n-propylthiouracil) .......... 188
Variation in Ear Wax or Cerumen ............................ 193
Chapter Summary ............................................ 196
Supplemental Resources ..................................... 197
9 DNA Markers ................................................ 198
Molecular Genetic Techniques and DNA Variation ............. 198
Polymerase Chain Reaction ............................... 198
Restriction Fragment Length Polymorphisms ............... 201
Insertions and Deletions ................................ 204
Interspersed Nuclear Elements: SINEs and LINEs .......... 206
DNA Sequencing .......................................... 207
Tandem Repeats .......................................... 219
Explorations in diversity: Copy Number Variants ......... 221
American Indians ........................................... 222
The Cohen Modal Haplotype and the Diaspora ................. 225
How Many Races Are Documented in Our DNA? .................. 229
DNA Markers and Individual Variation ....................... 230
Thomas Jefferson and the Descendants of Sally Hemings ... 231
Who Is Buried in Jesse James's Grave? ................... 234
Chapter Summary ............................................ 235
Supplemental Resources ..................................... 236
SECTION 3: Variation in Complex Traits
10 Quantitative Variation ..................................... 239
The Mendelian Basis for Quantitative Trait Variation ....... 239
Components of Variation for a Quantitative Trait ........ 243
Estimation of Narrow Sense Heritability .................... 244
Narrow Sense Heritability of the Cephalic Index ............ 250
Multiple Quantitative Traits ............................... 255
Evolution and Quantitative Traits .......................... 256
Mutation ................................................ 256
Selection ............................................... 256
Genetic Drift and Migration ............................. 257
Explorations in diversity: QTLs, LODs, and AIMs ......... 258
Chapter Summary ............................................ 258
Supplemental Resources ..................................... 259
11 Anthropometric Variation ................................... 260
Anthropometric Measures .................................... 260
Body Measures ........................................... 260
Skinfolds ............................................... 263
Head Measures ........................................... 264
Variation Within Populations ............................... 267
Genetics ................................................ 267
Explorations in diversity: Can We Tell Race from
Cranial Measurements? ................................... 268
Human Growth ............................................ 270
Aging ................................................... 277
Sexual Dimorphism ....................................... 277
Environmental Variations ................................... 280
Correlations with Climate ............................... 280
High-Altitude Adaptation ................................ 286
Explorations in diversity: The Practical Value of
Anthropometry ........................................... 288
Chapter Summary ............................................ 289
Supplemental Resources ..................................... 290
12 Pigmentation ............................................... 291
Skin Color ................................................. 291
The Biology of Skin Color ............................... 291
Variation in Human Skin Color ........................... 298
Explorations in diversity: Skin and Hair Color of the
Neandertals ............................................. 299
The Evolution of Human Skin Color .......................... 302
Selection for Dark Skin ................................. 303
Selection for Light Skin ................................ 305
Other Aspects of Human Pigmentation ........................ 309
Hair Color .............................................. 309
Eye Color ............................................... 311
Chapter Summary ............................................ 312
Supplemental Resources ..................................... 313
SECTION 4: Population Studies and Human Behaviors
13 Population Structure and Population History ................ 317
Genetic Distance ........................................... 317
Computing Genetic Distance .............................. 318
The Representation of Genetic Distance .................. 320
Population Structure ....................................... 322
Factors Affecting Population Structure .................. 322
Case Study: The Åland Islands ........................... 326
Case Studies in Population History ......................... 329
Admixture in African Americans .......................... 329
Explorations in diversity: The Colonization of the
Pacific Ocean ........................................... 330
The Population History of Ireland ....................... 333
Global Genetic Diversity and the History of the Human
Species .................................................... 336
Levels of Genetic Diversity ............................. 336
Genetic Distance ........................................ 340
Gene Trees .............................................. 341
Neandertal DNA .......................................... 342
Chapter Summary ............................................ 342
Supplemental Resources ..................................... 343
14 Genetics, Behavior, and Human Variation .................... 344
Human Behavioral Genetics .................................. 344
Genetics, Environment, and Behavior ..................... 345
Methods of Behavioral Genetics .......................... 345
Case Studies in Behavioral Genetics ........................ 346
Dyslexia ................................................ 346
Sexual Orientation ...................................... 348
IQ Test Scores .......................................... 353
Chapter Summary ......................................... 363
Supplemental Resources .................................. 363
Glossary ...................................................... 365
References .................................................... 379
Index ......................................................... 423
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