Human Variation Throughout History: Perspectives and Evolutionary Insights

1. Exploring Biological Anthropology: The Essentials, 3rd Edition CRAIG STANFORD JOHN S. ALLEN SUSAN C. ANTÓN

2. Chapter 6Human Variation: Evolution, Adaptation, and Adaptability

3. Human Variation at the Individual and Group Levels What is a Population? Deme Subspecies Race Polytypic Species

4. Historical Perspectives on Human Variation • Recording Human Variation in Past Civilizations • Ancient Egyptians: recognized physical differences of people around them • Ancient Greeks: recognized “Ethiopians” who were dark-skinned people • Romans: had at least as extensive knowledge as the Greeks of the variety of peoples that could be found in the western part of Eurasia and north Africa; limited contact with Han Chinese traders

5. Historical Perspectives on Human Variation (cont’d) • The Monogenism-Polygenism Debate • Monogenism: all people of all races are the product of a single creation • Environmentalism: the view that the environment has great powers to directly shape the anatomy of individual organisms • Polygenism: the different races can be viewed in terms of their own evolutionary history

6. Historical Perspectives on Human Variation (cont’d) Race and Racism in the Twentieth Century Racism: A prejudicial belief that members of one ethnic group are superior in some way to those of another.

7. Historical Perspectives on Human Variation (cont’d) Changing Attitudes Towards Race Focus on ‘populations’ Ethnic Groups

8. Historical Perspectives on Human Variation (cont’d) • Deconstructing Racial Features • Skin Color • Eye Form • Hair Color and Form • Head Shape

9. Population Genetics • Population genetics: the study of genetic variation within and between groups of organisms • Microevolution: the study of evolutionary phenomena that occur within a species

10. Population Genetics (cont’d) • Polymorphisms: ABO and Other Blood Type Systems • Polymorphic: two or more distinct phenotypes that exist within a population • Maternal-Fetal Incompatibility • The Human Leukocyte Antigen (HLA) System

11. Population Genetics (cont’d) Gene Flow and Protein Polymorphisms Migration ABO System

12. Population Genetics (cont’d) Gene Flow in Contemporary Populations Örség of Hungary African American Studies

13. Population Genetics (cont’d) • Polymorphisms and Phylogenetic Studies • Phylogeny: an evolutionary tree indicating relatedness and divergence of taxonomic groups • Branch • Node • Cavalli-Sforza: a genetic tree of the world’s populations

14. Polymorphisms and Natural Selection in Human Populations • The Evolution of Lactose Tolerance • The Genetics of Lactose Tolerance • Lactose/lactase • Lactose malabsorbers • LCT*P • Explanations for the Lactase Polymorphism • Cultural historical hypothesis • Lactose tolerance is an example of the interaction of biological and cultural factors

15. Polymorphisms and Natural Selection in Human Populations (cont’d) • Balanced Polymorphisms: Sickle cell and Other Conditions • Sickle cell • Heterozygous Advantage • Balanced Polymorphism • Other Possible Disease-Associated Balance Polymorphisms • Tay-Sachs disease and cystic fibrosis

16. Adaptation and Adaptability • Adaptability: the ability of an organism to make positive changes after exposure to stressful environmental conditions

17. Adaptation and Adaptability (cont’d) • Levels of Adaptability • Acclimatization: the process of short-term changes in physiology that occur in response to changes in environmental conditions

18. Adaptation and Adaptability (cont’d) • Heat and Cold • Vasodilation • Vasoconstriction • Body Size and Shape • Bergmann’s Rule • Allen’s Rule

19. Adaptation and Adaptability (cont’d) • Living at High Altitude • Hypoxia or “oxygen starvation” • Increasing heart and breathing rates • Increase in hemoglobin concentrations • Skin Color • Melanin • Latitude and clinal variation • Vitamin D and the Vitamin D line