Copyright © 2013 Pearson Education, Inc. All rights reserved. Exploring Biological Anthropology: The Essentials, 3 rd Edition CRAIG STANFORD JOHN S. ALLEN SUSAN C. ANTÓN

Copyright © 2013 Pearson Education, Inc. All rights reserved. Chapter 6 Human Variation: Evolution, Adaptation, and Adaptability

Copyright © 2013 Pearson Education, Inc. All rights reserved. Human Variation at the Individual and Group Levels Deme Race Subspecies Polytypic Species What is a Population?

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. Historical Perspectives on Human Variation (cont’d) Racism: A prejudicial belief that members of one ethnic group are superior in some way to those of another. Race and Racism in the Twentieth Century

Copyright © 2013 Pearson Education, Inc. All rights reserved. Historical Perspectives on Human Variation (cont’d) Focus on ‘populations’ Ethnic Groups Changing Attitudes Towards Race

Copyright © 2013 Pearson Education, Inc. All rights reserved. Historical Perspectives on Human Variation (cont’d) Deconstructing Racial Features – Skin Color – Eye Form – Hair Color and Form – Head Shape

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. Population Genetics (cont’d) Migration ABO System Gene Flow and Protein Polymorphisms

Copyright © 2013 Pearson Education, Inc. All rights reserved. Population Genetics (cont’d) Örség of Hungary African American Studies Gene Flow in Contemporary Populations

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. Adaptation and Adaptability Adaptability: the ability of an organism to make positive changes after exposure to stressful environmental conditions

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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

Copyright © 2013 Pearson Education, Inc. All rights reserved. Adaptation and Adaptability (cont’d) Heat and Cold – Vasodilation – Vasoconstriction Body Size and Shape – Bergmann’s Rule – Allen’s Rule

Copyright © 2013 Pearson Education, Inc. All rights reserved. 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