Download What is a Population?

Exploring Biological
Anthropology:
The Essentials, 3rd 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
What is a Population?
Deme
Subspecies
Race
Polytypic Species
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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
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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
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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.
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Historical Perspectives on Human
Variation (cont’d)
Changing Attitudes Towards Race
Focus on ‘populations’
Ethnic Groups
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Historical Perspectives on Human
Variation (cont’d)
• Deconstructing Racial Features
– Skin Color
– Eye Form
– Hair Color and Form
– Head Shape
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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
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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
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Population Genetics (cont’d)
Gene Flow and Protein Polymorphisms
Migration
ABO System
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Population Genetics (cont’d)
Gene Flow in Contemporary Populations
Örség of Hungary
African American Studies
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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
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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
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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
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Adaptation and Adaptability
• Adaptability: the ability of an
organism to make positive changes
after exposure to stressful
environmental conditions
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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
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Adaptation and Adaptability (cont’d)
• Heat and Cold
– Vasodilation
– Vasoconstriction
• Body Size and Shape
– Bergmann’s Rule
– Allen’s Rule
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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
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