Modern%20Human%20Biology:%20Patterns%20of%20Variation

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Chapter 14

• Modern Human Biology Patterns of Variation

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Chapter Outline

• Historical Views of Human Variation
• The Concept of Race
• Racism
• Intelligence

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Chapter Outline

• Contemporary Interpretations of Human Variation
• Population Genetics
• Evolution in Action Modern Human Populations
• Human Biocultural Evolution

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Historical Views of Human Variation

• Two schools of thought developed to explain
  diversity
• Monogenists believed that all humans were
  descended from a original pair of humans.
• Polygenists believed that all humans were
  descended from a number of pairs of humans.

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Historical Views of Human Variation

• Biological determinism - cultural and biological
  variations are inherited in the same way.
• Eugenics - "race improvement" through forced
  sterilization of members of some groups and
  encouraged reproduction among others.

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Traditional Concept of Race

• Since the 1600s, race has been used to refer to
  culturally defined groups.
• Race is used as a biological term, but has
  enormous social significance.
• "Racial traits" are not the only phenotypic
  expressions that contribute to social identity
  sex and age are also critically important.
• In the 1950's the use of the term "race" was
  replaced with "ethnicity "

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Allele FrequenciesWithin and Between Populations

• After World War II, the study of human variation
  shifted to the study of differences in allele
  frequencies within and between populations.
• The application of evolutionary principles to
  human variation has replaced the view that was
  based solely on observed phenotype.
• Races are no longer viewed as fixed biological
  entities, composed of individuals fitting a
  particular type.

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Groupings Used by Lewontin in Population Genetics
Study (1972)
Geographical Group Examples of Populations Included
Caucasians Arabs, Armenians, Tristan da Cunhans
Black Africans Bantu, San, U.S. blacks
Asians Ainu, Chinese, Turks
South Asians Andamanese, Tamils
Amerinds Aleuts, Navaho, Yanomama
Oceanians Easter Islanders, Micronesians
Australians All treated as a single group
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Distribution of B allele in Indigenous Populations
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Genetic PolymorphismsUsed to Study Human
Variation
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Population Genetics Research
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Environmental Factors

• Global warming may expand the range of tropical
  diseases.
• The spread of disease is associated with
  encountering people this includes crossing
  borders and penetrating remote areas.
• The increasingly large human population leads to
  overcrowding, unsanitary conditions and the
  spread of communicable disease.