Modern Human Diversity

1
Chapter 13

• Modern Human Diversity

2
Chapter Outline

• What are the causes of physical variability in
  animals?
• Is the biological concept of race useful for
  studying physical variation in the human species?
  
• Is there validity to studying differences in
  intelligence from one population to another?

3
Variation and Evolution

• In humans, most behavioral patterns are
  culturally learned or acquired.
• Other characteristics are determined by an
  interaction between genes and environment.

4
Genetic Variability

• Gene pools of populations contain various
  alternative alleles.
• When the environment changes, their gene pool
  confers the possibility for physical alteration
  to meet the change.
• When a species is separated into different
  regions, populations differ in the frequency
  with which genetic variability is expressed.

5
The Meaning of Race

• Early anthropologists classified Homo sapiens
  into races based on geographic location, skin
  color, body size, head shape, and hair texture.
• The presence of individuals who did not fit the
  type challenged these racial classifications.
• No examples of pure racial types could be found.

6
Race and Human Variation Limitations

• Race is an arbitrary category, making agreement
  on any classification impossible.
• Humans are complex genetically and often the
  genetic basis of traits on which racial studies
  are based is poorly understood.
• Race exists as a cultural as well as a biological
  category.

7
Factors in Variation of Skin Color

• Transparency or thickness of the skin.
• Distribution of blood vessels.
• Amount of carotene and melanin in a given area of
  skin.

8
Factors in Variation of Skin Color

• Exposure to sunlight increases the amount of
  melanin, darkening the skin.
• Selective mating, as well as geographic location,
  plays a part in skin color distribution.

9
Racism

• Racism is a social problem.
• Racist individuals react on the basis of social
  stereotypes instead of scientific facts.
• Behavioral characteristics attributed to race can
  be explained with culture rather than biology.