Genetics, Environment, and Behavior

1
Genetics, Environment, and Behavior

• How do they interact?

2
Variation

• Genotypes vary, except in identical twins
• Environments vary, even for identical twins
• Consequently, phenotypes vary We are different
  from one another
• Nonetheless, we are far more similar than we are
  different from one another.

3
Genetics

• Chromosome pairs and meiosis
• Expression of alleles
• Homozygous alleles
• Heterozygous alleles
• Dominant alleles
• Recessive alleles
• Polygenic control
• No genes for behavior

4
Evolutionary psychology

• An old idea is currently popular again
• Emphasis is on natural selection
• Or is it artificial selection?
• Example of mate selection
• Are all men potential rapists?

5
Criticism of evolutionary psychology

• Backward reasoning an effect looking for a cause
• An example of post hoc reasoning.
• Selective use of research results Infidelity is
  overestimated.
• Casual sex has far lower fertility than committed
  sex.
• The theory plays on gender stereotypes

6
More criticism

• Other causes socialization pressure, family life
• Female sexuality is highly variable, especially
  across time and situations
• Mate preferences are culture-related (Eagly
  Wood, 1999)

7
Gender influences

• Sex-linked traits
• Gene on sex chromosomes
• Sex-influenced traits
• Interaction of genetics and environment
• Hormones are key variables

8
Genetic abnormalities

• Mutations Hemophilia
• Aberrations Cri-du-chat (5p-) syndrome
• Interaction of genetics and environment
• Genetic disorders
• Down syndrome Genetic but not hereditary
• Huntingtons disease Genetic and hereditary, no
  interaction with environment
• PKU Genetic and hereditary, interaction with
  environment

9
Behavior genetics

• Animal breeding Artificial selection
• Eugenics
• Family studies Concordance
• Twin studies
• An example Schizophrenia

10
Sociobiology

• Parental investment
• The incest taboo
• Altruism
• Kin selection
• Reciprocal altruism

11
Ethnocentrism

• Altruism in the Inuit
• Kin selection
• Familiarity

12
Critical thinking about ethocentricity

• How is the question framed? Does it lead us down
  one path of thinking?
• What are our predispositions and assumptions ?
  What pattern of thinking would make us look good
  or feel better about ourselves?
• Avoid fallacious thinking The universality
  fallacy and the naturalistic fallacy

13
What do we look for in a mate? (Buss, 1998)

• Men prefer, in order
• 1. Kindness, understanding
• 2. Intelligence
• 3. Physical attractiveness
• 4. Exciting personality
• 5. Good health
• 6. Adaptability
• 7. Creativity
• 8. Desire for children
• 9. College graduate
• 10. Good heredity

• Women prefer, in order
• 1. Kindness, understanding
• 2. Intelligence
• 3. Exciting personality
• 4. Good health
• 5. Adaptability
• 6. Physical attractiveness
• 7. Creativity
• 8. Good earning capacity
• 9. College graduate
• 10. Desire for children