EVOLUTIONARY PSYCH
Natural Selection: inherited trait variations contributing to reproduction
and survival will most likely be passed on to succeeding generations
**Darwin’s finches (beaks) example
**wild wolves were naturally selected over time to become the dogs
we keep as pets today
**Other human behavior? Fear, taste preferences, etc.
**What about human sexual behavior? Males vs. females
Gender Differences
Men
Women
- 4/5 of adult video store
- cite affection rather than
customers are men
attraction as reason for first
- more likely to accept casual sex
intercourse
- report more sex than women do
- think about sex less often
- 50-75% would have sex with an
- report less sex than men do
unknown attractive stranger
- 0% would have sex with an
- more likely to perceive friendly
unknown attractive stranger
responses from women as
- Singles ad: offer looks; want
sexual come-ons
status
- Singles ad: offer status; want
looks
How would Evolutionary Psychologists explain these gender differences?
-each gender uses strategies to produce offspring – what are theses strategies?
What would be critiques of the evolutionary explanation?
How much of behavior is genetically influenced?
Behavior Genetics: the study of the power and limits of
genetic and environmental influences on behavior
Are identical twins behaviorally more similar than
fraternal twins? Evidence points to YES
- Extraversion and neuroticism genetically linked
- If identical twin divorced, 3x more likely to get
divorced yourself than if you had a fraternal twin
- Abilities, personality traits, and interests all shown to
have a genetic link
- Separated identical twins example
Key Critique Question: Does being genetically similar
also make your environment respond similarly?
Adoption Studies
Are adopted children more like their biological or adopted parents
personality-wise? BIOLOGICAL
So do adoptive parents do any good? YES
**children of adopted parents are less likely to experience child neglect
and/or abuse, score higher on intelligence tests, happier and more stable
Nature vs. Nurture debate
Heritability: proportion of variation among individuals that we can attribute
to genes
Environment (nurture) has an impact too! Let’s take the example of height:
- Height is highly heritable, but…nutrition plays a role too!
- Menarche (first period) example
Interaction: the effect of one factor (such as environment) depends on
another factor (such as heritability)
Key Point: almost nothing is just nature or just nurture… they work together