Evolutionary Forces on personality

1
Evolutionary Forces on personality

• Sociobiology the study of biological bases of
  social behavior
• psychological qualities have been retained in
  people over many years because they are adaptive
• 3 important points
• Reproductive success
• Adaptive value pertains to early life
• Adaptive value in terms of specific tasks in
  specific situations

2
What psychological mechanisms have evolved?

• Male/female mate preferences
• Females will have stronger preferences
• Females focus on mates ability to provide
  resources
• Males focus on reproductive potential
• Sex objects vs. success objects

3

• Evolutionary theory and attraction
•  
• Genetic similarity theory (Rushton, 1989
  Rushton, Russell Wells, 1984)
• more attracted to strangers who resemble you than
  who dont
• leads to offspring with not only your genes but
  genes like themselves
• Rushtons research shows that people are more
  attracted to genetically similar people
• People who go on to have children together are
  more alike than those who dont. Thus among
  sexually active couples, those most genetically
  similar are those most likely to have reproduced.
• Attraction not limited to the opposite sex. We
  tend to be friends with people who are
  genetically similar. Why? From an evolutionary
  perspective its because you are more likely to
  be altruistic to a friend than a stranger, making
  it more likely that the friend will go onto
  reproduce (similar genes to your own) and you may
  n\meet the friends opposite sex sibling - close
  genes again!
• How do we detect this genetic similarity either
  drawn to those with similar facial and bodily
  features OR via smell.

4

• Please think of a serious committed relationship
• you have had in the past, that you currently
  have,
• or that you would like to have. Imagine that the
• person with whom youve become seriously
• involved became interested in someone else. What
• would distress or upset you more?
• (a) Imagining your partner forming a deep
  emotional attachment to that person OR
• (b) Imagining your partner enjoying passionate
  sexual intercourse with that person

5
Sexual/relationship jealousy

• Based on evolutionary forces, men and women
  approach
• sexual jealousy differently
• Buss, Larsen, Westen, and Semmelroth (1992) men
  and
• women were asked to respond to the previous
  vignette
•  
• FEMALES 82 option (a) 18 option (b)MALES
  40 option (a) 60 option (b)
• Males jealous of sexual fidelity
• Females jealous of emotional fidelity

6
Brain function and personality

• Behavioral approach system (BAS)
• Incentives
• Left frontal lobe
• dopamine
• Behavioral inhibition system (BIS)
• withdrawal
• Right frontal lobe
• Serotonin?
• Anxiety/cues of threat
• BAS and BIS act independently

7
Link to temperament

1. BIS sensitivity and emotional instability/neurotic
   ism
2. BAS sensitivity related to extraversion
3. Role of impulsivity
4. Zuckerman sensation seeking

8
Role of hormones

• Sex hormones important
• weeks 8 24 prenatally, in months 1-5 after
  birth, and after puberty
• changes to nervous system

Link to behavior in children Reinisch, 1981 sex
difference effect of prenatal exposure filter
by cognitions
9
Hormonal links to behavior in children continued

• Berenbaum Hines (1992)
• Androgen exposed girls played with boys toys
• No difference in boys
• Jacklin, Maccoby, Doering (1983)
• Boldness or timidity of infant boys
• No effect for girls

10

• Testosterone and adult personality