1. Evolutionary Perspectives on Personality
Chapter 8
Evolutionary Perspectives on Personality

2. Sex Differences in Jealousy

3. Parental Investment Theory
Robert Trivers (1972)
Implications for human mating psychology: Gender differences

4. Parental Investment Theory
Sex with higher biological cost of reproduction (e.g., gestation, nursing) will be choosier about partners. (Trivers, 1972)
Implications for gender differences in human mating psychology: Females? More sensitive to signals of commitment and investment

5. Commitment has more DNA reproductive costs to males than to females

6. Females will tend to be more attentive and emotionally responsive toward indicators of pair bond commitment.

7. Nuptial Gifting: Fruitflies

8. Human female being choosy:

9. Paternity Certainty
“Definitive conclusions cannot be reached, but it appears that men are cuckolded about 10% of the time.” (!!!) (Bellis & Baker, 1990; Flinn, 1988; Gaulin, McBurney, & Brakeman-Wartell, 1997; McBurney, Simon, Gaulin, & Geliebter, 2002).

11. Sex differences in Jealousy

12. Buss et al. (1992) Men were more upset by sexual infidelity scenario
Women were more upset by commitment infidelity scenario

13. Shutzwohl & Koch (1994) Commitment infidelity: Sexual infidelity:
Students read dating scenarios where cues had been embedded that were relevant to two kinds of sexual jealously cues:
Commitment infidelity:
She doesn’t want to go out on dates with you as often.
She starts looking for reasons to start arguments with you.
She doesn’t respond anymore when you tell her that you love her.
She acts nervous when a certain man’s name comes up in conversations with you.
Sexual infidelity:
Her clothing style suddenly changes.
She suddenly has difficulty becoming sexually aroused when she and you want to have sex.
You notice that she seems bored when you have sex.
She suddenly refuses to have sex with you.

14. Schutzwohl & Koch (2004)
At a later time, participants were asked to recall the scenarios. As predicted men recalled more sexual infidelity cues, and women recalled more commitment infidelity cues, especially in the more threatening scenarios.

15. Criticisms: The “Doubleshot” hypothesis (DeSteno & Salovey, 1996)
Men believe a women’s sexual infidelity indicates BOTH sexual + romantic infidelity. Women are less likely to believe that. EVIDENCE? Under high cognitive load, effects disappear.
Not convincing evidence… “like dangling a hungry person over a cliff and concluding hunger doesn’t exist.”

16. Paternity Certainty & Evopsych
Daly & Wilson (1982)
In delivery room, “looks like father” is said more often than “looks like mother”
Christenfeld & Hill (1995)
Highest photo matching accuracy score was:
1 yr old child  father

17. Paternity Certainty & Grandparenting
Paternity certainty is
 Lowest for:
Father’s Father
 Highest for:
Mother’s Mother
Q: Is investment in grandchildren calibrated according to degree of paternity certainty?

18. Grandparents’ level of investment in grandchildren
Father’s father
Father’s mother
Mother’s father
Mother’s mother

19. Mate Retention Tactics

20. Mate Retention Effort by Spouse Age
Higher correlations for men than women
Why the sex difference?

21. Mate Retention Effort by Spouse Status
Higher correlations for women than men
Why the sex difference?

22. Marital separation and wife’s murder risk
Q: Are evolved mating mechanisms (e.g., sexual jealousy) implicated here?

23. The O.J. Simpson Murder Trial (Acquited)

24. Frequency of thinking about sex

25. Do you ever think of some else during sex with your partner?

26. Probability of consenting to intercourse by how long the person has been known
W > M (except, after 5 years of knowing someone)

27. Clark & Hatfield (1989)

28. Sex Differences in Mate Preferences

29. Sex difference in mating strategies
Importance of physical appearance

30. Wanting “good financial prospects” in a mate (Buss et al, 1989)

31. Minimum acceptable degree of intelligence

32. Age preferences

33. Ideally wanted age difference in a mate

34. Leading internet porn sites:

35. Walking Speed and Socioeconomic Status

36. Evolutionary Psychology (cont’d)
Fluctuating Asymmetry studies
Deviation from body symmetry
Negative cue for health ?
Q: Are human mating mechanisms sensitive to that? (an evolved preference?)
A: Apparently, yes ) Women prefer smell of symmetrical men
2) Especially true during fertile phase of menstrual cycle

37. Womens preference for the scent of symmetrical men as a function of their day in the menstrual cycle
Thornhill and Gangestad (1998; 1999; 2003)

38. Women’s probability of fertility correlated r=
Women’s probability of fertility correlated r=.54 with their preferences for the scents of more symmetrical men. This effect has been replicated in a larger, separate sample (Thornhill & Gangestad, in press), where the correlation between fertility risk and preference for the scents of symmetrical men was r=.42. Statistically controlling for a number of factors (e.g., men’s number of showers) increased the effect size. Gangestad & Simpson (2000)

39. Evolutionary Psychology (cont’d)
Facial masculinity
W prefer dominant facial features in M more strongly during fertile phase (Penton-Voak et al., 1999a)
Only for short-term sexual partners. Did not affect preferences regarding long-term partners. (Penton-Voak et al., 1999b)

41. How can we test SPH? Structural Powerlessness Hypothesis (SPH)
Q: Is womens’ preference for high status mates due to a history of cultural suppression of women?
Structural Powerlessness Hypothesis (SPH)
Historically, patriarchy is (almost) universal
This makes W dependent on M’s resources
Women’s preference for status/ power/ dominance in men is culturally based
How can we test SPH?

42. How test? Bakweri women High-aspiring college students
Ardener et al (1960)
High-aspiring college students
Weiderman & Allgeier (1992)
Law and med students
Townsend (1987; 1989)

43. The “No Good Men” effect
If stone age brains, and…
If gender differences in mate preferences
Then rising $status of women should
Raise mating amb/frustration in women
Raise sociosexuality in women (“hook-up culture”; sex-ratio theory)

44. The New Knowledge Economy & Men

45. Knocked Up (2007)

48. Age 15 – Avg Grades
Source: Statistics Canada. Youth in Transition Survey, Cohort A, 1999

49. University Graduation rates by Gender by Decade

57. The “No Good Men” effect
If stone age brains, and…
If gender differences in mate preferences
Then rising $status of women should
Raise mating amb/frustration in women
Raise sociosexuality in women (“hook-up culture”; sex-ratio theory)

58. Individual Differences
Three evolutionary views of individual differences
Environmental triggers of adaptive strategies
“R” reproductive strategy
Many offspring, Low investment
Early maturation, Short lifespan
RABBITS

59. Individual Differences
“K” reproductive strategy
Few offspring, high investment
Delayed maturation, long lifespan
ELEPHANTS.

60. Individual Differences
Environmental triggers of adaptive strategies
“R” vs “K” variability within species:
Unstable environment “R”
Stable environment “K”
Draper & Belsky (1990)

62. 1. Environmental Triggers of Individual Differences
Criticism of Draper & Belsky (1990)
1. Differences may be due to poverty
2. Cross-cultural research does not support (Schmitt et al, 2005)

63. Schmit et al (2005): SOI & culture

64. 1. Environmental Triggers of Individual Differences
Sibling Strategies Theory
Compete for parental resources
Sibling rivalry is an adaptation.
Nurse sharks
Cuckoo bird

65. (“Being Cuckolded”) The Cuckoo Bird
Cuckoo lays eggs in other birds’ nests. Hatchlings kick the other eggs out of the nest!

66. Human cuckolding is risky
Cuckold drives from Cuckoo, i.e., leaving potential offspring in a nest that ain’t “yours”.

67. Birth Order and Personality
Sibling rivalry ?
Resource extraction
Older get first “niche” pick: ally with authority
Younger must “diversify”
LB? liberal, open, curious, creative

68. Frank Sulloway (1996)
Reactions to scientific revolutions

69. Reactions to Scientific Revolutions by Birth Order

70. Reactions to Darwin’s Theory of Evolution by Birth Order

71. Frank Sulloway, birth order theory
Meta-analysis of Ernst & Angst (1983)
Big Five hypotheses (esp. Openness)
Strong support for laterborn = rebel
Paulhus, Trapnell, & Chen (1998)
Within family judgments show support
Between family data does not.

72. Sulloway Controversy Selection of historical examples might be biased.
Between family data does NOT support birth order theory
Within family data may be due to continuing sibling age stereotype.
If real, within family BO effect may be family specific (doesn’t transfer).

73. Individual Differences
2. Self-Assessment of Heritable Differences
Tall/Muscular/Physically attractive High power strategy
Smaller/Weaker/Less attractive Low power strategy
(Maybe Sheldon’s (1940) body typology wasn’t so crazy afterall)

74. 3. Frequency Dependent Strategies
Example: Bluegill Sunfish:
3 types of males: Parent, Mimic, Sneak
Are there human variations in mating strategies?
The sociosexual Inventory (SOI) has high heritability
Why was that variation preserved by evolution?
Does it represent opposing types of “mating strategies”?
Long-term (LT) vs Short-term (ST)
Perhaps the SOI questionnaire could be used as a direct measure of LT versus ST mating strategy differences in humans.

75. Sociosexuality Scale (SOI)

76. Sexual Strategies Theory:
Evolved psychological mechanisms are likely to exist that regulate enactment of LT or ST mating strategies depending on the comparative costs and benefits of each strategy afforded by environments. LT and ST mating strategy potentials will exist in BOTH women and men, although they are likely to be gender differentiated to some degree in their specifics.
Sociosexual Orientation
Restric
Unres
“Cad”
“Dad”
“Whore”
“Madonna”

77. SST Predictions Should be a mean gender difference:
Short-term strategy: M > F
Long-term strategy: F > M

78. Cross-national SOI Gender Differences

79. Sexual Strategies Theory
There should exist heritable variation in SOI within both sexes. Why?
How could short-term mating behavior be evolutionarily adaptive for some human females?
ST strategy is easy to fathom for men:
Millions of sperm millions of offspring.
So, how could it be adaptive in females?

80. Female Short-term strategy
Sacrifice commitment for… good genes
Symmetry
attractive
healthy
Masculine
Strong
Dominant
High status
High competence

81. Ratio of testicle size to body size
Associated with mating exclusiveness versus promiscuity
Humans are in-between chimps and orangutans.
Chimp females are promiscuous, but gorilla are orangutan females are exclusive.
This suggests hominid females are likely to have been in-between chimps and orangutans in characteristics sociosexual behavior, in other words, moderately promiscuous.

82. Sexual Strategies Theory (SST)
Sociosexuality represents a human behavior continuum of short-term vs long-term mating strategies.
There should be mean gender differences in sociosexuality.
There should be heritable within-sex variation in sociosexuality.
Each strategy should be associated with personality traits that faciliate that strategy.
Variance in SOI might have been genetically maintained by frequency dependent selection.

83. The Big Five from an evolutionary perspective: Why those 5 factors?
David Buss argues that the Big Five dimensions of personality might be recurrent dimensions in trait judgments around the globe because we share evolved “difference detectors” that are calibrated to notice and evaluate some classes of human behavior differences more than other ones.
From this point of view, those five categories are the behavior differences that demanded the most careful social evaluation to optimize one’s social adaptedness.

84. Limitations of Evolutionary Psychology
Evolutionary hypotheses are sometimes accused of being untestable and hence unfalsifiable
Evopsy defenders argue that this is caused by a double standard, and that, in fact, evopsy hypotheses or no more untestable than are hypotheses in any other science.

85. Summary and Evaluation
Selection is key to evolution, or change in a species over time
Variants that lead to greater genetic replication spread through the population
Evolutionary psychology has three premises: Adaptations are domain-specific, numerous, and functional

86. Summary and Evaluation (continued)
Evolutionary psychology proceeds through both deductive research approach and inductive research approach, like other sciences.
Evolutionary psychology can be applied to all three levels of personality analysis— human nature, sex differences, individual differences

87. Summary and Evaluation (continued)
Evolutionary psychology has several limitations, but this perspective adds a useful set of theoretical tools to the analysis of personality at all three levels of analysis (human nature, sex differences, and individual differences).