Social psychology II: Relations
Evolutionary psychology
1.1 Altruism and natural selection: an evolutionary perspective on human nature
1.1.1 Natural selection and behavior
Evolutionary psychology investigates the evolutionary origin of behavior and consequences for current
psychological mechanisms.
- The theory of natural selection was first described by Darwin in 1859: “The origin of Species” =
Selection in nature occurs because some organisms survive better and reproduce better in a certain
environment
• survival of the fittest: better adaptation
to environment is bigger chance for
reproduction and survival.
• better fitness (high fitness = higher
chance to transferring your own genes to
the next generation) = a good fit to your
environment
Primary interest: evolution of physical features
- Modern Darwinians:
• Primary interest = evolution of behavior
(e.g., altruistic behavior), why do people
behave like that?
• Evolutionary perspective on human nature: Universal characteristics: These successful
characteristics provide such an evolutionary advantage, that they spread throughout the
population and become typical for all mankind, become universal.
• For example: Bipedalism = standing up straight, walking on our legs and feet
• Evolutionary psychologists look for universal psychological features/characteristics.
1.1.2 Altruistic behavior
= helping others although it may be detrimental to your own fitness. How did we become so social?
How did the seemingly selfish process of natural selection ended up in us people also being able to behave
altruistically toward each other?
How to explain this?
→ The universal need to belong: being part of the group was very important for protection, reproducing etc.
Baumeister & Tyce (1990): this is the origin of “social anxiety”. Social anxiety is functional, as an adaptation
to prevent exclusion from the group.
1.1.3 Inclusive fitness and kinship (Hamilton)
= your personal reproductive success (how many children you have) + the effects you have on the
reproduction of your genetic relatives, weighted by the degree of genetic relatedness.
• identical twin: genetic relatedness = 100%
• parents - child: 50%
• brother/sister: 50%
• aunt/uncle - niece/nephew: 25%
• cousins: 12.5%
By saving the life of someone you’re related to, you also save you own genes, and you help to get your own
genes trough the evolution of time.
= better fitness (of next generation) by helping (genetic) relatives
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,This implies…
- One takes risks for genetic relatives.
- The higher the genetic relatedness, the higher the risk one takes
Daly & Wilson, 88
- less care by step-parents than biological parents
- more child abuse by step-fathers (100 x more than biological fathers)
Burnstein et al., 94
- we are more inclined to help relatives in trouble:
Conclusion:
- Who we help in different situations is predictable from an evolutionary perspective
- Strong evidence for the inclusive fitness theory
1.1.4 Reciprocal altruism (Trivers)
Why do we help unrelated people aswell?
- Helping and altruism became part of our DNA because the ones who helped other people had an
evolutionary advantage compared to the ones that didn’t. Helping increases our own fitness
(evolutionary perspective)
Trivers: first to describe the principle of reciprocal altruism = “I help you when you help me”
only possible if:
- the person being helped can be recognized later
- deceivers can be punished: cheaters are excluded
only in intelligent species (primates, humans)
only with acquaintances and small groups / tribes (guarantees reciprocity)
→ In the end, helping increases fitness!
1.2 Sexual selection and sex differences in behavior: an evolutionary perspective on sex differences
1.2.1 Sexual selection and parental investment
Sexual selection = the selection of –and different access to – sexual partners
Forms of sexual selection/competition:
• Intrasexual competition: the winner passes on more genes (male competition)
• Intersexual competition: choosing a mate based on their preferences (female choice)
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,Parental investment theory (Trivers, 72): Sexes differ in terms of time and effort spent in raising offspring
(pregnancy, feeding, protecting, …)
- women invest more in raising offspring (carry the baby, breastfeeding, …)
- men invest only in their seed
→ women are restricted in their reproduction (1 child a year) and this causes sex differences
• variation in reproduction between the sexes (female record: 69 children/ male record: over a
1000)
• These differences in investment will result in several sex differences!
Prediction:
- The sex that invests less in raising offspring will prefer having more (sexual) partners.
- Undergraduates – What’s the desired number of sexual partners? (Buss & Schmitt (1993)
• Women: 1 during the next month / 4 to 5 in their whole life
• Men: 2 during the next month / 8 during the next year / on average 18 in their whole life
- The sex that invests less in raising offspring will be less selective in choosing partners
Undergraduates – “I’ve noticed you around…I find you very attractive”: (Clark & Hatfield, 1989)
- Would you go out with me tonight? (F: 55% / M: 50%)
- Would you come over to my apartment tonight? (F: 6% / M: 69%)
- Would you go to bed with me tonight? (F: 0% / M: 75%)
Replication in Austria ~ identical findings (Voracek et al., 2005): Attitude towards casual sex: men more
positive
→ Men are less selective in choosing sexual partners
1.2.2 Mating preferences
Prediction:
- men are looking for partner who is young and physically attractive (~ sign of fertility)
- women are looking for a partner who can provide material support (good financial prospect)
Confirmed in 37 cultures (Buss, 1989); Replicated in 2011 (Russock)
‘Structural powerlessness hypothesis’: Alternative explanation for the difference / Eagly & Wood (1999):
men are associated with the role of breadwinner / ‘money maker’; women are financially dependent on their
man (gender roles)
↔ When women have a higher income/SES (“money is not an issue”), they place even higher importance to
financial means/SES in men
(Buss, 1989; Delton et al., 2006; Todosijevic et al., 2003; Wiederman & Allgeier, 1992)
Both sexes: a physically attractive partner
- waist-to-hip ratio:
• optimal .90 for men
• optimal .67-.80 for women
- Symmetry as a marker of “good genes”
↔ fluctuating asymmetry: the degree to which an individual deviates from perfect bilateral symmetry
shows "bad" genetic quality or developmental issues (e.g., genetic abnormalities, environmental influences)
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, 1.2.3 Young men: risk and violence
Evolutionary explanation: Sexual competition
- Female choice (certainty about motherhood / larger parental investment)
- Men have to compete to gain “sexual access” (intrasexual competition among men)
→ more aggression, more risks
Archer (2004):
- Physical aggression: largest differences (d = .80)
- Verbal aggression: less large (d = .51)
- Anger: no differences (d = -.04)
- Women score higher on indirect (or relational) aggression
(d = -.19), but only in late childhood and adolescence
- Men score higher on direct aggression (mainly physical),
consistently across ages and cultures, observable from
young childhood with a peak between age 20 and 30.
- Figure = arrest rates for violent crime
1.2.4 Cuckoldry and jealousy
Prediction: Men and women will differ in the value they place on cues that trigger jealousy
- Men: more distressed by sexual infidelity
- Women: more distressed by emotional infidelity
Confirmed; also with physiological measures (Buss et al., 1992)
- Both sexes react distressed by both options!
- Forced choice: strong sex differences in line with the evolutionary expectations
women avoid loss of material help and assistance (emotional infidelity)
men avoid cuckoldry/ responsibility for false fatherhood (sexual infidelity)
Social Interaction and dilemmas
2.1 How does a collective work?
2.1.1 Introduction
Hobbes: “How are collectives able to function if humans tend to be primarily concerned with pursuing their
self-interest?”
Adam Smith: If everybody pursues self-interest, society will benefit as an unintended consequence.
Therefore, conflicts between self-interest and collective interest do not exist. (not true)
→ we know that in the end helping others increases our fitness + conflicts between self-interest and
collective interest are an everyday reality.
- Bv. I am better off if I don’t pay taxes but society is not
This relates to neuroscience: Reward activates the orbito-frontal cortex
and the ventral striatum (nucleus accumbens)
Rewards is a dopamine related system. Every time the dopamine related
system is activated, we feel good. There is a very strong correlation
between the activation of these brain areas and feeling good. So for
example Ronaldo might feel a lot better if he chooses to score the goal
by himself and chooses for self-interest then if he gives the assist to
another team player.
→ we all strive for these feelings of feeling better and being rewarded
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