HC 7

Question 1

Why aggress?

6 volutionary functions

Answer 1

1 • Co-opt resources of others
2 • Defend against attack
3 • Eliminate sexual competition
4 • Climb up the hierarchy
5 • Deter rivals from future aggression 
6 • Deter infidelity

Question 2

Aggression as a Solution to Adaptive Problems

(1) Co-opt the Resources of Others

Answer 2

Humans stockpile resources valuable for survival and reproduction
• Fertile land
• Fertile women
• Access to 
– Water
– Food
– Tools
– Weapons

Question 3

Aggression as a Solution to Adaptive Problems

(2) Defense against Attacks: 2 ways

Answer 3

1 – Aggression can be used to defend against attack
• Prevents one’s resources from being co-opted by others
2 – Social exclusion as defense mechanism

Question 4

Aggression as a Solution to Adaptive Problems

(3) Inflict Cost on Intrasexual Rivals: 3 outcomes

Answer 4

– Same-sex rivals are vying for same (or similar) resources
– Aggression can inflict cost (verbal, physical) to same-sex rivals —> reducing desirability of victim to members of the opposite sex
– Direct versus indirect aggression (sex difference)

Question 5

Intra sexual competition

Answer 5

• The more intra sexual competition, the more sex dimorphism
• The more polygynous, the more sex dimorphic a sex.
• Gorillas: males +/- 100% bigger
• Chimpanzees: males +/- 38% bigger
• Humans :males +/- 18% bigger

Question 6

Aggression as a Solution to Adaptive Problems

(4) Negotiate Status and Power Hierarchies

Answer 6

Aggression can be used to increase status or power within existing social hierarchies
• Prevents one’s resources from being co-opted by others
• Bullying as a dominance strategy

Question 7

Aggression as a Solution to Adaptive Problems

(5) Deter Rivals from Future Aggression

Answer 7

Aggression can cultivate a reputation that may deter others from attempts at co-opting

Question 8

Aggression as a Solution to Adaptive Problems

6) Deter long-term mates from infidelity ((3)

Answer 8

• Domestic violence
• Jealousy as mate retention strategy:
– Male sexual jealousy and female emotional jealousy (Buss, 1999; Buunk et al., 1996);
• Homicide of wife by husband accounts for 1/3 of murders in USA

Question 9

Theory of rape

Answer 9

1. Rape as mating strategy in many species (e.g., ducks, urang-utans)
   ◦ especially for males with very few resources to get normal access to women
2. Does this apply to humans?
   ◦ Sexual coercion as adaptation or byproduct

Question 10

The Context-Specificity of Aggression (2)

Answer 10

– Aggression should only be triggered in contexts
that present the adaptive problem
– Culture of honour studies suggest cultural differences

Question 11

Why are men more violently aggressive than women? (3)

Answer 11

Intrasexual competition
• Parental investment: men lower than women
• Sexual selection and greater variance in men than women to reproduce
• Evolution of “risk-taking” among men, more strongly than women

Question 12

The young male syndrome (Wilson and Daly, 1985)

• Why would men die more often than women?

Answer 12

• Young men seeking a wife need to excel, i.e. risk taking behaviour.
• Carry over effects in reputation for the rest of their life (e.g. war heroes)

Question 13

“The Crazy Bastard Hypothesis”

The young male syndrome

Answer 13

Empirical work demonstrates a link between physical risk-taking and social perceptions of physical formidability

Question 14

Body Differences in Design for Combat

• Compared to women, men have…

Answer 14

61 percent more total muscle mass, 
75 percent more upper arm muscle mass, 
91 percent greater upper body strength, 
taller bodies, 
heavier bodies, 
thicker jaw bones, 
stronger bones, 
greater bone density in their arms, 
higher muscle- to-fat ratio, 
broader shoulders that facilitate weapon use, 
and even thicker skin

Question 15

Bullying

• Same-sex bullying in schools

Answer 15

Males compared to females show increased numbers of
• Number of times bullied 
• Joined in bullying others 
• Physically getting hurt
• Belongings taken away

– Females have increased scores compared to males on
» Name calling
» Spreading rumors

Question 16

Contexts Triggering Male-Female Aggression

• Sexual Jealousy against woman

Answer 16

– Largely targeted at spouses, mates, girlfriends
– When:
• Observation or suspicion of infidelity
• Women is terminating relationship
– Young females are far more likely to be killed than older females

Question 17

Contexts Triggering Female-Male Aggression

• Defense Against Attack against men

Answer 17

When:
• Woman is defending herself against a partner who is enraged over a real or suspected infidelity
• Woman who has been in a prolonged physically abusive relationship

Question 18

Contexts Triggering Female-Female Aggression
• Indirect aggression towards sexual rivals
When and how?

Answer 18

When?
– Competition over partners 
– Friendship disputes
– Failing to share resources 
How?
– Gossip
– Exclusion

Question 19

Why violence has declined in society over time? (4)

Answer 19

• empathy
• self-control
• moral sense
• reason

Question 20

Evolution of Warfare

• Four Conditions

Answer 20

1– The average long-term gain in reproductive resources must be sufficiently large to outweigh the reproductive costs of engaging in warfare over evolutionary time
2– Members of coalitions must believe that their group will emerge victorious
3– The risk that each member takes and the importance of each member’s contribution to the success must translate into a corresponding share of the benefits
4– Men who go into battle must be cloaked in a “veil of ignorance” about who will live or who will die

Question 21

male warrior hypothesis

Answer 21

Men, but not women, will have evolved psychological mechanisms designed for coalitional warfare

Question 22

Evidence for male warrior hypothesis (3)

Answer 22

• Men cooperate with ingroup more during intergroup competition
• Men’s groups are more hierarchical, facilitating warfare (van Vugt, 2006)
• In war games men attack more often than women (Johnson et al. 2006)
– Males made more unprovoked attacks
– They were more likely to either attack or retaliate rather than never fight