Evolution and Human Agression

Define the following words Evolution Genes Natural Selection Environment of Evolutionary Adaptation (EEA)

Evolutionary Explanations of Human Aggression Aggression is adaptive Discuss reasons for this statement

The evolutionary approach to explaining aggression sees aggression in terms of its ability to increase survival chances therefore to enhance reproductive success. How can aggression improve survival chances?

Aggressive behaviour has evolved to solve adaptive problems of social living Gain territory and resources i.e. children bullying others for money or toys, adults mugging and warfare. Defending against attacks: aggression to prevent loss of resources and status necessary for reproductive fitness i.e. “stick up for yourself.

Inflicting cost on same sex-rivals: aggression between same sex members to aid in the competition for resources and mates i.e. men fighting over women. Negotiating status and power hierarchies: aggression to gain prestige and dominance among same-sex members i.e. gang violence to “prove oneself” to aid sexual selection by opposite sex members i.e. women attracted to dominant and powerful men. Deterring rivals from future aggression: aggression to maintain dominance and fear in others i.e. making threatening gestures, reinforcing aggressive reputation, maintaining an aggressive appearance Deterring mates from infidelity: aggression against opposite-sex members to maintain fidelity of desired long- term mates and ensuring paternity i.e. wife-battering

What was the main priority for males? Therefore…. What was the main priority for males?

Why is aggressive behaviour an adaptive advantage? (4) Task Why is aggressive behaviour an adaptive advantage? (4)

How does this explain aggression? (Textbook 166 first two paragraphs)

Why do men and women express aggression differently? Need to compete with other males for access to choosy females Lower status men are willing to take greater risks by using aggression or face genetic extinction. If the female commits sexual infidelity the man faces paternity uncertainly Human males cannot risk wasting investment on offspring who are not their own so they should show more jealous violent aggression relating to female fidelity- both towards the male competitors and their long-term female mates if infidelity is suspected especially if the female is young and reproductively valuable

If a male is unfaithful the female partner risks losing his time, resources, energy, protection and commitment to her children. Human females can always guarantee that their offspring are their own and compete with other females for the quality of men rather than for the availability. Women take fewer risk with violence and use more indirect form of aggression.

Research Evidence Male-male aggression Cross-culturally, human violent aggression and homicide is far more common in males, against other males (Daly and Wilson, 1988). Homicide is more common in poor and unmarried men than richer, married ones (Wilson and Daly, 1985). Sexual jealousy produces more male-male homicides than female-female. Female-female aggression Female aggression is more verbal against other women to maintain status and reduce the attractiveness of competitors, especially by using verbal criticism of the physical unattractiveness of other females and their promiscuity (for men looking for long-term mates with sexual fidelity) to lower their appeal in the eyes of men (Buss and Dedden, 1990).

INTER-SEXUAL JEALOUSY AGGRESSION Most male non-sexual aggression against women involves girlfriends and spouses due to sexual jealousy. In a study of 36 Baltimore spousal homicides, 25 were attributed to jealousy, and the wives were the victims in 24 of these cases (Guttmacher, 1955). Verbal aggression and non-lethal physical violence against mates is often similar in men and women, but spousal homicide by women is less frequent and often due to defense against a jealous abusive husband (Daly and Wilson, 1988). Young wives/girlfriends are more likely to be killed than older ones (Daly and Wilson, 1988). In 100 cases of spousal violence, the husbands' frustration over their inability to control their wives and accusations of infidelity were the most reported causal factors (Whitehurst, 1971). In a study of battered women, 57 out of 60 attributed the violence to their husband's extreme jealousy and possessiveness (Hilberman and Munson, 1978).

Page 166 Why then females less aggressive than males? How does their aggression differ from males?

Task How does the role of evolution and natural selection explain aggression? (6)

Evaluation: You can use the studies in your textbook or on the slide Strengths Weaknesses There is evidence to support the explanation It is difficult to prove the explanation of aggression It has useful application It is reductionist because it does not take into account individual differences It is supported by other explanations such as males have more testosterone than females It is a culturally biased explnantion