1. Evolutionary explanations of human aggression

2. Learning objectives Understand how evolutionary psychology explains aggression Explain how jealousy and infidelity can influence aggressive behaviour Understand how to evaluate evolutionary explanations of behaviour

3. On Aggression by Lorenz (1966) Humans are animals and therefore show similar patterns of behaviour.

4. 4 main motivators For all types of animal Fear Reproduction Hunger Aggression

5. Functions of aggression Ensures that the fittest and strongest are selected (females select the best males) Ensure survival of the young (parents can fight off predators) Helps to distribute a species in a balanced way as animals have their own territories

6. Types of social organisation and relationships Family and social life Tribes and rat packs (gang) Anonymous crowds Love and friendship In each type, the aggression (if shown) is very different.

7. Ritualised aggression Often results in little damage done – e.g. stags Compare with Craig (1921) – animals fight but not to destroy - just to get rid of.

8. Morris (1990) – animal disputes show a lot of restraint. Gross (1998) refers to jackdaw behaviour. One often uses an appeasement tactic – showing the nape of its neck.

9. Lehrman (1953) Questions the correctness of making comparisons between species. Two behaviours may seem similar but the underlying mechanisms may be different.

10. Human aggression Fromm (1973) also questions Lorenz’s view Benign aggression Malignant aggression

11. Nelson (1974) Lorenz should have considered 3 basic factors that can affect aggression: 1. Bandura’s social learning theory 2. Structural causes – the nature of social life and its norms. 3. Psychological causes – personal feelings e.g., mood and feelings or situational factors such as heat or overcrowding.

12. Humans and animals Significant differences between the two. Generalisation is impossible Humans use weapons Humans label others as the ‘enemy’ even objects – Rapoport (1965) Tinbergen (1968) – humans are the only species in which aggression is ‘not part of elaborate system of ritual (for mating) but is rooted in a deep desire to hurt another’.

13. Evolutionary explanations Aggression is the result of sexual competition. In males aggression ensures reproductive success. The dominant man is ‘a provider of valuable resources’.

14. Mass killings and genocide Waller (2002) - ‘us’ and ‘them’ groups result in aggression. Tingenberg (1968) – appeasement gestures no longer appropriate with today’s technology. Easier to kill from a distance (role of buffers).

15. Buss (1999) Aggression in females is often verbal It is aimed at reducing the attractiveness of competitors in the eyes of males.

16. Influence of infidelity Infidelity perceived as a threat triggers emotional states Buss et al. (1992) - infidelity leads to violent and aggressive actions Different in males and females Males – uncertainty of paternity Females – insecurity about resources

17. Influence of jealousy Cascardi and Vivian (1995) found Jealousy is the most common factor in aggression in a relationship. Reliable finding in several studies. Although non violent ways of responding can be effective. Causes of jealousy can be complex.

18. Issues and debates Evolutionary psychologists state jealousy can be explained adaptively through mate retention (survival of the species) Any trait with survival value is passed on.

19. Differences in men and women Haden and Hojjat (2006) Men more likely to consider aggressive action when jealous. Women more emotionally and behaviourally reactive.

20. Key points Craig (1921) attempted to apply the principles of ethology to explain aggressive behaviour. Lorenz (1966) advanced the notion of ritualised aggression to encompass aggressive animal behaviour (e.g. stags rutting). Other ethologists have furthered this by stating that animals know when to stop…few kill their enemy.

21. Key points continued Lorenz generalised from animals to humans and was criticised for this. Nelson (1974) provides a well-structured criticism of Lorenz. He argues that Lorenz misses 3 fundamental issues that can affect human behaviour, (a) processes of learning, b) structural causes and c) psychological factors.

22. Key points continued Jealousy has a basis of explanation that links with evolutionary theory. Harvey et al. (2004) show support for the assertion that jealousy is a motivator for violence and suggest that the causes of jealousy are complex.