Evolutionary explanations of human aggession

Jealousy and Infidelity- A01


  • Men cannot be entirely certain that they are the father of a child. Cuckoldery refers to the reproductive cost that may be inflicted on a man as a result of his partners infidelity. Men might invest in a child that is NOT theirs
  • The consequence of cuckoldery is that a man may unwittingly invest his resources in offspring that are not his own.
  • The adaptive functions of sexual jealousy, therefore, would have been to deter a mate from sexual infidelity, thus minimising the risk of cuckoldery.


  • BUSS: Males have a number of strategies that have evolded specifically for the purpose of keeping a mate. These include DIRECT GUARDING of the females and NEGATIVE INDUCMENTS which would reduce the risk of a women straying e.g. coming home unexpectedly to check up on a women
  • WILSON ET AL: women who agreed with questionnaire answer 'he is jealous and doesn't want you to talk to people other than me' were twice as likely to have been violently attacked by their partner. 72% needing medical attension.
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Jealousy and infidelity - A01


  • Men can guard against their partners infidelity by either conferring benefits ot inflicting costs (such as violence) 
  • As a result not all men posses resources that might be used to provide benefits, some men are especially prone to the use of violence instead. 
  • DALY AND WILSON argue that death of the partner as a result of physical violence is anunintended consequnce of an adaptation designed for control rather then death. 
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Jealousy and Infidelity - A02

  • SHACKELFORD ET AL. found a clear relationship between sexual jealously, the use of mate retention strategies and violence towards women.  
  • Found that men who suspected that their wives might be unfaithful over the next year used greater punishment for a known or suspected infidelity than did men who did not expet future infiedities. 


  • that the neutral response to imagined scenes depicting sexual infidelity and emotional jealousy were different for men and women.
  • Men had a greater activation in amygdala and hypothalamas than their mate. 
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Jealousy and Infidelity - A02

There is research support for the link between infidelity and partner violence...


  • Found that the risk of a partner's infidelity predicts sexual coercion amoung males but not females. 
  • This is significant as only males are at risk of Cuckoldery 
  • Also found that men convicted of ****** their partners were more likely to have experienced cuckoldery RISKS prior to the offence.

There are problems with surveys... As many of the studies in this area have made use of surveys, but these have their problems. As answers may not be TRUTHFUL due to SOCIAL DESIRABILITY BIAS. 

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The Evolution of Homicide - A01

BUSS and SHACKELFORD- Homicide represents the most extreme form of aggression, and statistics worldwide reveal that the majority of the killers and victims are MEN 

In a study in DETROIT approx 40% of all male victims and killers were UNEMPLOYED, compare this to the unemployment rate in Detroit that year was 11%. So a lack of resources and an inability to attract long-term mates appears to lead to increased SOCIAL COMPETITION and MALE-MALE homicides. 

Unemployment = lack of money/resources/status are contributing factors in an increase in aggressive behaviour 

In order to attract a mate it would be important to have a good social status and an ability to provide resources for family therefore a lack of these may lead to increased male-male competition.

Also LOSS OF STATUS and SEXUAL JEALOUSY play a key motive in male homicide. Study by Daly and Wilson reported that in a summery of 8 studies of same sex killings involving love triangles - 92% were males and 8% females 

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The Evolution of Homicide - A02

Because humans face being killed in many different circumstances it is likely that they would have evolded anti-homicide defences, such as being able to read the signs of homicidal intent, and killing in self-defence. 

  • one such mechanisms is that homcide becomes far to costly to pursue - DUNTLEY AND BUSS. Its success rate becomes lower, and attempting to kill becomes increasingly dangerous for the killer. Both of these consequces mean that homicide gives decreased fitness benefits to the killer. 
  • Limitations of the evolutionary persective on homicide: it cannot explain why people react in such different ways when faced with the same adaptive problems. BUSS AND SHACKELFORD suggest that although some men may react to infedilty with mate retention statergies or even murder, others will respond less violently or simply get drunk. 
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A03 - Cultural differences

S: One limitation to the evolutionary approach to explaining aggression is that cultural differences cannot be explained.

E: The Yanomamo require violence to attain status, whereas the !Kung San people would not show violence, as it is not accepted and would ruin reputations.

E: This shows that society's values (proximate causes) have affected the display of aggression, rather than Ulimate causes, as suggested by the evolutionary approach.  

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A03 - Gender Bias

S: Most studies of infedility have foucused on men's mate retention strategies and male violence against women. However this view is gender biased.

E: Becuase women also practice mate retention strategies and engage in violence against partners for example FELSON found that women were twice as likely to murder out of jealousy as were men.

E: Evidence proves there is research to support the idea that women have mate retention strategies as well, which the theory does not take into consideration, as it foucuses too highly on male retention strategies. Therefore the theory on jealousy cannot be generalised to men and women as there is a large amount of support for men but not for women, ans so lacks validity that it is just men who show mate retention. 

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