Evolutionary Explanations of Aggression

  • Aggression in Humans as an Adaptive Behaviour
  • From an evolutionary perspective, the existence of aggression in humans must mean that it has survival value. Despite the apparent contradiction that behaviour which can cause harm could aid survival, research suggests that aggressive humans have existed for a very long time.
  • The high incidence of aggressive behaviour across cultures and through time (such as early remains of skulls and ribs with weapon wounds Vandermeerson & Leveque 2002) has led to the conclusion that the benefits must outweigh the potential costs. Aggressive behaviour seems to have evolved to support access to resource (food, water, territory, mates). If they have these resources that can defend and protect their families. Aggressive displays that ward off rivals also have benefits such as enhancing status and attracting females. This increases the chances of offspring and the continuation of genes for the successful male.
  • Acquisition of status is a motivator in males for aggression. High status males have access to resources necessary for survival and for females for breeding. Higher status men are more desirable mates and are more likely to receive more attention. (Li and Kendrick 2006)
  • Sexual Jealousy and Infidelity in Males
  • As females can always be 100% sure of their genetic position towards their offspring, males who cannot, have evolved to try to improve this level of certainty. As males are reluctant to expend energy raising not their own offspring. This is evident in lions who kill young sired by another male (Bertram 1975) Sexual jealousy has therefore evolved to help a male protect his lineage and ensure the raising of offspring is to his benefit.
  • Male aggression against females is designed to prevent female infidelity and bearing another mans child. Daly and Wilson (1985) noted that in 58 of 214 cases of murder studied, sexual jealousy was the underlying factor. The attempt by males to constrain female sexuality by the threat or use of aggression seems to be cross culturally universal. (Daly and Wilson 1982) Supporting this, of 44 battered wives living in a woman’s hostel in Ontario, Canada, 55% cited jealousy as the reason for their husbands actions. (Miller 1980). Actual infidelity was the reason for 11 of the cases, most common was suspicion or fear of adultery.
  • Females Show Lower Levels of Aggression than Males
  • Females are generally less aggressive than males, this can be attributed to the evolutionary risk of females engaging in aggressive behaviour. This is because a female knows the importance of her (a mothers) survival, a mothers survival is much more critical than a fathers. For example, among the Ache of Paraguay children are 5 times more likely to die if their mother does but only 3 times more likely if their father does. If the mother dies before the child’s age of 1, the mortality rate is 100% for the child. (Hill and Hurtado 1996)
  • Even in Western cultures the mother is likely to gain custody of the child in the event of a marriage breakdown. Therefore if a woman wants her child to survive, she must be concerned with her own survival, this leads to less aggressive behaviour than males.
  • Evaluation:
  • There is evidence to support the claim that the acquisition of status is a primary motivator in male aggression. The prediction that individuals most likely to commit aggressive acts are low status, trying to enhance their chances of reproduction is supported by Daly and Wilson (1985). Through their review of conflicts resulting in murder they revealed that the motive behind most of these incidents was status. The victims and the offenders were most likely to be unemployed and unmarried men, low status and without a mate. Therefore as these males had more to gain through the aggressive acts, they deemed the potential success worthwhile. This therefore supports the claim of status as an influential factor in aggressive behaviour.
  • There is supporting evidence for the explanation of aggression in males. Daly and Wilson 1982 found that in a sample of domestic murders, the victims were 44 husbands and 36 wives. 29% of the conflicts were due to sexual jealousy. Despite the evidence showing that more husbands were killed, further evidence shows that the murders were due to self defence on the wife’s part after the male instigated the conflict. This is supported by the convictions of this sample. 15 husbands were convicted but just 5 wives. However, it is questionable evidence as the findings are reliant on testimonies from the police and the individuals which may not be accurate. Therefore, there is no way to know that this evidence does support the prevalence of sexual jealousy in murder cases.
  • There are positive real world applications of the evolutionary explanation as the use of mate retention tactics (the threat of violence to prevent a mate from straying) can be an early indicator of violence against a female partner. The findings from these studies suggest that awareness of the strategies can be used to alert friends and family to the danger signs that may follow. At this point, help can be sought out by the partner or offered by the friends and family before the inter-mate violence ever begins.

 Evolutionary Explanations of Aggression- Essay Plan


Aggression in Humans as an Adaptive Behaviour

  • The existence of aggression means it has survival value
  • High incidence of aggression through cultures and time VANDERMEERSON & LEVEQUE 2002. Benefits of aggression outweigh the costs.
  • Evolved to support access to food, mates, resources, etc.
  • Wards off rivals, enhances reproduction and chances of survival of species.
  • High status is desired, acquisition of status is a motivator in males for aggression. LI AND KENDRICK 2006

Sexual Jealousy and Infidelity in Males

  • Males try to increase their certainty of genetic position towards offspring. Sexual jealousy has evolved to help a male protect his lineage and ensure the raising of his offspring is to his benefit.
  • Prevent female infidelity, use of mate retention tactics
  • DALY AND WILSON 1985: 58/ 214 murder cases, sexual jealousy was underlying factor.
  • MILLER 1980: 55% of 44 battered wives in Ontario cited jealousy as the reason. Actual infidelity was the reason for 11 cases, most common- fear of adultery

Females Show Lower Levels of Aggression than Males

  • Mothers survival is much more important than a fathers
  • ACHE OF PARAGUAY: children are 5x more likely to die if mother does. 3x if father does. A mother dies before 1, 100% likely. HILL AND HURTADO 1996


P: Support- acquisition of status as a primary motivator of male aggression

E: DALY AND WILSON 1985 support prediction that low status males commit aggressive acts.

E: reviewed murder cases, offenders- unemployed and unmarried men.  Therefore supports the case

P: Support for the explanation of aggression in males.

E: DALY AND WILSON 1982: domestic murders. 44 husbands, 36 wives. 26% due to sexual jealousy.

E: Despite showing more husbands killed, in self defence- 15 husbands convicted, 5 wives

E: However, questionable evidence, reliant on testimonies. Accurate?

P: Positive real world applications (IDA)

E: Use of mate retention tactics, early indicator

E: Can seek friends and families help- avoid domestic abuse

E: Prevents inter-mate violence