Evolutionary explanations of aggression

Evolutionary explanations of aggression

1. Infidelity and Jealousy

   • Cuckoldry occurs when a woman deceives her male partner into investing offspring conceived with another man.
     • Cuckolded men lose both invested resources and reproductive opportunities (platek and shackelford)
     • Males have evolved strategies to deter their mates from infidelity and so protect themselves, according to the evolutionary approach, all such mate retention strategies are due to sexual jealousy.
       • Studies of battered woman show that the majority of woman cite extreme sexual jealousy on the part of their male partners as the key cause of violence against them (Dobash & Dobash 1984)
     • The Cuckoldry Risk Hypothesis (Camilleri 2004) states that males will be more willing to use sexually coercive tactics such as partner rape when the risk of cuckoldry is high e.g. when there is suspicion of infidelity or there has been previous instances of infidelity.
       • According to Laluminere et al (2005) some men carry out partner rape to decrease paternity uncertainty.
       • Thornhill & Thornhill argue however that a woman who refuses to have sex with their partner may be signalling to him that she has been unfaithful, increasing the males sexual jealousy and risk of cuckoldry.
       • sexual coercion of females is an adaptive response to fear of infidelity. Camilleri (2004) found that the risk of a partners infidelity predicted the likelihood of sexual coercion in men, but not women. This is significant as it is men who are at risk of being cuckolded, not women. This is supported by Goetz and Shackelford (2006) found that women who reported that their partners had sexually coerced them often were more likely to admit to being sexually unfaithful
     • Mate retention and violence
       • Buss and Shackelford (1997) examined mate-retention tactics in married couples and found a difference in males and females. Women were more likely to be verbal possession signals, where as men were more physically aggressive and likely to make intrasexual threats. They also found that men with younger partners devoted greater effort to mate retention tactics, including violence against other males and threats against the female partner.

2. The evolution of murder

   • Buss and Duntley (2006) propose that humans possess adaptations specifically through natural selection which we now call murder. Evolutionary theory states muder could not have evolved if it was not associated with greater reproductive success than competing strategies. The high costs of committing a murder is outweighed by the benefits.
   • Murder as an adaptive strategy: 1. preventing harm from others e.g. through injury or killing of the individual or their family members by other humans. 2) reputation management e.g. avoid being perceived as easily exploited or injured by others. 3) protecting resources, e.g. territory, food or mates.
     • Predisposing factors for murder, Daly & Wilson (1988) found that men commit the vast majority of murders, and are more likely to kill other men whom they perceive to be sexual rivals or who challenge their position in the dominance hierarchy. common factors include: 1) sexual jealousy, 2) lack of resources, research on sexual selection in humans has shown that females are attracted to males who possess resources. W & D suggest that lack of resources increases male-male competition and the risk of murder.
       • 3) threats to male status: they argue that females are attracted to males who are dominant over other males and so men are shaped by evolution to seek status, loss of status would have been catastrophic for our ancestors and so the killing of competitors could have prevented this loss.