Evolutionary Explanations of Human Aggression

Evolutionary Explanations of Human Aggression

1. Jealousy

   • Daly & Wilson: men have evolved strategies to deter female partners from adultery.
   • Sexual Jealousy & cuckoldry
     • Men can never be certain they're father of child - fertilisation = hidden.
       • Means always at risk of cuckoldry. May invest in resources to offspring not his own.
       • Adaptive functions of sexual jealousy defer female from infidelity.
   • Sexual jealousy & extreme violence
     • Daly et al: Male sexual jealousy = most common motivation killing in domestic disputes in US.
     • Men mostly perpetrators & victims
     • 8 studies of same sex 'love triangles'. Found 92% = male-male murders, 8% female-female.
     • Daly et al: culture bias. The way US citizens brought up = different? Different attitudes towards aggression.
   • Buss & Shackleford
     • Men suspected wives unfaithful over next year: used greater punishments for known/suspected infidelity than those who didn't anticipate future infidelities.
   • Gender bias: Men only focus, without reviewing women. Cannot generalise to women.
   • Takahashi et al: Neutral response to imagined infidelity & emotional jealousy = diff. for men & women.
     • Using brain imagining techniques discovered men = greater activation in amygdala & hypothalamus when presented images depicting sexual infidelity in mate.

2. Infidelity

   • Violence towards pregnant partners
     • Female sexual infidelity can = pregnancy.
       • Male risks investing in offspring of another man's child. Lowers reproductive success.
     • When woman=pregnant with other man's child, function of violence towards her may be to terminate preg.
       • Eliminate possible offspring of rival - leaves her free to carry his offspring.
     • Burch & Gallup found evidence to prove jealousy can cause aggression...
       • Frequently violent acts towards pregnant mate = double directed towards those not pregnant. Sexual jealousy characterises men who have committed violence against preg partners.
   • Holistic
     • Considers environment and genes having influence on aggression
   • Uxorocide
     • Wife killing
       • Men can guard against partners infidelity by rewards of violence.
       • Not all men possess resources for rewards - prone to violence. Daly & Wilson: death of partner from physical violence may be unintended outcome of evolutionary adaptation designed to control infidelity.
     • Shackleford et al found evidence to refute that uxorocide is evolutionary logic.
       • 500,000 homicides analysed, selecting 13,670 where men had killed wife. Found: younger women = much higher risk of uxorocide regardless of partner age. Killing reproductively valuable women contradicts evol. logic.
   • Real World Application
     • July 2002: Man who battered wife to death in jealous rage given 2 yr suspended sentence. To stop this happening, (men) should be given an extended/ justifiable sentence.

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