Evolutionary explanation

• Adaptive nature of aggression

  Beneficial for survival and reproduction

  In ancestors
• Sexual competition and parental investment 


  Competition over mates

  How much resources put into rasing young and value of the young
• Parental investment in females 


  More likely to be loving and non aggressive

  High

  • Limited number children
  • More energy carrying baby
  • Greater risk to mother
• Parental investment males 


  Low

  • Sperm plentiful
  • No care for baby
  • Mate with as many females as possible to pass on genes

  Creates sexual completion

  Most aggressive males win conflict and genes passed on

  Adaptive in males over females
• Sexual jealousy 


  Jealousy - sexual infidelity threatened

  More aggressive towards same sex
• Sexual jealousy in males 


  At risk of cuckoldry (can't be sure of paternity)

  • Rasing offspring without passing on genes
  • Aggression as mate retention strategies
• Mate retention strategies 


  Aggression female to prevent infidelity

  Aggression male to drive away
• Sexual jealousy in females 


  less threatened by infidelity as can guarantee genes of offspring are hers

  no aggression as a result of sexual jealousy

  (may be aggressive to ensure looked after by male and offspring protected)
• AO3: strength of PI

  FBI data 1976-2005

  • 65% murders = male on male
  • 27% murders = male on female
  • 92% murders by a man

  males more likely to be aggressive

  driven by competition as males most likely victim

  (male on female as a result of sexual jealousy)

  
  

  adaptive feature present in males
• AO3: support sexual jealousy

  Shackelford, LeBlanc, Drass (2000)

  • identify emotional reaction to sexual/emotional infidelity
  • preliminary study 53 pts nominated emotional reactions
  • 655 pts rated likelihood of displaying reaction following s/e infidelity
  • men = higher homicidal/suicidal responses (aggression)
  • women = higher insecure/undesirable responses

  aggression is an adaptive feature in males to sexual jealousy - to prevent cuckoldry
• AO3: weakness of Shackelford

  data obtained through questionnaire

  • socially desirable responses
  • aggression= expected behaviour in men
  • security and desirability important for females

  decrease internal validity (Accuracy of measurements)
• AO3: weakness reductionism

  complex concept of aggression limited to evolutionary approach

  doesn't consider why males more aggressive in other situations

  eg. childhood

  role of testosterone not considered (young males have more testosterone so more likely to kill women - confounding variable)

  biology influences evolution.
• AO3: determinism strength and weakness

  responsibility diminished

  in nature for aggression so issues with convicting, eg domestic abuse cases

  however,

  predictive validity

  positive economic impact - understand cause of most murders can alert police of behaviours and minimise cases

  positive social and economic impact - less injury women (NHS) less prison sentences
• AO3: support for sexual jealousy

  13,670 real life uxoricides examined

  if reproductive age, increased risk of being killed

  males show more sexual jealousy when able to reproduce

  likely due to high risk of cuckholdry