Evolution and Aggression

• Evolution


  The process of change in all forms of life over generations
• Natural Selection


  The process by which heritable traits become more or less common in an environment
• Theory of Evolution


  • Outlined by Charles Darwin in 'On the Origin of Species' (1859)
  • Explains how living creatures were created and how they change over time
• Key ideas of the theory of evolution

  • Different species have all evolved from simple life forms which lived on earth 3 billion years ago
  • All species share some genes they all have common ancestors
  • Evolution occurs through natural selection
• Natural Selection


  • Organisms that adapt are healthier, live longer & are more likely to reproduce
• Darwin's evidence for natural selection

  • Finches and their different shaped beaks which would suit different environments
• Genes


  Collection of genes, guides what we are and what we will become, such as eye colour, temperament (aggressive), intelligence etc.
• Genes have developed from a process of evolution through natural selection

  Survival of the fittest
• Genes not suited (not adapted) to an environment will die out
• Evolution is how inherited characteristics are passed from generation to generation through reproduction
• Aggression


  An innate tendency, an adaptive response that aids survival
• Aggression is explained as an innate human behaviour, evolving from the 'fight or flight' responses in early humans


  Still part of our biological structure today
• Aggression might protect a mate or their child

  This is not aggression for the sake of it, but aggression that would aid survival of the genes
• Evolutionary explanations of aggression

  • Aggression in terms of its ability to increase survival chances and therefore enhance reproductive success - passing on genes
  • Acquiring and protecting resources such as food, territory and mates, and status within the group, especially in males
  • High status then leads to greater access to resources in general and to mates in particular
• Human males who behaved aggressively were seen as stronger and more dominant in a social group


  They were the ones more likely to survive
• If they were 'higher' in the group or not attacked because they were dominant and stronger

  That put them in a good position with regard to attracting mates and passing on their aggressive genes (reproductive success)
• Aggression towards another person threatening a male-female pair

  The male needs to reproduce to pass on their genes so another male competing for a female's attention would threaten that situation and an evolved response to such a threat is aggression
• The male who aggressively defended 'his' female

  Would have been the one who reproduced and whose genes survived
• Evolutionary explanations assume that behaviours which enable an individual to survive will ultimately be passed on to the next generation as part of a survival strategy
• Evolutionary psychologists believe that innate brain function and knowledge both help the individual to adapt to their environment
• The evolutionary perspective suggests that aggression is the result of social and sexual competition for reproduction and survival, i.e. an adaptive response
• Supporting research for genetic link to aggression

  • Chester et al. (2015): found low functioning MAOA genotype ('warrior gene') was linked to greater aggression
• Supporting research for aggression as an evolved solution to adaptive problems

  • Hill & Hurtado (1996): found aggression leads to increase in social status in the Yanomamö tribe in Venezuela
  • Daly et al. (1982): found domestic abuse was used to dissuade romantic partners from infidelity
  • Shackelford et al. (2005): found use of mate retention strategies (female-directed violence) supported by studies of battered women