evolution & natural selection

• what are genes

  a set of instructions that determine what the organism is like, its appearance, how it survives and behaves in its environment - these changes of genes lead to evolution
• how can genes change

  changes caused by random mutations leading to variation between members of the same species over time e.g: genetic changes could result in traits such as aggressive behaviour - MAOA gene is linked to aggression
• natural selection

  • some mutations are better suited for the environment a living thing is in as they have certain characteristics & those with useful mutations survive and produce offspring so are more likely to pass on their genes
  • changes occur over many generations which leads to trait & behaviours being adapted and changed in species over time
• what is the usefulness of aggression as an evolved trait

  1. gain resources, status, territory
  2. hunting and provide food for others
  3. scare off competitors or fight for resources for survival - survival advantage
• other way aggression is useful

  seen as a solution to adaptive problems e.g: prevention of infidelity and maintaining high status e.g: daly et al suggested domestic violence was a means of preventing romantic partners from straying
• strength

  • research to support idea of a genetic link to aggression
  • chester (2015) took sample of female saliva and found a positive correlation between a low functioning MAOA 'warrior gene' and aggressive levels
  • therefore, does appear to be a link between process of natural selection and aggressive behaviour
• weakness (counterpoint)

  • this research only correlational
  • this means we cannot establish a cause and effect between aggression directly linked to genes
  • therefore other theories such as SLT might also explain why people are aggressive
• strength

  • real life examples of aggression being useful in society
  • hill and hurtado (1996) found that aggression leads to an increase status in tribal communities in south america associated with access to food etc
  • demonstrates there is a link between status and aggression levels giving support to idea that these traits may be passed on through natural selection
• weakness (counterpoint)

  • evolutionary explanation does not account for culture
  • wolfgang and ferracuti (1967) found people from the kung san region of kalahari region of africa have low levels of aggression as behaviour is discouraged from childhood whereas yanomami people of venezuela are much more aggressive as aggressiveness was used to gain status in society
  • evolution explanation cannot account for the impact that culture has on aggression
• what does evolution & natural selection suggest (A01)

  aggression is a characteristic to aid survival