Theory of Aggression: Evolution and Natural Selection


  • Evolution is the gradual development of different kinds of living organisms from earlier forms during the history of the earth
  • Natural selection is the gradual process by which heritable traits and characteristics become more or less common in an environment
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Environment of Evolutionary Adaptedness (EEA)

The structure and function of the human brain evolved in order to serve an adaptive function for our ancestors so that they survived and reproduced.

This happened in the EEA. This isn't a specific time or place but the conditions in the environment that a species was adapting to. For humans, this is assumed to be the Stone Age (10,000 years ago).

We have inherited these characteristics so that certain behavioural characteristics are 'hardwired' in the brain. Therefore, human behaviour today results from evolutionary adaptions that served as a purpose in our ancestral past.

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EEA and Aggression

Evolutionary psychologists suggest that in the EEA, aggression might have been an adaptive trait for humans to possess. Agression might have served a purpose, so rather than just being aggressive for the sake of it, it aided survival and increased the chances of reproductive success.

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Gaining Territory and Resources


Limited resources in the human EEA meant that those who successfully fought for food and shelter (even attacking other humans so they could take their resources) as well as being able to defend their food and shelter from others were more likely to survive. This would have required them to be aggressive

Modern Day Example: 

Children bullying others for money or toys. Adults mugging and warfare 

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Defence Against Attackers


Males would have needed to be aggressive in order to protect their mate and their offspring from predators/attackers if they were to ensure the survival of their genes.

Modern Day Example:

'Sticking up for yourself' - protecting resources and status

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Sexual Jealousy


Males who aggressively defend and guarded their females when another male was competing for the female's attention out reproduced those who did not.

Modern Day Example:

Men fighting over women - aggression between same-sex members of a group

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Negotiation Status and Power Hierarchies


Humans who were aggressive would be seen as stronger in a social group and so be placed 'higher' in the group. This meant they would be less likely to be attacked because of their status and so would be more likely to survive.

Modern Day Example:

Gang violence to 'prove oneself' to aid sexual selection by opposite sex members - women attracted to powerful/dominant men

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Mate Selection


Successful females chose mates who provided good genes. Males who displayed aggressive traits would be more likely to be selected as a mate because females would think that they could provide better resources in terms of food and shelter, and also offered good protection for them and their offspring. 

Modern Day Example:

Women look for a physically fit male

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  • Harvey et al (2004) - aggression is often linked to sexual jealousy which supports the idea that males have evolved to be aggressive in order to secure exclusive mating privileges
  • Not possible to test the theory that aggression has an evolutionary basis because it isn't possible to access the EEA so can't be empirically tested
  • Conclusion: evolutionary theory is a 'post hoc' (after the event) argument where the theory is developed to fit the facts but cannot be scientifically tested
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The theory suggests that since aggression is in our nature, it would be futile to try to stop people from being aggressive. To reduce undesirable aggression, we need to provide safe, socially acceptable outlets for aggression such as sport, video games, painting etc.

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  • Scientific credibility in that evolution has been demonstrated by the development of resistance to antibiotics by certain strains of bacteria (also fossil records suport evolution of species)
  • Deterministic - suggests that aggression is in our nature and therefore is not much we can do to reduce these aggressive urges (removes responsibility)
  • Conclusion: while there is evidence to support the theory of evolution of humans, there isn't much to show that our brains of aggression have evolved
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Alternative Theory

Learning theories suggest that how aggressive we are is a consequence of our learning experiences such as upbringing, parenting, peers, culture, the media etc 

In conclusion, evolutionary theory of aggression in humans is reductionist as it oversimplifies the complex array of factors that determine how aggressive we are.

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