Evolutionary Theory

The evolutionary theory suggests that the behaviours and thinking that we currently have, have adapted an advantage in our evolutionary past. It focuses on: 

- Jealousy and infidelity.
- Aggression as an evolutionary advantage.
- Cuckoldry
- Mate retention tactics - violence and vigilance
- Individual survival
- Procreation potential
- Competition for limited resources
- Competing to increase own fitness
- Natural selection
- Adaptive trait
- Group display
- Warfare

Jealousy and infidelity 

Early human males lived in fear of losing their mate to another male - something that would have devastating consequences for them in terms of passing on genes. This may have led to sexual jealousy. Male sexual jealousy was caused by the female's suspected infidelity.

Research:
- Buss et al (1992) 
- Pipat

Group Display

There is a widespread belief that people behave differently when in groups compared to how they behave as individuals. Some behaviours only occur when like-minded people come together for the same purpose. This is often seen in: 

Hooliganism and Xenophobia

Research: 
- Marsh (1978) 
- Cialdini (1976)

Territoriality

- Threat displays - Protective response to an invasion of one's territory. Aggressive displays would have been adaptive for our distant ancestors because they allowed groups to defend valuable resources associated with their territory.

Research: 
- Neave and Wolfson (2003) 
- Pollard and Pollard (2005) 

Warfare

War is an extreme course of action contradictory to survival so it must be assumed that the benefits will outweigh the cost. Male warriors have been found to be more sexually attractive to females, making them more likely to get a mate and pass on their genes. Even in modern day, men fight to secure access to women. More than 20,000 Muslim women were raped in Bosnia by the Serbs in order for them to increase the number of Serbian babies born. 

Research: 
- Lehmann and Feldman (2008) 
- Kelly and Dunbar (2001) 
- Farthing (2005)