The evolutionary explanation, or instinct theory, states that aggression is an adaptive response. This response enables us to obtain resources, defend against attack, eliminate competition for mates and force sexual fidelity from mates. In 1966 Lorenz stated that there were four main drivers behind animal aggression; fear, reproduction, hunger and anger. He also stated that aggression could occur only within a species not across two different species. Lorenz discussed that aggression between two animals is often ritualised. Ritualised aggression itself is aggressive, but little harm actually comes to either animal.
This theory is backed up by Morris in 1990, he found that animal disputes show a lot of restraint, this restraint is called an appeasement tactic e.g. dogs show their belly when they feel threatened to stop the opponent from taking the fight any further. The evolutionary approach to aggression states that there are four aims of aggression; to win or control territory, increasing solidarity between males and females, becoming and maintain a dominant role and natural selection through survival of the fittest. There are three main problems with the instinct theory. Firstly, it fails to take into account variations in aggression across individuals and cultures. Secondly, Lorenz compares man to animals and we are not like animals as we have culture to an extent animals do not. The final evaluation point of the instinct theory is that it can be argued that aggression can be learnt socially through social learning theory, not through genes.
Infidelity and jealousy is another evolutionary explanation of aggression. Infidelity is having a sexual relationship with someone other than your partner. Jealousy is a state of fear caused by either a real or imagined threat to a person’s status an exclusive sexual partner. Cuckoldry is often the cause of sexual jealousy. Cuckoldry occurs when a woman deceives her male partner into investing into offspring conceived with another man.
A main researcher in this area is Young. In 1978 Young asked students to describe how they would react to a jealousy inducing scenario. Men in general said they would become drunk, respond angrily and threaten their rival male. Women on the other hand pretend not to care, cry and try to increase their own attractiveness to get male attention. One major problem with Young’s study is that the participants may have answered differently on the questionnaire to how they would react normally due to social desirability.
Another explanation of aggression as an adaptive response is murder. Buss and Duntley (2006) said that humans have evolved adaptations through natural selection to produce what we now call murder. They discussed how if murder is used is determined by four factors; the degree of relatedness between killer and victim, the relative status of killer and victim, the sex of killer and victim and the size and strength of the killer’s and victim’s alliances.
In order to evolve as a strategy it must have been associated with greater reproductive success than conflicting strategies. Wilson and Daly in 1985 said that sexual jealousy, lack of resources and threats to male status are all reasons for murder to occur. Wilson and Daly support both their prior study and the study by Buss and Duntley by over viewing the Detroit murders of 1972. They found that the motive behind most of the killings, both killers and victims were unemployed, unmarried and young, low status without a mate. The problem with Buss, Duntley, Wilson and Daly’s research is that is says the act of murder is determined by our evolutionary past and freewill does not come into play, murder could not be committed due to a grudge or hatred is the act is determined.
The final explanation of aggression as an adaptive response is group display. There are three levels of group aggression: a crowd, a mob and a riot. A crowd is a lot of people who have gathered into one group very closely, mobs are disorderly crowds and a riot is crowd or gathering which is protesting in a violent manor. Examples of group display fall into three categories; lynch mobs, sport aggression and religious displays. One theory which underpins the idea that group displays are an adaptive response to aggression is the power threat hypothesis. Blalock, in 1967 said that as a minority group grows, the majority group intensifies their efforts to remain dominant.
Group displays of solidarity are discrimination against outsiders are more likely when the group feels at risk. Another way groups show aggression is by dehumanising the victim and reducing them into something non human. This makes it easier to carry out aggressive acts e.g. lynching. These aggressive deeds are sometimes made easier for an individual if they de-individuated. When someone is part of a crowd the loose their sense of individuality and therefore will do things they would not normally do. Convergence theory is another theory into group aggression; the group is made up of individuals who all have similar thought processes. Each individual is not influenced by the rest of the group, but all the members behave the same, due to their similar thoughts. Similarly, Contagion theory can also explain group aggression; people are influenced by the way a group acts.
The individuals do not need to think similarly, they conform to the behaviour of one ‘bad egg.’ Smelser (1963) argued that social life and its processes affect how individuals behave. This is weakness of the evolutionary theory; aggression is not only affected by our genes it is also affected by our social learning and environment. Smelser also argued that six things are necessary for a social movement to emerge. Structural conduct and if people realise their society has a problem, if society fails to meet expectation and deprives the people, growth and spread of an explanation, if one event triggers a reaction from a crowd, mobilisation for action where people distribute information about a cause and finally a lack of social control leads to a protesting crowd.
In conclusion, the instinct theory can explain aggression; the only problem is it doesn’t take into account factors such as culture and it completely ignore the fact that we could learn to be aggressive through social learning. So overall a mixture of different explanations is needed to explain aggression.