Evolution

Further strong evidence to support evolutionary explanations of aggression comes from Buss and Dedden who found that females were more likely than males to use verbally aggressive behaviour, such as criticising the physical attractiveness of higher status rivals.

Strong evidence to support evolutionary explanations of aggression comes from Daly and Wilson, who found that American murderers (and murderers in other cultures), were most likely to be unemployed, unmarried males whose victims were also men. This shows that low status males (unemployed) are most likely to engage in direct intra-sexual aggression to compete with other men for resources to be selected by high status females.

Finally evidence to support evolutionary explanations of aggression comes from Buss, who found that men would be more jealous if their partner had sex with someone else, whereas a woman would be more jealous if their partner formed a close emotional bond with someone else. This shows that men are more jealous of sexual infidelity; as a woman if giving her fertility to another man, a characteristic she was inter-sexually selected for. It also shows that women are more jealous of emotional infidelity; as the man is giving away his protection and provision to another woman, a characteristic he was inter-sexually selected for.

Interesting evidence to support evolutionary explanations of aggression comes from Chagnon, who found that in the Yanomamo tribes of South America, men who returned from battle having killed, were more likely to marry. This shows that if men are successful in direct intra-sexual selection, it is more likely they will be inter-sexually selected, supporting the ‘sex for meat’ hypothesis.

For the same reasons, partners are unlikely to show direct inter-sexual aggression as both men and women seek to pass on their ‘selfish genes’ (Dawkins). Instead, partners have evolved ‘mate guarding’ behaviours (displaying signals that their mate is ‘taken’) as a way of reducing their mate’s access to other partners (e.g. wedding rings). Inter-sexual aggression only becomes ‘adaptive’ (in the evolutionary sense) if a partner have reason to be jealous of infidelity. Men are more jealous of sexual infidelity because they select their partners’ fertility, whereas women are more jealous of emotional infidelity because they select their partners’ provision and protection.

According to evolutionary theories displays of aggression are Naturally Selective as they allow an individual to defend themselves and their kin, providing access to resources necessary for survival (e.g. food and clothing), and aid cognitive development (e.g. through the development of tools and language necessary for aggressive acts). Aggression is also Sexually Selective because it increases an individuals change of sexual reproduction (as aggression make them more attractive). In particular, intra sexual aggression between (younger) low status males is most adaptive, as it allows individuals to compete with other men to achieve higher status to be selected by females. Conversely, direct intra-sexual aggression between women is unlikely, as injury may damage their change of successful childbirth or their facial symmetry (lowering their status). Instead, low status females have evolved to show indirect-sexual aggression (e.g. verbal insults of ‘bitching’) to reduce the attractiveness of their competition. . 

However, undermining the role of evolutionary factors in human aggression, this theory can be criticised for being simplistic because it ignores other important influences. This is because it ignores the role of Social Learning Theory (Bandura), the role of cue arousal and ignores the role of nurture; this is because it only emphasises the importance of biological factors in evolution, ignoring the influence of the environment and learning.

Finally, due to it being from the evolutionary approach it can becriticised for being unfalsifiable; it cannot be tested using an independent or dependent variable, and speculative; makes assumptions about research beyond findings, this is because it is impossible to test an evolutionary theory as no one can be alive so see and evolution within a population or culture. 

For the same reasons it can be criticised for being constrained and alpha biased, as it ignores the idea of free will and unfairly exaggerates the differences between men and women. This is because it suggests that we have no free; which is undermined by the Amish; who show no aggression, creating the idea that it is to do with our environment. However, according to genetics the Q20* gene, the MAOA-L gene and the XYY chromosomes, play a role in our aggression which is biologically controlled. Also it claims that all men fight and all women ***** which is not true. Conversely, adding weighting to the role of evolution in aggression research shows that there are 80,000 men in prison and only 4,000 women.

On balance it may be likely that aggression has evolved, evolutionary explanations can never wholly be accepted because they are unfalsifiable.

Furthermore, the theory states that aggression is naturally selective because the need to be aggressive forced our cognitive development (in particular, our language skills). For example, complex language skills would have evolved to successfully plan for acts of aggression, and our cognitive skills would have been developed through the invention of tools (spears), to carry out aggressive acts. 

It is debated whether evolutionary explanations of aggression are sufficient in themselves to explain human aggression.

Adding further weighting to the role of evolution in aggression is that research evidence is Culturally Absolute, this is because this theory can be fairly applied to all cultures, this is due to the strong research evidence provided by Daly and Wilson in all cultures.