The high incidence of aggressive behaviour across cultures and through time has led evolutionary psychologist to conclude that the adaptive and functional benefits of aggressive behaviour must outweigh the possible costs (Buss and Duntley, 2006). From an evolutionary perspective humans are most likely to survive if they have access to resources (food, water and territory); if they can defend their resources and protect their families and if they can attract or gain access to mates. Aggressive behaviour seems to have evolved to support the human race in achieving all of these primary goals.
One example of evolutionary adaptation is the sex differences in jealousy that have evolved in order to ensure mate retention and reproductive success. Daly and Wilson (1988) claim that men have evolved several different strategies to deter their female partners from committing adultery (i.e. Infidelity).These range from vigilance to violence, but all are fuelled by male jealousy, an adaptation that evolved specifically to deal with the threat of paternal uncertainty.
So why have men evolved the emotion of sexual jealousy? Unlike women, men can never be entirely certain that they are the fathers of their children, as fertilisation is hidden from them, inside the woman. As a result men are always at risk of cuckoldry, the reproductive cost that might be inflicted on a man as a result of his partner’s infidelity. The consequence of cuckoldry is that the man might unwillingly invest his resources in offspring that are not his own. The adaptive functions of sexual jealousy therefore, would have been to deter a mate from sexual infidelity, thereby minimising the risk of cuckoldry.
Buss (1988) suggests that males have a number of strategies that have evolved specifically for the purpose of keeping a mate. These include direct guarding of the female and negative inducements that would prevent her from straying. By restricting their partner’s sexual autonomy (direct guarding) our male ancestors would have been able to deter rivals from gaining access to their mates. This was supported by a study completed by Wilson et al (1995), who found that women who agreed with questionnaire items such as “he is jealous and doesn’t want you to talk to other men”, were twice as likely to have experienced serious violence from their partners, with 72% of these having required medical attention following an assault from their male partner.
Further support for sexual jealousy being the underlying cause of male violence towards their female partners comes from studies completed on battered wives, which have shown that in the majority of cases, women cite extreme jealousy on the part of their husbands or boyfriends as the key cause. (Dobash and Dobash, 1984). Other research also supports this connection. Buss and Shackelford (1997) found that men who suspected that their wives might be unfaithful over the next year exacted greater punishment for a known or suspected infidelity than men who did not anticipate future infidelities. This finding is consistent with the claim made by evolutionary psychology that mate retention strategies are evoked only when a particular adaptive problem is faced in this case the belief that the wife’s infidelity is likely.
On the other hand in a sample of 80 murders where the victim and murderer were married or living together, the victims were 44 husbands and 36 wives and 26% of these conflicts were deemed to have arisen as a result of sexual jealousy (Daly and Wilson, 1982). The statistics are interesting as they show more husbands murdered by their wives. Evidence from these cases however points to the fact that the conflict was instigated by the husband and the wife killed him in self-defence. This is supported by the convictions: there were fifteen husbands convicted for murder compared with five wives, from the sample studied....