The Role of Evolutionary and Social Factors in the Same-sex and Partner Aggression

Abstract

Many theories have attempted to explain aggressive behaviour, ranging from social theories (Bandura, 1973) to evolutionary theories (Buss, 1999). This report uses evolutionary theory to derive predictors of aggressive behaviour, in particular whether there are sex differences in predicting aggression. Four evolutionary-derived predictors (impulsivity, dominance, competitiveness and sexual jealousy), and three aggression measures, were used: these were the aggressive questionnaire, specific acts of partner and same-sex aggression (both aggressor and victimization measures). The measures were presented to the participants via an online questionnaire, in which 322 participants (96 males and 226 females) took part in the study. The findings are described in three chapters: (1) sex differences in aggression measures; (2) the relationship between proneness to aggression (the aggressive questionnaire), specific forms of aggression and evolutionary-derived predictors; and (3) whether there were sex differences in the relationship between evolutionary derived predictors and specific forms of aggression. The main findings were: (1) no sex differences in the means of partner direct and indirect aggression whilst higher levels of same-sex direct and indirect aggression were reported by males than females; (2) a strong relationship between proneness to physical aggression and partner direct aggression; (3) impulsivity was more strongly related to same-sex aggression than to partner aggression; (4) dominance was a significant predictor of partner direct and indirectaggression for both sexes, a significant predictor of same-sex direct aggression for males only, and a significant predictor of same-sex indirect aggression for females only; (5) sexual jealousy was a particularly strong predictor of partner direct aggression in males but not females, and overall a weak predictor of same-sex aggression. Overall there was some support for evolutionarily-based hypotheses the relationships between these variables. However, evolutionary theory is better at explaining aggressive behaviour in males than females.