Intra-sex differences in human sexual strategy : an evolutionary perspective

Ten empirical studies were employed to investigate intra-sex differences in human sexual strategy at the genetic, psycho-physiological and psychological levels, all from an evolutionary perspective. The first five studies considered male intra-sex differences. Chapter 7 investigated intra-sex differences in sexual orientation at a genetic level and discovered that averaged gay male faces were perceived as more attractive and less aggressive than averaged straight male faces. Chapters 8 and 9 investigated intra-sex differences at a psycho-physiological level, finding shorter males to be less restricted in sociosexual behaviour than taller males, although no relationship was found between height and potential parental investment. 2D: 4D digit ratio and sociosexuality was also investigated, in which negative relationships were found with sociosexual desire and attitude, but not behaviour. Chapter 10 considered male intra-sex differences at a psychological level and found that sociosexuality was negatively correlated with potential parental investment and positively correlated with self-perceived attractiveness, although no significant relationship was found between potential parental investment and self-perceived attractiveness. Chapter 11 ascertained that there was a significant gender difference in self-perceived attractiveness and sociosexuality. The remaining studies investigated female intra-sex differences at a psycho-physiological and psychological level. Chapter 12 established a significant relationship between a physiological correlate of anxiety, diastolic blood pressure, and cosmetic usage. It also used multilinear regression to provide a model for the prediction of cosmetic usage through personality variables. Additionally, Chapter 13 found no relationship between cosmetic usage and self-perceived attractiveness but a significant relationship between cosmetic usage and sociosexuality. In all empirical studies evolutionary explanations were offered focussing, in the main, on the tenets of Conditional Mating Strategy Theory and Strategic Pluralism as well as Parental Investment Theory and the Multiple Fitness Model. Substantial support was offered for evolutionary explanations of intra-sex diversity within human sexual strateg