Abstract

Evolutionary psychology suggests that predispositions toward many behaviours exist because they were adaptive in the evolutionary environment. Adaptive behaviours are often sex differentiated due to biological differences in reproduction. Men are typically more competitive than women due to their innate motivation to compete for access to a greater quantity of mates which then typically decreases as reproductive resources are acquired. However, in the ancestral environment, this reproductive strategy was not adaptive for women therefore this variation in the competitiveness of women should not be evident. Research into the effect of reproductive resources on competitiveness is in its early stages and predominantly uses niche samples of highly competitive individuals. This thesis therefore aimed to explore this phenomenon using more representative samples of men and more accessible measures of competitiveness than those used in previous research. In a novel, online, behavioural measure of competitiveness, single non-fathers were shown to be more competitive than committed fathers, consistent with the evolutionary explanation of the origins of competitiveness. Furthermore, this variation in competitiveness was not evident in women. Fluctuating levels of testosterone have previously been implicated as supporting mate acquisition behaviours in men. Although this finding was not evident in the current research, testosterone levels did predict the competitive motivation of men in committed relationships consistent with self-reported interests in pursuing mates. Female mate preferences corroborated these findings showing women prefer for men to evidence a decrease in mating effort as relationship commitment increases. Finally, there was no evidence that priming cues relevant to reproductive success influenced competitiveness. Overall, the results provide some support for the evolutionary
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account of competitiveness in men, consistent with the suggestion that it reflects mating motivations and varies adaptively to promote reproductive success.