Testing Evolutionary Hypotheses Regarding Individual Differences in Human Mating Strategies

Abstract

Finding and attracting a mate is an enormous component of human life, and indeed the life of all sexually reproducing organisms. In this search, we share many common goals in attaining a partner. For instance, most people typically seek a partner who is kind, attractive, and funny. Yet, we also differ remarkably in the traits that we desire in our partners and what drives us towards choosing some mates over others. This variation represents somewhat of a Darwinian paradox, as selection typically reduces variation in traits under strong selection, such as those relating to mating strategy. To resolve this paradox, evolutionary psychologists have proposed adaptive mechanisms that cause variation in mating strategy in response to environmental contingencies. In this thesis, I present tests of a number of these hypotheses, and integrate approaches from evolutionary behavioural genetics to provide alternative explanations as to how variation in mating strategy arises.Firstly, I review broad evolutionary approaches to explaining variation in psychological traits. Specifically, I introduce evolutionary literature regarding a proposed trade-off between parenting traits and signals of genetic quality in males that permeates approaches to various aspects of mate choice. Evidence for and against this trade-off is reviewed in the context of the maintenance of variation in facial masculinity in males and inter-partner variation in female orgasm frequency during penetrative sex. I then introduce behavioural genetics as an approach to understanding both genetic and environmental causes of variation in human mating strategy.In my first empirical study, I present a paper testing evolutionary hypotheses regarding female variation in orgasm frequency in response to male characteristics. Where previous research has focused on women reporting on a single partner and observing male characteristics across the sample, this paper had females report on partners with whom orgasm was easy and with whom orgasm was difficult. This controls for the possibility of confounds relating to between-subject studies and increases our power to detect male traits associated with orgasm over and above between women differences. Furthermore, the study also included measures of male sexual behaviour, as these are highly likely to be related to female orgasmability. We showed mixed support for evolutionary theories regarding variation in the female orgasm, but were unable to distinguish the two leading hypotheses. Additionally, we found important contributions of male sexual behaviour to female orgasm. Consequently, little can be inferred about the role of variation in the evolution of the female orgasm. However, we demonstrate that within-subjects designs are able to detect between-partner variance with high resolution. We also demonstrate that future studies need account for male sexual behaviour when attempting to explain adaptive variation in female orgasm between different male partners.ii I then present a paper providing evidence that facial ...