HUMAN FEMALE ORGASM AND MATE FLUCTUATING ASYMMETRY

Human, Homo sapiens, female orgasm is not necessary for conception; he nce it seems reasonable to hypothesize that orgasm is an adaptation fo r manipulating the outcome of sperm competition resulting from faculta tive polyandry. If heritable differences in male viability existed in the evolutionary past, selection could have favoured female adaptation s (e.g. orgasm) that biased sperm competition in favour of males posse ssing heritable fitness indicators. Accumulating evidence suggests tha t low fluctuating asymmetry is a sexually selected male feature in a v ariety of species, including humans, possibly because it is a marker o f genetic quality. Based on these notions, the proportion of a woman's copulations associated with orgasm is predicted to be associated with her partner's fluctuating asymmetry. A questionnaire study of 86 sexu ally active heterosexual couples supported this prediction. Women with partners possessing low fluctuating asymmetry and their partners repo rted significantly more copulatory female orgasms than were reported b y women with partners possessing high fluctuating asymmetry and their partners, even with many potential confounding variables controlled. T he findings are used to examine hypotheses for female orgasm other tha n selective sperm retention. (C) 1995 The Association for the Study of Animal Behaviour