ORIGINAL PAPER Why Women Have Orgasms: An Evolutionary Analysis

Abstract Whether women’s orgasm is an adaptation is argu-ably the most contentious question in the study of the evolution of human sexuality. Indeed, this question is a veritable litmus test for adaptationism, separating those profoundly impressed with the pervasive and myriad correspondences between organ-isms ’ phenotypes and their conditions of life from those who apply the ‘‘onerous concept’ ’ of adaptation with more caution, skepticism or suspicion. Yet, the adaptedness of female orgasm is a question whose answer will elucidate mating dynamics in humans and nonhuman primates. There are two broad compet-ing explanations for the evolution of orgasm in women: (1) the mate-choice hypothesis, which states that female orgasm has evolved to function in mate selection and (2) the byproduct hypothesis,whichstates that femaleorgasmhasnoevolutionary function, existing only because women share some early ontog-eny with men, in whom orgasm is an adaptation. We review evidence for these hypotheses and identify areas where relevant evidence is lacking. Although additional research is needed before firm conclusions can be drawn, we find that the mate-choice hypothesis receives more support. Specifically, female orgasm appears to have evolved to increase the probability of fertilization from males whose genes would improve offspring fitness