A necessary element of analyzing the human species through a sexual lens is recognizing that sexual activity is more expansive than a dichotomy of reproduction and pleasure. If either of these two goals, or their conjunction, were the sole goals, then nature would have found a more efficient way to do so: “sex is in every sense a gratuitously consuming and risky activity” (122). It takes time and resources, and has a generally low rate of success (reproductively speaking). The reason why sexual dimorphism and reproduction are present in mammals is simple: “sex creates diversity” (122). In asexual reproduction, offspring are exactly like their parent organism; in sexual reproduction, offspring combine genetic material from two parents, resulting in genetic diversity that is impossible to achieve otherwise.

Genetic diversity is the best adaptation against the possibility of a changing environment that would render a species’ current adaptation ineffective. One of the obstacles that sexual dimorphism creates, however, is male/female conflict and aggression: “conflict of interest between the sexes is a property of not only human beings but also the majority of animal species” (124). The males of most species are rewarded for aggression and assertiveness, while females are often rewarded for patience and high selectivity (of mates).