How human sexuality came to be what it now is. Human sexuality seems normal to us but it is bizarre by the standards of other animals. Jarad Diamond Argues that our stange SEX lives were as crucial to our rise to human atatus as were our large brains. Among the usual aspects of human sexuality siscussed are female menopause, the role of men in human societies, our having SEX in private, our often having SEX for fun rather than procreation, and the explanation of women's breats even before use in lactation. These features might seem too natural to require explanation, but on reflection thay prove surprisingly difficult to account for.