No / There is a series of common assumptions about prehistoric sex, associated with the prejudice that it must have been more natural because it happened closer to our evolutionary origins. The development of primate studies reveals a high degree of social variation between and within primate species, along with evidence for the practice of non-reproductive sex both recreationally and for expressing dominance relations. Yet, hypotheses about the behavior of human ancestors and early modern humans have been hampered by a lack of an integrated methodology. Although there is no single trajectory for either the elaboration or restriction of sexual behaviors after the emergence of culture, I argue here that it is possible to identify key turning points with more or less universal validity. These points include the reasons for and implications of brain size increase at the time of the emergence of genus Homo, the crystallization of impersonal gender by mid-Upper Paleolithic Ice Age societies, the early development of systems of control over both fertility and the projection and alteration of sexual identity, and the inferred emergence of homonegativity in early, reproduction-oriented farming societies. Further, archaeological data allows naturalist assumptions to be effectively refuted.