This chapter examines the origins and evolution of human sexuality. The author summarizes the classical concept of sexual strategies and presents several critical arguments based on empirical evidence from anthropology. Monogamous marriage and the condemnation of adultery are not universal and “natural.” The author treats multiple layers of sexual structures as correlative with different stages of anthropogenesis and subsequent history. The lowest layer, or “core,” is the oldest biological system of reproduction. Verbal representations of sex, eroticism, love, etc. constitute the most superficial and mobile layers. The “core” does not define the “periphery,” which has autonomy and a close connection to the encompassing social orders. Throughout prehistory and history, new practices, technologies, and social relations created new sexual challenges-threats and challenges-opportunities. Hominins responded with behavioral attempts, the successes of which were fixed in sexual practices and in systems of genetic and cultural inheritance. According to the “principle of minimal harmony,” the forms of sexual life at each stage of evolution more or less corresponded to objective group concerns, including the maintenance of inner peace. There are still tensions and disharmonies in human sexuality, “habitual peculiarities” of our intimate life. These include the discordance of male and female behavior during coitus, the waning of passion over time, adultery, jealousy, aggression. These “inconsistencies” reveal a basic internal conflict between ancient behavioral patterns characteristic of life in small hominin groups and later superstructural layers, including social and normative ones. At the end of the chapter, the author proposes logical schemes for testing hypotheses about the correspondence between the hierarchy of innate structures of sexuality and the antiquity of their origin.