The aim of the paper is to identify psychosomatic evolutionary adaptations of hominids, which direct them at maximizing their reproductive success, and on the basis of which their various social structures are built. Selected features of the hominid last common ancestor were extracted; by reducing the influence of the social structure, they were defined as the hominid "sexual nature"; these considerations were supported by the analysis of sexual jealousy as a function of socio-environmental conditions. The "sexuality core" of a hominid female was defined as "selective polyandry"-the female selects the best males among those available; and of a hominid male as "tolerant promiscuity"-the male strives for multi-male and multi-female copulations with sexually attractive females. The extracted "sexuality cores" condemn hominids to a patriarchal social structure and thus to sexual coercion and jealousy. The source of male sexual jealousy is limited access to females. Hominid female jealousy of the male results mainly from the need for protection and support. Hominids' social structures are determined by females' sexual selectivity or opportunism and by their continuous or periodic proceptivity and estrus signaling. Evolutionary functions developed by women: out-estrus sexuality, copulation calls, multiple orgasms, allow them to obtain the best possible spermatozoid. The institution of marriage blocks the influence of sexual selection in the species Homo sapiens.

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