Phylogenesis of mammal sexuality. Analysis of the evolution of proximal factors

Abstract

Summary The aim of this article is to make a precise identification of the factors involved in the evolution of human sexuality. The analyses presented concern mainly the evolution of proximal factors that govern prototypical heterosexual copulation in mammals. The data was collected from a review of the literature concerning the evolution of neurobiological factors of sexual behaviour in mammals. Several studies, in biology, genetics and neurosciences, have shown that some of these factors have changed over the course of evolution. In primates, the olfactory circuits are impaired, sexual activities are dissociated from hormone cycles (reproduction and sexual behavior have become independent one from the other), the lordotic mating reflex is no longer functional and the cortex is highly developed in human beings. For these reasons, the analysis of available data suggests that: (1) the dynamics of sexual behaviour has significantly evolved from the anthropoid primates; (2) the functional dynamic of heterosexual copulation is very probably disorganized; (3) the behavioural dynamics that emerge with the hominidae – from factors that still exist in heterosexual copulation – would seem to be based on a quest for erotic reward, by stimulation of the erogenous zones; and (4) in humans, due to the extensive cognitive development, sexuality is structured by cultural representations.