English: Evolution of the main neurobiological factors that control the sexual behavior of mammals.

Sexual reflexes, such as the motor reflex of lordosis, become secondary. In particular, lordosis behavior, which is a motor reflex complex and essential to carry out copulation in non-primate mammals (rodents, canines, bovids ...), is apparently no longer functional in women. Sexual stimuli on women do not trigger any more neither immobilization nor the reflex position of lordosis. On the level of olfactory systems, the vomeronasal organ is altered in hominids and 90% of the pheromone receptor genes become pseudogenes in humans. Concerning hormonal control, sexual activities are gradually dissociated from hormonal cycles. Human can have sex anytime during the year and hormonal cycles. On the contrary, the importance of rewards / reinforcements and cognition became major. Especially in humans, the extensive development of the neocortex allows the emergence of culture, which has a major influence on behavior. For all these reasons, the dynamics of sexual behavior was modified.

Diagram adapted from: Agmo A. Functional and dysfunctional sexual behavior. Elsevier, 2007 --- Georgiadis J.R., Kringelbach M.L., Pfaus J.G. Sex for fun: a synthesis of human and animal neurobiology. Nat. Rev. Urol., 9(9):486-498, 2012 --- Nei M., Niimura Y., Nozawa M. The evolution of animal chemosensory receptor gene repertoires: roles of chance and necessity. Nat. Rev. Genet., 9(12):951-963, 2008 --- Wunsch S. Comprendre les origines de la sexualité humaine. Neurosciences, éthologie, anthropologie. L'Esprit du Temps, 2014. --- Zhang J., Webb D.M. Evolutionary deterioration of the vomeronasal pheromone transduction pathway in catarrhine primates. Proceedings of the National Academy of Sciences of the United States of America, 100(14):8337-8341, 2003.