This comprehensive review focuses on comparative data in nonhuman primates and humans in relation to signaling secondary sex characteristics (SSC), sexual behavior, and neurophysiology of sexuality during the female cycle. Obviously, sexual activities of primates are not limited to specific cycle phases. In higher evolved primate species no distinction can be drawn between sexual interactions as a prerequisite for reproduction or as a pleasurable tool. However, cyclic depended changes of body

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... rphology and behavior, such as feeding, risk taking, mood changes, are documented for both groups. Neurophysiologically, homologous brain areas, sex steroids and receptor compartments are involved in mediating sexual and pleasure during all cycle stages. The interaction between the subcortical reward system and the social brain network and its projection to the prefrontal cortex are of importance. The advertising of SSC indicate analogous strategies between human one male social units and multifemale-multimale groups in nonhuman primates. Women do advertise SSC permanently after the onset of puberty. In contrast, some nonhuman primate species express attractive signals during specific cycle stages and prolong them beyond fertile periods. The physiological and morphological nature of primate SSC and their flexibility of expression in relation to their information content for males will be discussed during different cycle periods for both groups. Because of permanent sexual attractiveness in humans the use of clothes as a specific eye catcher to advertise SSC in relation to biological function will be illustrated. The latter is suggested to be an example of culture-biology adaptation in human sexual behavior.