Sexual attractiveness: a comparative approach of morphological, behavioral neurophysiological signaling in women and nonhuman primate females

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 morphology 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.

Sexual attractiveness: a comparative approach of morphological, behavioral neurophysiological signaling in women and nonhuman primate females

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 morphology 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.

Mothers may shape the variations in social organization among gorillas

When mothers continue to support their offspring beyond infancy, they can influence the fitness of those offspring, the strength of social relationships within their groups, and the life-history traits of their species. Using up to 30 years of demographic data from 58 groups of gorillas in two study sites, this study extends such findings by showing that mothers may also contribute to differences in social organization between closely related species. Female mountain gorillas remained with their sons for significantly longer than western gorillas, which may explain why male philopatry and multimale groups are more common among mountain gorillas. The presence of the putative father and other familiar males did not vary significantly between species, and we found only limited support for the socio-ecological theory that the distribution of adult males is influenced by the distribution of females. Within each gorilla species, variations in those distributions may also reflect the different stages in the typical life cycle of a group. Collectively, our results highlight the potentially far-reaching consequences of maternal support that extends beyond infancy, and they illustrate the opportunity to incorporate additional factors into phylogenetic analyses of variations in social organization, including studies of human evolution.

Troop Takeover and Reproductive Success of Wild Male Japanese Macaques on Yakushima Island (Macaca fuscata yakui)

Troop takeover is common in one-male primate groups, but there are few reports in multimale groups. Japanese macaques (Macaca fuscata) form multimale groups and males commonly join troops at the bottom rank. On Yakushima island, however, where group size is relatively small, entrance into groups at the alpha position is also observed. This paper reports on the general features of troop takeover, on the predictors of takeover events, and on the reproductive success of takeover males. Troop takeovers occurred only in the mating season; nontroop males (NTMs) did not cooperate with each other; former alpha males were rarely expelled from the troop; new alpha males did not commit infanticide; new alpha male tenure in the group was usually less than two years. Logistic regression analysis showed that the number of NTMs associating with a troop predicted the occurrence of troop takeover. Paternity discrimination revealed that 33.3% (3/9) of takeover males succeeded in siring offspring. Contrary to this low success rate, binary logistic regression analysis revealed that the takeover males can expect higher reproductive success compared to troop males. Entering a troop and out-competing the alpha male is one of many available strategies to attain reproductive success in male Japanese macaques.