Chemical communication in primates

The mammalian olfactory system is specialized for the perception of chemica l compounds that regulate a number of functions. The pheromone is the chemi cal compound most used among species, its effects being either physiologica l of behavioral, depending on the message transmitted and the context in wh ich it is perceived. Chemical communication by pheromone in mammals is important for regulating reproductive processes and affecting social interactions within populations . Mammals' most active pheromones are usually found in urine and vaginal se cretions. These chemical compounds are perceived via the olfactory epitheli um and the vomeronasal organ, which have neural connections with different brain nuclei associated with reproductive regulation and emotions. Yet, it remains controversial whether pheromones are present in Old World anthropoi ds and humans. Although in other primates, such as prosimians and New World monkeys, chemical communication is acknowledged in territorial marking, co nspecific recognition and socio-sexual behavior. There is still disagreemen t ii in catarrhines, pongids and humans, pheromones participate in sexual a ttraction. First, because this primates have a small olfactory region, both nasal and neural, when compared to the rest of the mammals. And second, be cause to date the functionality of the vomeronasal organ, seemingly special ized in pheromone perception in mammals, is considered vestigial in catarrh ine monkeys and apes. Some recent works provide evidence that in humans suc h organ is not vestigial, as it was considered, being a specialized structu re in the perception of pheromones which are able to promote sex-dependent physiological changes.