Berkeley -- Just a few whiffs of a chemical found in male sweat is enough to raise levels of the stress hormone cortisol in heterosexual women, according to a new study by University of California, Berkeley, scientists.
The study, reported this week in The Journal of Neuroscience, provides the first direct evidence that humans, like rats, moths and butterflies, secrete a scent that affects the physiology of the opposite sex.
"This is the first time anyone has demonstrated that a change in women's hormonal levels is induced by sniffing an identified compound of male sweat," as opposed to applying a chemical to the upper lip, said study leader Claire Wyart, a post-doctoral fellow at UC Berkeley.
The team's work was inspired by previous studies by Wyart's colleague Noam Sobel, associate professor of psychology at UC Berkeley and director of the Berkeley Olfactory Research Program. He found that the chemical androstadienone - a compound found in male sweat and an additive in perfumes and colognes - changed mood, sexual arousal, physiological arousal and brain activation in women.
Yet, contrary to perfume company advertisements, there is no hard evidence that humans respond to the smell of androstadienone or any other chemical in a subliminal or instinctual way similar to the way many mammals and even insects respond to pheromones, Wyart said. Though some humans exhibit a small patch inside their nose resembling the vomeronasal organ in rats that detects pheromones, it appears to be vestigial, with no nerve connection to the brain.
"Pheromones are chemical molecules expressed by a species aimed at other members of the species to induce stereotyped behavior or hormonal changes," Wyart explained. "Many people argue that human pheromones don't exist, because humans don't exhibit stereotyped behavior. Nonetheless, this male chemical signal, androstadienone, does cause hormonal as well as physiological and psychological cha
Contact: Robert Sanders
University of California - Berkeley