Researchers at the University of California, Berkeley have conducted a study that concluded a few whiffs of androstadienone–a pheromone found in male sweat and perfumes–can raise levels of the hormone cortisol in women. Cortisol is associated with stress, but also arousal and brain activation.
The study, reported this week in The Journal of Neuroscience
, provides the first direct evidence that humans, like rats and some insects, secrete a scent that affects the physiology of the opposite sex.
"Many people argue that human pheromones don’t exist, because humans don’t exhibit stereotyped behavior," said Claire Wyart, a postdoctoral researcher in the Berkeley Olfactory Research Program
, in a prepared statement. "Nonetheless, this male chemical signal, androstadienone, does cause hormonal as well as physiological and psychological changes in women. More cognitive studies need to be done to understand how androstadienone affects female cognitive functions."
In two trials, 48 female undergrads at Berkeley were asked to take 20 sniffs from a bottle containing androstadienone, which the researchers say smells vaguely musky. Over a period of two hours, the volunteers provided five saliva samples, from which cortisol levels were determined.
The control group sniffed a yeast solution, while the other group took a hit of androstadienone. The group exposed to the pheromone reported an improved mood and significantly higher sexual arousal, as well as physiological responses such as changes in blood pressure and heart rate.
Cortisol levels in the group exposed to androstadienone rose within about 15 minutes and remained elevated for more than an hour.
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Although androstadienone appears to incite changes in hormonal levels in women, there is no hard evidence–or any personal, anecdotal experience for that matter–that male sweat induces subliminal or instinctual behavior on the part of women that might make them gravitate toward a sweaty male.
In rats, hormonal secretion can cause behavior changes in the sniffer because of a vomeronasal organ rodents have. Humans have a similar organ, but it appears to be vestigal with no nerve connection to the brain.