14 DAY TRIAL // Many mammals and insects expel chemicals, called pheromones that induce sexual arousal in the opposite sex. This is the dream of many men, and a recent study at the University of California, Berkeley, has for the first time answered the thorny question: do humans possess pheromones?
"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" said study leader Dr. Claire Wyart.
In a previous study, Noam Sobel, associate professor of psychology at UC Berkeley and director of the Berkeley Olfactory Research Program had discovered that the chemical androstadienone, encountered in male sweat and a common additive in perfumes and colognes triggered mood changes, sexual 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.
Some humans possess a small vomeronasal organ inside their nose, like rats and other mammals do for sensing pheromones, but it is vestigial, lacking 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 changes in women. More cognitive studies need to be done to understand how androstadienone affects female cognitive functions."
As androstadienone raises cortisol levels, it can be employed for treating conditions characterized by low cortisol, such as Addison's disease, instead of current hormonal therapy, which has harmful side effects like ulcers and weight gain.
Since ever, researchers looked for human pheromones in the sweat, and male underarm sweat has been found to raise women's moods and impact their levels of luteinizing hormone, implied in tuning the ovulation.
Some researched discovered that female sweat put to the upper lip of other women induces changes in their menstrual cycles and synchronic ovulation with the sweat's owner.
Androstadienone is a testosterone break down product abundant in male sweat and all other body secretions. The new research proved that androstadienone does indeed induce hormonal changes in women.
The researchers focused on cortisol, the stress hormone. They experimented in 48 heterosexual student women asked to take 20 sniffs from a recipient containing androstadienone, which possesses a slight musky odor. After two hours, the researchers assessed cortisol levels in their saliva.
Those that sniffed androstadienone displayed a sexual and physiological arousal, including increased blood pressure, heart rate and breathing and their cortisol levels boomed within 15 minutes of sniffing the chemical, staying high for more than an hour.
The researchers warn that this may not be the only human chemical with a pheromonal activity. But the research does not explain what triggers what: the higher cortisol level changes mood or arousal; or mood change rises cortisol amounts? "We next need to look at other hormones that could explain the diversity of effects of androstadienone on sexual arousal and mood," said Wyart.