Writing in the journal Psychological Science, Florida State University psychologists Saul Miller and Jon Maner find evidence of a connection between male testosterone levels and the scent of an ovulating female. They describe a study in which 68 male undergraduates, age 18 to 23, put their nose to the opening of a plastic bag containing a T-shirt and inhaled deeply three times. They repeated this exercise after five and then 10 minutes.
One-third of the men smelled a shirt that had been worn by a woman when she was near ovulation; another third smelled a shirt worn by a woman when she was far from ovulation. The final third smelled shirts that hadn't been worn at all. All had their testosterone level measured, via a saliva test, before and after the experiment.
"Men exposed to the scent of an ovulating woman subsequently displayed higher levels of testosterone than did men exposed to the scent of a non-ovulating woman or a control scent," the researchers report. Their testosterone levels remained steady, while the others saw decreases (which, according to the researchers, presumably reflect the normal drop in testosterone that occurs during the course of a day).
Surprisingly, this is apparently the first study of this kind, although previous research has documented increased testosterone levels after men interact with an attractive woman or watch an erotic film. Scent appears to be "a more subtle stimulus" than those examples, the researchers report, but it is a stimulus nonetheless.
According to Miller and Maner, "the relatively higher testosterone levels arising from exposure to ovulatory scents suggests that those scents might lead men to respond with greater mate-seeking behaviors than they would otherwise. In addition, high testosterone levels are associated with competitiveness, dominance and risk-seeking, all traits typically valued by women — particularly women near their peak of reproductive fertility."
In other words, the olfactory cue emitted by a woman's body during her period of peak fertility seems to spark an increase in testosterone in the male body, which in turn increases a man's tendencies to display the sort of assertive behavior women find attractive. Mate-seeking among humans is a complicated, challenging business, but nature seems to be doing its best to help the process along.
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