Just a whiff of a woman close to ovulation is enough to stimulate another woman's testosterone levels, along with her desire to compete.
Competition among women may be, in large part, nose-driven, as a new study finds that the scent of a woman close to ovulation triggers a testosterone boost in the smelling female.
Testosterone, in turn, can affect behavior.
"It's well known that testosterone is linked to aggression and competitiveness," lead author Jon Maner, a Florida State University psychologist, told Discovery News. "Based on our testosterone findings, one could speculate that women exposed to the scent of ovulation might become more antagonistic or competitive."
For the study, published in the latest issue of the journal Evolution and Human Behavior, Maner and co-author James McNulty measured the testosterone levels of women before and after they smelled t-shirts that were previously worn by other women aged 18-21. The latter group wore the shirts when they were at high fertility -- days 13, 14 and 15 of the menstrual cycle -- and at low fertility- days 20, 21 and 22.
For the duration of the study, the t-shirt wearers refrained from engaging in sexual activity. They also showered with unscented soap and shampoo, did not use any perfumes or deodorants, didn’t smoke, and avoided eating odor-producing foods, such as garlic and asparagus.
The sniffers were told that the study concerned "how much we can tell about another person without even meeting them," but had no idea about how and when the t-shirts were collected.
Women exposed to the scent of high fertility females displayed greater levels of testosterone. The smell of a low fertility woman actually caused testosterone levels in the sniffers to significantly drop.