Women 'smell' their competition: study

The scent of a woman close to ovulation boosts testosterone levels in another female, fuelling her desire to compete, a new study has found.

US researchers 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.

Women exposed to the scent of high fertility females displayed greater levels of testosterone. The smell of a low fertility woman caused testosterone levels in the sniffers to significantly drop.

"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," Maner said.

"Humans are influenced much more strongly by ovulatory cues than we tend to think," Maner explained.

"For the most part, people aren't likely to be consciously aware of the effects ovulatory cues have over them.

"There is solid evidence that people find the scent of ovulation to be pleasant and attractive (relative to the scent of a woman who is far from ovulation), but beyond that, most of the behavioural and hormonal effects are likely to occur below the conscious radar," Maner said.

The study was published in the journal Evolution and Human Behavior.