Sweating genetic details: It's all in the nose, researchers say

Last Updated: Monday, September 17, 2007 | 12:40 PM ET

Why do sweaty men smell sexy to some and disgusting to others? The nose knows, scientists say.

Genetic variations in people's odour receptors explain why some perceive the smell as repugnant while others find it appealing or smell nothing at all, according to researchers at Rockefeller University in New York, who reported their findings in the latest issue of Nature.

Androstenone, or a potent ingredient in male body odour that is derived from testosterone, can smell sweet like vanilla or unpleasant like stale urine or have no smell at all to people depending on differences in a genetic receptor named OR7D4. Androstenone is used by some mammals to convey social and sexual information. The ability to perceive its scent may have significant behavioural implications, the researchers said.

"Since some mammals clearly use androstenone to communicate sexuality and dominance within a social hierarchy, it's intriguing to think whether the same thing may happen in humans," said Leslie Vosshall, Chemers Family associate professor and head of the laboratory of neurogenetics and behaviour at Rockefeller, in a release. "If so, what happens to humans who can't get the signal because they have the nonfunctional copy of the gene? Or the hyperfunctional one? What could be the social and sexual implications of this on one's perception of the smell of fellow humans?"

In performing their study, researchers asked nearly 400 participants to rate the pleasantness and intensity of 66 odours at two different concentrations. After learning that androstenone selectively activates the OR7D4 receptor, the researchers studied DNA samples from participants.

In collaboration with scientists at Duke University in North Carolina, the researchers were able to determine two variations of the gene: an RT version and a WM version. Participants with an RT/RT type found androstenone's scent as foul, while those with the RT/WM or WM/WM types found it pleasant. Many with the RT/WM and WM/WM variations could not detect any odour, although researchers found that they could develop the ability to smell it after daily exposure for six weeks.