Body odor reveals more than when we last showered - it also packs important biological information. And apparently women are better at catching the scent of body odor than men, a new study found.

"It is quite difficult to block a woman's awareness of body odor. In contrast, it seems rather easy to do so in men," said Charles Wysocki, a behavioral neuroscientist at the Monell Chemical Senses Center in Philadelphia.

The researchers think women are more attuned to underarm stink because the biological data it contains helps them choose mates. The fact that most women are even better at smelling male body odor than female body odor seems to support this idea.

Wysocki and colleagues asked women and men to rate the strength of underarm sweat samples collected from both genders. When the scent was presented on its own, it smelled equally strong to both women and men. But when the researchers combined the body odor with other fragrances, the smell was often masked for men, though women could usually still detect it.

The study tested 32 fragrances to see how well they could hide B.O. Among the male subjects, 19 of the fragrances did the trick, though among women, only two of the scents successfully overpowered the sweaty stench.

"Our studies indicate that human sweat conveys information that is of particular importance to females," Wysocki said. "This may explain why it is so difficult to block women's perception of sweat odors."

The scientists also tested the female volunteers' reactions to odors from men versus odors from women. They found that even though the female sweat smelled just as strongly as the male sweat did, it was easier to mask with perfumes. About 19 percent of the fragrances tested successfully reduced the strength of male underarm odor, while more than 50 percent decreased the intensity of female underarm odor.

The new study, published in the Flavour and Fragrance Journal, fits in with other research on how women use their sense of smell romantically. A study published in December 2008 found that women can tell when a man is interested from the scent of his sweat. The scientists found that women's brains responded differently when smelling sweat samples from men who were sexually aroused and men who weren't.

Men also use their noses to choose mates, research has shown. A January 2006 study found that the scent of a woman's body odor is more attractive to men at certain times in the female's monthly cycle. Female underarm sweat seems to communicate when a woman is fertile, making her more desirable to men.