Maybe she’s attracted to him because of his great personality. Perhaps it’s his wild sense of humor. Maybe it’s his fat wallet. Maybe it’s his … body odor? Women seem very aware of men's personal scents, according to a 2009 study at Monell Chemical Senses Center in Philadelphia. This goes way beyond wanting old socks picked up from the floor. Though both sexes have identical nose structure, a larger part of women’s brains are involved in the sense of smell, an earlier study at the center found. Though this could just make some women wrinkle their noses several times a day, it might have a serious impact on the human species.

I Work Out

Whether or not they like it, women are better at smelling sweat than men. The 2009 study at Monell had both men and women sniffing samples of sweat; each was combined with one of 32 other scents. Women sensed the perspiration in almost all cases. Just two fragrances managed to hide the stink from them. However, men’s noses were fooled by 19 of the added scents. They couldn’t detect any body odor.

The Nose Knows

Unless a woman works on the cleaning crew at a gym, the finely tuned ability to sense sweat might not seem to have much practical use. However, researchers believe that women can use smells to choose mates. Forget the romance: from a strictly biological point of view, body odor has information for the opposite sex. A woman might unconsciously learn about a man’s immune system based on his scent. If you consider reproduction as a way to keep the species alive, this kind of data allows females to choose mates who are more likely to father children and continue the human race, Monell studies have found.

The Scent of a Woman

Women don’t get all the credit. Men’s noses are helping the species survive, too. Back in 2006, researchers from Charles University in Prague, Czech Republic, examined how men responded to women’s underarm odors during different times of their menstrual cycles. Although women’s scents are less strong when they're fertile, men found those smells most attractive. This isn’t a secret to women, though. In 2009, scientists at Rice University in Texas discovered that women can tell the difference between men who are turned on and those that aren’t just by their odor.

A Bit Better

Coffee, baking cookies, autumn leaves, gasoline: when it comes to sensing ordinary smells, women and men are equal. However, when researchers from Monell studied unfamiliar smells in 2002, women won the sniff test. They could sense certain chemicals -- with cherry almond or banana scent -- better after having smelled them several times, even when the scent grew weaker and weaker. Men’s ability didn’t improve. These differences only showed up when the participants were in their reproductive years, so scientists wonder whether women’s hormones are causing the effect.