Most women have had the mysterious experience of being turned on by a partner's smell. Though personality and looks definitely play a part in initial attraction, smell may play a larger role than we suspect. Studies have found that how a person smells gives us clues to their genetic make-up, and thus, their potential to be a compatible mate. The first study to indicate this was conducted by Claus Wedekind. 44 men wore the same t-shirt for three days. They refrained from deodorants and scented soaps to keep their natural smell. Women then smelled the shirts and recorded which ones smelled the best. By comparing the DNA of the women and men, it was found that women didn't just choose randomly. They preferred the scent of man whose major histocompatibility complex (MHC), series of genes involved in our immune system, was most different from their own. From an evolutionary perspective, choosing a mate with a different immune system makes survival sense. Kids of parents with different immune genes are more likely to be disease-resistant and are therefore more likely to survive. An interesting exception to the MHC attraction is for women taking the pill, who responded the opposite than would be expected. Because the pill tricks your body into thinking it is pregnant, it chemically alters your sense of attraction. Instead of finding the scent of genetically dissimilar men attractive, women on the pill found the scent of men with MHC's similar to their own to be attractive. This may be because when a woman is pregnant, she isn't looking for a new mate, and may benefit from being around those with a similar genetic make-up. Though certainly the scent of a man can be a powerful indicator of genetic compatibility, it certainly doesn't dictate everything. If a woman falls in love with a man, and then begins the pill, she's not likely to lose interest. And there are certainly other factors at play than just scent. Our noses may help us find the mate most suited to us, but it's ultimately up to our minds to decide whether or not we like what we've sniffed out. So in my opinion, use your nose, but make sure you don't only depend on scent.