You meet her in the produce section and there's an instant attraction. Maybe it's her sparkling smile, or your lucky shirt. But more likely, according to some experts, it's how you both smell. 

"When we're saying 'love at first sight' it should be 'love at first sniff,'" said Dr. Alan Hirsch, author of Scentsational Sex. The part of the brain responsible for processing odors "is directly connected to the limbic or emotional brain," he said, so our noses are hardwired to our libidos. 

"I was very much attracted to my husband by his smell when I first met him — he smelled like sandalwood," said Joanne, a writer from New York City. "The art director who I work with is a very attractive guy, but at one point he was wearing something that really turned me off, something like musk." 

 
'I believe people have their own pheromones. When you're in love or whatever, you're like a magnet,' — Joanne 
 

Lucy, a New York art student, and her boyfriend, Richard, a screenwriter, say smell plays a big role in their relationship. 

"At one point we broke up, but I could still smell her," Richard said. "She was still there, even though she wasn't." 

"And why was that? Because you broke up with me!" Lucy interjected. 

"She had worn a sweater of mine, and it was a nice feminine smell," Richard said. 

"It reminded him of how stupid he was for throwing me out," Lucy said with a smile. "In the morning, Richard smells nice, like an animal — it's the pheromones, I think." 

Like Swapping Business Cards 

The entire animal kingdom — and even some plants — send and receive smells through the exchange of pheromones, like two people in a bar trading business cards. 

The word is derived from the Greek pherein, meaning to transfer, and hormon, to excite. The same process may exist in humans — but despite the claims of pheromone cologne ads in the back of certain "gentleman's" magazines, the jury's still out on whether sexual human pheromones even exist. 

There are two types of pheromones, defined as chemicals excreted by an animal that influence members of the same species. Primer pheromones are slow-acting chemicals that work over long periods of time. For example, studies have found that male mice who weren't exposed to the pheromones of female mice at an early age had difficulty mating later in life. 

"There is proof that primer pheromones exist in humans," said Dr. George Preti, of the Monell Chemical Senses Center in Philadelphia. "The most obvious effect is the phenomenon of menstrual synchronicity," in which women living in close quarters will eventually shift to identical monthly cycles. 

Fast-Acting Pheromones? 

As for releasor pheromones, which have immediate effects — like sudden feelings of lust for the person checking out tomatoes next to you in the grocery store — Preti has his doubts. Because we don't overtly smell such chemicals, such a reaction would probably require the use of a special "sixth sense," known as the vomeronasal organ. The VNO once existed in humans, but many researchers believe that it has become inactive over time, like the appendix. 

Still, there has been some intriguing evidence that sexually exciting pheromones, excreted from the underarm, groin, eyelids and outer ear, really do exist in humans. Researchers at University College in London exposed women to androstenol, a hormone closely related to testosterone, and found they had more social exchanges with men the following day. 

Men in the study were exposed to short-chain fatty acids called copulines, which occur in human vaginal fluid and are "known to be sexually attractive to the male rhesus monkey," the researchers said. But they showed no increase in social interaction with women; it may be that sex pheromones are only detectable by women, who have a much sharper sense of smell than men. 

"I believe people have their own pheromones," said Joanne, the New York writer. "When you're in love or whatever, you're like a magnet. It's very noticeable." 

Hirsch conceded there is little direct evidence for releasor pheromones, but there is a long list of reasons why they should exist. "We have glands under our arms that release high-density steroids," he said. "We don't know what their purpose is, but in sub-human primates they release pheromones." 

"Also, what happens when you're sexually aroused? Your nasal tissue is engorged, allowing you to smell better. Women already have a better ability to smell, and it gets even better during ovulation," when libidos are at their peak, he said. 

How to Smell Better 

So sex — or at least the possibility of it — smells, albeit in ways that we may not be fully conscious of. But what to do about it? 

According to one study by Hirsch and his colleagues, fellas should lay off the cologne, and ladies should make a stop at the bakery. 

Here's how it worked: Hirsch had medical school volunteers, male and female, don scented surgical masks while simultaneously measuring their level of sexual arousal. The results were somewhat surprising. 

"Some odors inhibited women: cherries, barbecue meat and men's cologne," said Hirsch. In a bizarre turn, the biggest turn-on smell for women was a combination of cucumbers and Good-n-Plenty. 

Men have a less discriminating nose: every smell boosted sexual arousal. Perfumes increased arousal by a mere 3 percent, cheese pizza by 5 percent, and a combination of lavender and pumpkin pie by 40 percent. 

"It could just be a Pavlovian response," Hirsch said, in which men associate sex with certain odors, "or maybe the odors induced an olfactory nostalgic response" — wasn't there a certain scene in that movie American Pie

Smell, it seems, is one aspect of the mating dance that has yet to be deciphered — and perhaps that's for the best.