The pill subverts a woman's ability to sniff out a compatible mate by causing her to misinterpret the scent messages she receives. But it may warp olfactory communication channels in the other direction as well, distorting the signals she sends—and making her seem less appealing to men, an irony given that women typically take the pill to boost their appeal in a partner's eyes.
Geoffrey Miller, an evolutionary psychologist at the University of New Mexico and author of The Mating Mind, noticed the pill's connection to waning male desire while studying a group of exotic dancers—women whose livelihoods depend on how sexually appealing they are to male customers. Non-pill-using dancers made about 50 percent more in tips than dancers on oral contraceptives. In other words, women who were on the pill were only about two-thirds as sexy as women who weren't.
Why were the pill-takers in the study so much less attractive to men? "Women are probably doing something unconsciously, and men are responding to it unconsciously," says Miller. "We just don't know whether it has to do with a shift in their psychology, their tone of voice, or if it's more physical, as in the kind of pheromones they're putting out."
The biggest earners in Miller's study were non-pill-using dancers at the time of ovulation. Other studies have shown that men rate women as smelling best when they are at the most fertile point of their menstrual cycles, suggesting that women give off scent-based signals that broadcast their level of fecundity. "The pill might be producing cues that a woman is in the early stage of pregnancy , which would not tend to elicit a lot of male sexual interest," Miller says. "It makes sense for men to be sensitive to that and for them not to feel the same chemistry with the woman."
Drowning in Fragrance
The pill isn't the only way we might confound sexual chemistry. Every day, far more people may be subverting their quest for love with soap and bottled fragrances. In ancestral times, smelling ripe was just a fact of life, absent hot showers and shampoo. This held true well into the 19th century, when the miasma of body odor in Parisian streets grew so thick that it was dubbed "The Great Stink of 1880." Back when a person's scent could waft across a room, a mere handshake could provide valuable information about attraction.
Since the 20th-century hygiene revolution and the rise of the personal-care industry, however, companies have pitched deodorants, perfumes, and colognes to consumers as the epitome of sex appeal. But instead of furthering our quest to find the perfect mate, such products may actually derail it, say researchers, by masking our true scent and making it difficult for prospects to assess compatibility. "Humans abuse body smell signals by hiding them, masking them, putting on deodorant," says Devendra Singh, a psychologist at the University of Texas. "The noise-to-signal ratio was much better in primitive society."
Miller argues that modern hygiene may be such an impediment to sexual signaling that it could explain why so many people in our culture get so physical so fast. "Hunter-gatherers didn't have to do a lot of kissing, because they could smell each other pretty clearly from a few feet away," Miller says. "With all the showering, scents, and soap, we have to get our noses and mouths really up close to people to get a good idea of their biochemistry. People are more motivated to do a lot more kissing and petting, to do that assessment before they have sex." In other words, the need to smell our mates—and the comparative difficulty of doing so in today's environment of perfumes and colognes—may actually be driving the sexual disinhibition of modern society.
Other scientists counter that odor detection is a bit subtler. For one thing, it's possible we select store-bought scents to complement our natural odorprints, rather than mask them entirely: One study found that people with similar MHC profiles tend to go for the same colognes. And Garver-Apgar points out that in spending hours together each day, partners have ample opportunity to experience each other sans artificial scents. "Once you're in a close enough relationship," she says, "you're going to get a real whiff at some point."
Scents and Sensibility
There's no way to know whether couples who shell out thousands of dollars to fertility clinics—and those who struggle to make a relationship work because "the chemistry just isn't there"—suffer MHC incompatibility. We might never know, since a multitude of factors contributes to every reproductive and romantic outcome. But we can, at least, be cognizant of the importance of natural scent.
"Scent can be a deal breaker if it's not right, just like someone being too stupid or unkind or short," says Miller. Nevertheless, smell isn't the be-all and end-all of attraction, but one of a constellation of important factors. Armed with knowledge of how scent-based attraction operates, we have some power to decide how much priority we want to accord it. Is it more important to be with the partner who smells amazing and with whom you have great chemistry, or with the one who may not attract you quite as much on a physical level but is honest and reliable?
"People tend to treat this as an either-or situation: Either we're completely driven by pheromones, like moths, or we're completely in charge of our own destiny," University of Chicago psychologist McClintock says. "But it's not a wild idea that both factors are involved." While people like Estelle Campenni have reaped untold benefits by trusting their scent impressions, it's ultimately up to us how highly we value what our noses tell us.