Research has shown that we use scent-based signaling mechanisms to suss out compatibility. Claus Wedekind, a biologist at the University of Lausanne in Switzerland, created Exhibit A of this evidence by giving 44 men new T-shirts and instructing them to wear the shirts for two straight nights. To ensure that the sweat collecting on the shirts would remain "odor-neutral," he supplied the men with scent-free soap and aftershave.
After the men were allowed to change, 49 women sniffed the shirts and specified which odors they found most attractive. Far more often than chance would predict, the women preferred the smell of T-shirts worn by men who were immunologically dissimilar to them. The difference lay in the sequence of more than 100 immune system genes known as the MHC, or major histocompatibility complex. These genes code for proteins that help the immune system recognize pathogens. The smell of their favorite shirts also reminded the women of their past and current boyfriends, suggesting that MHC does indeed influence women's dating decisions in real life.
Women's preference for MHC-distinct mates makes perfect sense from a biological point of view. Ever since ancestral times, partners whose immune systems are different have produced offspring who are more disease-resistant. With more immune genes expressed, kids are buffered against a wider variety of pathogens and toxins.
But that doesn't mean women prefer men whose MHC genes are most different from theirs, as University of Chicago evolutionary biologist Martha McClintock found when she performed a T-shirt study similar to Wedekind's. Women are not attracted to the smell of men with whom they had no MHC genes in common. "This might be a case where you're protecting yourself against a mate who's too similar or too dissimilar, but there's a middle range where you're OK," McClintock says.
Typically, our noses steer us in the right direction when it comes to picking a reproductively compatible partner. But what if they fail us and we wind up with a mate whose MHC profile is too similar to our own? Carol Ober, a geneticist at the University of Chicago, explored this question in her studies of members of the Hutterite religious clan, an Amish-like closed society that consists of some 40,000 members and extends through the rural Midwest. Hutterites marry only other members of their clan, so the variety in their gene pool is relatively low. Within these imposed limits, Hutterite women nevertheless manage to find partners who are MHC-distinct from them most of the time.
The few couples with a high degree of MHC similarity, however, suffered higher rates of miscarriage and experienced longer intervals between pregnancies, indicating more difficulty conceiving. Some scientists speculate that miscarriages may be the body's way of curtailing investment in a child who isn't likely to have a strong immune system anyway.
What's more, among heterosexual couples, similar MHC profiles spell relational difficulty, Christine Garver-Apgar, a psychologist at the University of New Mexico, has found. "As the proportion of MHC alleles increased, women's sexual responsiveness to their partners decreased, and their number of sex partners outside the relationship increased," Garver-Apgar reports. The number of MHC genes couples shared corresponded directly with the likelihood that they would cheat on one another; if a man and woman had 50 percent of their MHC alleles in common, the woman had a 50 percent chance of sleeping with another man behind her partner's back.
Women generally prefer the smell of men whose MHC gene complements are different from theirs, setting the stage for the best biological match. But Wedekind's T-shirt study revealed one notable exception to this rule: women on the birth-control pill. When the pill users among his subjects sniffed the array of pre-worn T-shirts, they preferred the scent of men whose MHC profiles were similar to theirs—the opposite of their pill-free counterparts.
This dramatic reversal of smell preferences may reflect the pill's mechanism of action: It prevents the ovaries from releasing an egg, fooling the body into thinking it's pregnant. And since pregnancy is such a vulnerable state, it seems to activate a preference for kin, who are genetically similar to us and likely to serve as protectors. "When pregnant rodent females are exposed to strange males, they can spontaneously abort," Herz says. "The same may be true for human females." What's more, some women report a deficit in sex drive when they take the pill, a possible consequence of its pregnancy-mimicking function.
The tendency to favor mates with similar MHC genes could potentially hamper the durability of pill users' relationships in the long term. While Herz shies away from dubbing hormonal birth control "the divorce pill," as a few media outlets have done in response to her theories, she does think the pill jumbles women's smell preferences. "It's like picking your cousins as marriage partners," Herz says. "It constitutes a biological error." As a result, explains Charles Wysocki, a psychobiologist at Florida State University, when such a couple decides to have children and the woman stops taking birth control, she may find herself less attracted to her mate for reasons she doesn't quite understand. "On a subconscious level, her brain is realizing a mistake was made—she married the wrong guy," he says.
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.
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.
the body's way of curtailing investment in a child who isn't likely to have a strong immune system anyway.
Very interesting concept. Absolute balderdash but a curious study nonetheless.
I dunno how ridiculous the study is, but that is only because smell is pretty important to me.
There's also been research into the fact that when you suddenly feel really attracted to people for reasons you can't adequately explain it could be because you are actually attracted to their scent.
Well consider that the sense of smell is stronger for human females than it is for males. There's also been research into the fact that when you suddenly feel really attracted to people for reasons you can't adequately explain it could be because you are actually attracted to their scent. As the sense of smell is no longer all that important in regards to survival in humans, the part of the brain that regulates olfactory sensation (limbic system? it's in the frontal lobe at the very least) is also strongly connected to our emotions which is why particular perfumes make you feel all nostalgic for a past lover or even going on holiday when you were young. So an old love-interest used to wear a particular scent and you meet someone wearing the same scent you will be reminded of the emotions you felt for the past lover (as opposed to the actual person) and therefore mistake that feeling for actual attraction or revulsion.
Hmm, I got this kinda recently. A guy I was seeing about 5 years ago used to smell of a mixture of benson and hedges cigarettes and spearmint gum. I still love that scent to this day... And it's going to be hard to forget again, since he's moving in with his sister and I soon, and there's still a huge attraction there.
Attraction is overwhelmingly psychological. I've probably had a hundred or so relationships of various degrees of seriousness over the years and not a single encounter was to do with smell or pheremones.
words
Are you a masochist?
complimentnooooooooooooooooooooooooooooooooo
Hm. I'm interested in the part about women on the pill. I have never experienced a lower sex drive despite being on it. I somehow personally have a harder time believing that men are less attracted to women on the pill; how do they know? I'd like to learn more about that part. Curious.
Well consider that the sense of smell is stronger for human females than it is for males.Really? Could you link me to a study on that? I would hate to have a more sensitive nose than I already have, it is freakish.
Really? That's beyond weird. I should conduct a poll around campus; just walk around and ask guys if they think I'm on the pill or not.
Were you less attracted to those 6 girls you knew were on the pill?
there have been one or two things that I have smelled on dudes that were musky and ...rougher*, I guess?
(except, like, Old Spice)
Whenever I smell it now, my tent-making abilities increase.
It's okay dudes, I don't have asthma.
I don't know why that Iron Man picture was posted
My first girlfriend washed all of her clothes with Downey
I don't know why that Iron Man picture was posted
oh come on this isn't hardMy first girlfriend washed all of her clothes with Downey
QuoteWhenever I smell it now, my tent-making abilities increase.
You should... go camping? :|
Man if those are the colognes chicks are into these days I'm way off, I just wear Joop.
Valrus, please return and demonstrate to the class what an erection is.
I hope you brought enough erection for everyone.
Man if those are the colognes chicks are into these days I'm way off, I just wear Joop.
*shudders* thats pretty much on par with old spice in my book
maybe it is really the perfume he loves and not me :(
maybe it is really the perfume he loves and not me :(He likes that perfume because it reminds him of his other girlfriend.
I'm fairly sure that if you put the perfume on an old, wrinkly man, he would still find you sexier.
Joe Hocking: Making girls cry since*ahem* I'm not that old.18791979.