You probably think you know how attraction works: You gaze upon a fine specimen of a woman; you breathe her in; your heart, loins or both flutter; and … swoon. But the truth is, attraction is far more complicated than that, and far more complex than even experts understand.
Many people think pheromones are the hidden force behind attraction. By inhaling someone’s pit-stained essence, the theory goes, our bodies make a gut decision for us—whether we should have sex in order to create the healthiest spawn. One whiff and you become irresistible. It’s an incredible shortcut to love and marriage that digital dating can’t touch.
And so people throw pheromone parties to introduce what could be genetically compatible singles. Other people sell pheromone products for profit. They’d like to you think someone’s smelly essence is like a menu selection for your future offspring’s health, and even better, it’ll give you an intoxicating, druggy high. Ahh, science!
There’s just one little problem. There’s no solid evidence that pheromones work, or even exist, in humans.
Pheromones are real—they’re like chemical tweets that tell other members of the species how attractive you are, or if there’s danger. We know they work in animals and insects, because we’ve actually identified them. The male silkworm moth will track a lady moth’s scent trail for 30 miles to hook up—based on a mere few molecules of pheromones. Queen bees tell the whole worker colony when the enemy is approaching via pheromones (they’re said to smell like bananas). Male mice spritz their pheromone-laced urine around their bachelor pads like bread crumbs, so when female mice catch a whiff of it, they remember it and know where to return later to fuck that mouse.
But is all that jazz happening in humans? Unclear.
Some research, at least, suggests the following: that ovulating women ramp up testosterone in nearby men; that male sweat keeps a woman’s menstrual cycle regular; that women’s menstrual cycles sync up if they live together. (The latter does not seem to hold up to scientific scrutiny, however.)
Not all smells we release are pheromones, but all pheromones are smells. Our general smell is a highly personalized, unique signature called an “odortype” or “odor print” that sends messages about our genetics, diet, lifestyle and environment via our urine, sweat and the air.
The question is, are those pheromones? Are there at least a few in there? Can we really smell them? Are they making us act different sexually or socially as a result?
The Mysteries of Love Are Still Exactly That
As neuroscientist Charles Wysocki told Scientific American in 2012, there’s “no good literature in the biomedical field to support that sexual-attractant pheromones exist.”
If we’re talking about the places our human bodies already produce smells, like our armpits, then we know, he said, that there’s “some action” there along these lines. And while there are a whole host of things that seem pheromone-y in our behavior, we haven’t actually locked down the chemical culprit behind them.
As Scientific American notes:
Other results over the years have hinted at pheromones altering adults’ moods. Odors given off by the breasts of breast-feeding women, for example, can render childless females downright randy — although a particular chemical messenger remains unidentified. … Yet more studies with sweat have explored the strongest isolated candidate so far for a human pheromone, known as androstadienone, which derives from the male hormone testosterone. The presence of this compound has been reported to make women feel more relaxed. Wysocki and his colleagues are currently seeking National Institutes of Health grants to find out just what the “magic bullet — or bullets — are in male body odor” that elicit female responses, he says. They also hope to study whether female odors can similarly influence male mood and hormonal activity.
Of the four potential human pheromones identified, it’s unclear if what they seem to do even classifies them as actual pheromones or if they’re just other smells we don’t totally grasp yet.
What’s more, the animals in which we’ve identified working, honest-to-God pheromones all have a specific organ in the nasal cavity called a VNO, or vomeronasal organ, that allows them to pick up pheromones in the first place. Humans have one too, only it doesn’t do anything—because it’s not connected to our brains.
Animals Are Sniffing Out an Immune System
So what does this have to do with hooking up? Well, when animals sniff potential mates and ignore certain ones, it’s because they are detecting whether the immune system is a good genetic match for breeding.
There’s some evidence people do this. A Swiss researcher in 1995 named Claus Wedekind found that women preferred the odors of men who happened to be genetically compatible to them. Genetic compatibility in this sense means two people have a genetically different major histocompatibility complex (MHC), or immune system, than ours. Breed with someone with too similar an MHC and you end up with problems like miscarriages and birth defects.
But the key word here is “odors” and not “pheromones” for a reason. “I don’t use the word pheromone,” Wedekind told me by phone. “That’s because we have no evidence of them. All the evidence we have at the moment points to this direction that we can consciously describe these odors.”
And as for what the odors are: “I don’t know the physiology,” he said. “That’s not worked out. There are groups working on that for 20 or 30 years. It’s really complicated. My best guess is that the MHC profile in the skin interacts with the microbial community and sweat glands.”
To test this, Wedekind asked male participants to wear cotton T-shirts for a few nights to collect their body odor. Women then smelled those T-shirts and ranked them for pleasantness, sexiness and intensity. The result: Women preferred the smell of the men whose immune system was most different from theirs.
But there was a catch: Those women weren’t on oral contraceptives.
What Does Birth Control Have to Do With It?
“The Pill effect really surprised me,” Wedekind told the New York Times. He also realized that there was no objectively better type of immune system that was more appealing for these women. It was just the ones that were different from their own.
That was 1995, but in 2008, a study found a similar result: Women on the Pill are no longer attracted to what they’d normally prefer in a mate, at least according to existing research. Generally speaking, those would be men who signal good health and fertility with their broad shoulders, clear skin, clearly defined masculine features and — maybe — a smell that indicates a good immune system match.
The theory is that when trying to get pregnant, a woman would be drawn toward the aforementioned so-called banger of a dude who could give them the best baby. But when they’re not fertile, they prefer a more feminized man, as in, one who could better help take care of a baby. Put more crassly, they want an alpha to fuck and a beta to parent with.
But is that still true? Likely not.
A new study this year, the largest of its kind, found that hormonal birth control has no effect on women’s preferences for men’s faces. “The idea that hormones influence how much women like masculine men used to be pretty well established,” Ben Jones, the lead author on the study, told MEL by email. “This new work, along with the work by a few other labs, suggests that those early results might be misleading, potentially because they tested only small groups of women. In our new bigger studies, we really don’t see much evidence for it.”
So What the Hell Is Going On?
“It could be that women have a stereotype that masculine guys are really not looking for commitment and are open to casual relationships, whereas more feminine guys are perceived as more trustworthy and interested in longer term relationships,” he said.
As for the question of whether hormonal birth control can block anything in this process, Jones says studies have not been able to replicate the earlier studies either.
“Recent, much larger studies did not find these effects,” he writes. “There have been smaller studies that suggest pill use alters preferences for odors associated with MHC profile, but these haven’t yet been the focus of the type of large scale replication effects described above. It would be really interesting to see if they replicate in larger studies.”
That doesn’t mean we don’t smell people, and respond to the way people smell. Getting off on your lover’s body odor is a universally understood phenomenon. It’s just that we don’t really understand how or why. So for now, you should still trust your nose, but you should definitely save your money.