Just What The Heck is Chemistry? (Hint: It’s Not What You Think)

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Kayt Sukel is the author of “Dirty Minds: How the Brain Influences Love, Sex and Relationships” – a new book that examines all the ways our neurons can wreak havoc with our hearts. She’s here to break down the science of love.

One of my girlfriends was recently lamenting her dating adventures over a glass of wine. “It’s not that the guys I’m going out with aren’t great guys. They are, for the most part, smart, funny and good looking. Exactly what I’m supposed to be looking for,” she told me. “But despite that, I haven’t felt an ounce of chemistry for any one of them. It’s frustrating.”

It appears to be a common feeling. Chemistry ranks high on the list of must-haves for a romantic partner. But it’s just so hard to explain what we mean. When pressed, most reach for love-related synonyms: You know, that click. That connection. That sizzle. That spark. And that elusive (and so aptly named) je ne sais quoi. But most won’t even bother trying to tell you what it is—they’ll simply focus on the notion that you either have it with someone or you don’t.

Recent research into the neurobiology of love and attraction, however, has started to unravel a bit of this old-age mystery. Chemistry is, in fact, real. And it plays an important role in forging an attachment with another human being. Instead of flowing from your heart or your head like you might think, the chemistry that subconsciously affects your sense of attraction is actually a complex product released from your armpits.

Like a fingerprint

You already know that you have certain features that are completely unique to your person, like your fingerprints or your iris pattern. But you have something else that makes you one-of-a-kind: your odor print. No one else out there in the world smells exactly like you do. Our brains are fine-tuned to pick up these small chemical messages when we interact with others. We’re just not that aware of it.

Smell is a very important sense. In other species, that’s very clear: Dogs smell each other’s butts as a matter of greeting. Male cats spray urine to help mark their territory. Male rats can tell if a female rat is up for a quickie just by sniffing her urine. But while we may not be able to catch a whiff of a companion and consciously know everything about them, they are giving off a lot of information.

“People have considered humans to be a microsomatic animal. That is, that we’re very small-nosed and don’t use our noses the way other animals do and so smells aren’t important,” says Charles Wysocki, a neurobiologist from the Monell Chemical Senses Center. “But we’re learning that smells do play a role in helping us choose a mate.”

Odor prints are made up of thousands of chemical messengers—proteins created by the same genes that make up our immune systems, something called the major histocompatibility complex (MHC). These messengers are released through our skin as we go about our business, with the highest concentrations coming from our armpits and groin. Regions in our brains implicated in sex, attachment and risk/reward processing are all activated when we smell another person — we’re just oblivious to the fact. But deep down, we pick up a lot of information and it’s all meant to help us choose a mate that will produce the best offspring.

“There are hundreds of different compounds that make up your unique odor print encoded by those MHC genes,” says Wysocki. “They help us seek out partners who have a MHC complex that is optimally different, not maximally different, than our own. And we’ve seen this in studies where people rate the attractiveness of smells. The most attractive body odors are the ones from potential mates who have MHC complexes that aren’t too close to your own, but not too different either.”

Not a pheromone

Scientists are still hard at work to understand just what compounds in our odor-print help foster an attraction. But Wysocki is quick to point out that MHC complex smells are not pheromones. While researchers have characterized the role of pheromones as sexual attractants in insects, rats and pigs, there has not been a single pheromone identified, to date, in humans.

“Pheromones, anecdotally, make for a good story. But there has been no evidence to suggest that there are certain chemicals that fuel the chemistry of desire or attraction,” he says. “That’s not to say that they don’t exist, or are likely or unlikely to exist, but we don’t see the same kind of data you see in animals when we do experiments on humans. Plus, the idea that pheromones are only a sex attractant are wrong. They do much, much more than that in animals and they work in concert with other variables, even in that context.”

The case for going natural

While there are tons of colognes and other spray products already touted on the Internet as “instant chemistry,” Wysocki suggests saving your money and simply paying the right attention to your own personal hygiene so you don’t unwittingly cover up your odor print and derail “chemistry.”

“Given the work that is out there, fragrance manufacturers are finally coming around to the idea of designing fragrances that allow our personal body odor to do what it is meant to do. That is, not cover up our odor print in a social atmosphere but enhance the components in human body odor that are pleasant to us,” he says. “But until those products become available, I’d recommend using deodorant and personal care products sparingly.”

The take-home message

So what is the take-home message from all this? Chemistry is elusive—and despite these fascinating studies, MHC complex can only explain so much of why one person speaks to your soul while another leaves you cold. And, unfortunately, the current research can’t offer much in the way of telling you how to improve or control chemistry. Until more studies are conducted, that old je ne sais quoi will reign.

As a single woman, I’m happy to take Wysocki’s advice and minimize my fragrance usage. But, for me, the real take-home is that my gut is worth listening to. It may very well know something about a date that my conscious doesn’t.