Your Brain on Hot People

During my five years of kickboxing training at a now-defunct martial-arts-Crossfit-type gym in East Austin, Texas, I developed an unusual pre-workout ritual. As I commuted the 50 minutes through ever-thickening traffic from my office to the gym, I'd painstakingly apply a full face of makeup, taking every red light as an opportunity for another stroke of my mascara wand or dab of cheek paint.

The reason I was hastening to get dolled up only to sweat it off in a kickboxing gym? His name was Toby, and he was my kickboxing coach. A former professional MMA fighter of Japanese-Mexican descent, Toby was arrestingly gorgeous: rippling muscles, sleeves of tribal tattoos and a bad-boy sneer. He reminded me of the sexy commanding officer in Disney's 1998 animated version of "Mulan": just as hot, just as good at martial arts and just as intimidating.

I was as enchanted as I was terrified by him. Kickboxing training was tough enough, but having my hunky coach there, threatening constantly to pop out of the shadows to critique my form or tell me my sports bra was inside out, took classes to a whole new level of stress.

What goes on in your brain when you see someone hot

Reflecting back years later, my reaction to my smoking-hot teacher continues to baffle me. I wasn't in love with Toby—in fact, I was kind of terrified of him—but something about him turned me into a bumbling, giggly, furiously blushing klutz around him just the same.

Curious to know exactly what rendered me so useless in the presence of my strapping coach, I spoke to Helen Fisher, Ph.D., a biological anthropologist, senior research fellow at The Kinsey Institute and chief science advisor for Match.com.

Fisher, who uses MRI and other brain-scanning technologies to study desire and love, explained that when you encounter a potential mate, "the right ventral tegmental area (VTA) [of your brain] becomes active and pumps out dopamine."

Dopamine is a neurotransmitter that gives you focus, energy, motivation and elation. Higher levels of dopamine—particularly in the VTA—have been linked to all kinds of addictions. In fact, Fisher often likens it to the same area of the brain that becomes active when you feel a rush from cocaine.

Fisher said when the VTA is active, you may feel an eruption of positive emotions—like motivation, energy, curiosity and elation.

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All of this rang true for my kickboxing classes with Toby, when I often felt giddy, adrenalized and eager to impress. But what about the not-so-positive, kind-of-debilitating feelings of a racing heartbeat, clammy palms and general anxiety that sometimes came up?

Here, again, brain chemicals could be to blame. In addition to revving up dopamine, seeing someone you find attractive can trigger the release of adrenaline and norepinephrine. While dopamine generates feelings of elation, adrenaline and norepinephrine are behind your racing heart, restlessness and overall anxiety.

In addition, contact with an attractive person can increase your levels of cortisol, your body's stress hormone. It's cortisol often behind the feeling of lovesickness, contracting the blood vessels in your stomach and making you feel uneasy or even literally queasy.

All of this is only likely to happen, Fisher noted, if you are looking for love.

"If you're happily married to somebody and you walk down the street or go to a meeting and start talking to an attractive man, you can just notice they're attractive—without being nervous, excited or anxious to say the right thing—just like you notice that the sky is blue or that it's a nice day."

How your brain decides who's hot

Furthermore, what does and doesn't trigger the potent outburst of hormones and brain chemicals may be different for different people. While allowing that, generally, humans are attracted to a symmetrical face and body, Fisher said a host of factors—from our socioeconomic background to our upbringing to our level of education—influence who and what activates our brain's reward and stress systems.

"We all evolved and developed a love map, or a host of traits that we find attractive. I might find one kind of man attractive and you might find a very [different] kind of man attractive," she said. "I don't know about you, but I don't find a man attractive if he's got a lot of tattoos." (Thinking of Toby's tribal tattooed pecs, I wonder how she guessed.)

She went on to list other factors, such as our subconscious tendency to like people who are similar to us—similar height, physical form and ethnic backgrounds.

Gender, too, can influence the type of person our brain identifies as attractive.

"Women tend to be attracted to men with those facial cues of high testosterone," she said. "You will see, if you look carefully at our male movie stars, that they tend to have a heavy brow above the eye, high cheekbones and a very square jaw—all of that is built by testosterone."

'We all evolved and developed a love map, or a host of traits that we find attractive.'

Why do chicks dig dudes with high levels of testosterone?

"Being able to tolerate high levels of testosterone indicates a strong immune system," said Fisher. "Also, [men with high testosterone levels] may be more assertive at work, so they tend to get better jobs and make more money."

Evolutionarily, this is important, she explained, "because for millions of years, women needed a partner to help them raise their babies."

On the other hand, "Men tend to be attracted to women with a much softer face, puffier lips, bigger eyes, clear skin—these are signs of high estrogen," Fisher said, adding that "clear skin is a sign that a woman has been able to fight off various diseases."

"The bottom line is that VTA will be activated by different kinds of things," Fisher said—height, strong jawline, sleeve tattoos, a resemblance to your animated crush from a '90s Disney movie. "But when it's activated, it triggers a similar pattern."

Namely, it releases a mighty gush of chemicals that generate energy, focus, motivation, ecstasy, despair and craving. It's a pattern that can impel the lover to believe, say and do inappropriate, silly and dangerous things, Fisher conceded—like frantically applying mascara while speeding down the highway to get to kickboxing class.