When you see or hear the word heart, two distinctly different visions come to mind. Funnily enough, the first picture probably isn’t of the throbbing mass of muscle and tubes that keeps each and every one of us alive, but of the ever present valentine-style version, an international symbol for love, which bears little resemblance at best to our beating organ. (Not a bad thing, in our opinion. An anatomically correct heart-shaped box of chocolates might be less than appetizing.)

 

As different as these two may look, their meanings are intertwined. Dating back to the most primitive times in history, the heart was thought to be the center of all human activity and emotions. Even once we became a little more biologically savvy and gave the brain some credit, the idea of the heart as the motherboard of human feelings remains.

And it’s more than just an idea. We’ve all felt it: the racing that can mean anything from fear to excitement. Our physiology and biology really can reveal our emotions, especially when it comes to attraction and love.

In the case of attraction, your higher heart rate is caused by the same thing as it would be in a fight-or-flight response: an adrenaline rush. This chemical response is also responsible for feelings of anxiety or nerves when you see that special person.

YOUR LOVE IS MY DRUG

Some scientists claim that love is not a feeling, it’s an addiction. This is because the body in love is remarkably similar to the body on drugs. And not just a little buzz; we’re talking someone who has just smoked crack-cocaine and is feeling great about it (psychologytoday.com). Laugh at this comparison if you must (we did), but it is very serious. The chemicals bouncing around are the same in both love and coke highs: dopamine, which is released when we feel good, and norepinephrine, which causes our bodies to produce adrenaline. Your blood pressure and heart rate shoot skyward. You can’t sleep and have no appetite. You feel confident. Could be love, could be crack. (For your sake, we hope the former).

Also like someone who likes getting high, a person in love craves these feelings again almost immediately after they fade, and is rendered practically powerless to their desires. This should be sounding familiar. Those early stages of love when the “falling in” metaphor becomes crystal clear. You could no more easily stop yourself than gravity.

 

I PUT A SMELL ON YOU

So, other than behaving like someone who isn’t fit to operate heavy machinery, what else is going on when you’re beginning to feel all the feels? Unromantic as it may be, a lot of love is chemical and below our level of consciousness. Although we often hear about love at first sight, we might want to start replacing that last part with smell. We’re talking pheromones, the chemical-blends that are produced by almost every living thing to prompt a reaction in other members of their species. Many times these reactions relate to sex or attraction, and until recently it was not widely accepted that this played a big role in human relationships.

To be fair, there is little concrete science to go on. No human pheromones have been definitively identified, and there are still a lot of holes in what we do know. However, we do know that pheromones are probably detected by the Vomeronasal organ in the nose, which sends these signals to the more primitive areas of the brain that control hormone release, as opposed to the cerebral cortex, where most ordinary, conscious smells are processed.

Data from recent studies cannot be ignored. The most notable is one that showed that we can infer gender from chemosensory—or pheromonal— cues (Current Biology, 2014). Other experiments indicate that women are more attractive to men when they are most fertile, which likely has to do with pheromones emitted just before ovulation. The votes aren’t in just yet, but for now it seems like, if you’re looking for love, it’s a safe bet to follow your nose.

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BODY TALK

When we’re not sniffing around for good partners, we’re chatting them up. The catch is, most of the chat is happening sub-textually. More than half of communication is conveyed with body language, and love is no exception to this rule. You probably know how to tell if someone likes you—flushed face, leaning in, eye contact, feet pointing at you—but body language can say more than just that.

There are actually physical signs that a person is fertile. The way a woman walks—specifically the sway of her hips—indicates fertility and thus directly translates to increased attractiveness, according to a 2012 German study conducted by scientists at the University of Gottingen. The way men walk is indicative as well; squared shoulders and a wide stance are the cues you should look for.

Another, simpler body conversation is one of openness. It is easy to tell if someone is open to you: are their arms crossed or uncrossed? Their legs? Have they placed something, like a purse or briefcase, between you, or conversely moved something out of the way? Are they gazing upward toward your face or downward at the floor, their shoes—or worse—their phone? These seem basic, but can actually communicate to you the way this person feels before he or she has even consciously recognized it.