Her emerald green eyes stare into yours as you slip your arm around her waist and pull her in. Your lips approach as if drawn in by an invisible force.

As your faces draw close, your heads tilt to the right so your noses and foreheads don’t clunk together, even while your eyes are closing at the same time.

At that moment, your lips touch for the first time, and an electric feeling courses through your whole body. Whatever that feeling is, you know you crave more of it, you need more of it. In that moment, the last thought on your mind is “why am I sucking another person’s face?”

Why do people kiss?

Obviously we do it because it feels great, but unlike intercourse, there’s no obvious evolutionary benefit - unless we dig a bit deeper.

Fortunately, there is an actual field of scientific study devoted to the evolutionary origins and anatomical effects of kissing. The study of kissing is known as philematology, and these devout researchers of the kiss certainly have some interesting theories. They’ve also figured out exactly what happens in our bodies when we embrace in a passionate saliva-swap (as my 5 year old nephew would say, “yuck!").

Where Does Kissing Come From?

One of the most obvious questions that arises when we look at kissing with an academic eye is whether kissing is a learned behavior or whether its instinctual. Is this something we do because we see other people do it, or would you still feel the urge to lock lips if you were say, raised by wolves?

One argument for the kissing as a socially learned behavior is the fact that there are tribes around the world that don’t make out. Although anthropologists estimate that 90% of humans kiss, how do we account for the 10% that don’t?

Another camp argues that kissing is instinctual, and that not kissing is the learned behavior. This group points to the fact that animals engage in kissing-like behaviors as well. For example, you may have seen your dogs or cats rubbing noses affectionately.

There are even animals that like to lock lips and swap spit, the Bonobo ape for example is notorious for making out - all the time. In fact, their kissing behavior looks a lot like ours - they kiss to make up after a fight, they kiss before sex, and they kiss for no apparent reason.

Today, most scientists who study kissing agree that we have a strong biological instinct to kiss. When we kiss, our brain’s natural rewards system kicks up a storm, making kissing and getting kissed feel amazing.

Kissing a mate might be a sign of affection, but kissing could also be a way to help us identify a quality mate. When you kiss someone, your bodies might exchange subtle information about whether you’re compatible biologically. A strong biological match could mean more fit offspring.

While we have no way of knowing exactly why kissing evolved with 100% certainty, we know the act of kissing is intimately tied to the act of finding a mate - an act fundamental to passing on one’s genes.

No matter what the evolutionary explanation, there’s one thing we can all agree on whether you care why we kiss - kissing feels great. Our lips, tongues, and skin are filled with sensitive nerve endings, and the close touch and smell of someone we’re attracted to triggers endorphins and other “feel-good” hormones.

All of this means dizzying sensations of passion and arousal when we press our lips to someone we find attractive. And in the thrill of a passionate embrace, that’s all we really need to know.