Romantic chemistry is all about warm, gooey feelings that gush from the deepest depths of the heart…right? Not quite. Actually, the real boss behind attraction is your brain, which runs through a very quick, very complex series of calculations when assessing a potential partner. Check out these 11 GIFs from Dawn Maslar’s TED-Ed Lesson ‘The science of attraction‘ to get your attractors warmed up in time for Valentine’s Day. 

We know. The idea of so much of our attraction being influenced by chemicals and evolutionary biology can seem cold and scientific rather than romantic. But the next time you see someone you like, try to appreciate how your entire body is playing matchmaker to decide if that beautiful stranger is right for you.

After all, just because the calculations are happening in your brain doesn’t mean those warm, fuzzy feelings are all in your head. In fact, all five of your senses play a role, each able to vote for (or veto) a budding attraction.

The eyes are the first components in attraction. Many visual beauty standards vary between cultures and eras, but signs of youth, fertility and good health, such as long lustrous hair, or smooth, scar-free skin are almost always in demand because they’re associated with reproductive fitness.

The nose’s contribution to romance is more than noticing perfume or cologne. It’s able to pick up on natural chemical signals known as pheromones. These not only convey important physical or genetic information about their source but are able to activate a physiological or behavioral response in the recipient.

Our ears also determine attraction. Studies have shown that heterosexual men prefer females with high-pitched, breathy voices and wide formant spacing, correlated with smaller body size, while heterosexual women prefer low-pitched voices with a narrow formant spacing that suggest a larger body size.

And not surprisingly, touch turns out to be crucial for romance. In one experiment, not realizing the study had begun, participants were asked to briefly hold a coffee, either hot or iced. Later, the participants read a story about a hypothetical person and were asked to rate their personality. Those who had held the hot cup of coffee perceived the person in the story as happier, more social, more generous, and better-natured than those who had held the cup of iced coffee, who rated the person as cold, stoic and unaffectionate.

If a potential mate has managed to pass all these tests, there’s still one more: the infamous first kiss, a rich and complex exchange of tactile and chemical cues, such as the smell of one’s breath and the taste of their mouth. This magic moment is so critical that a majority of men and women have reported losing their attraction to someone after a bad first kiss.