It’s Saturday night, and the bar is packed. A beautiful brunette is sitting at the bar, sipping a vodka soda and chatting with a friend. Then, out of the corner of her eye, she catches the glimpse of a man. Their eyes lock.

And they lived happily ever after. But is it really that easy?

Legend of Love — Why It Matters

Photo by Marissa Angell

Don’t get too sloppy on that first date — researchers who study human attraction say people form opinions quickly when it comes to romance. In fact, some researchers think it takes just three minutes to decide whether someone’s a potential mate (and that’s before the drinks come out). And findings about friends who click immediately might also apply to romantic partnerships. In one study on friendships, people who enjoyed the first few minutes together were likely to develop a close relationship after nine weeks.

But instant attraction isn’t just in our heads: There may be a biological basis to love at first sightThe Genetic Basis for Male × Female Interactions Underlying Variation in Reproductive Phenotypes of Drosophila. Chow, C.Y., Wolfner, M.F., Clark, A.G. Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York. Genetics, 2010 December; 186(4): 1355–1365.. Studies have found animals are more likely to mate with partners they’re genetically compatible withStrain-Dependent Differences in Several Reproductive Traits Are Not Accompanied by Early Postmating Transcriptome Changes in Female Drosophila melanogaster.McGraw, L.A., Gibson, G., Clark, A.G., et al. Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York. Genetics, 2009 April; 181(4): 1273–1280.. It’s unclear whether this research applies to humans, but some scientists think we might be pre-programmed to spot “the one.” Romantic attraction could serve an evolutionary function — we seek out specific people that will be suitable mates, and give everyone else the bootRomantic love: a mammalian brain system for mate choice. Fisher, H. Aron, A., Brown, L. Department of Anthropology, Rutgers University, 131 George Street, New Brunswick, NJ. Transactions of the Royal Society B: Biological Sciences, 2006 December 29; 361(1476): 2173–2186. But meeting that special someone’s gaze and falling in love may be a bit more complicated.

Instalove? — The Answer/Debate

Although about half the American population believes in love at first sight, not everyone falls head over heels right away. Perhaps surprisingly, women aren’t always the romantics in this love equation: One study found men experience love at first sight more often than women. Researchers think that’s because men respond to physical cues more readily than women, and women tend to develop trust more gradually than men. And people might be more inclined to believe in love at first sight when they’re younger. Folks over 50 are six percent less likely than people under 50 to think people can fall in love immediately (possibly because they’ve had more romantic relationships with different partners).

But it’s unclear how often love at first sight turns into a successful partnership. One survey in Israel found only about 10 percent of people say their long-term relationships began that way. While people can be instantly attracted to each other, some scientists say being in love means really getting to know someone over time.

So don’t throw in the towel if that first date didn’t go so hot. Psychologists believe more interactions with someone can make them look more attractive and intelligent. (Wanna’ hang out tomorrow, and the next day, and the next…?) It may be worth giving love at second or third sight a chance, too.

The Takeaway

Sometimes one look is all it takes to fall in love. But some experts think real affection develops gradually over time.