The Science of Kissing


“Kissing really matters in relationships,” said Sheril Kirshenbaum, author of the book, The Science of Kissing, published in January 2011. “It’s a way to connect with someone and get your feelings across when words simply just won’t do. It’s the body’s way of how conveying we feel.”

She told us that a kiss, and especially a first kiss, plays a big role in determining the future of a relationship, according to scientific studies. She said:

Fifty-nine percent of men and 66 percent of women say they have ended a budding relationship because a kiss didn’t go well. It’s your body’s way of saying, look elsewhere.

Kirshenbaum said kissing is sort of like Nature’s litmus test — whether it’s consciously or subconsciously, humans use the information encoded in a kiss to decide where a relationship is headed, whether to pursue a relationship, or end it. She said:

When we kiss, we engage all of our senses. We’re learning so much about a person, not just visually, but we’re engaging our noses, our taste buds, the sense of touch. And through that information, all sorts of signals are being sent to our brain, telling us about the other person.

Plus, kissing activates neurotransmitters and hormones — for example, the neurotransmitter dopamine, which gives us feeling of pleasure, and oxytocin, which fosters feelings of attachment.

Humans kiss for a variety of reasons, Kirshenbaum said.


There’s the biological reasons, the reasons that it’s good for us — things like assessing a partner, figuring out how compatible they might be, getting a sense of who they are and if you might have a future together. We also kiss for a lot of reasons that go back in terms of why humans started kissing. That can have everything to do with nursing behaviors, and pre-chewing food, called pre-mastication.

She said that humans aren’t the only species to engage in kissing. You can find kissing-like behaviors across the animal kingdom.

It might be brushing noses, nuzzling up to one another, licking like dogs do, turtles tap heads, giraffes entwine their necks. Probably serve a similar purpose as some of our own behaviors, and they’re probably due some kind of affection, sometimes conflict, feeding, or social grooming.

In animals, Kirshenbaum said, these displays of affection are an adaptive advantage, meaning that “kissing” provides some benefit to the species’ survival. But how does kissing benefit humans? Kirshenbaum said one example is that women may be able to sniff out a man who will provide future offspring with genetic benefits.

Scientists have actually found that women tend to prefer to the scents of men who have a distinct genetic code for immunity. And that’s something we pick up when we are in very close proximity, doing something like engaging in a kiss. And so in turn, people who have diverse genes for immunity, down the line would have children that may potentially be stronger and healthier.

Written by

[Image by Boltron]


About the author

EarthSky – a clear voice for science for broadcast and the Internet – advocates science as a vital tool for the 21st century. Our award-winning science content – in audio and video formats, in English and Spanish – is seen or heard 15 million times every day on multiple platforms via both traditional and new media outlets including National Public Radio (NPR) in the United States, independent commercial broadcast outlets in the U.S. and around the world, XM/Sirius satellite radio, WRN (formerly World Radio Network) out of London, International Community Radio Taipei (ICRT), iTunes, Facebook, Twitter, YouTube, Google Earth and dozens of online podcast aggregators. We have been a world leader in bringing the voices of scientists directly to you and millions of others across the globe since 1991. EarthSky brings scientists’ words and insights to a large audience thanks to the support and partnership of thousands of scientists and scientific institutions