The Intersection

Science Of Kissing


It’s February once again, just a week away from that very special holiday in which we celebrate the one we love (or bemoan the greeting card industry). Last year, I composed a post called The Science of Kissing provoking all sorts of interesting discussions on and offline. Now that I’m about to participate in the upcoming AAAS symposium of the same title, let’s talk osculation (the scientific term for kissing). Here’s the original entry…

I expect most of us hope to experience the ‘ever-elusive, out-of-the-ballpark-home-run, earth-shattering, perfect kiss,’ but what exactly is it? How does it happen? Wait a sec, this is ScienceBlogs for goodness sake, so let’s dissect this one carefully and get down to exploring the science of kissing…

Why do we kiss? It’s one of the most intimate expressions between two people, inspiring all forms of art from music to painting to literature. It’s arguably shaped history and legend.

And sure, kissing feels completely natural, but is it instinctive? Given up to ten percent of humanity doesn’t even touch lips, should we accept it’s actually a cultural phenomenon? I’m not convinced. You see, kissing undoubtedly allows us to find out all sorts of information about our partner. We’re exchanging pheromones. In fact, when we’re engaged, our bodies release a cocktail of chemicals related to social bonding, stress level, motivation, and sexual stimulation. We become, in effect, ‘under the influence.’ It’s powerful.

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The right kiss boosts feelings of euphoria stimulating pleasure centers in the brain leading me to suspect there’s something to kissing that goes beyond social mores. While it may have evolved from primates feeding their babies mouth-to-mouth (I know, how terribly unromantic!), other scientists suggest it’s crucial to the evolutionary process of mate selection.

Ever notice the way a bad first kiss can stop a relationship cold? It may very well be a subconscious cue that a pair is not well suited to produce offspring.

Still, for anyone who’s experienced the right chemistry… well… you know. That special and rare kind of kiss makes you weak in the knees and sends your heart racing. And once in a while, if you’re very lucky, there’s that magical kiss that makes the rest of the world fade away…

So as the science goes, I don’t think we’ll ever quite figure out the rationale behind the perfect kiss. And thing is, we don’t need to. Call me a romantic, but I have to admit I like that when you experience one such ephemeral moment, the feeling defies explanation.


  1. #1 Ashutosh
    February 6, 2009

    How about kissing being a good evolutionary trick for swapping diverse germs and conferring better immunity? Any thoughts on that?

  2. #2 J-Dog
    February 6, 2009

    As an undergrad, I did a lot of research in this area, mostly Friday and Saturday nights. Although my target sample was large, the pool was small, although I found it expanded enormously when random doses of stimuli such as alchohal were applied liberally.

    Unfortunately my current wife will not allow any further outlier testing in this area, even though I have tried to explain about proper sampling size. However, if there is grant money available for further research, please let me know.

  3. #3 Cannonball Jones
    February 6, 2009

    Kissing doesn’t exist, it’s just a liberal conspiracy. At least that’s what I think cause I haven’t had a kiss for a long, long time. *sob*

  4. #4 Guitar Eddier
    February 6, 2009


    Do you have occasion to play tonsil hockey very often? 🙂


  5. #5 Lilian Nattel
    February 6, 2009

    What about holding hands? Lots of germs get on hands. There’s a way to check out immunity. Is romantic kissing cross-cultural?

  6. #6 eddie
    February 6, 2009

    Slightly on topic, but the latest XKCD is very romantic in its own way.

  7. #7 Sheril R. Kirshenbaum
    February 6, 2009

    Ashutosh and Lilian are onto something with germs. Kissing means swapping all sorts of bacteria and mucous that can have both positive and negative effects.

  8. #8 Mike Treder
    February 7, 2009

    …when you experience one such ephemeral moment, the feeling defies explanation.

    Come on, Sheril, you’re a scientist, and you know that’s not true. Sure, it’s a nice feeling to think that nothing could explain the magic of the moment, but even feelings have natural explanations.

    I’m not trying to throw a wet towel on your romanticism – heck, I cry regularly during Frank Capra movies – but a blog about science should not even hint that seeking real answers is ever the wrong thing to do.

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