Kiss and Tell

By Phil Plait | June 8, 2009 10:00 am

Why do we kiss?

It’s a weird ritual. As a scientist I don’t know much about it (as a human, of course, I am an Olympic medalist) — why we do it, what neurological events it triggers, how it may have developed as a behavioral pattern. Why would mashing your lips against someone else’s be of any use? Or brushing their cheek with your lips? And licking? Really?

Very strange.

Kiss

And there are so many kinds! We kiss someone hello, we kiss them goodbye, we kiss when we show friendship, or when we’re proud of someone, or when we are in love, or when we want to instigate sex. Who can make sense of all this?

My fellow Hive Overmind blogger Sheril Kirshenbaum is trying to. She’s writing a book called The Science of Kissing, and she’s running an experiment at her blog, The Intersection; she’s asking readers to look at 15 photos of people kissing, and to categorize them into the type of kiss: friendly, erotic, or relationship. To avoid bias, comments are turned off and she’s asking folks to email her with their answers. Results will be published in her book!

So head over there, look at pictures of people necking, and send in your thoughts.

I’m looking forward to seeing how this turns out. Looking over the pictures, I discovered a couple of things about categorizing kissing I hadn’t thought of before. While I’m not an expert at kissing (the Olympics medal was a fluke due to the East German judge) I’ve been doing it a while, so I was surprised to see some trends in the pictures I hadn’t considered before. What do you see?

CATEGORIZED UNDER: Cool stuff, Science

Comments (44)

  1. Wow, the possibilities for interpretation. Even something as simple as cultural norms will have a lot of play! I’ll surely have to participate for fun.

  2. mus

    Interesting! I like it how many same-sex kisses there are. I find that interesting too.

    Without getting specific, I thought most of them were pretty obvious. However, I thought two or three of them belonged in more than one category

  3. Jay

    The way she’s collecting the data is extremely error prone. Too bad she wasn’t able to setup an online poll or some such to collect the data.

  4. Doc

    I’m very impressed with her selection of images. There are several that have elements carefully chosen to test for bias due to setting, clothing, age, etc. I look forward to seeing the results.

  5. Mike

    Phil, you forgot the kiss of death!

  6. What I am surprised by, is that she doesn’t collect info on culture, gender etc. of the respondents to her test. I am quite sure there are large cultural differences in kissing behaviour and the perception of a kiss, a.o. In fact, kissing is not cross-cultural behaviour: there are cultures on this planet who do not kiss (or at least not in the way Europeans and Americans do, i.e. with the lips).

  7. Some of them are not that obvious, specially because the definitions of each type of kiss is far from detailed and the context is missing. I guess that is the point, to leave it up to our culture and personal interpretation.

  8. “While I’m not an expert at kissing (the Olympics medal was a fluke due to the East German judge) ”

    You bribed an East German judge with a kiss? Shame on you!

  9. In addition, kiss *patterning* also plays a role. Here in Holland, a guy giving a girl (or vice versa) three kisses on the cheeks would indicate friendliness (not necessarily friendship – even relative strangers can sometimes do this in a social context).

    Doing it only once instead of three times, would however indicate something more serious, more towards affection, love. You wouldn’t gather such things from a photo!

    Doing it more than 3 times just means you are drunk…. ;-)

  10. TEQUILA

    There should have been a poll there, with users being asked to provide some cultural context to their responses. We’d be eager to participate again with a lot more pictures.

    Meanwhile, when I saw the picture above, Phil, I assumed one of them was you at a younger age, experimenting… “not that there’s anything wrong with it”.

  11. I listed them all as erotic!

  12. I would have liked to see a fourth category for familial kisses – a mother kissing a son, an uncle kissing a niece. There were photos among the ones she displayed that I felt could have fit into such a category.

  13. Ted Powell

    “The way she’s collecting the data is extremely error prone. Too bad she wasn’t able to setup an online poll or some such to collect the data.”
    Clearly Jay is not familiar with Pharyngula!
    http://scienceblogs.com/pharyngula/2009/06/a_more_challenging_poll.php

  14. Unfortunately, if there were research (in lab) on kissing, I’d probably be in the ‘control group’

    :(

    J/P=?

  15. I think the results will be somewhat biased by the context presented in the photos. The presence or absence of clothing, the type of clothing, the location evident in the photos, the attitude of the subjects (by which I mean were they standing up or lying down), their facial exprressions; all these things will contribute to the nature of the responses. I suspect that, with most of those pictures, you could black out the area around the mouths of the subjects, so the actual kiss was not visible, and still get exactly the same set of responses. So, what is she actually testing?

  16. Albert Bakker

    I really, truly hate it. This is really something of a problem in my very few and also extremely limited social interactions when I turn my head away from overly enthusiastic people who don’t yet know me. Because as it turns out women especially are really sensitive to your facial expressions while doing this and as it appears I do not have much control over my face. It just basically expresses things randomly without my knowing.

    And while being honest, I am extremely biased against age too, really. But even more against two men exchanging saliva. I am sorry if it is not politically correct, but I just can’t help finding it a disgusting sight, no matter what age. At least that was what I thought until I saw exhibit H and then I started thinking differently.

    I will never and frankly don’t want to get used to it and I’ll look away when I suspect sudden impact to occur in my line of sight. Nevertheless I think I am reasonably able to discern the motivation behind this weird human behavior when it occurs and that’s why I decided to toil some burdensome hours in the name of science.

  17. JD

    My instincts leads me to think of kissing as a means of social bonding. Other primate species (especially Pan paniscus) also use kissing in social situations, as well as other social mammals such as dogs. Touch is a very important mode of sensory input for many mammals and the mouth is one of the most sensitive tools we have for this, including the added benefit of taste. Infants instinctively put everything in their mouths as a way of learning about them as their eyesight isn’t fully developed for several months. We arguably use eyesight more than any other sense, but we generally use touch as a means of communicating good intentions with one another, often expressed through kissing since the mouth is so sensitive.

    Social creatures are successful because they work together, so there must be a biological reward system for this interaction with one another. How intriguing that our brains releases all sorts of pleasurable drugs when we interact with each other through touch!

  18. RL

    “As a scientist I don’t know much about it…”

    Heh.

  19. davem

    She’s not going to get any useful results from this. When you see two women, naked, in bed, you’re hardly going to say this is 2 mere acqaintances meeting, are you? And why are the majority homosexual couples? Bias is guaranteed. Bad experiment.

  20. sophia8

    zandperl@14: Those would be included in the “relationship” category. At least, that’s how I interpreted it.

  21. I’m collecting preliminary data on these images so I can best select those to include in a cognitive neuroscience experiment. Readers responses are extremely helpful.

    Thanks to all who have participated so far!

  22. IVAN3MAN
  23. jasonB

    Took a look. Based on the experiment I can now state that there are no straight people.

  24. mus

    @#5, Doc: “There are several that have elements carefully chosen to test for bias due to setting, clothing, age, etc. I look forward to seeing the results.”

    Actually, I took that into account when judging what type of kiss they were. The instructions do say “…you’ll see a 15 photos (labeled A-O) of couples kissing. We need you to help us categorize them into three groups”. That to me suggests what what you are rating is the photos as a whole, not just the kisses.

    Besides, I don’t think it is humanly possible to simply rate the kisses, at least not unless everything BUT the kiss is blacked out. What’s more, what exactly would that involve? I think kissing involves a lot more than just the lips/mouth, correct interpretation of the meaning of a kiss depends even on more things that can be shown in a photo (as another commenter pointed out).

  25. Remind me never to go to a party at Mr. Bakker’s house.

  26. According to the austrian ethymologist Irenäus Eibl-Eibesfeldt kissing may be originate from the mouth-to-mouth feeding behavior of some primates and/or “primitive” human tribes.

    Damn, i lent this book to someone i kissed sometime and it never came back … :-(

  27. Torbjörn Larsson, OM

    When I heard that there were experiments involving kisses, I thought of something a bit more exciting.

    That said, kisses are interesting habits. (Well, duh!)

    Selection, especially strong in humans, have been centered on immune system and sexual characteristics according to genome studies. I suspect that both can have driven the general loss of body hair while keeping secondary sexual characteristics hair patches. In any case, the result was that instead of social delousing humans had to start to fondle each other in more ritualistic manner.

    Especially as regards to continue to use the mouth – it can be diverting an older habit. Also, seeing that we seem to pair off according to complementary immune systems, and the suspected mechanism is by smelling, it’s a good habit to continue to put the nose close, as it were.

  28. Restraint….re…straint….

  29. QUASAR has been banned from commenting. If you see anything from him, please let me know.

  30. MadScientist

    Just be glad we didn’t evolve the same sensibilities as dogs. I’d find it inconvenient to bend down all the time and sniff people’s butts.

  31. Rift

    Maybe you should turn off comments for this too Phil, I see a lot of comments that would influence the voting here too.

  32. Gary Ansorge

    Ivan3Man:

    You are a bad,BAAAADD man,,,but I love your sense of humor,,,

    Gary 7
    PS. I spent all of 90 seconds on this “test”. First impressions count with me,,,

  33. Mark

    Having shirts off seems to make it fairly obvious, but they could be at the beach, so you never know. Another stumbling block is having still pictures rather than video, caught at the right moment in a snapshot a peck could look like a more prolonged smooch.

    All in all, an interesting experiment.

  34. Michelle

    I have a hypothesis. There were two cavemen, see, and one had food the other guy wanted to save for his lunch tomorrow. Thinking “Damn it, that’s mine! Well, I might as well eat it right now!” the second caveman jumped on the first and tried to snatch his food out of the other one’s mouth by eating it too. Eventually, like the spaghetti scene from all romantic movies, they smooched and went “hey this feels sorta nice! Let’s try this on our mates later!”

    So yes. By my hypothesis, the first people to kiss were bi cavemen.

    PS: I’m tired. I ramble stupid things when I’m tired.

  35. “According to the austrian ethymologist Irenäus Eibl-Eibesfeldt kissing may be originate from the mouth-to-mouth feeding behavior of some primates and/or “primitive” human tribes.”

    I was going to write the same thing. The context is: due to the fact that humans are born
    as essentially embryos and spend a long time with their parents, the social bond between
    parents and children is important. This bond later gets transferred to other adults during
    love starting around puberty. Many aspects of the former are appropriated for the latter.
    Kissing might arise from mouth-to-mouth feeding. What were the cavemothers to do with
    no baby food, no spoons etc?

    “the result was that instead of social delousing humans had to start to fondle each other in more ritualistic manner.”

    This is actually the reason acne evolved, and why it occurs in puberty, just when one is
    searching for a partner for the first time. Watch two apes de-lousing each other, then
    watch two humans squeezing out each other’s pimples and blackheads. It is exactly the
    same behaviour. If you think your best friend will be jealous when you have sex with his
    wife, just wait for his reaction when he learns she has been squeezing out your blackheads!

  36. Stone Age Scientist

    Phil wrote,

    as a human, of course, I am an Olympic medalist

    You’re an Olympic medalist? Er, which decade was that? :)

    ———

    Now on to business. To tell the truth, when I saw the picture that came along with your article, I suspected that the subject may have something to do with Franklin Kameny. I read about Mr. Kameny the other day (here) and couldn’t help but wonder if you timed your article with the DC Pride Festival that honored him.

  37. Stone Age Scientist

    Phil wrote,

    Why would mashing your lips against someone else’s be of any use? Or brushing their cheek with your lips? And licking? Really?

    Well you know, Phil, sex wouldn’t be what it is without the wetness. Without the fluids, and I mean ALL the fluids, it would be like sandpapers grating against each other.

    My philosophy.

    P.S., those two lads in the picture look like twins.

  38. 33. MadScientist Says:

    Just be glad we didn’t evolve the same sensibilities as dogs. I’d find it inconvenient to bend down all the time and sniff people’s butts.

    A long time ago, IAMS pet food had some commercials that had humans behaving as animals, including two businessmen (suits, briefcases, etc.) ‘sniffing’ each other, though they tended more toward ‘sniffing each other’s backs’.. and the woman stretched out on the back of the couch (yes, on TOP of the back of the couch) was also hilarious.

    I also wonder about kissing as possibly deriving from breastfeeding as an infant….

    J/P=?

  39. Irving

    I have always assumed it was a by-product of breastfeeding and oxytocin, the hormone related to ‘love’ and pair bonding that is released by stimulation of the nipples in the mother and presumably of the lips in the infant. Both nipple stimulation and kissing are encouraged by some during labour for the release of oxytocin.

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