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Nov 01 2009

Why do we kiss? To build immunity!

Asking why humans kiss may seem like a silly question to an average person – because it feels good, duh. But an evolutionary biologist wonders why it feels good. Why is kissing a nearly universal human behavior? Dr. Colin Hendrie from University of Leeds has a hypothesis:

They say the gesture allows a bug named Cytomegalovirus, which is dangerous in pregnancy, to be passed from man to woman to give her time to build up protection against it.

The bug is found in saliva and normally causes no problems. But it can be extremely dangerous if caught while pregnant and can kill unborn babies or cause birth defects.

Writing in the journal Medical Hypotheses, researcher Dr Colin Hendrie from the University of Leeds, said: “Female inoculation with a specific male’s cytomegalovirus is most efficiently achieved through mouth-to-mouth contact and saliva exchange, particularly where the flow of saliva is from the male to the typically shorter female.”

Alright, this kind of sounds like a bit of armchair speculation (aka BS) to me, but at least it’s properly labeled a hypothesis. Especially the shorter female part – what? I’m pretty sure all saliva doesn’t gush into the females mouth…of course, I’m a tall female, so maybe I have some biased sampling.

It would be interesting to test levels of certain types of infections depending on how many people an individual has kissed, or something like that. That seems like a study worth participating in! Or at the very least, a good pick up line if you’re trying to snog a biologist – “Hey baby, want to increase your immunity to Cytomegalovirus?”

22 comments

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  1. 1
    Veritas

    That's going in my repose to use on cute biologists. Not that I know *any* cute biologists. Well, that's not true, but one is dating one of my best friends, and the other lives in West Lafayette and went to a party with the President of the US the other night.

    Foiled again.

  2. 2
    Veritas

    That’s going in my repose to use on cute biologists. Not that I know *any* cute biologists. Well, that’s not true, but one is dating one of my best friends, and the other lives in West Lafayette and went to a party with the President of the US the other night.Foiled again.

  3. 3
    Joé McKen

    Dang those bloody scientists, they always gonna ruin the romance with their sciency gobbledygook …

  4. 4
    Joé McKen

    Dang those bloody scientists, they always gonna ruin the romance with their sciency gobbledygook …

  5. 5
    Tyler DiPietro

    Spinning adaptive yarns about each and every observable human behavior doesn't seem very productive in the first place. Just looking at the article, I don't see much in the way of falsifiable science. It's just yet another adaptationist just-so story in the heap of similarly unfalsifiable conjectures.

  6. 6
    Tyler DiPietro

    Spinning adaptive yarns about each and every observable human behavior doesn’t seem very productive in the first place. Just looking at the article, I don’t see much in the way of falsifiable science. It’s just yet another adaptationist just-so story in the heap of similarly unfalsifiable conjectures.

  7. 7
    The Big Blue Frog

    I agree. Sounds fishy. Would our ancestors have just passed along their genes if they kissed, and that's why only kissers survived? Can you tell I'm reading "The Selfish Gene"?

  8. 8
    The Big Blue Frog

    I agree. Sounds fishy. Would our ancestors have just passed along their genes if they kissed, and that’s why only kissers survived? Can you tell I’m reading “The Selfish Gene”?

  9. 9
    Mike Brownstein

    To quote Robert Wexler: I like kissing because its a fun thing to do.

  10. 10
    Mike Brownstein

    To quote Robert Wexler: I like kissing because its a fun thing to do.

  11. 11
    mcbender

    That seems a little implausible… granted, it's only a hypothesis, but still.

    In all frankness, kissing has always been something that's baffled me, even without trying to figure out where it comes from. It just seems very bizarre… do we know of any other animals that do it, or is it just us?

  12. 12
    mcbender

    That seems a little implausible… granted, it’s only a hypothesis, but still.In all frankness, kissing has always been something that’s baffled me, even without trying to figure out where it comes from. It just seems very bizarre… do we know of any other animals that do it, or is it just us?

  13. 13
    Hugo Grinebiter

    I always assumed that the purpose of kissing was to exchange chemicals that conveyed specific information about reproductive fitness. Other animals don't need to do it because their fur or plumage or mating call is sufficiently information-rich. @Frog: That would work in the selfish-gene world, surely, inasmuch as non-kissers would make poorer mating choices, leading to impaired repro. success? @Tyler: Indeed, testing would not be easy. You'd need a snogathon large enough so that you could correlate "Yech!" responses with genetic predisposition to undesirable medical conditions. And if kissing was meant to warn us about behavioural issues too, then we don't yet have the genomic knowledge for that, even if it's genetically coded in the first place. A university research snogathon on that scale would probably result in outbreaks of mono and congresscritters, no?

  14. 14
    Hugo Grinebiter

    I always assumed that the purpose of kissing was to exchange chemicals that conveyed specific information about reproductive fitness. Other animals don’t need to do it because their fur or plumage or mating call is sufficiently information-rich. @Frog: That would work in the selfish-gene world, surely, inasmuch as non-kissers would make poorer mating choices, leading to impaired repro. success? @Tyler: Indeed, testing would not be easy. You’d need a snogathon large enough so that you could correlate “Yech!” responses with genetic predisposition to undesirable medical conditions. And if kissing was meant to warn us about behavioural issues too, then we don’t yet have the genomic knowledge for that, even if it’s genetically coded in the first place. A university research snogathon on that scale would probably result in outbreaks of mono and congresscritters, no?

  15. 15
    Anonymous

    Does the article specify if the bump up in immunity comes from the virus carried by *men*, or just other people?

    I.e., what about the lesbians? Do they get immunity boosts from kissing, or is it only from teh menfolk?

  16. 16
    Anonymous

    Does the article specify if the bump up in immunity comes from the virus carried by *men*, or just other people? I.e., what about the lesbians? Do they get immunity boosts from kissing, or is it only from teh menfolk?

  17. 17
    Sili

    I know I'm just weird, but the idea of kissing still baffles me. I know it supposedly feels good, as you say, but it looks too damn odd.

    I recall hearing that the origin of kissing could be mouth-feeding by grandparents. Chewing food and delivering it by mouth to infants. So it's a cultural thing.

    Now if they can demonstrate that kissing is prevalent in all societies in all times, and that lack of kissing is associated with cytomegalovirus-infection, then I might consider hearing them out.

  18. 18
    Sili

    I know I’m just weird, but the idea of kissing still baffles me. I know it supposedly feels good, as you say, but it looks too damn odd.I recall hearing that the origin of kissing could be mouth-feeding by grandparents. Chewing food and delivering it by mouth to infants. So it’s a cultural thing.Now if they can demonstrate that kissing is prevalent in all societies in all times, and that lack of kissing is associated with cytomegalovirus-infection, then I might consider hearing them out.

  19. 19
    Anonymous

    OMG! Medical Hypotheses? Quack journal. Ask Orac, or Steve Novella, or any one of those guys what they think of MH. Let's just say it is NOT the place to find real science. Although, I have to say, that I'm all for anything that promotes kissing…

    Dawn

  20. 20
    Anonymous

    OMG! Medical Hypotheses? Quack journal. Ask Orac, or Steve Novella, or any one of those guys what they think of MH. Let’s just say it is NOT the place to find real science. Although, I have to say, that I’m all for anything that promotes kissing…Dawn

  21. 21
    allison

    Yeah, not really buying this. First of all, kissing feels good no matter what the gender, and there are lots of animals that engage in a similar practice. Check out the Discovery Channel…they did a whole special on kissing a while back. I'm pretty sure it has more to do with discovery and exploration, like when babies put things in their mouths, and also about marking (as in YOUR MINE SO IZ SMOOCH U). Did you know that people kiss differently (as in, different synapses, etc.) depending on the situation? Kissing is awesome. =)

  22. 22
    allison:

    Yeah, not really buying this. First of all, kissing feels good no matter what the gender, and there are lots of animals that engage in a similar practice. Check out the Discovery Channel…they did a whole special on kissing a while back. I’m pretty sure it has more to do with discovery and exploration, like when babies put things in their mouths, and also about marking (as in YOUR MINE SO IZ SMOOCH U). Did you know that people kiss differently (as in, different synapses, etc.) depending on the situation? Kissing is awesome. =)

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