The evolution of laughter

Laughter appears to be a “human universal”: one of those many traits that Donald Brown, in his book Human Universals, found in every society.  Well, does that mean it is a trait that evolved in our ancestors, or did it merely appear as a cultural phenomenon early in human society, and spread to all other societies?  One bit of evidence is that children who are deaf and blind, and thus can’t see or hear other people laughing, still laugh.  This suggests (but of course does not prove) that it is an innate, genetically coded trait, though it says nothing about whether it might have been an adaptive trait.

New research just reported in Current Biology by Davila Ross et al. (see here for a short BBC summary of the work; be sure to click on the video to see a gorilla “laughing”!) suggests that laughter is at least an evolved phenomenon, for our relatives appear to show similar vocalizations when tickled, and our closer relatives show more similar vocalizations.

Davila Ross et al. tickled 3 human infants, 7 orangutas, 5 gorillas, 4 chimpanzees, 5 bonobos (pygmy chimps) and 1 siamang, recording their vocalizations. (What a great job!)  Acoustic analysis of the vocalizations produced a phylogeny, or “family tree” of their similarities.  Strikingly, the family tree based on “tickle-vocalization” analysis is congruent with the known phylogeny based on DNA analysis:

laffs

Importantly,  the authors note that several features of human laughter, like its rapid “ha ha ha” type of vocalization, and its expression only during “egressive airflow” (science-ese for “breathing out”) are found in our relatives as well.

So laughter, at least when being tickled, appears to be an evolved, innate phenomenon.  As I emphasized above, this says nothing about whether it was selected for directly, whether it was a byproduct of something else that was selected, or is simply a nonadaptive epiphenomenon.  But as I write, evolutionary psychologists are working on why evolution may have promoted laughter.  Stay tuned.

11 Comments

  1. Posted June 5, 2009 at 9:26 am | Permalink

    Are the differences in sound due to the differences in the overall vocalization abilities of each species? Since we seem better build to talk is that what makes our laughter sound different? If their throats were shaped like ours would their laughter be the same?

    • annie
      Posted March 28, 2010 at 11:08 pm | Permalink

      and what if there throats are shaped like ours, does that mean they would be better equipped to speak as we do?

      • Kevin
        Posted April 17, 2010 at 7:17 pm | Permalink

        Just because the anatomy of the throat is the same doesn’t guarntee that they would have the same production of laughter. There are no doubt a lot of different genes involved in speech and furthermore undoubtly laughter. Check out the KE family involging FOXP2 gene.

  2. Erasmussimo
    Posted June 5, 2009 at 9:42 am | Permalink

    A fine point in reference to this pair of sentences:

    “One bit of evidence is that children who are deaf and blind, and thus can’t see or hear other people laughing, still laugh. This suggest (but of course does not prove) that it is an innate, genetically coded trait”

    I realize I’m nitpicking, but I think we can say that this datum negates the hypothesis that laughter is a culturally transmitted trait. With that hypothesis out of the way, we have just one other plausible hypothesis: that it’s genetic. Now, there remain a few “wild blue yonder” hypotheses, such as the possibility that the capacity to laugh is somehow transmitted by a common virus, but I think we can set those aside. Thus, the only serious hypothesis left on the table is the genetic one, so that’s what we run with for now. No hypothesis is ever proven; we merely accept those hypotheses that outlast their competitors. We’d like to see more supporting evidence before we really feel confident with this one, but I’d say it’s solid enough to run with.

    Yes, I’m being picky…

  3. Hempenstein
    Posted June 5, 2009 at 10:43 am | Permalink

    Excellent: “Strikingly, the family tree based on “tickle-vocalization” analysis is congruent with the known phylogeny based on DNA analysis:”

    To paraphrase Mary Chapin Carpenter, the stars may lie but the DNA never do.

  4. Rebecca
    Posted June 5, 2009 at 11:02 am | Permalink

    But I laugh when I’m breathing in.

  5. James F
    Posted June 5, 2009 at 12:52 pm | Permalink

    But as I write, evolutionary psychologists are working on why evolution may have promoted laughter.

    Ironically, creationism promotes quite a bit of laughter.

  6. newenglandbob
    Posted June 5, 2009 at 1:34 pm | Permalink

    The primordial comedian:

    “Take my treetop. Please!”

  7. Posted June 5, 2009 at 9:08 pm | Permalink

    Have you read Laughter by Robert Provine? Really good read on the subject. Guy spent ten years delving into everything from the way laughter is scored in music to the physiological differences in breathing that make human laughter sound so different from that of other primates.

    The coolest congruency he notices, in my opinion, is that laughter serves nearly identical social functions for humans and apes. Individuals lower in a social hierarchy laugh to show submission to those above them. And individuals high in a social hierarchy initiate derisive laughter against those they wish to exclude.

  8. Dr. Arv Edgeworth
    Posted June 6, 2009 at 9:52 am | Permalink

    It is definitely in the genetics. We have to be really careful here though. Someone might get the idea that humans were designed to laugh, and we all know where that line of thinking could lead. It just makes so much more sense that it happened by accident for no purpose.

  9. Jim
    Posted December 19, 2011 at 11:43 am | Permalink

    I know this is an old thread now but I was thinking about laughter after a recent conversation.
    It’s hardly a surprise that there are genetic similarities and traits (including laughter) between humans, bonobos etc etc. The question that isn’t being answered is where does laughter come from and what purpose does it serve?
    I reckon it’s a bonding mechanism. Cavemen sit down after the hunt and talk about their day, laugh together, bond. The bonds strengthen the group and the stronger group work together more effectively as a team. They hunt better.
    This would also explain why laughter is naturally selected and why (it is said) that women find humour and the ability to make others laugh attractive in a mate. The caveman with GSOH is more likely to be a member of a strong-knit effective hunting team and a better provider to his offspring.
    I know it’s an old thread but if anybody wants to comment I’d be interested.
    Cheers.


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