Richard Wrangham: The Evolution of Cooking:

"We always tend to think that humans have just had a continuous surge in brain size over the last two million years, but actually over the last thirty thousand years brain size has decreased by 10 to 15 percent. [...] This gracility is exactly the same pattern we see in the evolution of dogs from wolves, or bonobos from chimpanzees, or domesticated foxes from wild foxes. In all these cases an increasing gracility of the bone is an incidental effect.

I think that we have to start thinking about the idea that humans in the last 30, 40, or 50 thousand years have been domesticating ourselves. If we're following the bonobo or dog pattern, we're moving toward a form of ourselves with more and more juvenile behavior. [...] I think that current evidence is that we're in the middle of an evolutionary event in which tooth size is falling, jaw size is falling, brain size is falling, and it's quite reasonable to imagine that we're continuing to tame ourselves."

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23 Responses:

  1. zeppo says:

    I think this goes hand in hand doublemint twin style with my sincere belief that due to the technological surge humanity is advancing into another dark age.

  2. fantasygoat says:

    I've always contended that humanity is getting dumber and dumber.

    However, that theory applies to recent history, not the timescales they're talking about here. I'm sure we have the same brain size we did during the 1600's that we have now. But then they didn't have "America's Most [Blankety Blank]" on TV.

    • nrr says:

      But then they didn't have "America's Most [Blankety Blank]" on TV.

      Let's not forget that, let alone even having such shows on TV, the bastards in the 1600's didn't even have that mindrot to begin with. In other words, people either had to play outside or read or do some sort of other brain-employing action for entertainment. Or, well, they could just have sex, but even then, that involves some use of one's brain.

      And, yes, I contend the same thing here, but I attibute my stance more to the fact that we have people protecting us from ourselves instead of simply letting natural selection take over and blow the whistle on the dumb people wading around in the gene pool.

      • jwz says:

        Sure, go "play outside" while waiting for tonight's dinner special: half a moldy onion! What was the literacy rate of "people" in the 1600s? Or by "people" did you mean "aristocracy"?

        Hate TV if you like, but don't forget that the past sucks!

        Say to these annoying people, ``Hey kids - the past wasn't like a trip to Waikiki: the only sure thing about the past is some ghastly disease, carnage, toil that defies all description, starvation, and boredom of a sort that makes waiting in line at the Department of Motor Vehicles seem like Disneyland on heroin.''

      • jkonrath says:

        I think the people protecting us from ourselves most likely for the rise in life expectancy are not the of the "evil government entity" sort, but rather the manufacturers of pennecillin and MMR vaccinations.

        And why does having sex involve the use of a brain? Are you saying that mice are displaying their superior intellect when they mass produce themselves instinctively?

        • ctudball says:

          And why does having sex involve the use of a brain? Are you saying that mice are displaying their superior intellect when they mass produce themselves instinctively?

          I think the act of enticing a partner would cover this, not to mention having to figure out a way of avoiding pregnancy. As for the act itself . . yeah, the brain is pretty much switched off.

      • flipzagging says:

        Right on! The only way to advance civilization is to get rid of civilization.

    • dzm6 says:

      The masses stuck to good wholesome entertainment like hangings, witch trials, drawing-and-quartering, etc.

      The masses have always preferred spectacle to anything mentally stimulating.

  3. alynch says:

    Maybe HG Wells was right, in imagining the Eloi...

  4. jkonrath says:

    Seems like I remember reading that it isn't the size of the brain, but rather the lobe depth and structure. I.e. throw Einstein's brain on a scale and it won't weigh nearly as much as people who are physically much bigger, but not much smarter.

    Trying to google on this brought up a lot of fierce debate on this, and many white supremacist sites trying to argue various racial theories on brain size.

    • nelc says:

      The best thing to read on this subject is Stephen Jay Gould's 'The Mismeasure of Man'. Also the various collections of his essays.

      Short version: There is a correlation between intelligence on an animal scale and brain size as a proportion of body weight. There is no measurable correlation between modern human brain size and IQ. No measurable correlation in modern humans between convolutions and IQ, no measurable correlation between dendrite complexity and IQ, and so on, and so on.

      As far as gracility goes, since gracile forms are physically smaller than robust forms, then gracile Homo will have brains of a smaller absolute size. That fact alone doesn't say much about comparisons of intelligence between gracile and robust Homo.

      Actually, I'm not sure what Wrangham means when he says brain size has decreased. While it's true that H. neanderthalis had a bigger brain (since they had bigger bodies), it's generally agreed now that we're not descended from Neanderthals, but we both descended from a common ancestor. And untamed big brains don't seem to have done a lot for Neanderthal Man....

  5. baconmonkey says:

    30 is the new 18.

    look at when animals are domesticated, basically the animal is kept at a repressed juvenile state, trained and bred to be responsive to the wishes of it's master. Now go look at the advertizing industry.

    • ammonoid says:

      Actually, in medieval times people didn't marry and start playing house until 25-30, because it took that long to aquire enough money etc to start out on their own. The idea of 18 being the beginning of independence is a relatively recent phenomenon that seems to be on its way out, anyway.

      • suppafly says:

        and by people, you mean men. women were married off as soon as possible.

        • xenogram says:

          That was true in some times and places, but not all times and places. Europe is a big place, and the medieval period covers at least 1000 years depending on how you count it.

          There's a lot of absurd myths about the middle ages. Knights were winched onto their horses. Food was heavily spiced because it was rotten and undercooked. Woman wore chastity belts. There was no such thing as democracy. There were no machines, nails, buttons or coffee. There were inns in every village. Heraldry was unique. The aristocracy was a permanent unbroken line. Swords were the primary weapon in hand-to-hand combat. Blah, blah, blah, blah, blah.

          Yeah, anyway, not always true. But I agree, the past sucks, I wouldn't want to live there. Unless I get to be somebody like Roger of Sicily.

  6. kdarr says:

    "We'll make great pets"


  7. harryh says:

    A while back you posted a link to a Crighton piece on bogus environmentalism. Well for me, that wasn't the interesting part of the article. The interesting part was how he pointed out how humans seem to be hard wired to the mythology of "Things used to be better back in the day and now because we're doing something stupid doom and gloom is inevitable."

    I now see evidence of this phenomenon everywhere.

    • jwz says:

      I do too, but I don't think Wrangham was implying that self-domestication and smaller brain size were a bad thing. He was saying that this change is likely what made it possible for us to tolerate each other at all.

  8. torgo_x says:

    I've always wondered why it took our esteemed ancestors so
    damned long to figure out that they should boil their
    drinking water. Their ancient massive hyoomon brains were probably
    just occupied with paranoia.

  9. urbanape says:

    Galapagos, anyone?

    I so want to be an otter, but not in a Furry (ick) way.

  10. g_na says:

    This month's Discover Magazine has an article ("Dogs of Rarotonga", unfortunately not available online) which hypothesizes the same. Apparently breeding for some traits of domesticity (docility, subservience, etc.) can also result in seemly unrelated traits associated with juveniles.

    Personally, I think it's fascinating, as well as a big nose-thumbing to both believers of creationism, and to those people who think humans are invincible.

  11. sethg_prime says:

    So the smarter humans were killed by their peers before they could reproduce? Sounds like junior high school to me....