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There are now 14 comments... what are your thoughts?
  1. sewblon says

    “Give in or give up.” What exactly is the difference?

  2. jb says

    It isn’t necessarily true that “the effects on our brains [or anything really] haven’t changed one bit”. There is good reason to believe that all the changes in human society threw biological evolution into overdrive, and that humans who have lived in dense agricultural/urban societies for thousands of years are not entirely the same animal that their distant band-living ancestors were.

    • It is absolutely true that humans have continued to evolve. The book you cite to may not be the most accurate source, as most of the really cool discoveries have been made since they wrote it (and much of the book is more speculation than reporting). But leaving that book aside, there is excellent evidence of continuing genetic evolution both throughout the human species and separately within its various populations.

      Recall from earlier in this section that the Cognitive Revolution was an example of evolution in overdrive. The survival benefits of each incremental improvement were so dramatic, that the new genes spread like wildfire. Ordinarily, it takes a much longer time for genes to drift out into the larger population. With us, it’s as if they were blasting across the landscape.

      That was not the end of it. But that’s also where it starts to get harder to ascribe purely genetic cause-and-effect. Because now we had the memes of our cultures spreading in addition to the genes of our DNA, and even faster.

      Nevertheless, since 2010 there have been many discoveries of genetic mutations in our bodies and in our brains as we’ve continued to adapt over the past 50,000 years. We’ve also gotten pretty good at nailing down the timing of these mutations, as well as the speed with which they spread through various populations. For example, once people had started living in Europe and East Asia, both sets of populations went through a rapid and parallel evolution of light skin—two completely different genetic adaptations to the change in UV exposure after those populations had diverged, but convergent to essentially the same result in just a few thousand years. About 10,000 years before the rise of agriculture, the Inuit had evolved sophisticated adaptations to a high-fat diet and life in a frozen environment, again very fast. All of that and much more happened before the rise of civilization.

      Around the beginning of the agricultural junk food revolution, as well, you start seeing comparatively instantaneous evolution of genes enabling us to take advantage of it. While barley and wheat were being domesticated in Mesopotamia, for example, people in southern China were domesticating rice. A big problem was alcohol damage to the body from fermented rice. Almost immediately, you see a mutation to the ADH1B gene, giving that population protection against the alcohol (affecting alcohol sensitivity to this day). And a couple thousand years after that, increased reliance on cattle (as well as use of linear pottery) coincided with the origin of a lactase persistence gene mutation in central Europe.

      This “bigger narrative” we’re about to explore also just happens to coincide with a mutation in the abnormal spindle-like microcephaly gene suddenly becoming a dominant trait. It was a brand new allele that rapidly blasted through the population, just as the cognitive revolution had. In other words, instead of genetic drift, it was so successful that we went through “positive selection” for it. It swept through the Middle East and Europe, a little less so across Asia, and hardly made it into sub-Saharan Africa at all. (Before the Bell Curve people jump onto this, studies indicate zero correlation with IQ. However, and much more interestingly, those populations with the older version of the allele tend to speak tonal languages the rest of us have a hard time mastering.)

      More genetic mutations have arisen since the first civilizations about 6,000 years ago. (Don’t quote me on this, because I have to check my notes, but I think I remember reading about some mutation or other coinciding with the invention of writing in various places, as well.)

      But—and here’s the thing—none of these mutations seem to affect our social brain. That is, the brain bits relevant to social regulation, worth, social emotions, self-regulation, effects of population size… these are all essentially the same now as they were 50,000 years ago.

      So far as our social brains are concerned, we are still paleolithic, pre-agricultural foragers living in small, tight, loyal, loving bands. And to the extent the real world conflicts with that wiring, we got problems.

      But we’re good at solving problems. I wonder what this “bigger narrative” might be. Or whether there might have been more than one? I can’t wait to find out!

      • “That was not the end of it. But that’s also where it starts to get harder to ascribe purely genetic cause-and-effect. Because now we had the memes of our cultures spreading in addition to the genes of our DNA, and even faster.” I am not sure that memes are actually a thing. It isn’t clear that culture can be divided up into discrete scientifically measurable units, or that we can see the effects of memes anywhere besides the things that they are supposed to explain. (The Myth of Culture by Nigel Barber, page 107-108).

        • If you define a meme as a true genetic analogue? As a discrete unit carrying a distinct element of culture? Yeah, that’s iffy. That’s not really how culture works.

          If you define a meme as an instance of human creativity that gets passed around on the internet for a while? That’s a new definition, sure, but not the usage that’s applicable here.

          But if you use the word “meme” as I do, to refer more generally to instances of culture that happen to carry forward from one generation (or population) to the next? Regardless of what carries them or how? It’s a good fit.

          It’s not a perfect analogue to genetics, because it’s focusing on the effect instead of the cause. Like focusing on the trait being passed on—blue eyes,say—rather than the underlying DNA bits responsible for the trait.

  3. SeanR says

    I think this is a key component in the US Left-Right divide. Those on the Right tend to be more rural, while those on the Left tend to be more urban. What we demand of our neighbor changes with how many neighbors we have.
    Personally, I do NOT want to live in a city. They might be a nice place to visit,…Cabela’s, Bass Pro Shop, or Academy Sports.
    The absolute irony is, it is the specialization of labor, enabled by the cities, that allows me to own the very things those in the cities typically want to dispossess me of.
    And I can understand why. If I had sheet rock thin walls between me and the next guy, “Castle Doctrine” would make a lot less sense to me, too.

  4. STM says

    I wonder if the data on mental illness and urban/rural residence controls for income, social class, race, healthcare access, support networks, etc; not to mention subcultural differences both between and within these populations. Are similar results seen in non US, non WEIRD countires?

    • Yes, similar results are seen in studies from a variety of countries.

      One of the coolest studies, from I want to say 2017 or 2018, came out of Germany. They were looking at the effects of “green space” as a way to moderate the negative impact of urban living on the brain. They found that even a few days in true woodsy wilderness was enough to recharge the brain and wash out a lot of the negativity, with lasting effects well after returning to the city. But merely having parks and trees and greenbelts wasn’t enough to have much of an effect. Apparently (and this really surprises me), our ideal habitat is not the shore (my guess) or rolling green fields or savannah (the most common guesses) but true forest land. Apparently it offers precisely the variety, stimulation, and sensory inputs our brains are wired to thrive in. Who knew!

  5. sewblon says

    What are the sources for the fun fact about children being raised in larger groups, especially boys, developing less grey matter in parts of the brain associated with conscience?

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