Is the human species still evolving? Of course.

It looks like Bill Nye, the science guy, is coming out with a new book on evolution, with an excerpt at Popular Science: Is The Human Species Still Evolving? | Popular Science.

We cannot step away from evolution. Our genomes are always collecting mutations, and we are always making mate selections. Are humans preferentially mating with other humans who are tall? Blonde or not blonde?

Are smart people actually producing significantly smarter offspring, who end up making more money and ever so slowly outcompeting other families? Or is intelligence a losing trait, because highly educated couples tend to have smaller families, so when something goes wrong there are fewer siblings left to carry the genes forward? Or since highly educated men and women have babies later in life than those that don’t squander their best childbearing years in universities, do the babies of the highly educated enter the world with more trouble in childbirth, and are they prone to more subtle gene troubles that result from later mother and fatherhood? Cue the spooky music.

When I was younger, I reasoned that evolution had ended for humanity because we lived in organized societies that protected the weak.  Without the weak dying in the wilderness, I thought, natural selection couldn’t…select.  And without that selection, traits couldn’t disappear nor new ones dominate, and so evolution couldn’t happen.  But my understanding of natural selection was simplistic.

First off, just because we now live in societies that, at least sometimes, protect the weak, doesn’t mean that mutations don’t happen.  Without the harsh wilderness selection that our ancestors lived in, that probably means that there’s a lot more variation in the human genome than existed, say, 10,000 years ago.  Mutations that might have quickly been selected out in hunter gatherer societies have more of a chance in civilization.

But my second misunderstanding was in believing that natural selection is about survival.  It is, partly, but it’s more about reproductive success.  And animals with certain traits don’t have to be completely unsuccessful reproductively for their traits to disappear.  Given enough time and generations, they only have to be slightly less successful than animals with different traits.

And finally, traits that will be successful in a hunter gatherer culture, such as males with athletic ability and aggression, might be less successful in a farming or industrial society.  Selection is still happening.  It’s just happening at the mate selection and cultural selection level.  (Which is actually still natural selection, if you take a long enough view.)  Humans have just developed the ability to manipulate our environment, and hence the selection criteria.

Another interesting complication with all this is the development of birth control, which essentially allows us to indulge our reproductive instincts without actually reproducing.  That plus the cost of raising additional kids in a modern society means that the most successful people aren’t always going to produce the most offspring.  What effect this might have on evolution over the long term is hard to predict.

Of course, as Nye briefly alludes to, this assumes we won’t go through some type of Singularity in the near future, or, perhaps more likely, take control of our evolution with genetic engineering.  It might be that the era of unguided evolution on this planet is nearing its end, at least for humans.  Possibly.

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10 Responses to Is the human species still evolving? Of course.

  1. Steve Morris says:

    The idea of “survival of the fittest” is perhaps one of the most unhelpful scientific metaphors ever created. As you say, it’s much more about reproduction.

    One factor that intrigues me is that, as people in the west postpone having children until much later in life, there must be a natural selection of those who retain their fertility (and overall state of health). This would presumably select for genes favourable to longevity and increased long-term health. This could perhaps even happen quite quickly – over several generations.

    I also wonder if changes in lifestyles is leading to the evolution of greater diversity amongst the population. Different groups of people make increasingly different choices in life.

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    • On longevity, it’s possible. Of course, there are complicating factors. People in the west are increasingly having access to treatments that allow less fertile people, including older people, to have children. I suspect that medical technology is going to increasingly complicate the selection process.

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  2. john zande says:

    The movie, Idiocracy, sums this up wonderfully. The idea is fantastic, but the execution is pretty damn horrible.

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    • I saw that movie. I think it’s best moments was in the opening sequence where it described the concept. Evolution doesn’t always mean progress, at least not in a way that we’d define “progress”.

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      • john zande says:

        110% correct. The first 15 minutes are good. The rest is atrocious.

        Liked by 1 person

      • Wyrd Smythe says:

        It’s a low-budget effort painted with a broad brush (Mike Judge did Bevis and Butt-head after all), but it’s downright prescient about where society is headed. Parts of it have come true now! For all that it’s silly and crudely done, it’s actually a brilliant film.

        The opening part, about the couple who didn’t reproduce, is a direct take on the “Marching Morons” theory, which comes from a 1951 SF story. See my blog article for more info:
        http://logosconcarne.com/2014/06/09/idiocracy/

        All that said, I think many of these are social changes rather than evolutionary ones (those take 10,000s of years). We’re still the same people we were 5000 years ago. That ancient Greek comedies are still funny demonstrates that — comedy is subtle and very human. But that’s a whole other discussion!

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  3. Just a few days ago I caught a few minutes of Gattaca before my Roku pooped out. It’s genetic manipulation theme seems a propos here. I wouldn’t be surprised if you’ve seen it…it’s about a “not-too-distant future” in which genes are selected from parents in order to give their children their best hereditary traits.

    As for reproductive success, and this is purely speculative—I wonder if the emphasis is on quality rather than quantity? Could it be an evolutionary virtue to have fewer children but also greater ability to ensure their success? Suppose you have three children, but can’t afford to send any of them to college. Their chances of getting an education are slimmer, and it seems education matters for health: “In 1999, the age-adjusted mortality rate of high school dropouts ages 25 to 64 was more than twice as large as the mortality rate of those with some college.” (http://www.nber.org/digest/mar07/w12352.html). So you could say that having fewer children might even be a survival instinct. That may seem like a far stretch, I know, and I’m not sure about this source…I just Googled education and health 🙂

    Oh, I could speculate all day. Who knows.

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    • I’ve never seen Gattaca (or at least, not all of it). Just checked and neither Netflix or Amazon has it for free. Pity. I’m home sick and it would have been a good afternoon to watch it.

      On reproductive success, it all depends on the probability of them passing on their genes. Let’s say you’ll be able to afford to send one child to college, which makes the probability of that child passing on their genes, say, 60%. But if they hadn’t gone to college, the probability would only be, say, 30%. If that holds, then having two children without sending them to college is evolutionarily equivalent to having one child sent to college (30%+30%=60%). Having three kids who can’t go to college ends up being superior. Although technically, having two children and sending only one of them to college might be the best move, from a pure evolutionary perspective (60%+30%=90%).

      But wait, there’s another factor. Your children aren’t your genetic twins. They only share 50% of your genes. So, from your genomes point of view, more offspring is better since it raises the probability of any one gene getting passed on.

      Of course, this is all simplified hypothetical reasoning. (There’s tons of this kind of thing in ‘The Selfish Gene’) Reality is far more complicated. But what we regard as success for us and our children isn’t necessarily going to be the best evolution strategy. (Not that what’s good for evolution should have any influence on what we regard as success.)

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      • This is awesome. Very well explained indeed. I usually stink at probability, but this made perfect sense to me.

        Yeah, so there goes another idea.

        I’m smiling to myself as I think about having three kids and telling them all they have to compete with each other over my funds because only one gets to go to college. How’s that for an incentive to get good grades? Well, why stop at three? 🙂

        Do you have Crackle? It’s free…that’s where I found Gattaca. There are really annoying commercials, however. I’m surprised you haven’t seen it already! I think it will be right up your alley. Don’t forget, it’s kind of old, so it will be interesting in that way too…the technology in retrospect.

        I’m about halfway through Dune, BTW, and really enjoying it. Might have to do a post once I finish.

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