Sir David Attenborough is wrong, humans are still evolving

Sir David Attenborough, one of my favourite broadcasters, recently suggested humans have stopped evolving. As much as I love they guy, he’s simply wrong about this.

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I’ve just got back from a holiday and whilst I was gone it seems Sir David Attenborough has said something wrong. Again. In fairness to him (and with that voice of his he deserves the best treatment in the world) only one paragraph in his interview with the Radio Times was factually disagreeable. The rest is pretty good, excerpts of which (including his big mistake) can be found in this Guardian piece.

We stopped natural selection as soon as we started being able to rear 90-95% of our babies that are born. We are the only species to have put a halt to natural selection, of its own free will, as it were

To cut Sir David even more slack, this is an idea that seems superficially plausible. Unlike the time he was promoting that Aquatic Apes nonsense. After all, most of us no longer have to contend with the problems animals have to deal with. We’re not threatened by sabre tooth tigers, shivering because we aren’t well suited to the environment or fearful of disease. We have created an environment that has eliminated most “traditional” forms of natural selection.

I mean, it's not like this is regular occurrence any more.

I mean, it’s not like this is daily occurrence.

But to use this to suggest natural selection has ceased entirely is missing a big point: we’ve created a whole new environment. This is the premise of niche construction theory, which notes that whilst animals may isolate themselves from natural environments they often create whole new ones in the process that expose them to new selection pressures.

And our environment is certainly brand new. We’re living in cities of millions where we have to socialise to the extreme. Given living in large groups is likely one of the reasons our brains got so big there’s a strong chance that this new social development will also influence our brains.

Then there’s the fact that our success is now dependent on a whole host of behaviours which may have not been so important long ago. Jon Ronson‘s book The Psychopath Test notes how psychopaths are often very successful in business and politics. Might our new world, which places such importance on these institutions, start selecting for a more ruthless human?

The idea of humans continuing to evolve isn’t just speculation, we’ve actually discovered many examples of recent evolutionary change. Despite the fact  we no longer have to fear sabre tooth tigers, we’re still evolving.

One way our new environment has shaped modern evolution is in our mouths.  With the advent of farming new food was introduced into our diet that drove changes to our teeth and jaws. In fact, different populations around the world now have a slightly different jaw structure based on their local diet! As our diet continues to change, this trend will also continue.

Other examples of our current evolution began a lot longer ago than farming. For example, during the last glacial maximum (colloquially known as “the ice age”) humans became short and stocky, a body plan that helps minimise heat loss. Now we’re out of the LGM we’re becoming tall and lanky again. Whilst some people might credit this change with improved diet, a large chunk of it is genetic. One study found that a minimum of 45% of the variance in human height is genetic. In other words, it’s heritable change over time; the very definition of evolution.

Other examples include our brain size, which has been decreasing over the past 10,000 years. Although the exact cause of this is unknown there are many possibilities. It may be linked to the ice age, with extra brain matter helping heat the head and keeping it all ticking along. Now we don’t need the extreme central heating we could cut down on the power bill (i.e. amount of food we have to consume) by reducing  It may be that it’s becoming more efficient and doesn’t need so much raw power to achieve the same goal. And don’t get to downhearted about our smaller brains, IQs are still increasing.

These are just three ways in which we are continue to evolve, despite (or perhaps because of) the fact we’re living in our new, non-natural environments. Sir David Attenborough is simply wrong about the end of evolution. As biologists are fond of saying “evolution is smarter than you“.

I’ll end with a comment from the Guardian article, which summarises this issue better than I ever could.

attenborough summary

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34 thoughts on “Sir David Attenborough is wrong, humans are still evolving”

  1. stupidbadmemes says:

    I was told that I had to wear braces because of evolution. This was many years ago and I’ve forgotten the details of the argument, but yeah…it had something to do with how the human mouth was changing as people evolved due to eating habits. Whether that’s true or not, I don’t get why people think we aren’t evolving. I think some people believe that if we’re evolving, we should be sprouting wings or something.

    1. Adam Benton says:

      Our ancestors had much bigger teeth an jaws to cope with the tougher diet of a hunter-gatherer. This isn’t a concern these days, so they’ve shrunk in modern humans. Unfortunately not all bits have shrunk equally, so they often don’t quite fit together. This is also the reason wisdom teeth are an issue

      On an another note, I had an example of recent jaw evolution I forgot to include. Thanks for reminding me, the post now contains 3 examples of why Sir David got it wrong

      1. marc verhaegen (@m_verhaegen) says:

        Adam, this is pure wishful thinking (anthropocentric = pre-darwinian), contradicting human biology, physiology, nutrition etc. Homo did not disperse to Mojokerto, Aïn-Hanech & Dmanisi running over open plains, but simply followed African & Eurasian coasts & rivers, even reached Flores, Sulawesi, Crete, Cyprus & the Dodekanesos = far overseas. Sir David = 100% correct. Brain growth requires iodine, DHA, taurine etc., which are abundant at the seacoast, but scarce or absent in savannas. For recent info on the Coastal Dispersal Model (Munro 2010), see (BTW, Homo had a smaller mouth, teeth & jaws than apes-australopiths, google e.g. “MYH16” inactivation.)

        1. Adam Benton says:

          Calm your horses, this article was discussing another of Sir David’s claims.

  2. Ashley Haworth-roberts says:

    I also flagged some of his comments (I didn’t see the Radio Times article itself) here:

    1. Adam Benton says:

      In fairness to the guy most of the interview (at least the excerpts from the Guardian) raise reasonable, valid points. It’s a single paragraph about evolution where he makes a mistake, I only focus on it because creationists seem to be exploiting it to refute evolution in that weird way only creationists can.

  3. agnophilo says:

    Not to even mention sexual selection.

    1. Adam Benton says:

      I’m loathe to talk about sexual selection because a lot of the EvoPysch studies behind it are horribly horribly flawed. For details see just about any post I’ve written about.

      1. agnophilo says:

        Oh I can imagine. Why can’t fundamentalists bash the bits of evolution science that actually are rife with BS and pseudoscience?

        1. Adam Benton says:

          Even when they do it never ends well. I was once talking to a creationist about the aquatic ape hypothesis. He was astounded I was criticising it. After all, evolution is a faith based religion shouldn’t we just accept any just-so story about origins?

        2. agnophilo says:

          The insistence that scientists are as dogmatic and pig-headed and ideological as the worst fundamentalists gets really, really tiring.

        3. Adam Benton says:

          In an ironic twist the claim is itself has become dogma amongst certain people

        4. agnophilo says:

          Oh there’s no end to irony in the creationism movement.

  4. eyeonicr says:

    One study found that a minimum of 45% of the variance in human height is genetic.

    While that means that height can evolve, does that really mean that a lot of the change we have observed so far is genetic?

    1. Adam Benton says:

      Although the 45% paper didn’t directly examine whether these genes were under the influence of selection (and thus related to the current rise in human height) other studies have examined some of these genes (as well as others the paper didn’t pick up on) and revealed they are being selected for. Unfortunately I don’t think any have examined the full range of genes associated with height.

      In other words at least some of the recent changes in height are genetic. The exact influence is unknown due to lack of large scale analyses. But even if the total is still small it doesn’t matter, that’s evolution baby

  5. Artem Kaznatcheev says:

    It may be linked to the ice age, with extra brain matter helping heat the head and keeping it all ticking along.

    This is hilarious! It is a great way to bring back Aristotle’s view of the brain as a radiator/general heating-control system. I always knew my head is nothing but a refrigerator.

    More importantly, where is that picture from?

    1. Adam Benton says:

      There are a bunch of LGM related reasons people have given for the larger brains Neanderthals (and humans) of the time. One is that larger brains generate more heat, keeping the whole affair warm whilst wandering around on ice sheets.

      I never thought of it as connected to that ancient Greek idea, but that’s brilliant. Like atoms and evolution, it turns out they predicted this! Although given it’s still quite speculative, they shouldn’t get too much credit for their prediction

  6. Jim Birch says:

    I think that the Attenborough comment has a bit of the evolution-as-progress conflation hiding in the background – the idea that evolution starts with bacterial blobs and through the fiery forge of selection ascended to the celestial height of modern humans. Eliminate those selection pressures and we begin to slowly revert to bacterial blobs. Nice quasi-religious story with a moral twang, but that’s not what evolution is, at all. For a start, only one case in a zillion has produced humans. What about the all other guys?

    Genetic evolution only stops when genes no longer influence success at procreation and there’s no reason to think that this has occurred. The fact that some historical selection pressures that have created modern humans have reduced or even disappeared does not imply that all selection is over. Only in the fiery forge story. Out there, niches have been changing relentlessly, selection pressures change, and species move on – or fall into the mud and fossilize.

    1. Adam Benton says:

      I don’t think he’s making that conflation because he doesn’t try and argue that the alleged cesation of evolution is a bad thing, that we’ll begin to slide “backwards”. In fact, he even goes out of his way to suggest that it isn’t negative because we’re continuing to evolve culturally.

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  9. Dave Patricks says:

    “Given living in large groups is likely one of the reasons our brains got so big there’s a strong chance that this new social development will also influence our brains.”

    I don`t really understand this. A strong chance? What would be the actual mechanism that causes this? The other examples you give living in large groups and brain development and humans being short and stocky during ice ages gives natural selection as the mechanism to guide these changes, what mechanism would guide this strong chance of change?

    1. Adam Benton says:

      The social brain hypothesis is one of the most well supported theories for why we have big brains. It posits that living in large groups is beneficial but cognitively demanding, so would act as a selection pressure for bigger and better brains; allowing for bigger and better groups. Living in todays culture is surely more demanding than any we’ve been in, so may continue to select for lager brains

  10. Ed says:

    Humans may be still evolving in a cultural, socail and mental way, but in terms of physical health and ruggedness of our species, we seem to be devolving.
    The ever present fear of the unknown that our species as in abundance, and the seriously overblown superiority complex we have in regards to the other species on the planet, lead us to believe that we should survive, no matter what the cost.
    This leads to our selfish, and uncontrolled expansion across the planet, severely altering and or down right destruction of the previous ecosystem; In the long run, this will lead to complications for ourselves. Also, because of the generally wide spread belief that every one of us must survive, we use medical technology to keep people alive, that woud be otherwise be long dead because of genetic abnormalities. If we had jsut left well enough alone, many if not all of these heriditary ilnesses would have vanished long ago.
    Basically, I believe that we are still enolving, just in the wron direction.

    1. Adam Benton says:

      Devolution isn’t really a thing. Sometimes traits or advantages are lost sure, but there’s some benefit to be gained by doing so. If you’re not using say, huge muscles, then freeing up the energy they would take to grow would be very useful. Evolution is a balancing act; and sometimes it subverts our expectations to stay on the highwire.

      1. Brandon says:

        Dysgenics, not devolution. There can be no evolution without reproduction. Before modernity, evolution worked favorably because the personal success of the (usually male) animal was almost interchangeable with its reproductive success. By contrast, in modern human society it’s negatively correlated! Successful people have fewer biological children, and some even choose to have none. Tragically, there’s no rational reason for the individual to reproduce. And when it comes to unintentional pregnancy, it’s more common among inept people. Also, population growth today is higher in underdeveloped parts of the world. The reason why average IQ scores are increasing is presumably environmental, coming ultimately from economic progress, but generational genotypic intelligence is probably decreasing. Not that intelligence is the only good trait that’s under threat, obviously: willpower, for example, is a big one. I don’t think that “evolution is smarter than you:” it’s effective, not efficient, and only at developing reproductively successful organisms, vestiges all over the place.

  11. Jurgen van Lunenburg says:

    You seem to give examples of how we evolved in the past and state they are proof we are still evolving. I do not see how this follows. I agree that physical evolution is probably ongoing, but to argue it there must be a clear description of a driving evolutionary pressure.
    One can not observe evolution in real-time, so we must predict based on evolutionary pressures. I don’t think starvation or tooth infections pose realistic pressures for the case of the jaw/teeth evolution. Nor does being taller help much with temperature control or our ability to gather food anymore. If you had mentioned a new, perhaps aesthetic, pressure that can drive evolution based on jaw or height phenotypes it would make more sense to me.
    The case for the better brain evolution is more coherent, as functioning in society does rely a lot on intelligence. Brandons point on intelligence being under threat is interesting, but numbers are not the only factor in survival of the fittest. Stability is also important. If lower educated people increase population faster, it comes with the risks involved with that growth such as food shortage, disease and social disorder. In economic terms rapid expansion is followed by strong contraction.

    1. Adam Benton says:

      Spotting evolution in action is difficult, if not impossible, but by looking for examples of recent changes in humans that occurred whilst we were living in similar “artificial” environments shows that such environments do not stop our evolution

  12. Haroon says:

    with due respect. man is still the same as he was 16 million years ago. you say that his diet has changed. what is it exactly has it changed to. before we were earting dinosours and now we are not? the same thing the “hunter gather” was eating is the same thing we are eating. there is no big change. man has not stopped evolving he never evolved in the first place. there no is no link at all between the hominids. JAW. HEIGHT. these are all trivial matters. evolution means something new. some new trait. you only talking about things that are already there.

    1. Adam Benton says:

      You’re not even wrong about that.

  13. Jax says:

    I did not evolve, neither did any human. Adam Benton is putting all his certainty into a theory that is, still a theory. It can’t explain why humans have media, language, and entertainment. Those things are not essential for survival. That is something to consider.

    1. Adam Benton says:

      Humans evolved to be intensely social animals; and that is necessary for our survival. Media, language and entertainment are all outgrowths of that. Language helps you communicate with more people, as does media. And being entertained with people helps reinforce social bonds, and is quite enjoyable to boot (we evolved to feel good about socialising, to encourage us to do it since it’s so important).

      However, all of that is I suspect a red herring. The existence of language, media and so forth isn’t the reason you’re skeptical of evolution. Now, whilst I’m very confident evolution is correct I’m perfectly happy to admit it could be wrong. Any scientific idea could be wrong. That’s why I go looking for dissenting opinions, like David’s, to ensure it hasn’t been disproven yet. So I’d be interested to hear what your real reason is; it might be quite compelling.

  14. gordon says:

    don’t forget how big our genetic pool is now aswell

    1. Adam Benton says:

      The gene pool of humans is, compared to other apes at least, relatively small. I think.

  15. Brian P Allen says:

    Oh course we are still Evolving and the hippocampus is too, it will probably be the tool used to transmit and receive signals when the time comes. But what signals? maybe human to human at close range or the simple frequencies that we 1st created with electronics. Something will happen weather it is that or something ells and when it comes we will know it. But to Evolution, it’s not only humans, we must also think of phones, computers, highways and all technology AND humans being the earths highest accomplishments of Evolution. We are a part of something much bigger than people, see from the roof of a 30 story building at night and visualize the energy as derived and related to the energy that evolved into the mass that allowed us a place to thrive. Circles, we are still going in circles just like the atoms we evolved from. To the store, to home, to sleep, to work, to the store, to home etc… humans are only a part of earths Evolution that is easier to see from the roofs of tall buildings in the middle of 5th ave. Look how far weve come from the climbing of trees and walking on all 4s. This is US ! we did it and though our power to survive is strong, it is still vulnurable and hell, we only have a hundred years to live before our worst vulnerability takes us one by one.
    Brian Allen

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