Evolving Thoughts

The nonsense claim about human evolution

Posted by John S. Wilkins on October 17, 2006
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There’s a really really dumb article getting a lot of attention in the media about the future of human evolution. Razib has a deprecating post about it, but I thought I’d add my two Australian cents (=0.006 US cents) worth.

Let’s look at the major claim: that humans will subspeciate. I can’t think of anything less likely among a species that has major gene flow between all its populations on a scale of thousands of generations. Species aren’t formed by selection for differing adaptive traits within a population, but by the interruption of the gene flow that is caused by migration or invasion between populations. Take a look at human gene flow over the past 10,000 years – massive amounts of interbreeding and invasive gene flow. Not a hint of the sorts of isolation required for a mammalian species to speciate in sight. Not even the Tasmanian aborigines, who were isolated for about 10,000 years. Not even the San or M’buti. Nada.

So why would we think that it will happen in the future? What possible “trend” is observed that could indicate this? The “genetic haves” are already among us – they are the people whose genes allow them to fight off certain pathogens like plague or HIV, those whose genes allow them to ingest dairy products when dairy industry is ubiquitous, those whose genes allow them to fight off malaria (but who become “have nots” when they are no longer in a malarial region, because the homozygotes die young). The entire premise of there being some sort of genetically privileged pure strain is biologically implausible.

What about the “reliance on technology reducing our ability to fight disease”? This is classical eugenics. The exact same arguments against medical treatment were made in the 1910s and 1920s. And it was false then, too. Medical technologies allow those who might succumb to some diseases to live, but that doesn’t affect our genetic constitutions all that much for (you guessed it) tens of thousands of generations. Is it likely that we will manage to maintain medical treatments consistently for that long – 30,000 years or so? On what possible reading of cultural history can we make that claim?

And what’s this “physical peak” we are supposed to reach? Where in biology is it written that any species has a “physical peak? Adaptive peaks are defined by the conditions in which a species lives, and if our environment happens to include the products of industrial and medical technologies, then that is what defines our “peak”. Evolution doesn’t aim for classical Greek ideals or the standards of Playboy. It in fact is generated by the environment and organisms’ behaviours, and if it turns out that your genetic fitness is best increased by being ugly, short and squat, to quote the Monty Python hymn, then that is where it will go.

This scenario is based on little biology and the idea that human society is the driving force of human evolution. Biology will surprise us – it cares nothing for the transitory fashions and institutions of human culture, except when that culture persists for a very long time or the influence on genetic evolution is striking (like the introduction of agriculture and dairy farming). That “damage”, if that’s how you want to see it, has already been done. We evolved resistance to a slew of diseases the hard way, and we will continue to do so. Medicine can ameliorate the impact, but not stop evolution in any way. The very idea that our immune systems will somehow deteriorate through lack of use shows how little this guy understands about immunology, epidemiology, evolution or history.

Articles and claims like this are responsible for a host of misunderstandings by the ordinary person about biology and evolution. The ideas it espouses were out of date in 1930. Even then, they were known to be wrong, but were still accepted by the uneducated. But to argue that there even could be long term trends that we can predict about evolution, when we don’t know enough about the boundary conditions of culture or the environment, and history, if it teaches us anything, teaches us that there are no certainties in history, is to make stupidity a virtue.

Now it’s entirely possible that Curry is in fact not saying any of these things, but merely speculating for a popular TV show, in which case everything I just said applies to the PR people and the journalists, but whether he said it, or not, the ideas are ridiculous, unbiological, unhistorical and implausible. Such claims make us all a little bit stupider.

Late note: See John Hawks’ smackdown too.

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Comments

  1. #1 Koray
    October 18, 2006

    How much time do evolutionary experts spending looking into the future? And then, what is the typical timeframe? 1000 years sounds awfully long for a complex system like our ‘species’ to make predictions.

  2. #2 John Wilkins
    October 18, 2006

    They don’t. Consider the variables: if there is a slight shift in temperature, prevailing winds or currents, a dust storm, earthquake, volcanic eruption halfway around the world, a major drought, an invasion by a pest species, a rare but enormously advantageous mutation, etc., anything could happen. Predicting evolution makes predicting the weather in 20,000 years look easy.

    However, under certain conditions – when only a few variables actually vary, as in the Galapagos Island study of Darwin’s finches by the Peter and Rosemary Grant, or the sheep on Soay – you can indeed make predictions based on prior knowledge. For next year or a few years after that.

    There is no phylogenetic impetus – nothing makes long term trends continue except external conditions and unanticipated mutations, and so extrapolations of the present into the future are rife with error. Which pretty much sums up futurology.

    But it may be, as I said, that Curry did not say this as a prediction (it would not surprise me – anyone who has done the slightest study would know all this). In which case we must expect that journalists are involved (he muttered darkly).

  3. #3 Larry Moran
    October 18, 2006

    From the article,

    Dr Curry believes humans will reach physical peak around the year 3,000, with improved nutrition and understanding of the human body. Men will reach average heights of between 6ft and 7ft. Physical features will evolve to emphasise features valued in the opposite sex by men and women looking for potential mates.

    Men will therefore have more symmetrical facial features, squarer jaws, and deeper voices. Women will have lighter skin, large clear eyes, firmer breasts, glossy hair, more symmetrical features and smooth, hairless skin. Variations in skin colouring are expected to be smoothed out, with most humans moving towards a brown tone.

    Further into the future the outlook is less rosy, Dr Curry argued, with humans declining physically thanks to excessive reliance on technology and medical interventions.

    Given a population of 6 billion and reasonable selection coefficients (e.g. s=0.1 or a 10% selective advantage) it will take way more than 100,000 years to fix any significantly “advantageous” mutations in Homo sapiens. The idea that there’s going to be significant adaptive evolution in only 1000 years is so stupid that one has to question the scientific competence of any scientist who puts forth such a claim.

    Imagine what would have to be happening right now in order for genes for firmer breasts to be increasing in the population at a rate significant enough to make a difference in only 50 generations (1000 years). First, there would have to be such genes and I don’t know of any evidence to support such a claim. Second, there would have to be millions of childless women with less than ideal physical features. You should be able to walk the streets of New Delhi, London, Brisbane, and Nairobi and encounter hordes of women with “soft” breasts who are unable to find a mate.

    Similarly, there should be huge numbers of men who will never be fathers simply because their jaws aren’t square. What kind of stupidity is this? Dr. Oliver Curry is a Research Associate in the Centre for Philosophy of Natural and Social Science at the London School of Economics. His main interest is evolutionary psychology. It’s no wonder that the field of evolutionary psychology has a reputation of being “really, really dumb.”

  4. #4 mark
    October 18, 2006

    You really think it worth bothering for anyone that one stupid man’s theory is good enough to judge some science he is claiming as the background of his idea?

    You think it is worth writing an article about that article at all?

    Or you have been paid for this one?

  5. #5 your mom
    October 18, 2006

    I think you should look at it in a positive light! Sure it was a dumb article, but at least it is saying that humans evolved and aren’t images of God or whatever. I don’t think anyone took that story seriously, I think of it just as an interesting “what if” scenario.

  6. #6 John Pieret
    October 18, 2006

    PZ Myearshertz, barely over gloating about his seeing Darwin’s worms when you didn’t, also had a whack at this piece of fluff:

    http://scienceblogs.com/pharyngula/2006/10/utter_nonsense.php

    But I’m just using that as an excuse to bring up this article from New Matilda

    http://www.newmatilda.com/home/articledetailmagazine.asp?ArticleID=1869&HomepageID=165

    that I strongly suspect is moderately (or above) clever if we ‘Merkins only had an Oznian to translate it. Oh, wait . . .

  7. #7 Steve Watson
    October 18, 2006

    The best (and I use the term “best” in a specific and narrow sense!) chance of H. sapiens speciating is if civilization crashes very hard, taking with it almost all of humanity and much of the ecosphere, leaving small bands of survivors scattered across different land-masses, eking out a bare existence in a devastated environment. Small groups, diverse environments, geographic isolation — the starting point for divergence. However, consider that back in the Stone Age, using nothing more than their own feet and the most primitive of watercraft, our ancestors succeeded over the span of a few dozen millenia in colonizing the entire earth, and yet without splitting into separate species. So conditions in the Next Stone Age would have to be desperate enough to discourage travelling (or at least ocean crossings) and stay that way for a very long time (like probably 100kyrs or more — Larry could probably suggest a ballpark figure). Seems like an unlikely combination of circumstances (and needless to mention, the outcome does not much resemble Curry’s speculations).

  8. #8 John Wilkins
    October 18, 2006

    That’s how I see it too, Steve. But if that happened, with small relict populations in, say, Patagonia or Siberia, what would also happen is that local variants would be sexually selected and local alleles would drift to fixation, thus undercutting the Morlock/Eloi “trend” Curry thinks obtains.

    Think of humans as if they were any mammalian species but us. What species would evolve into two subspecific variants like Curry suggests? Sans strong local adaptive pressures, I can’t think of one that would evolve the way he suggests. It’s stupid, and shows a complete lack of understanding of how speciation occurs.

    And skin colour, which is a trivial trait to evolve differently in local populations, tends to be based on latitude – witness the fact, as Razib noted, that it relies on 4-5 alleles, and can be modulated according to intensity of sunlight easily. Secondary “browning” of skin colour occurred in the Asian populations of India and Melanesia. Continual outbreeding didn’t change that much.

  9. #9 RPM
    October 18, 2006

    Species aren’t formed by selection for differing adaptive traits within a population, but by the interruption of the gene flow that is caused by migration or invasion between populations.

    Well, Dr. Wilkins, there are some people who think that species are formed by the interruption of gene flow AND differential selection between populations.

    But, yeah, this guy is an absolute moron.

  10. #10 John Wilkins
    October 18, 2006

    Yes, there are, but that is almost always associated with host race specialisation. I personally think that sympatric speciation is possible and probably even has occurred, but for the purposes of this particular species – us – we can leave it to one side as implausible.

  11. #11 John Not Wilkins
    October 19, 2006

    Surely we are all missing the point – speciation is already occurring.

    Yes, we could still interbreed with English football supporters, we simply choose not to.

  12. #12 John Wilkins
    October 19, 2006

    Sexual selection in action…

  13. #13 David Harmon
    October 19, 2006

    I’m with whoever (on another blog) theorized that this guy fell asleep reading H.G. Wells, and then figured a softporn channel didn’t deserve anything more creative on his part.

  14. #14 Neal
    October 20, 2006

    At this point I almost feel bad for this guy. If he had any serious interest in being taken seriously as an “evolutionary psychologist” he’s totally junked his reputation. Over an interview on Bravo…

  15. #15 John Wilkins
    October 20, 2006

    My original draft was much more scathing of Curry himself – untilit occurred to me that he was being quoted. Giving an interview like that is always a danger, but yes, he’s junked his professional reputation among specialists, and now probably will not get attention outside business schools.

  16. #16 Will Snyder
    March 29, 2008

    I think it is wrong for everyone to be attacking this man’s integrity.

    “Curry fully admits that the Bravo Evolution Report was a “think piece,” not a scientific study, and that its main goal was to introduce some basic evolutionary principles to a popular audience, not to foretell our ultimate fate.”

    http://seedmagazine.com/news/2006/10/i_cant_believe_its_science_for_7.php

    Even with the inaccuracies that were made, it isn’t his fault that the other media sources took it as an actual scientific report instead of an idea. Saying that Curry is a complete idiot is like saying Dougal Dixon actually believes that the species from After Man will really be the species of the future.