Are we still evolving….

By Razib Khan | March 1, 2011 1:23 pm

The question whether humans are still evolving is something that crops up now and then. If the story is British you know that the evolutionary geneticist Steve Jones will be approached for his obligatory quote. There’s apparently going to be a program today in Britain about continuing human evolution. You can already watch it online if you are British. In any case, there’s at least going to be some balanced treatment if this BBC story is representative. Two quick points which I think need to be emphasized:

– When we talk about natural selection there’s too often a focus on nature. Exogenous shocks. A lot of intra-specific competition occurs between individuals, without nature intervening. Jacob Zuma has 20 children. Barack Obama has 2. If there are some differences in inherited trait values, then there’s some selection going on right there.

– Steve Jones likes to point out that death rates are low today compared to the historic average. But we’re ignoring that ~2/3 of fertilized eggs are subject to spontaneous abortion. There’s probably natural selection going on at this stage, and it may be that as more and more genetic load accumulates in human populations due to lack of death and, later conception and gestation, the miscarriage rate will increase concomitantly in a classic pattern of mutation-selection balance.

A major difference between classical physics and biology is that because of evolutionary adaptive processes biology’s parameters are protean. We may talk today about the end of natural selection, but the specter of infectious disease looms larger and larger with every coming year due to the rise of resistant bacteria. The Red Queen’s race is still on.

MORE ABOUT: Genetics
  • Blackbird

    I just watched it. Far too much Steve Jones in it and too little – in fact none – John Hawks. Steve Stearns was in it. No mention of spontaneous abortions. Anyway, it could have been worse, the conclusion, despite SJ was that yes, we are.

  • Zachary Kurtz

    People can’t think abstractly about evolution on a long enough timescale. This leads to two general conclusions: people have stopped evolving OR that evolution isn’t bunk.

    I think the “people have stopped evolving” crowd have a point, from a certain light. Migration and “intermarriage” dilute the potent founder effects that once was a bigger deal for small isolated populations. Negative selection pressures are eased by modern medicine.

    This seems to leave sexual selection as the dominant selection force: of course, it always was one.

  • Zachary Kurtz

    oh and PS – since when do serious biologists not consider inter-species competition as crucial part of natural selection. Hell, that’s what competing for resources *means*!

  • Razib Khan

    I think the “people have stopped evolving” crowd have a point, from a certain light. Migration and “intermarriage” dilute the potent founder effects that once was a bigger deal for small isolated populations. Negative selection pressures are eased by modern medicine.

    1) we’re talking about selection here. so founder effects are arguably less important , and i’m not sure if that’s even relevant. there is a line of thinking which argues that interconnected populations will experience more natural selection because they have more genetic variance to draw upon.

    2) as i point out above, increased miscarriage rates could be exactly that hidden “negative selection pressure.” we might have just stuffed a lot of it in utero.

    This seems to leave sexual selection as the dominant selection force: of course, it always was one.

    i think this is highly disputable. i.e., whether it was that important (perhaps it is, perhaps it isn’t), or, whether it is the dominant force (this i’m rather skeptical of). in many ways the distinction between natural and sexual selection is one that i think confuses a lot more than it illuminates, but it seems to be accepted, so i’ll go with it….

    since when do serious biologists not consider inter-species competition as crucial part of natural selection. Hell, that’s what competing for resources *means*!

    it isn’t biologists who are the problem here, but the public. they think of adaptation to climate and such, because they’re salient and so easy to connect causally.

  • pconroy

    Right now with more women being educated than ever – in the West especially – there is obvious selection for the ability to have children at more advanced years.

    In terms of the recent past past, I read Peig Sayers autobiography of life on the Blasket Islands – off the South West Coast of Ireland – where she worked as a servant then married a fisherman, and was struck by the fact that out of 13 live births, only 4 children survived to adulthood. She was born in 1873. I contrast this with my own grandmother, born the same time but to better circumstances, who out of 13 live births, had 12 survive to adulthood…

  • Shecky R.

    Wow, I don’t follow all the evolution debates, so had no idea there even existed a “human evolution is over” crowd — am flabbergasted! (…they actually have science degrees!??) Ya know in chaos theory the flapping of a butterfly’s wings affects the weather 6 months later, half-a-world away; similarly, in evolution (or natural selection if you prefer) the variables operative are so multitudinous, complex, immeasurable, (and even undefined, and yes, chaotic) that we remain in a very primitive stage of understanding it… despite our hubris.

  • ohwilleke

    A point John Hawks likes to make is that mutation rate is a function not just of how many generations pass, but of population size. If selectively beneficial mutations are rare, a large population is more likely to produce them in a given number of generations than a small one. Small, isolated populations can be somewhat ill suited to their environment but fail to evolve because they don’t get lucky enough to wind up with the mutations that they need.

    * * *

    The Zuma example is something of an exception that proves the rule to another long term trend. While the rich are more fabulously rich than ever before in history (about half of the wealth of the United States is owned by one percent of the population and modern society has a great deal of wealth), the reproductive advantage that accures from a position at the top of the social pyramid has steadily declined.

    From antiquity it was the norm for powerful men to have many children, something that gradually declined but still persisted until as recently at the 19th century in England and in the Ottoman Empire, when it was still relatively common for aristocrats and members of the upper middle class to have large passels of bastards (not infrequently with maids who were their servants). Now, Italy’s prime minister faces a looming criminal prosecution for his affair with teenaged girl, President Clinton faced impeachment proceedings over a lie about a White House blow job with an intern, and sexual harassment lawsuits against mid-level to senior business managers are not uncommon, and the only rich guys with really large numbers of descendants are Arab monarchs. There are a few outliers of powerful Western men with large numbers of children in Hollywood (Steven Speilberg, for example), but even then, adoption is a bigger factor than procreation. In general, the Forbes 400 don’t have vast numbers of heirs ready to share in their loot.

    Wealthy American men still want beautiful young women as trophy wives, but the social reality today (my neighborhood is an epicenter of Mountain State trophy wife society), is that these men aren’t interested in reliving fatherhood, make their desires clear, and their young second wives are willing to make this sacrifice.

    In biological terms, for whatever reason, modern populations no longer provide large genetic fitness premiums for being powerful.

    Perhaps this is because, in larger organized societies, qualified leaders able to handle extreme levels of responsibility are no longer a scarce resource because each exceptional leader can preside over a much larger governmental or business organization. Mayors of medium sized cities preside over populations larger than the entire Eurasian population in the Out of Africa era, while having far less power (and hence far less capacity to deeply screw things up). People who would have been likely candidates to be justices of the U.S. Supreme Court in the Colonial era when there were three million people in America now face such a crowded field that they are lucky if the manage to become judges on an intermediate appellate court in a state court system, with two layers of their betters between them and last word authority on American law. The kind of people who might have been name partners of nationally prominent law firms (like Abraham Lincoln, who was a railroad lawyer) in the 19th century, are now lucky to be one partner of many in firms with thousands of lawyers. A few thousand CEOs control the vast majority of the U.S. GDP, and our society will continue to do fine even if people qualified to be CEOs of economically critical enterprises are literally ten in a million individuals. Who knows what you have to do to become a nationally prominent figure in China or India? Our society needs lot of competent people, but not nearly as many true alpha dogs as it once did, as a percentage of the population.

  • John Hawks

    too little – in fact none – John Hawks

    Interesting story, that. The producers were very nice and I talked with them several times. I suggested Stearns, and I’m glad they followed up on it, that was the direction they really wanted to go with the documentary. In the end, I think that they really wanted to accentuate the “now and future” evolution, and not the “last 10,000 years” angle.

    I think there is some interest in following up next season with some similar stuff. That or Neandertals.

  • John Hawks

    You know what would actually be a hoot for a documentary?

    What if we ran SNP chips on several people who study Neandertals, and I tell them which Neandertal parts they have, all in front of the cameras.

    That would be so much fun!

  • Razib Khan

    not sure trinkaus would be game for that :-)

  • Justin Giancola

    John Hawks loved your discussion of brains size shrinking.

    Ever coming to Pittsburgh?

  • John Hawks

    not sure trinkaus would be game for that

    Oh, such an evil thought…

  • Markk

    Couldn’t we point to fairly major changes in gene frequency over the whole human population even in our lifetimes? I am thinking about the ratio of people tolerating lactose to those not, and perhaps Vitamin D utilization. I would think since 1900 these ratios in the whole human population have changed quite a bit. Would you call that drift or signs of selection? Are these kinds of shift due to massive non-homogeneous population increases and changes in reproduction rate not signs of evolution?

  • AG

    Have you all heard The Darwin Awards? Evolution is on going. With changed enviroment like industrialization, information age ect, selection will always favor those who fit in the new enviroment. Also evolution by no mean always give you smarter brain. Wale evolution make them lost land moving ability. Human might evolve back to monkey, which might fit new enviroment better. Evolution means change. Change is the rule of this universe.

  • Eleanor

    It’s funny how Western focussed this question always is. I don’t think anyone would question that some population in sub-Saharan Africa are under intense selection (e.g. HIV epidemic, anyone?).

  • Laban Tall

    I can’t understand why people who worry about (say) global warming don’t worry about drug-resistant pathogens – and particularly about the worldwide agricultural practice of routinely adding antibiotics to animal feedstuffs. Don’t a lot of human diseases originate with animal disease?

    As I understand it, they’re not discovering effective new antibiotics the way they used to.

    You cut your finger. Three days later it’s swollen, and the infection’s spreading up the hand to the wrist. Antibiotics sort it in a week (but you take the whole course). Imagine going back to the pre-penicillin days. Not nice.

  • Dunc

    I can’t understand why people who worry about (say) global warming don’t worry about drug-resistant pathogens – and particularly about the worldwide agricultural practice of routinely adding antibiotics to animal feedstuffs.

    We do. That precise concern is one of the major arguments in favour of organic agriculture.

  • dave chamberlin

    The million dollar question is when and how we evolved advantageous brain function. I hope I live long enough to see this can of worms opened up. I would get great satisfaction from seeing the look on the face of the disbelievers in evolution when they finally realize that not only is evolution real, they are next.

    It is all rediculous speculation to think that Moore’s Law will work it’s magic in genetics as it did in computers and all those tiny Stooge Effects that gave small bumps to better brain function will be isolated and placed in a 47th chomosome before a fertilized human egg starts dividing, right?

    Just fun stuff to think about…. for now.

  • daw

    “Perhaps this is because, in larger organized societies, qualified leaders able to handle extreme levels of responsibility are no longer a scarce resource because each exceptional leader can preside over a much larger governmental or business organization.”

    Can’t agree that there is much evidence that current larger populations have blessed us with a greater number of exceptional leaders.

  • pconroy

    Call me skeptical, but “Organic Farming” is just marketing hype to sell the gullible types higher priced food, and have them feel good about themselves at the same time. No farming can be totally organic for long, as disease would wipe out crops, unless the farmer were to use a crop rotation strategy – which they don’t, ergo they are not organic. Plus, organic farming can’t possibly feed the billions, as it’s not productive enough. So wake up to reality.

    Global Warming and Global Cooling occur in cycles, and we are currently long overdue a COOLING cycle, which has probably been defrayed in part by the emission of industrial gases. It’s laughable that people talk about climate in terms of years/decades, when it can only be evaluated by the centuries/millenia…

  • Dunc

    No farming can be totally organic for long

    We did it for 10,000 years. We’ve been doing so-called “conventional” farming for about 60 years, and in that time we’ve managed to massively deplete our best soils, massively deplete our major aquifers, and develop some really amazingly dangerous new pathogens. Thanks, but I think I’ll go with the system with the longer track record.

  • Razib Khan

    for most of those 10,000 years the human population was under 500 million.

  • Sandgroper

    “I think I’ll go with the system with the longer track record.”

    You plough by hand?

    ‘We’ developed some really amazingly dangerous new pathogens when ‘we’ domesticated animals. Great system.

  • Dunc

    for most of those 10,000 years the human population was under 500 million.

    Sure. And we were farming vastly smaller areas, with much poorer techniques, inferior crop varieties, and absolutely no idea how any of it worked. Unfortunately, the need to feed much larger numbers does not make the issues of soil erosion, aquifer depletion, and the obvious risks of massive prophylactic antibiotic use in high-intensity livestock operations magically disappear.

  • dave chamberlin

    I tried shopping at Whole Paycheck grocery store, once.

  • pconroy

    I’ve no intention of getting into an argument with a religious person like yourself – as I don’t do religion myself.

    Having said that, the only way to farm organically, without crop rotation, would be to plant a mix of legumes, cereal crops, trees, weeds, root crops ALL TOGETHER in the one area, so that the nitrogen fixing of the legumes would offset the nitrogen extraction of the cereals and so on – nobody but nobody does that. If you are buying organic grain, and being told that all the grain is grown organically over a period of years in the same field – then you are being sold on a lie.

    Likewise organic milk=milk from cows that are not treated with BST (Bovine Stimulating Hormone) and a few medications, but that doesn’t stop the farmer giving his cows many other medications.

    Like it or not Organic farming is largely a marketing strategy. What’s even funnier is that China has plans to go into “Organic Farming” in a big way 😉

  • Durant S.

    Interesting article, followed by equally interesting comments ! As human thought developed, it probably appeared self-evident to many that homo sapiens was a special creation. I think that this is a rather arrogant position in view of the history of other life forms on earth. It would be nice if we evolved into a form that could, in a couple of million years (a blink of the geologic eye !), remember our culture and be able to compare it and our fossilized remains with those of the then present-day humans … assuming that we do not pass into extinction in the interim.

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  • DavidB

    I saw the programme. Not bad overall. I thought it was going astray half way through, when Steve Jones was saying (basically) that human evolution has recently come to a stop because nearly everyone now survives to adulthood, and the presenter (Alice Roberts) seemed to buy this. But a few minutes later Alice said, quite correctly, that even if differential mortality is no longer important (unless new infectious diseases emerge), there could still be evolution through differential fertility. That led into Stephen Stearns’s research, which I wasn’t aware of – very interesting. The programme also explictly rejected the ‘race is only skin-deep’ meme.

  • annette Shippam

    I found the programme about humans and evolution most interesting .I have a question about the Sherpas. If someone was to move down to a “normal”atmosphere would that person suffer in the same way that most of us suffer at great height?
    Also a comment
    I was a primary school teacher for 40 years. I lived for 12 years in Hong kong where I taught in the schools for British armed services schools. It was exactley the same as being in a local Primary school nexcept that we had other Western European children of many Nationals they all seemed able to learn or pick up Enlish much easier and quicker than we Britishers pick up other languages. To get to the real pointof my observation. It was seeing very young Chinese Chidren 4or5 years old outside their makeshift homes doing their homework.Yes even those tinies had homework! The most amazing thing was that they could manage to form the most intricate Chinese Characters and write them in books of tiny squares (no bigger than were used for Arithmetic in the 1930’s )I never came across a European child who had that moter skill at 4or5 ,to accomplish such neat small caligraphy. Our 5 year olds have a job to form our letters when first introduced to writing. Do the experts think that generations of Chinese people have evolved their moter skills at an earlier age and is that a form of evolution?

  • Stewart Murray

    I’ve never written to complain about a poor Horizon program. This was a poor one. All the information could have been put into less than 30 minutes. I don’t find Alice Roberts’ voice easy to listen to. Whether it’s her inflexion or accent I’m not sure. Nevertheless she was enthusiastic and built up excitement for the next shot but she had no back up from the production team and her build-ups ended in a flop.

  • miko

    pconroy, I agree that “organic” is a marketing term, and the criteria for being allowed to use it are somewhat arbitrary. (Your very strict criteria for “organic” are just as arbitrary–there is no “natural” agriculture.) However, there is a spectrum of farming methods that are more or less harmful to the environment in terms of pollution and resource use, or present more or fewer health hazards to humans. “Organic” is an imperfect label and probably getting worse, but I would bet on average things marked “organic” do better than those that aren’t on that spectrum.

  • Strangetruther

    I attended a Steve Jones talk 18 months ago, and he seemed to be saying pretty clearly we hadn’t stopped evolving. But the BBC programme seemed to say we had. (Steve’s pretty good on TV but much more impressive ‘live’.)

    I strongly suspect a lot of Chinese etc fast development/academic ability shows strong support for the principle of early training.

  • Sandgroper

    #30 – My daughter started attending a Chinese kindergarten in Hong Kong at age three and a half. At that age the kids were starting to learn English and how to write Chinese characters. So by the time they started primary school they already had some skills.

    When she started at the kindergarten she spoke only English. One year later she could also speak fluent Cantonese, and she and her little Chinese pal that she played with every day had also developed their own private language.

    My daugher had to attend an interview b0ard of adult teachers (by herself, without her parents in the room) at age four to get into the primary school she attended. My wife and I watched through a window from outside the school. She was seated on a little stool in front of 5 -6 adults sitting at a long bench. They were asking her questions and she was answering. At one point my heart froze because she carefully lifted up the hem of her skirt and put it over her head, concealing her face (and thereby exposing her knickers to the interview board). I don’t know what impression that made on the board, but she passed the interview.

    By age four and a half she was attending primary school and coming home with homework every day. No big deal. I was learning to write Chinese characters at the time, so I decided she and I could learn together. Forget it, within 3 months she had left me far behind.

    She’s half Chinese, half northern European with some minor amount of Australian Aborigine, so I can’t say what effect genes might have, but I’d say early training is a more obvious answer, having factored in that she has a high IQ, quite a bit higher than either her mother or myself, which is somewhat lucky.

  • Liz

    I was wondering if someone can explain the segment on milk – regarding lactose tolerance/digestion being selected for. As far as I know, raw (unpastuerised) milk contains the enzyme lactase, which breaks down lactose, and, also, as far as I know, routine pastuerisation of milk (which destroys the enzymes) is a very recent development and there’s still plenty of populations around the world where milk is consumed raw.

    So, my question is, how would lactose tolerance (production of lactase in the digestive system of humans) need to be selected for when lactase was present in the milk? Hoping someone can clear this up for me, thanks!


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About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at


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