Open thread, 4/29/2013

By Razib Khan | April 29, 2013 2:47 am

What’s going on?

MORE ABOUT: Open Thread
  • Karl Zimmerman

    Is the referenced study confusing correlation with causation, or is there something to this?

    Seems like an odd idea, honestly. And I’m not sure about their underlying hypothesis – that too much genetic similarity makes societies too cooperative, and too little makes them too competitive. If anything, from what I’ve read the inter-group competition in Africa (at least among non-agricultural groups) was somewhat subdued compared to the New World.

    • razibkhan

      this is a debate between the population geneticists and the economists. who do you go with on this issue?

      • marcel proust

        Based on our forecasting record over the last half a dozen years (and what it says about our understanding of not just economics but statistics as well), I’d say the economists win hands down 😉

  • gwern seems like an interesting confirmation of genetics of intelligence.

    • razibkhan

      little confused. don’t have time to read the whole thing, but they don’t challenge the proposition that effect sizes at a given locus are going to be small, right? if so, then it might be harder to differentiate noise from true positive than they make out.

      • gwern

        No; this is something of a followup or replication of Davies, which you may remember was working with whole genomes of unrelated adults and finding that variation in intelligence was consistent with additive effects from many thousands of variants. As I understand it, this new paper works with twins and just SNPs and finds pretty much the same thing, and confirms the usual twin-based estimates of heritability.

        Which is good news, I think, since it’s more reason to believe that you just need more genomes or SNP data to finally start nailing variants (“Larger sample sizes alone will be sufficient to identify many of the genetic variants that influence cognitive abilities”). And it also is an interesting perspective on the IQ wars: so many people spilt so much ink explaining why the twin studies didn’t necessarily mean anything at all about the genetic contribution of intelligence and so weren’t good evidence – but when we actually start looking at the genes or SNPs directly…

        • razibkhan

          yeah, i get the follow up of the davies results. and i’m sure the SNPs are there. my question is will we be able to give 1,000 SNPs to explain 66% of the variation in a homogeneous population for IQ to an individual asking? we may able to say with a high degree of likelihood that a substantial # of those SNPs are related to IQ, but i’m not sure that we’ll have high confidence in any given SNP. what people want are “IQ genes.” not QTLs that are possible…. though you are correct that once we get into the millions of N’s who knows what the power will scoop up?

          • gwern

            Dunno. At least from the practical side, it’s fine if we can simply rank genomes since that’s all you need for, say, embryo selection (make 16 embryos, rank 1-16, implant #1, then #2, etc).

            I think somewhere in the paper they estimate that something like 100k SNPs ought to be enough to do a lot of identification; my personal question is how this affects the Beijing project since AFAIK they were only going to have like 10k participants…

          • razibkhan

            the beijing project, if i recall it correctly, isn’t sampled from the generation population. so it’ll look for SNPs which exhibit huge diff. between general and selected pop, so N need not be so big…

          • gwern

            I thought it was doing full genome sequencing, not just SNP genotyping? But yeah, that’s why I’m hoping someone like you or Hsu will weigh in and tell me what to think (and one reason I brought it up here): clearly they need <100k participants, but is it really as low as 10k?

          • razibkhan

            last i talked to steve he was cautiously optimistic. but i’d still say at this point unless you are working on the research and need to motivate yourself have a skeptical prior :-) plomin tends to be a bit more optimistic than steve, but steve has a better grasp of “the sums”.

            of course, we’re talking about this, while many ppl in anthropology are still ignorant of the heritability of IQ (or its non-zero value) from what i can tell….

  • Anthony_A

    There’s a series of posts about the evolution of language, from a linguist who’s fairly skeptical. First post is
    Worth reading if you’re at all interested in linguistics, and to give you a reality check on anthropological explanations drawn from linguistic “evidence”.

    Spoiler alert: The last sentence of his next post is “No single language, then; at any rate not in anatomically modern humans. We have always been multilingual.”

  • Robert Ford
    Is this study going against the popular (liberal) narrative of saying that “more education for women” is the key to curbing population? It seems like they’re saying that they real key is the price of raising a child. Somebody know?

    • Sandgroper

      You’re reading that differently from the way I’m reading it.

      “Economic factors — in particular, increased education of women and mass migration from agricultural villages to bigger cities — drove much of the fertility drop.”

      • Sandgroper

        It is interesting, though, that if you extend this model of demographic transition, the next logical step is a move in parental preference from boys to girls. Which happens.

      • Robert Ford

        Ok, I got ya. I was focusing on the part about demand for better educated children.

        • Sandgroper

          It looks like a feedback loop, rather than just simple cause and effect.

  • Riordan


    Considering your interests in history as a whole, have you ever considered being a historian, by any chance?

  • Chad

    Interesting paper:

    Recent human history is marked by demographic transitions
    characterized by declines in mortality and fertility [1]. By
    influencing the variance in those fitness components, demographic
    transitions can affect selection on other traits [2].
    Parallel to changes in selection triggered by demography
    per se, relationships between fitness and anthropometric
    traits are also expected to change due to modification of
    the environment. Here we explore for the first time these
    two main evolutionary consequences of demographic transitions
    using a unique data set containing survival, fertility,
    and anthropometric data for thousands of women in rural
    Gambia from 1956–2010 [3]. We show how the demographic
    transition influenced directional selection on height and
    body mass index (BMI). We observed a change in selection
    for both traits mediated by variation in fertility: selection
    initially favored short females with high BMI values but
    shifted across the demographic transition to favor tall
    females with low BMI values. We demonstrate that these differences
    resulted both from changes in fitness variance that
    shape the strength of selection and from shifts in selective
    pressures triggered by environmental changes. These
    results suggest that demographic and environmental trends
    encountered by current human populations worldwide are
    likely to modify, but not stop, natural selection in humans.

  • Dmitry Pruss

    R you posted Iz’s Over the Rainbow on the pinboard, and since it’s sorta offtopic there, I guess primes for an OT question :) Do you dance to it?

    • razibkhan

      no, not really.

  • Patrick Wyman

    I just finished reading Nature’s special issue on GMOs. It takes a refreshingly evidence-based look at the issue, and comes down firmly in their defense without acting as apologists for agribusiness.


    And coverage from Science Sushi:

  • Sandgroper

    This apparently boring, stupid and pointless piece is actually quite unwittingly interesting, not least because of where it is published:

    “Baby boomers have been mythologised as not just middle class but also white, and yet over a million Italian, Greek and central European migrants poured into Australia after World War II. ”

    I think ‘central Europe’ is meant to refer to the former Yugoslavia. So Italians, Greeks, Croats, Serbs and other sundry Europeans are not ‘white’ – which appears to be a code word for people of British/Irish ancestry (and possibly also Scandinavians, but there were so few of them they are irrelevant in this context).

    So the looming financial crisis in Australia is not due to all of the financially disadvantaged Anglos who poured into Australia after WWII, it was all of those dodgy off-white Europeans who did it, never mind those who had the sheer bad taste not even to be off-white Europeans, despite the fact that those groups have been notably relatively financially successful.

    Note this was published by the Australian government funded news organisation – not ABC in the USA, but the Australian Broadcasting Commission.


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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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