Skip to content

The Fenimore Cooper of sociobiology

Oddly enough, I’ve received two unrelated emails attaching articles shooting down hypotheses of the notorious Satoshi Kanazawa: a paper by Kevin Denny in the Journal of Theoretical Biology:

Recently Kanazawa (2005) proposed a generalization of the Trivers–Willard hypothesis which states that parents who possess any heritable trait that increases male reproductive success at a greater rate than female reproductive success will have more male offspring. . . . This note shows that analysing the same data somewhat differently leads to very different conclusions.

and one by Vittorio Girotto and Katya Tentori in Mind & Society:

According to Kanazawa (Psychol Rev 111:512–523, 2004), general intelligence, which he considers as a synonym of abstract thinking, evolved specifically to allow our ancestors to deal with evolutionary novel problems while conferring no advantage in solving evolutionary familiar ones. We present a study whereby the results contradict Kanazawa’s hypothesis by demonstrating that performance on an evolutionary novel problem (an abstract reasoning task) predicts performance on an evolutionary familiar problem (a social reasoning task).

These, on top of other debunkings of this work by Volscho, Freese, and others, makes me think that Kanazawa is actually serving a useful role in the fields of biology and sociology by evoking such interesting rebuttals.

P.S. I probably should stop bringing this stuff up–it’s just that I got those two emails one right after the other. As David Weakliem and I discuss in our paper, Kanazawa’s work is not particularly interesting in itself except as an example of genuine statistical challenges that arise in the estimation of very small effects. Basically, the multiple comparisons problem in action, but with a twist in that Kanazawa has been successful enough at getting his ideas out there that he’s attracted debunkers. Presumably, there’s lots of stuff like this out there in the scientific literature that nobody even notices. In studying these problems, I’d like to think that I’m contributing to the search for better methods of estimating small effects, not simply making fun of the errors of non-statisticians.

It’s also interesting to me that biologists and economists seem to fall for this stuff, while sociologists and psychologists see the flaws right away. Presumably because sociologists and psychologists have lots of experience studying small effects in the context of individual variation.


  1. Cosma says:

    No links to the papers?

  2. Andrew says:


    Denny's article is in Journal of Theoretical Biology 250 (2008) 752–753.

    Girotto and Tentori's is in Mind & Society (in press).

    The articles were emailed to me and I'm not sure if it's ok to post them.

  3. Jack says:

    It's a bit flippant to state: "…biologists and economists seem to fall for this stuff." I see that Kanazawa's work is published in biology journals, but economists are for the most part very well trained in stats/econometrics.

  4. Andrew says:


    I was flippant only because I don't exactly know how to be "snarky" . . . Seriously, though, I agree that economists are serious about statistics. But here I'm actually talking about the substance of Kanazawa's claims. Some economists (and some biologists, too) are suckers for this sort of "schoolyard evolutionary biology"–the idea that boys are different from girls in some area because of what life was life when we were swinging in the trees, running away from saber-toothed tigers, etc. I think that a lot of economists and biologists will suspend their natural skepticism and just accept such results. It's my impression that, in contrast, sociologists and psychologists, perhaps due to their experience with studying individual variation, are more aware of the potential problems in this sort of research.

  5. statisticians, sociologists, and psychologists seem to have their own blindspot when it comes to discussing statistics and race/phenotype/ethnicity. Not that any other discipline sees more clearly, but I think it's perhaps a stronger mythology that succeeds in turning more of us into stakeholders. Thus obviously messy and incoherent realities about race, phenotype, and ethnicity are force fitted into narratives and the discussion tends to be focused on justifications of the force-fitting without any kind of dissent. I'm thinking about the lack of studies that look specifically at a spectrum of skin color and/or a spectrum of ethnicities without race as a reduced categories proxy.

  6. Mitchell Young says:

    I am pretty sure that Kanazawa is a sociologist by training. As for the attention and 'debunkings', that is no doubt due to the his subject, differences in intelligence between population groups. He is working in a taboo area and so there are an army of 'debunkers' awaiting.

  7. RLWemm says:

    There is theoretically no reason why some operational definition of "intelligence" could not be a heritable trait in an isolated race of people. There are still some of these around.

    There are some studies which support this notion but the "intelligence" they speak of is not the K-12 success predicting kind.

    The biggest problem in this area is that any findings that suggest racial differences in the K-12 predictive type of intelligence are undermined by racists using this as a reason to abuse and discriminate against individuals who have any connection to that race at all.

  8. Andrew Gelman says:

    Mitchell: There is an army of debunkers because Kanazawa repeatedly makes mistakes and follows up by not acknowledging his mistakes. He also has a knack for getting press attention. Newspaper coverage + mistkes in print = easy debunking. To put it another way, just because something is "taboo," that doesn't mean it's correct.

    RLWemm: You may be right here. One could certainly argue that shoddy researchers harm their own cause as much as anything else. My impression is that there is a lot more signal and a lot less noise in the psychometric data (intelligence tests and the rest) than in the sex ratio data. But I think it will be up to better researchers than Kanazawa to make the case.