Diversity: In For A Penny, In For A Pound

There’s a lively chat going on over at Mangan’s about how people react to the growing body of data about the diversity of various human groups with regard to IQ and general intelligence. That such differences actually do exist is at this point uncontroversial amongst those who study psychometrics, but it is of course a radioactive topic in public discourse; in Guns, Germs, and Steel, for example, Jared Diamond ruled it off-limits as a “loathsome” explanation for the differential success of various groups. That human groups vary in conspicuous ways is a plain fact — nobody would have any trouble, say, sorting out a mixed group of Afars and Inuits, no matter how thoroughly you jumbled them up — but to suggest that long-separated populations, developing in very different environments, may have systematic cognitive differences as well is to violate a strongly defended taboo. And by making such a suggestion, no matter how sensible it may be, or how well supported by evidence, one invites the nastiest sort of opprobrium. (Indeed, I have no doubt that some of you are forming dark, excommunicatory thoughts about me as you read this.)

Even highly acute minds can shut right down when this topic comes up. Because such diversity would be, for many, an intolerable fact, a common move is to deny the impartiality of the measurement, or — in an even more audacious rejection of reality, and of the evidence of our own experience — to deny that the concept of “intelligence” actually corresponds to anything real in the first place. As an example of this, here’s a column by David Brooks from a few years back. Read it first, and then read this point-by-point demolition of it by Alex B. over at Gene Expression.

As for why there should be such diversity of IQ amongst various groups, various suggestions have been put forward; perhaps the most compelling is the idea, presented with clarity and rigor in Michael Hart’s Understanding Human History, that adaptation to agricultural life in temperate zones — which requires careful planning and technical innovation in order to survive cold winters — creates a selection pressure in the direction of higher intelligence.

Critics of such views often insist that group differences in average intelligence, to the extent that they are real, must be the result of cultural influences: poverty, racism, and so on. There is no doubt whatsoever that these are important factors, that exert a significant influence. What is often overlooked, however, is that biological and cultural evolution are far from separate processes, and that they are often tightly connected.

In his book Apes or Angels?, Cornelius Troost cites the Ashkenazi Jews as a particularly instructive example of this. The Ashkenazis have among the highest IQs of any human population, and the reason appears to be due to a process of cultural pressure that in turn led to selection at the biological level. We read [p. 146];

Gregory Cochran, Henry Harpending, and Jason Hardy found that Yiddish-speaking Jews from Germany, France, and Poland were discouraged from any occupations except money-lending and tax collection. These occupations required high intelligence, especially in mathematics. From 800 A.D. to 1700 A.D. they served as the financial experts in these societies. Since they were also a self-contained population reproductively, they were subject to … selection which removed genes detrimental to success in those restricted jobs.

There is no doubt about the superiority of Ashkenazim in IQ. They are 3 percent of the US population but have won 27 percent of its Nobel prizes. They account for half the world’s chess champions. They are 20 percent of the professors at our major universities. The Ashkenazim are greatly overrepresented in the winner’s circle of the esteemed Fields Medal in mathematics.

On IQ tests the Ashkenazim score some 12-15 points above the white mean of 100 in the US. While this difference is impressive, at the upper end of the bell curve one out of 70 Ashenazim score above 145 while only one out of 700 white gentiles do so. About one-fourth of all white Americans above 145 are Ashkenazi Jews.

This is a remarkably salient result, made so in particular by the high reproductive isolation of the Jewish people.* If you had wanted to design an experiment to try to cultivate high intelligence, you could hardly have concocted a better one. And note that although the shaping influence was entirely cultural throughout — restriction of Jews to particular occupations, together with self-imposed reproductive isolation — the effect, after centuries, is now innate: Ashkenazi babies are born smart.

“Well,” you may object, “even if all of this may be true, why bring it up? It serves no purpose but to further divide and stratify an already tense and factious society. There’s nothing you can do with this knowledge, after all, other than to discriminate against people.”

The answer to that is that as matters stand, we do not proceed from an agnostic stance on this topic. We have already staked out a position — that all human groups are necessarily exactly identical as regards cognitive faculties — and it is one that entails enormous costs, in particular with respect to stubborn “achievement gaps” that we insist must be closed no matter how vain the effort, or ruinous the expense. It is increasingly clear, however, that this position appears to be at odds with reality — so the only recourse is either to perform ever-more-painful social and intellectual contortions to defend it (including harsher and harsher censure of those who insist on looking at the facts), or else to do the hard work of accommodating this knowledge in a just and compassionate way, by realizing that the aim of a just society simply ought to be the fair and equal treatment of all, as individuals, under the law: a goal that should in no way require the political suppression of facts, however unwelcome they may be. As Steven Pinker wrote in The Blank Slate, such thinking “elevates sappy dogmas above the search for workable solutions.”

Well, it appears that some of my more liberal-minded Park Slope neighbors have already gathered outside with a cauldron of pitch and a bushel of feathers, so that probably ought to be all for now, I think. Somebody’s at the door.

* Note: In the original version of this post, I quoted an erroneous statistic that said the current rate of Jewish intermarriage was 0.5%. This appears, clearly, to have been quite wrong. I apologize for my carelessness.

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  1. gcochran says

    “even now their rate of procreation with non-Jews is a fantastically low 0.5% ”

    Of course that is not so. Intermarriage rates today are pretty high, more like 50% in the US.

    Intermarriage was very low in the past. Not now.

    Posted February 22, 2010 at 3:17 am | Permalink
  2. Kevin Kim says

    Sounds as if we need to start linking to sources before we get into a statistics debate.

    From this site:

    Intermarriage rates are increasing dramatically:

    Before 1965, 10% of Jews who married, did so outside the faith.

    Since 1985, 52% of Jews who married have done so outside the faith.

    How legit is the above site? No idea. But it was the first result when I typed “Jewish intermarriage statistics” into Google.

    From The Jewish Federations of North America:

    Since 1985, the rate of increase in intermarriages has slowed as intermarriage levels have stabilized in the mid-40% range. Among Jews whose marriages started in 1985-90, the intermarriage rate is 43%. The intermarriage rate is also 43% for Jews whose marriages began in 1991-95. Jews who have married since 1996 have an intermarriage rate of 47%.

    From an About.com: Judaism: “Snapshot of American Jewry” article:

    The rate of intermarriage is rising, but at a steady pace, with 47 percent of today’s Jewish newlyweds marrying non-Jews. This is a 4 percent increase from 1990.

    Malcolm, does the “0.5%” stat refer to all Jews everywhere in the world, to Jews in America, or specifically to Ashkenazim in America? The above-linked references all seem to be talking about the US or about North America as a whole.

    An Australian Jewish resource says:

    INTERMARRIAGE among Jews is on the up around the world -– with Australia’s rates hovering around 25 per cent, according to new research.

    Posted February 22, 2010 at 3:39 am | Permalink
  3. Malcolm says

    Hi all,

    I was clearly careless in quoting this statistic. I had assumed that it referred to Jews worldwide, and I agree that it does seem very low for America. You are quite right to ask for confirmation of this, and I will try to find it; if I can’t I’ll let you know.

    Whatever the current rate, the reproductive isolation of Jews throughout the past has certainly been very, very low.

    Posted February 22, 2010 at 10:13 am | Permalink
  4. Malcolm, If you haven’t read “The Red Queen” yet, I am certain you will enjoy it:


    Posted February 22, 2010 at 10:16 am | Permalink
  5. Malcolm says

    Another point: because something like half the world’s Jews live in North America, clearly if the intermarriage rates are as high as they are here then the overall rate, it seems, would have to be higher than 0.5 percent.

    I am going to amend the post; the current rate is not relevant to the point being made anyway.

    Thanks for keeping me honest.

    Posted February 22, 2010 at 10:21 am | Permalink
  6. bob koepp says

    “We have already staked out a position — that all human groups are necessarily exactly identical as regards cognitive faculties.”

    Well, who has actually staked out such a position? I know that a few people have taken a more qualified view, to the effect that _the law_ does not discriminate between “normal” and “super-normal” intelligence. Is that objectionable?

    Posted February 22, 2010 at 11:07 am | Permalink
  7. Malcolm says

    Hi Bob,

    I know that a few people have taken a more qualified view, to the effect that _the law_ does not discriminate between “normal” and “super-normal” intelligence.

    Certainly that is not objectionable. But would you not agree that the position I mention — that any difference in group-level outcomes in education, careers, etc. must be due entirely to cultural inequities, and therefore remediable by social intervention — is deeply entrenched orthodoxy in government and academia?

    Posted February 22, 2010 at 11:16 am | Permalink
  8. bob koepp says

    Malcolm –
    I’m not sure what counts as a “deeply entrenched orthodoxy.” I remain hopeful that PCness is not very deeply entrenched, but more of a passing fad, albeit one that causes much unnecessary suffering and which, consequently, should be vigorously opposed. In any case, I think the way to combat sloppy thinking is with nuanced thinking — not more sloppy thinking.

    Posted February 22, 2010 at 1:40 pm | Permalink
  9. Malcolm says

    I’m not sure what counts as a “deeply entrenched orthodoxy.”

    Well, if anything does, this does, I’d say.

    In any case, I think the way to combat sloppy thinking is with nuanced thinking — not more sloppy thinking.

    I’m not about to disagree with that.

    Posted February 22, 2010 at 2:16 pm | Permalink
  10. the one eyed man says

    I agree with everything you write. The facts are what they are, not what people wish them to be. If there are bona fide differences in intelligence between races or ethnicities, so be it.

    However, you avoided the truly explosive question. Are there gender differences in intelligence? If so, what then?

    Posted February 23, 2010 at 11:16 am | Permalink
  11. There are indeed gender differences in intelligence, namely a wider distribution among men as compared to women, i.e. there are more really stupid and really smart men than women. Mentioning the possibility got Larry Summers fired from Harvard.

    Posted February 23, 2010 at 11:38 am | Permalink
  12. Malcolm says

    Thanks, Peter.

    I don’t know that the gender issue is any more explosive than the racial one, but as as far as I know the difference generally seems so far to be that males have a flatter distribution, with more individuals out at both ends of the curve. The mere suggestion that this might be why there are more men in the elite ranks of the sciences is what got Larry Summers pilloried at Harvard; the notion that there might be any systematic cognitive differences between men and women was blasphemy, and not to be tolerated.

    Posted February 23, 2010 at 11:49 am | Permalink
  13. Malcolm says

    Ah, well there you are – Dennis popped that in as I was writing my own response.

    Posted February 23, 2010 at 11:50 am | Permalink
  14. the one eyed man says

    Well, I’m all for blasphemy. Sometimes blasphemy turns out to be true.

    Posted February 23, 2010 at 12:05 pm | Permalink
  15. Malcolm says

    How can blasphemy be true??? That’s blasphemy!!!!!

    Posted February 23, 2010 at 12:17 pm | Permalink
  16. the one eyed man says

    Dunno. Ask Galileo.

    Posted February 23, 2010 at 1:00 pm | Permalink