Ashkenazi Jewish IQ and disease

Here are two curious facts about the Ashkenazi (European-derived) Jews. As a group, the Ashkenazim:
  • average higher IQs than the European norm, by a standard deviation
  • have much higher incidence of certain nasty genetic diseases. The persistence of these diseases in the population is something of a puzzle due to their simple genetic character but drastic effect on fitness. For example, Tay sachs, happens in homozygotes for a single damaged gene, and kills all of them by age 5. The incidence of a damaged copy of this gene in the Ashkenazi population is something on the order of 3%.
Are these two facts related somehow?

Yes, according to a new paper by Greg Cochran, Jason Harper, and Henry Harpending:
Our general hypothesis is that high IQ test scores of Ashkenazim, along with their unusual pattern of abilities, are a product of natural selection, stemming from their occupation of an unusual social niche. All the required preconditions low inward gene flow and unusually high reproductive reward for certain cognitive skills, over a longenough period did exist. These preconditions are both necessary and sufficient, so such a selective process would almost inevitably have this kind of result. The pattern of high achievement among Ashkenazi Jews and the observed psychometric results are certainly consistent with this hypothesis.

Our more specific prediction is that some or most of the characteristic Ashkenazi genetic diseases are by-byproducts of this strong selection for IQ. ... We predict that heterozygotes for the sphingolipid storage mutations should have higher scores on psychometric tests of verbal and mathematical abilities than their non-carrier sibs.
It appears the internet is breaking the logjam in the popular press in discussing politically incorrect ideas like this one. The NYT, to its credit, ran with this story. However it is not getting wide coverage in the MSM, which is a pity since it is solid science, fascinating history, relevant to our lives, and even better if it turns out to be correct.

Not only that, but important for the general populace to understand the truth here. Groups are not all the same. This contradicts the "uniformatism" of the PC worldview, where all groups are the same. No group is any smarter than any other group, nor does any group excel in any way that might result in differential "success", however defined.

Within the uniformatist worldview, there can be no explanation for underrepresentation of a group in any particular profession, other than chance (which is not believable if the group and profession size is large), prejudice, or conspiracy. But the same must also be true of overrepresentation. It must be chance, prejudice (favoratism), or conspiracy.

Well, Jews in the USA are almost all Ashkenazim. They are smarter, on average, than the average American. Jews are overrepresented in practically every high-visibility profession there is: doctors, academics, lawyers, money men, hollywood, you name it. How can Jews be 10% or 20% of the top professionals when they are only 3% of the population?

To a person who knows the truth about IQ, the answer is simple enough. The top professions require high IQs, and a disproportionate number of the really high-IQ people in America are Jews. That is, the Jewish representation is merited.

To a uniformatist, it can't be merit. So, it's a CONSPIRACY! This is the genesis of at least some antisemitism.


Lea said...

In response to both this post, and a comment posted by Leonard on the Liberty Belles blog:
It may very well be true that on average Jews have higher IQs than most others, and women have lower IQs than men. My question (as a Jew and a woman...) is: why is this worth focusing on? We should never lose faith in people's ability to succeed (or become libertarian :)) regardless of what group they're part of; and the kind of rhetoric we use influences our ability to keep that faith.

Jacob Roth said...

Lea, I wouldn't be so quick to buy into racial theories of human history. The average IQ of a European Jew in Israel is around 94, while the average in America is somewhere between 112-115. This is a powerful discrepancy that can't be explained easily. Skepticism is warranted.

Leonard said...

Lea, it is not true that women have lower IQs than men, or at least, there's not a lot of evidence for that proposition.

Rather, it is true that men have higher variability in IQ than women do. This is not surprising since men also have higher variability than women on most normally distributed traits.

As for why this is worth focusing on: well, for one thing because it's (arguably) true and the truth is inherently interesting. (Of course, as Jacob says skepticism is always warranted.)

For another, knowing the truth often leads to different policy than ignorance. For example, should libertarians focus real resources - money, time - on trying to win electoral races? According to my theory, we should not, because we'll never ever get some 85% of the population to buy the ideas. According to the mainstream idea that "everyone can do everything and we're all above average", you would not conclude the same thing.

I submit to you, that the history of libertarian agitation in America shows much evidence of the latter mistake.

As for faith... well, as a strategy to deal with ignorance it is not bad. Just pick a position and believe it, and act on it. You've often got to do something. But relying on faith when we have knowledge is an invitation to error.

More specifically to your point: individuals will become libertarian (or succeed) on their own merits. They are what they are; you may gain information about who they are from what groups they are a part of, but such general information should always be overridden by your knowledge of the particular individual, if you have it. I think it is safe to say we've got the rhetoric of individualism in hand.