You gotta have some jews...

...to succeed on Broadway, or so Spamalot would have it.

A few days ago I commented on a NYT story linking genetic diseases among Ashkenazi Jews with higher intelligence. I was pretty skeptical, but in the meantime have been reading the study, and I have to say that they make a better case than I expected. The basic logic is motive -> opportunity -> evidence (evolutionarily speaking).

Motive: Strong selective pressures existed in the period in question - rich people left a lot more descendants than poor people. Jews in Europe were confined to primarily intellectual occupations, like banking, trading, and tax farming. Smarter people had a lot more likelyhood of leaving descendants. Of course this part relies heavily on the heritability of IQ and the effectiveness of IQ as a predictor of academic and business success - both of which are controversial even though established indisputably, in the opinion of most experts.

Opportunity: Because there was relatively little gene flow between the general European population and the Ashkenazi - they estimate inward gene flow at less than 0.5% per generation - selection could lead to rapid evolution. This is a well know genetic effect in isolated populations.

Evidence: Ashkenazim show systematic advantages in IQ, but chiefly in the arithmetic and verbal components, together with visiospatial deficits. No other group has such a large discrepancy between components. Probably the most interesting evidence for me was the correlations of disease and high intelligence for a couple of the mutations. Some parts I found rather amusing, perhaps inappropriately.
Selection for IQ among the Ashkenazim then would have had associated costs. First, genetic changes that aided fitness in a urban environment where most jobs had high IQ elasticity almost certainly reduced fitness in more typical environments, simply because any such gene frequency change is change away from the optimum mix for a traditional environment. The expectation is that Ashkenazim would most likely suffer competitive disadvantage as peasant farmers or hunter-gatherers, for example.
I'm afraid that this called up in my mind an image of a fur-clad Woody Allen facing off against a charging Mammoth.

The authors assure us that nobody in the ancient world noted any special Jewish intellect. Of course the ancient Greeks did an awfully good job of distinguishing themselves artistically and culturally. Anybody got any good theories for them?

But read it and make up your own mind.

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