...Ashkenazi Jews occupied a different social niche from their European hosts, and that is where any selective effect must have operated, the Utah researchers say. From A.D. 800, when the Ashkenazi presence in Europe is first recorded, to about 1700, Ashkenazi Jews held a restricted range of occupations, which required considerable intellectual acumen. In France, most were moneylenders by A.D. 1100. Expelled from France in 1394, and from parts of Germany in the 15th century, they moved eastward and were employed by Polish rulers first as moneylenders and then as agents who paid a large tax to a noble and then tried to collect the amount, at a profit, from the peasantry. After 1700, the occupational restrictions on Jews were eased.A 600% relative increase in near-genius. If the averages are in fact similar, however, this may imply a roughly 600% increase in the rate of retardation (autism?). (Note if 1/250 humans are almost-genius, imagine how clever the 6,500 1/1 million minds on earth are.)
As to how the disease mutations might affect intelligence, the Utah researchers cite evidence that the sphingolipid disorders promote the growth and interconnection of brain cells. Mutations in the DNA repair genes, involved in second cluster of Ashkenazic diseases, may also unleash growth of neurons.
In describing what they see as the result of the Ashkenazic mutations, the researchers cite the fact that Ashkenazi Jews make up 3 percent of the American population but won 27 percent of its Nobel prizes, and account for more than half of world chess champions. They say that the reason for this unusual record may be that differences in Ashkenazic and northern European I.Q. are not large at the average, where most people fall, but become more noticeable at the extremes; for people with an I.Q. over 140, the proportion is 4 per 1,000 among northern Europeans but 23 per 1,000 with Ashkenazim.
This article appears in the Times next to one about the genetic determinants of gender preference in fruit flies. A useful coincidence. I'm amazed this article was written without mention of the infamous Bell Curve book. Similar comments about ethnicity and IQ, by the way, have been made about Scots and South Koreans.
If I were to bet I'd guess most of the diseases the authors refer to are in fact 'founder effect' diseases and unrelated to a selection for extreme IQ variability (both high and low); in other words, the main point of the paper is incorrect. I would further guess that the IQ variability is real and is genetically, not environmentally, determined.
I'd also guess that the IQ variability is primarily among males, and that the "genius" outcome operates through the same gene family variation produces autism in some people.
Of course the extremely incorrect aspect of this article is that if an ethnic group has a selection for higher IQ, the converse is also likely. Let's assume this were found to be so. Consider now my recent comments on the genetics of behavior. IF we have still have an advanced technological human culture in 2025, I suspect "meritocracy" may carry little more moral approval than plutocracy. Both represent the outcomes of chance.