Sunday, June 05, 2005

SINCE MY EX-HUSBAND AND I are carriers for Tay-Sachs disease, and since we actually did have a child with the disease (she died 15 years ago at the age of 3), I found this New York Times article interesting. Geneticists at the University of Utah will be publishing the results of research that they say provides an answer to the mystery of why Tay-Sachs and several other related genetic diseases cluster in the Ashkenazic Jewish population in Europe. Their theory is that the mutation that produced the Tay-Sachs gene is the result of natural selection factors that favored intelligence. Those selection factors, the Utah scientists say, were the laws that restricted Jews to a small number of very specific occupations -- all of which, as it happened, required "more than usual mental agility."

The explanation that the Ashkenazic disease genes must have some hidden value has long been accepted by other researchers, but no one could find a convincing infectious disease or other threat to which the Ashkenazic genetic ailments might confer protection.

A second suggestion, wrote Dr. Jared Diamond of the University of California, Los Angeles, in a 1994 article, "is selection in Jews for the intelligence putatively required to survive recurrent persecution, and also to make a living by commerce, because Jews were barred from the agricultural jobs available to the non-Jewish population."

The Utah researchers have built on this idea, arguing that for some 900 years Jews in Europe were restricted to managerial occupations, which were intellectually demanding, that those who were more successful also left more offspring, and that there was time in this period for the intelligence of the Ashkenazi population as a whole to become appreciably enhanced.
The hypothesis is controversial because it argues for the inheritability of intelligence in groups. I don't really see it as a racist argument, though. There's a difference between saying that a specific ethnic or racial grouping is less or more intelligent by nature -- as some kind of immutable characteristic of that group -- and saying that societal or environmental factors became a selection force for a particular skill.

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