Did Jewish intelligence evolve in tandem with Jewish diseases as a result of discrimination in the ghettos of medieval Europe? That’s the premise of a controversial new study that has some preening and others plotzing. What genetic science can tell us—and what it can’t.

Last summer, Henry Harpending, an evolutionary anthropologist at the University of Utah, and Gregory Cochran, an independent scholar with a flair for controversy, skipped cheerfully into the center of this minefield. The two shopped around a paper that tried to establish a genetic argument for the fabled intelligence of Jews. It contended that the diseases most commonly found in Ashkenazim—particularly the lysosomal storage diseases, like Tay-Sachs—were likely connected to and, indeed, in some sense responsible for outsize intellectual achievement in Ashkenazi Jews. The paper contained references, but no footnotes. It was not written in the genteel, dispassionate voice common to scientific inquiries but as a polemic. Its science was mainly conjecture. Most American academics expected the thing to drop like a stone.

It didn’t. The Journal of Biosocial Science, published by Cambridge University Press, posted it online and agreed to run it in its bi-monthly periodical sometime in 2006. The New York Times, The Economist, and several Jewish publications risked their reputations to legitimize it. Today, the paper has a lively presence on the Internet—type “Ashkenazi” into Google and the first hit is the Wikipedia entry, where the article gets pride of place.