Hence the title of the article. The authors go on to suggest that these circumstances led to real genetic changes in the genome of the Ashkenazi Jews that benefited them in ways that are evident today:
Cochran and Harpending single out the Ashkenazi Jews as a textbook example of how cultural decisions from just a few hundred years ago (a nanosecond in the conventional view of evolution) have already resulted in new genetic advantages. Prior to the Middle Ages, Ashkenazi Jews lived in the middle of an important cultural route, linking Europe to key parts of Asia. The Jews were the recipients of tremendous genetic variety as ancient people crossed through their territory, settled down, married, or just mated.
As increasing numbers of Jews moved into Europe during the Middle Ages, cultural rules against marrying outside the group, coupled with external social pressures, resulted in a relatively closed genetic circle. The more useful chromosomal traits picked up in the Levant rose to the top as genetic of dilution was contained. More importantly, the difficult conditions in Europe ensured a strong biological imperative to adapt and survive.
Indeed, while most Europeans experienced the Middle Ages as a clear improvement over the preceding dark ages, European Jews were roundly persecuted and, by and large, were locked out of land-ownership. They developed a set of shared survival tactics that happened to be ideally suited for the changes sweeping the continent. Without the legal ability to own large tracts of land, most were relegated to towns and hamlets. This gave them a head start on urban life. The primary occupations available to the Jews who settled in these nascent urban centers were service trades requiring literacy and arithmetic skills. Abstract intelligence and reasoning skills were valued more highly within the group than was the ability to wield an ax or pull a cart. Over the course of multiple generations, a cultural emphasis on developing quantitative intelligence rather than physical strength accentuated one particular genetic trait at the expense of others. The chosen trait in question was intelligence.
Although this certainly falls under the category of microevolution, it still shows how changes in environments, both topographical and cultural can shape the genetic make-up of a population. This research derives in part from the vast population genetic research that Harpending has been doing for the last thirty years.
The authors go on to show that people of European Jewish descent, regardless of family background, perform better than average on IQ tests. They are disproportionately well represented among lists of major math and science award winners.
Although they account for less than 3% of the U.S. population, they comprise 27% of U.S. Nobel Prize winners over the past two generations, account for about a fifth of CEOs, and about 22% of Ivy League students.
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