This idea is getting a lot of play. From Are Jews Smarter? What Genetic Science Tells Us:
This story begins, as it inevitably must, in the Old Country.At some point during the tenth century, a group of Jews abandoned the lush hills of Lucca, Italy, and — at the invitation of Charlemagne — headed for the severer climes of the Rhineland and Northern France. These Jews didn’t have a name for themselves, at first. They were tied together mostly by kinship. But ultimately, they became known as Ashkenazim, a variation on the Hebrew word for one of Noah’s grandsons.
In some ways, life was good for the Jews in this strange new place. They’d been lured there on favorable terms, with promises of physical protection, peaceful travel, and the ability to adjudicate their own quarrels. (The charter of Henry IV, dated 1090, includes this assurance: “If anyone shall wound a Jew, but not mortally, he shall pay one pound of gold . . . If he is unable to pay the prescribed amount . . . his eyes will be put out and his right hand cut off.”) But in other ways, life was difficult. The Ashkenazim couldn’t own land. They were banned from the guilds. They were heavily taxed.
Yet the Ashkenazim did very well, in spite of these constraints, because they found an ingenious way to adapt to their new environment that didn’t rely on physical labor. What they noticed, as they set up their towns, located mainly at the crossroads of trade routes, was that there was no one around to lend money.
So there it was: a demand and a new supplier. Because of the Christian prohibition against usury, Jews found themselves a financially indispensable place in their new home, extending loans to peasants, tradesmen, knights, courtiers, even the occasional monastery. The records from these days are scarce. But where they exist, they are often startling. In 1270, for example, 80 percent of the 228 adult Jewish males in Perpignan, France, made their living lending money to their Gentile neighbors, according to Marcus Arkin’s Aspects of Jewish Economic History. One of the most prolific was a rabbi. Two others were identified, in the notarial records, as “poets.”
Success at money-lending required a different set of skills than farming or any of the traditional trades. Some, surely, were social: cultivating connections, winning over trust (or maybe bullying your way there, Shylock’s awful pound of flesh). It probably required some aggression, because the field was competitive, with Jews suffering so few professional options. But it also required cognitive skills, or something my generation would call numeracy — a fluency in mathematics, a dexterity with numbers — and my grandmother’s generation would call “a head for figures.” If you were Jewish in Perpignan in 1270, and you didn’t have a head for figures, you didn’t stand much of a chance.
Numeracy, literacy, critical reasoning: For millennia, these have been the currency of Jewish culture, the stuff of Talmudic study, immigrant success, and Borscht Belt punch lines. Two Jews, three opinions . . . Keep practicing, you’ll thank me later . . . Q: When does a Jewish fetus become a human? A: When it graduates from medical school.
Of course, there’s another side to this shining coin. Jewish cleverness has also been an enduring feature of anti-Semitic paranoia. In the sixteenth century, Martin Luther said Jewish doctors were so smart they could develop a poison that could kill Christians in a single day — or any other time period of their choosing (and four centuries later, Pravda suggested Jewish doctors were spies sent to kill Stalin). After the calamities of September 11, one of the creepier conspiracy theories to whip through the Muslim world was the idea that only Jews were cunning enough to have pulled off the hijackings.
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.
Update: As Robert McHenry points out in The Education of Gesture, that intro can’t be true:
If you haven’t caught it yet, here’s the problem: Charlemagne died in 814 CE. No one is expected to know that particular fact, but many generally educated persons might recall that he was crowned Holy Roman Emperor at Christmas in 800. This would make his survival into the tenth century highly unlikely on the face of it.
Years ago, fantasy writer Michael Moorcock attacked the popular works of Tolkien (Lord of the Rings), C.S. Lewis (Chronicles of Narnia), and Richard Adams (Watership Down) as 
When you hear that paleontologists have found a 