...The appearance of an advantage in average intelligence among Ashkenazi Jews is easier to establish than its causes. Jews are remarkably over-represented in benchmarks of brainpower. Though never exceeding 3 percent of the American population, Jews account for 37 percent of the winners of the U.S. National Medal of Science, 25 percent of the American Nobel Prize winners in literature, 40 percent of the American Nobel Prize winners in science and economics, and so on. On the world stage, we find that 54 percent of the world chess champions have had one or two Jewish parents.

Does this mean that Jews are a nation of meinsteins? It does not. Their average IQ has been measured at 108 to 115, one-half to one standard deviation above the mean. But statisticians have long known that a moderate difference in the means of two distributions translates into a large difference at the tails. In the simplest case, if we have two groups of the same size, and the average of Group A exceeds the average of Group B by fifteen IQ points (one standard deviation), then among people with an IQ of 115 or higher the As will outnumber the Bs by a ratio of three to one, but among people with an IQ of 160 or higher the As will outnumber the Bs by a ratio of forty-two to one. Even if Group A was a fraction of the size of Group B to begin with, it would contribute a substantial proportion of the people who had the highest scores...