My grandparents were immigrants from Eastern Europe who owned a small necktie factory on the outskirts of Montreal. While visiting them one weekend, I found my grandfather on the factory floor, cutting shapes out of irregular stacks of cloth with a fabric saw. He explained that by carving up the remnants that were left over when the neckties had been cut out and stitching them together in places that didn’t show, he could get a few extra ties out of each sheet of cloth. I asked him why he was doing this himself rather than leaving it to his employees. He shrugged, tapped his forehead, and said, “Goyishe kop,” a term of condescension that literally means “gentile head.”
He wasn’t exactly serious, but he wasn’t exactly not serious either. Jews have long had an ambivalent attitude toward their own intelligence, and toward their reputation for intelligence. There is an ethnic pride at the prevalence of Jews in occupations that reward brainpower. A droll e-mail called “New Words to Add to Your Jewish Vocabulary” includes “jewbiliation, N: pride in finding out that one’s favorite celebrity is Jewish” and “meinstein, N: My son, the genius.” Many Jews subscribe to a folk theory that attributes Jewish intelligence to what would have to be the weirdest example of sexual selection in the living world: that for generations in the shtetl, the brightest yeshiva boy was betrothed to the daughter of the richest man, thereby favoring the genes, if such genes there are, for Talmudic pilpul.
But pride has always been haunted by fear that public acknowledge of Jewish achievement could fuel the perception of “Jewish domination” of institutions. And any characterization of Jews in biological terms smacks of Nazi pseudoscience about “the Jewish race.” A team of scientists from the University of Utah recently strode into this minefield with their article “Natural History of Ashkenazi Intelligence,” which was published online in the Journal of Biosocial Science a year ago, and was soon publicized in The New York Times, The Economist, and on the cover of New York magazine.
The Utah researchers Gregory Cochran, Jason Hardy, and Henry Harpending (henceforth CH&H) proposed that Ashkenazi Jews have a genetic advantage in intelligence, and that the advantage arose from natural selection for success in middleman occupations (moneylending, selling, and estate management) during the first millennium of their existence in northern Europe, from about 800 C.E. to 1600 C.E. Since rapid selection of a single trait often brings along deleterious by-products, this evolutionary history also bequeathed the genetic diseases known to be common among Ashkenazim, such as Tay-Sachs and Gaucher’s.
The CH&H study quickly became a target of harsh denunciation and morbid fascination. It raises two questions. How good is the evidence for this audacious hypothesis? And what, if any, are the political and moral implications?
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.
The CH&H theory can be divided into seven hypotheses. The first is that the Ashkenazi advantage in intelligence is genetic in the first place. Many intellectuals dismiss this possibility out of hand, having been convinced by Stephen Jay Gould’s book The Mismeasure of Man that general intelligence does not exist and that there is no evidence for its heritability. But a decade ago, the American Psychological Association commissioned an ideologically and racially diverse panel of scientists to review the evidence. They reported that IQ tests measure a stable property of the person; that general intelligence reflects a real phenomenon (namely, that measures of different aspects of intelligence intercorrelate); that it predicts a variety of positive life outcomes; and that it is highly heritable among individuals within a group. This does not imply that differences between groups are also genetic, since one group may experience a difference across the board, such as in wealth, discrimination, or social and cultural capital.
The most obvious test of a genetic cause of the Ashkenazi advantage would be a cross-adoption study that measured the adult IQ of children with Ashkenazi biological parents and gentile adoptive parents, and vice versa. No such study exists, so CH&H’s evidence is circumstantial. The Ashkenazi advantage has been found in many decades, countries, and levels of wealth, and the IQ literature shows no well-understood environmental factors capable of producing an advantage of that magnitude.
It remains possible that the advantage is caused by some poorly understood environmental cause. Environmental hypotheses tend to get a free pass in intellectual life, but they must be scrutinized as well. The possibility that Jewish mothers produce smarter children is unlikely in light of abundant evidence that families have no lasting effect on intelligence. Siblings reared together are no more correlated in IQ than siblings who were separated at birth, and adopted siblings are not correlated at all. Growing up in a given home within a culture seems to leave no lasting stamp on intelligence.
But is it good for the Jews? More to the point, is it good for ideals of tolerance and ethnic amity? On one interpretation, perhaps it is. Jewish achievement is obvious; only the explanation is unclear. The idea of innate Jewish intelligence is certainly an improvement over the infamous alternative generalization, a worldwide Jewish conspiracy. And attention to the talents needed in the middleman niche (whether they are biological or cultural) could benefit other middleman minorities, such as Armenians, Lebanese, Ibos, and overseas Chinese and Indians, who have also been targets of vicious persecution because of their economic success.
And yet the dangers are real. Like intelligence, personality traits are measurable, heritable within a group, and slightly different, on average, between groups. Someday someone could test whether there was selection for personality traits that are conducive to success in money-lending and mercantilism, traits that I will leave to the reader’s imagination. One can also imagine how a finding of this kind would be interpreted in, say, Cairo, Tehran, and Kuala Lumpur. And the CH&H study could lower people’s resistance to more invidious comparisons, such as groups who historically score lower, rather than higher, on IQ tests.
What can be done? In recent decades, the standard response to claims of genetic differences has been to deny the existence of intelligence, to deny the existence of races and other genetic groupings, and to subject proponents to vilification, censorship, and at times physical intimidation. Aside from its effects on liberal discourse, the response is problematic. Reality is what refuses to go away when you do not believe in it, and progress in neuroscience and genomics has made these politically comforting shibboleths (such as the non-existence of intelligence and the non-existence of race) untenable.
Rather than legislating facts, could we adopt a policy of agnosticism, and recommend that we “don’t go there”? Scientists routinely avoid research that may have harmful consequences, such as injuring human subjects or releasing dangerous microorganisms. The problem with this line of thought is that it would restrict research based on its intellectual content rather than on its physical conduct. Ideas are connected to other ideas, often in unanticipated ways, and restrictions on content could cripple freedom of inquiry and distort the intellectual landscape.