Jewish Intelligence

August 19. 2007

Jewish intelligence has become a hot topic following the publication of a paper by Greg Cochran and Henry Harpending in The Journal of Biological Science. Charles Murray weighed in with an article in Commentary (Jewish Genius, April, 2007). Murray's theory is quite a bit like the one I published in my 1994 book, A People That Shall Dwell Alone (Ch. 7). I discussed eugenic events such as the Babylonian exile in which the elite Israelites were relocated to Babylon and refused to intermarry with those left behind when they returned (as graphically recounted in the Books of Ezra and Nehemiah). I also described a great deal of discrimination against the illiterate in the ancient world, with the effect that such people were excluded from the Jewish community. Marriage to such a person was especially abhorrent. And I recounted the history of Jewish education and Jewish idealization of the scholar, including especially the practice of wealthy Jews marrying their daughters to scholars and providing them with business opportunities. Because wealth was correlated with reproductive success in traditional societies, this had the effect of eugenic selection for intelligence. All of these practices originated in the ancient world and are well attested among both Ashkenazi and Sephardic populations in later centuries.

The argument of Cochran and Harpending depends on Ashkenazi uniqueness. Their major contribution is to elaborate evidence that Ashkenazi intelligence is linked to mutations associated with brain metabolism and to certain Jewish genetic diseases (e.g., Tay-Sachs disease). I certainly do not want to deny that there is some unique genetic basis for Ashkenazi IQ. Indeed, I described the evidence available as of 1994 on Ashkenazi CNS mutations linked to brain metabolism in A People That Shall Dwell Alone (Ch.2):


Eldridge (1970; see also Eldridge & Koerber 1977) suggests that a gene causing primary torsion dystonia, which occurs at high levels among Ashkenazi Jews, may have a heterozygote advantage because of beneficial effects on intelligence. Further supporting the importance of selective processes, eight of the 11 genetic diseases found predominantly among Ashkenazi Jews involve the central nervous system, and three are closely related in their biochemical effects (see Goodman 1979, 463). [Further,] Motulsky (1977a) suggests that the higher incidence of myopia in Ashkenazi Jewish populations could be the result of selection for higher verbal intelligence. Myopia and intelligence have been linked in other populations, and Jews tend to have higher intelligence and higher rates of myopia.
Eldridge, R. (1970). The torsion dystonias: Literature review and genetic and clinical studies. Neurology 20:1–78.
Eldridge, & T. Koerber (1979). Torsion dystonia: Autosomal recessive form. In Genetic Diseases among Ashkenazi Jews, ed. R. M. Goodman & A. G. Motulsky. New York: Raven Press.
Motulsky, A. G. (1979a). Possible selective effects of urbanization on Ashkenazi Jews. In Genetic Diseases Among Ashkenazi Jews, ed. R. M. Goodman & A. G. Motulsky. New York: Raven Press.


Cochran and Harpending base their argument of Ashkenazi uniqueness on their belief that Jews did not have a reputation of being smart in the ancient world. However, if you look at Jewish religious writings, such as the Mishnah (2nd century AD) and the Talmuds (4th and 6th century), their elites were at a very high level. And it should be remembered that until the Enlightenment, the vast majority of Jewish scholarship was directed within the Jewish community, rather than at science or philosophy. As a result, Jewish intelligence may not have been apparent to non-Jews. In the ancient world, Jewish education was the norm and the system where scholars benefited with advantageous marriages was already in place. And in any case, the historical record supports the idea that Jews were quite successful economically in the ancient world. After the failed rebellions against the Romans during the 1st and 2nd century, Jews achieved a very prominent economic position in the Roman Empire and dominated some industries, so the familiar pattern of Jews as an elite group was well underway at that time. Consider, for example, the following passage from Separation and Its Discontents:

Bachrach (1985) suggested that the Jews were so wealthy, powerful, and aggressive that until around the middle of the 5th century the government viewed a strong anti-Jewish policy as not politically viable, even though it was continually being pressured in this direction by the Church. The rather limited anti-Jewish actions of the government during the 150 years following the Edict of Toleration of 313 are interpreted “as attempts to protect Christians from a vigorous, powerful, and often aggressive Jewish gens” (Bachrach 1985, 408). The Jews themselves were perceived by the emperors, the government, and the Church fathers as “an aggressive, well-organized, wealthy, and powerful minority” (p. 408). Particularly revealing are the suggestion that the solvency of the municipalities depended on Jews paying their taxes and the fear that offending the Jews could set off widespread and costly revolts, such as the one led by Patricius in 351.
Bachrach, B. S. (1985). The Jewish community in the Later Roman Empire as seen in the Codex Theodosianus. In “To See Ourselves as Others See Us”: Christians, Jews, “Others” in Late Antiquity, ed. J. Neusner & E. S. Frerichs. Chico, CA: Scholars Press.


In short, Jews in the ancient world had all of the characteristics associated with later Ashkenazi populations: Economic preeminence, an occupational profile emphasizing business, finance, trading, and manufacturing, high levels of education, and a scholarly elite producing complex, religious writing. Scholarship was an excellent means to achieve upward mobility and presumably greater than average reproductive success.

These traits also characterized the Sephardim. I agree with Murray on the Sephardim because of the complete dominance of Spain by the New Christians (economic, political, and intellectual) after the "conversions" of the early 15th century. This group remained influential in Amsterdam and elsewhere, but they gradually lost their grip in Spain because of the Inquisition. They became separated from the wider Jewish community—mainly the lower classes of Jewish society—after the expulsion of 1492. This was a dysgenic event for that group, and their descendants do not seem especially accomplished. This is a passage from Ch. 7 of A People that Shall Dwell Alone:

Jews who continued to practice Judaism in Spain during the 15th century and were subsequently expelled in 1492 were less educated and less economically successful than their Converso brethren who remained to endure the wrath of the Inquisition. In this case, the less wealthy Jews certainly suffered fewer casualties and eventually were able to emigrate to North Africa or the Levant. Eventually, the Levantine Sephardim underwent a distinct atrophy of their culture..., while the descendants of the Conversos continued their highly elite and exclusivist profile on the international economic scene. When these Levantine Sephardim immigrated to the United States in the 20th century, they exhibited much higher rates of illiteracy, alcoholism, prostitution, and wife abandonment than did the Ashkenazim (Sachar 1992, 338). While the Ashkenazim were quickly upwardly mobile in American society, the Sephardim achieved only “a modest economic foothold” and were more likely to engage in lower-status occupations (Sachar 1992, 340).


My view is that the Jewish population of Spain had all the characteristics of Ashkenazi populations, including the emphasis on Jewish scholarship and favorable marriages for scholars. The Conversos were at least as accomplished as Ashkenazi groups and dominated Spain at least until the Inquisition and even for quite a while thereafter. The section on the ups and downs of Jews in the Muslim world is here:

http://www.csulb.edu/~kmacd/OrientalJewsIQ.htm

The argument emphasizes the pattern of lower Sephardic IQ than for Ashkenazi populations within Israel. Nevertheless, it also notes that in general Jewish populations had higher intelligence and achievement in Arab societies when they were politically allowed to prosper. Perhaps the accomplishments of the Levantine Sephardim during some periods were facilitated because of the low average IQ of the peoples they lived among. In other words, they were highly capable compared to the native populations. There seems to be good evidence that the decline of the Levantine Sephardim was due at least partly to anti-Jewish actions.

Anthropologist Peter Frost has proposed a variation on the theme of Cochran and Harpending. Frost emphasizes the shift to early marriage, especially by "semi-rural artisans who produced on contract for urban merchants and who could ably exploit these larger, more elastic markets. . . . Their workforce was their household. In more successful households, the workers would marry earlier and have as many children as possible. In less successful ones, they would postpone marriage, or never marry."

This theory also demands Ashkenazi uniqueness, which is at least questionable given the above. The cottage industry niche was a fairly short-lived phenomenon, so a more formal argument would have to be made involving the power of selection among Jewish artisan families and between Jews and non-Jews. Frost's proposal reminds us that the stereotype of Jews as financiers, money lenders, merchants, and traders can be overdone. Indeed, the general pattern was for Jews to be involved in vertically integrated business and trading arrangements. For example, in Poland by the end of the 18th century, Jews dominated almost all areas of trading, manufacturing, and estate managing, and they had become dominant among the artisans as well (A People That Shall Dwell Alone, Ch. 5; Zionism and the Internal Dynamics of Judaism). The Jewish economic niche began with trading, estate managing, and money lending, but eventually they dominated virtually the entire economy except agricultural labor as the Jewish population increased.

Given this pattern, it seems gratuitous to attribute causality to one part of this pattern, especially when artisanry was the last economic niche to become dominated by Jews. Indeed, the Jewish involvement with artisanry seems to have been a consequence of their already dominating other areas; artisanry was the last remaining niche above agricultural labor to be dominated by Jews. For Frost's model to work, he must assume that the IQ of the Jewish population prior to their involvement in artisanry was at the population average. But the progenitors of Jewish artisans in Eastern Europe were Jewish traders, money lenders, and estate managers—hardly low-IQ professions. Overall, the Jewish occupational profile in Eastern Europe is familiar in other times and places, including the ancient world and Spain prior to the Inquisition, so it's difficult to see how this fits as an argument for Ashkenazi uniqueness.

It should also be noted that Jewish fertility was very high not simply because they were involved in artisanry, but also for religious reasons: the rise of the Hasidic movement. Poor Jewish families continued to have high fertility even when the result was poverty (see Zionism and the Internal Dynamics of Judaism). My argument is that eventually Jews overshot their economic niche entirely. This had huge consequences for the modern world not only because it figured prominently in the pressures resulting in anti-Semitism in Eastern Europe throughout the 19th and into the 20th century, but also because the main Jewish responses to their misery in Eastern Europe were Zionism and political radicalism—two very potent forces indeed.