Jewish population genetics and intelligence revisted

When I reviewed the data on Jewish population genetics for my 1994 book, A People That Shall Dwell Alone, the take home message was that Jews were a Middle Eastern group. But that was before the massive improvements in population genetic methods of recent years. One would think that this would result in a clear picture, but that has not been the case. Data showing a strong Middle Eastern connection was challenged by a paper championing the Khazar hypothesis.

I can’t tell you how many people have sent me emails urging me to endorse the Khazar hypothesis, the logic being that if the Khazar hypothesis is true, then Jews have no biological link to Israel.

But my population genetics guru was quite skeptical about that paper, and now a new paper by Marta Costa et al. puts yet another spin on Ashkenazi origins by finding that around 80% of their mitochondrial DNA has a prehistoric European origin and ruling out the Khazar hypothesis. The new results would likely  indicate that the Ashkenazim would be less Near Eastern and more European, so fans of the Khazar hypothesis may have something to cheer about after all.

Combined with previous Y chromosome studies indicating that  the male line is Middle Eastern, the results suggest a scenario in which Jewish males married European females after traveling to Europe. This has happened elsewhere, as with the Lemba.

This study is getting good reviews, but of course we have to remain open to new findings. Science marches onward.

But taking these results at face value, one might hope that Ashkenazi Jews would feel more kinship with Europe rather than the characteristic posture of hostile outsiders adopted by the organized Jewish community and very common among Ashkenazi Jews generally. But I won’t hold my breath. Such attitudes are far more influenced by social identity processes, which are not sensitive to genetic differences, and according to which Christian Europe is a hated outgroup because of its perceived past history of little more than expulsions and persecution.

Nor do the new findings alter the conception of Judaism as a genetically closed group, with all that implies for an evolutionary analysis of between-group competition. After the original matings in the ancient world, the walls were erected; the new findings indicate very little mtDNA from Eastern Europe.

Greg Cochran’s blog “Jewish Moms” discusses the implications of the new study for theories of Jewish IQ:

Charles Murray suggested that selection leading to higher intelligence in Jews occurred a long time ago, as far back as  the Babylonian Captivity.  That’s not true …. It never made any sense, because there’s not a scintilla of evidence that Jews in Classical times were smarter than the average bear – but  the Ashkenazim being half Italian crushed it yet again. If ancestral Jews had the genetic IQ magic, the Ashkenazim should be watered-down, closer to the European norm: but they’re not.

Lots of European admixture does not contradict our model of the evolution of superior Ashkenazi intelligence, because we think that the relevant selection occurred well after that admixture, during a period in which inward gene flow among the Ashkenazim was very low – as evidence by the fact that this study found plenty of Italian mtDNA, but little from Eastern Europe.

I think  Cochran is wrong about this. The theory I developed in my 1994 book, A People That Shall Dwell Alone is pretty much the same as Murray’s, and I have previously commented on Cochran’s theory and Murray’s article (see “Jewish intelligence“). There are two basic problems with the theory: There is in fact good reason to believe that Jews were quite intelligent in the ancient world; and the theory ignores the accomplishments of the Sephardic Jews in Spain. Just for the record, I’ll repeat the argument here, slightly elaborated.

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. Jews were not part of the public culture of the ancient Greco-Roman world, but rather lived in their own very inward-looking communities.  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 from advantageous marriages was already in place.

Talmud: ““For marriage, a scholar was regarded . . . as more eligible than the wealthy descendant of a noble family”; Baron (1952b, 221) notes that in Talmudic times wealthy men selected promising scholars as sons-in-law and supported them in their years of study). The Tannaim did not tire of reiterating the advice that “under all circumstances should a man sell everything he possesses in order to marry the daughter of a scholar, as well as to give his daughter to a scholar in marriage. . . . Never should he marry the daughter of an illiterate man” (Baron 1952b, 235).

“A girl with a good pedigree, even if she be poor and an orphan, is worthy to become wife of a king” (Midrash Num. R.i, 5; quoted in Feldman 1939, 34). … Feldman interprets the k’tsitsah (severance) ceremony, described in b. Kethuboth 28b, as intended to show the extreme care the rabbis took to ostracize anyone who had contracted a marriage not made according to eugenic principles.7 A barrel of fruit was broken in the market place in order to call attention to the event, and the following words spoken:

 “Listen ye our brethren! A. B. married an unworthy wife, and we fear lest his offspring mingle with ours; take ye therefore an example for generations to come that his offspring may never mix with ours.” (PTSDA, Ch. 7, p. 18ff)

Consistent with high intelligence, 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 who are ignored by Cochran. It’s a complex picture, but any good theory has to deal with 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.