Ashkenazi intelligence

Ashkenazi intelligence refers to the controversial theory purporting the general intelligence of Ashkenazi Jews, the Jews of Central and Eastern European origin who are the descendants of Jews who settled in the Rhineland beginning about the year 800 AD.

Psychometric Findings
Psychometrics research has found that Ashkenazi Jews have the highest mean score of any ethnic group on standardized tests of general intelligence, with estimates ranging from 7 to 17 points above the mean IQ of the general white population at 100, which ranges from 107 for Germany to 90 for Turkey according to Richard Lynn's estimates for 2006. These studies (see references) also indicate that this advantage is primarily in verbal and mathematical performance; spatial and visual-perceptual performance is average. However some statistic data on Israel, which has about 50% of Ashkenazi Jews in its population show that Israel achieves lower average IQ scores than countries of Europe or East Asia (IQ and the Wealth of Nations). (Israel 94, England 100, Hong Kong 107). Besides being controversial, this work relies on existing studies "of questionable validity", leading to results even the authors don't believe to be correct.



Cochran et al.
The 2005 study Natural History of Ashkenazi Intelligence by Gregory Cochran, Jason Hardy, and Henry Harpending at the University of Utah noted that European Jews were forbidden to work in many of the common jobs of the middle-ages from C.E. 800 to 1700, such as agriculture, and subsequently worked in high proportion in meritocratic jobs requiring higher intelligence, such as finance and trade, some of which were forbidden to non-Jews by the church. Those who performed better are known to have raised more children to adulthood, according to Cochran et al., passing on their genes in greater proportion than those who performed less successfully.

Cochran et al. hypothesized that the eugenic pressure was strong enough that mutations creating higher intelligence when inherited from one parent but creating disease when inherited from both parents would still be selected for, which could explain the unusual pattern of genetic diseases found in the Ashkenazi population, such as Tay-Sachs, Gaucher's disease, Niemann-Pick disease, Mucolipidosis type IV, and other lipid storage disorders and sphingolipid diseases. Some of these diseases (especially torsion dystonia) have been shown to correlate with high intelligence, and others are known to cause neurons to grow an increased number of connections to neighboring neurons.

Reviews of the controversial paper have been both positive and negative, with critics claiming the argument to be far-fetched and unsupported by direct evidence. Many genetically-isolated human groups have faced multifarious adaptive pressures one could cherry pick to justify presently exhibited group traits.

Alternative Explanations

 * Israeli Ashkenazi's scores may average lower than U.S. and British Ashkenazi, Lynn suggests, due to selective migration effects in relation to those countries, and to immigrants from the former Soviet Bloc countries having posed as Ashkenazim. The data isn't necessarily strong enough, however, to rule out identical scores for Ashkenazi across these nations.


 * Jews settling in the Rhineland were from the beginning mostly money-lenders and merchants (as well as rabbis). A biological (hereditary) explanation for high Ashkenazi IQ may be that modern Ashkenazi Jews are descended mostly from the several thousand Jewish settlers that belonged to these traditionally high-IQ occupations. This self-selection may also explain why Ashkenazi Jews have significantly higher IQ scores than Mizrahi Jews. An environmental (cultural) explanation for high Ashkenazi IQ is that since it was forbidden for Christians to take interest and money-lending, Jews took the opportunity and developed into a relatively wealthy social group, which traditionally can afford higher education to their children. The extent to which intelligence is hereditary (determined by genes) remains a controversial subject.


 * Talent in the study of Torah traditionally contributed to one's social success in Jewish communities; those more lacking in the capacity for such study were perhaps more prone to assimilate into general culture, thereby raising the average intelligence of the given community. (Murray 2003, Shafran 2005)


 * Among the devout, daily study of the Talmud was required and respected. Those who left the fold of Orthodoxy replaced daily Torah study with rigorous secular scholarship.


 * The affluent tended to be more intelligent and fertile, as well as educated, propagating higher intelligence and a greater reverence for scholarship. A Torah scholar would often marry the daughter of an affluent merchant in exchange for the latter's extended financial support for the scholar's studies.
 * European Jews' history of persecution selected for high intelligence, leaving a positive effect on the hereditary component of their IQ.
 * Persecution led Jews to embrace education as a transportable asset, to better adapt to novel surroundings.
 * Jews reached a population bottleneck in the 14th Century at the height of the Black Death when they were widely blamed for the plague. This small population allowed a few random genetic changes (genetic drift) to take root as they could not do so in a larger population that resists drift.