Jewish American Heritage Month

Posted By richards on March 5, 2016

The intelligence of Ashkenazi Jews relative to other ethnic groups has been an occasional subject of scientific controversy.[1] A 2005 scientific paper, "Natural History of Ashkenazi Intelligence",[2] proposed that Ashkenazi Jews as a group inherit higher verbal and mathematical intelligence with lower spikes in spatial intelligence than other ethnic groups, on the basis of inherited diseases and the peculiar economic situation of Ashkenazi Jews in the Middle Ages. Opposing this hypothesis are explanations for the congenital illnesses in terms of the founder effect, explanations of intellectual successes by reference to Jewish culture's promotion of scholarship and learning, and doubts about whether a group difference in intelligence really exists.[citation needed]

One observational basis for inferring that Ashkenazi Jews have high intelligence is their prevalence in intellectually demanding fields. While only about 2% of the U.S. population is of full Ashkenazi Jewish descent,[2] 27% of United States Nobel prize winners in the 20th century,[2][3] 25% of Fields Medal winners,[4] 25% of ACM Turing Award winners,[2] 6 out of the 19 world chess champions, and a quarter of Westinghouse Science Talent Search winners have either full or partial Ashkenazi Jewish ancestry.[4] However, such statistics do not rule out factors other than intelligence, such as institutional biases and social networks[citation needed]. Undue weight is also given to the Ashkenazi statistics because people of partial Ashkenazi ancestry (half or less) are included, but only compared to the portion of the US population of full Ashkenazi descent.[citation needed]

A more direct approach is to measure intelligence with psychometric tests. Different studies have found different results, but most have found above-average verbal and mathematical intelligence in Ashkenazi Jews, along with below-average spatial intelligence.[3][5][6][7]

The average IQ score of Ashkenazi Jews have been calculated to be 112115 (Cochran et al.),[8] and 107115 (Murray; Entine).[9][10][11] These measurements place them as the ethnic/racial group with the highest IQ in the world.[citation needed] A study found that Ashkenazi Jews had only mediocre visual-spatial intelligence, while their verbal IQ (which includes verbal reasoning, comprehension, working memory. and mathematical skills) compensated for this with a high median of 125.6.[12][13]

Assuming that today there is a statistical difference in intelligence between Ashkenazi Jews and other ethnic groups, there still remains the question how much of the difference is caused by genetic or environmental factors.[14]

"Natural History of Ashkenazi Intelligence",[2] a 2005 paper by Gregory Cochran, Jason Hardy, and Henry Harpending, put forth the conjecture that the unique conditions under which Ashkenazi Jews lived in medieval Europe selected for high verbal and mathematical intelligence but not spatial intelligence. Their paper has four main premises:

Other scientists gave the paper a mixed reception, ranging from outright dismissal to acknowledgement that the hypothesis might be true and merits further research.[15]

In an interview in the documentary Hjernevask Gregory Cochran said:[16]

"It doesn't have to be extremely heritable for this [intelligence inheritance] to have happened, because you only need small changes in each generation, and there might be forty generations over 1000 years. So if [Ashkenazi Jews] increased a third of an IQ point per generation, that would almost certainly be enough to make this effect happen."

The enforcement of a religious norm requiring Jewish fathers to educate their sons, whose high cost caused voluntary conversions, explaining a large part of a reduction in the size of the Jewish population;[17] that historic persecution of European Jews fell disproportionately on people of lower intelligence.[15]

In medieval Ashkenazi society, wealth, social status, and occupation were largely inherited. The wealthy had more children than the poor, but it was difficult for people born into a poor social class to advance or enter a new occupation. Leading families held their positions for centuries. Without upward social mobility, genes for greater talent at calculation or languages would likely have had little effect on reproductive success. So, it's not clear that mathematical and verbal talent were the prime factors for success in the occupations to which Jews were limited at the time. Social connections, social acumen, willingness to take risks, and access to capital through both skill and nepotism could have played at least as great a role.[14]

Genetic studies have suggested that most Ashkenazi Jewish congenital diseases arose from genetic drift after a population bottleneck, a phenomenon known as the founder effect, rather than from selective pressure favoring those genes as called for by the Cochran, et al. hypothesis.[14][18] To take one example, the mutation responsible for Tay-Sachs disease arose in the 8th or 9th century, when the Ashkenazi Jewish population in Europe was small, just before they spread throughout Europe. The high frequency of this disease among Ashkenazi Jews today might simply be the result of their not marrying outside their group, not because the gene for Tay-Sachs confers an advantage that more than makes up for the fact that the disease usually kills by age three.[14] However, an examination of the frequencies and locations of the genes for 21 Ashkenazi Jewish congenital diseases suggested that six of them do appear to result from selective pressure, including the mutation for Tay-Sachs.[18] There is still no evidence one way or the other about whether the reason for this is increased intelligence for commercial skills or something else.[19][20]

Evolutionary psychologist Steven Pinker suggested that "[t]he 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", but noted, "No such study exists, so [Cochran]'s evidence is circumstantial."[21]

Another type of explanation for higher intelligence in Ashkenazi Jews is differences in culture which tend to promote cultivation of intellectual talents.

For example, after the destruction of the Second Temple in 70 CE, Jewish culture replaced its emphasis on ritual with an emphasis on study and scholarship.[22] Unlike the surrounding cultures, most Jews, even farmers,[2] were taught to read and write in childhood. Talmudic scholarship became a leading key to social status. The Talmudic tradition may have made the Jews well suited for financial and managerial occupations at a time when these occupations provided new opportunities.[14][23]

The emphasis on scholarship came before the Jews turned from agriculture to urban occupations. This suggests that premise #3 of Cochran et al. may have the causal direction backward: mastery of written language enabled Jews to thrive in finance and international trade rather than the other way around.[14] Preoccupation with Torah and Talmud study keeps alive a certain intellectual acumen, attuned to weighing situations and opinions.[24][25]

Other proposed cultural explanations:

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