Ashkenazi intelligence
Encyclopedia
Whether Ashkenazi Jews
have higher intelligence
than other ethnic groups has been an occasional subject of scientific controversy. The 2005 paper "Natural History of Ashkenazi Intelligence" by Cochran
, Hardy, and Harpending
, argued on the basis of inherited diseases and the peculiar economic situation of Ashkenazi Jews in medieval Europe
, that Ashkenazi Jews as a group now inherit a cognitive profile that includes higher verbal and mathematical intelligence than other ethnic groups, along with lower spatial intelligence. Opposing this hypothesis are ambiguous statistical results regarding how much difference in intelligence really exists between Ashkenazi Jews and other groups, and causes that might explain the congenital illnesses and economic and intellectual successes of Ashkenazi Jews better than natural selection
for cognitive traits. Such causes include the founder effect
for the mutations that cause the congenital diseases, and elements of Jewish culture.
, Jason Hardy, and Henry Harpending
, argued that the unique conditions under which Ashkenazi Jews lived in medieval Europe selected for high verbal and mathematical intelligence but not spatial intelligence. Their argument 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. The Cochran et al. hypothesis is not widely accepted as true, nor is there consensus that it's false. Present-day knowledge cannot definitively settle the question of whether Ashkenazi Jewish intelligence has a genetic origin.
to social success in Jewish communities; 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; that historic persecution of European Jews fell disproportionately on people of lower intelligence.
.
One observational basis for inferring that Ashkenazi Jews have high intelligence is their prevalance in intellectually demanding fields. From 1901–2010, 21.5% of Nobel prize winners were Jewish, while Jews make up a much smaller fraction of the population of the countries represented. For example, 36% of Nobel prize winners from the United States
have been Jewish, while Jews make up 2.1% of the U.S. population. G. Cochran, J. Hardy and H. Harpending additionally cite the disproportionately high percentage of Ashkenazi Chess Grandmasters and Fields Medalists in mathematics. However, such statistics do not rule out factors other than intelligence, such as institutional biases and social networks.
A more direct approach is to measure intelligence with psychometric tests
(although the validity of such tests as a measure of intelligence has often been disputed). 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. Some studies have found IQ scores amongst Ashkenazi Jews to be a fifth to one full standard deviation
above average in mathematical and verbal tests. However, most studies of Jewish intelligence have used samples which were either poor representations of the whole population or were too small to give reliable results, and some studies from the beginning of the 20th century had found Ashkenazi groups to have below-average intelligence. In reference to the latter, G. Cochran, J. Hardy and H. Harpending argue that it is "a widely cited misrepresentation by Leon Kamin
(Kamin, 1974) of a paper by Henry Goddard (Goddard, 1917). Goddard gave IQ tests to people suspected of being retarded, and he found that the tests identified retarded Jews as well as retarded people of other groups. Kamin reported, instead, that Jews had low IQs, and this erroneous report was picked up by many authors including Stephen Jay Gould
, who used it as evidence of the unreliability of IQ tests (Seligman, 1992)." On the other hand, the validity of IQ tests in general has often been questioned.
starting from a population bottleneck
, not with selective pressure favoring its spread.
Though long thought to be a genetic isolate, recent studies have found that modern Ashkenazi Jews are more closely related to other European ethnic groups than to their Middle Eastern forebears. This throws doubt on premise #2 of Cochran et al.
It's not clear that mathematical and verbal talent were the prime factors for success in the occupations that Jews were limited to. Social connections, social acumen, willingess to take risks, and access to capital (through inheritance, as above) likely played at least as great a role.
in 70 CE
, Jewish culture replaced its emphasis on ritual with an emphasis on study and scholarship. Unlike the surrounding cultures, most Jews, even farmers, were taught to read and write in childhood. Talmudic
scholarship
became a leading key to social status.
The emphasis on scholarship came before the Jews turned from agriculture to urban occupations. This suggests that premise #3 of Cochran et al. might have the causal direction backward: mastery of written language due to the Talmudic tradition may have made the Jews well suited for financial and managerial occupations at the time when these occupations provided new opportunities. Similar cultural traditions continue to the present day, possibly providing a non-genetic explanation for contemporary Ashkenazi Jews' high IQs and prevalence in intellectual fields.
Ashkenazi Jews
Ashkenazi Jews, also known as Ashkenazic Jews or Ashkenazim , are the Jews descended from the medieval Jewish communities along the Rhine in Germany from Alsace in the south to the Rhineland in the north. Ashkenaz is the medieval Hebrew name for this region and thus for Germany...
have higher intelligence
Intelligence
Intelligence has been defined in different ways, including the abilities for abstract thought, understanding, communication, reasoning, learning, planning, emotional intelligence and problem solving....
than other ethnic groups has been an occasional subject of scientific controversy. The 2005 paper "Natural History of Ashkenazi Intelligence" by Cochran
Gregory Cochran
Gregory M. Cochran is a physicist and adjunct professor of anthropology at the University of Utah who has developed some new ideas in evolutionary medicine and genetic anthropology. Cochran is known for several controversial theories....
, Hardy, and Harpending
Henry Harpending
Henry C. Harpending is an anthropologist and population geneticist at the University of Utah, where he is a distinguished professor...
, argued on the basis of inherited diseases and the peculiar economic situation of Ashkenazi Jews in medieval Europe
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...
, that Ashkenazi Jews as a group now inherit a cognitive profile that includes higher verbal and mathematical intelligence than other ethnic groups, along with lower spatial intelligence. Opposing this hypothesis are ambiguous statistical results regarding how much difference in intelligence really exists between Ashkenazi Jews and other groups, and causes that might explain the congenital illnesses and economic and intellectual successes of Ashkenazi Jews better than natural selection
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
for cognitive traits. Such causes include the founder effect
Founder effect
In population genetics, the founder effect is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population. It was first fully outlined by Ernst Mayr in 1942, using existing theoretical work by those such as Sewall...
for the mutations that cause the congenital diseases, and elements of Jewish culture.
"Natural History of Ashkenazi Intelligence"
"Natural History of Ashkenazi Intelligence", a 2005 paper by Gregory CochranGregory Cochran
Gregory M. Cochran is a physicist and adjunct professor of anthropology at the University of Utah who has developed some new ideas in evolutionary medicine and genetic anthropology. Cochran is known for several controversial theories....
, Jason Hardy, and Henry Harpending
Henry Harpending
Henry C. Harpending is an anthropologist and population geneticist at the University of Utah, where he is a distinguished professor...
, argued that the unique conditions under which Ashkenazi Jews lived in medieval Europe selected for high verbal and mathematical intelligence but not spatial intelligence. Their argument has four main premises:
- Today's Ashkenazi Jews have a high average mathematical and verbal IQ and an unusual cognitive profile compared to other ethnic groups, including Sephardic and Oriental Jews.
- From roughly 800 to 1650 CECECE, Ce or ce may refer to:* Common Era , secular alternative to Anno Domini * Cerium, chemical element with symbol Ce- Titles :* Chief Executive, administrative head of some regions...
, Ashkenazi Jews in Europe were a mostly isolated genetic group. When Ashkenazi Jews married non-Jews, they usually left the Jewish community; few non-Jews married into the Jewish community. - During the same period, laws barred Ashkenazi Jews from working most jobs, including farming and crafts, and forced them into finance, management, and international trade. Wealthy Jews had several more children per family than poor Jews. So, genes for cognitive traits such as verbal and mathematical talent, which make a person successful in the few fields where Jews could work, were favored; genes for irrelevant traits, such as spatio-visual abilities, were supported by less selective pressure than in the general population.
- Today's Ashkenazi Jews suffer from a number of congenital diseases and mutations at higher rates than most other ethnic groups; these include Tay-Sachs, Gaucher's diseaseGaucher's diseaseGaucher's disease is a genetic disease in which a fatty substance accumulates in cells and certain organs.Gaucher's disease is the most common of the lysosomal storage diseases. It is caused by a hereditary deficiency of the enzyme glucosylceramidase. The enzyme acts on the fatty acid...
, Bloom's syndrome, and Fanconi anemiaFanconi anemiaFanconi anemia is a genetic disease with an incidence of 1 per 350,000 births, with a higher frequency in Ashkenazi Jews and Afrikaners in South Africa.FA is the result of a genetic defect in a cluster of proteins responsible for DNA repair...
, and mutations at BRCA1BRCA1BRCA1 is a human caretaker gene that produces a protein called breast cancer type 1 susceptibility protein, responsible for repairing DNA. The first evidence for the existence of the gene was provided by the King laboratory at UC Berkeley in 1990...
and BRCA2BRCA2BRCA2 is a protein that in humans is encoded by the BRCA2 gene.BRCA2 orthologs have been identified in most mammals for which complete genome data are available....
. These mutations' effects cluster in only a few metabolic pathways, suggesting that they arise from selective pressure rather than genetic driftGenetic driftGenetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
. One cluster of these diseases affects sphingolipidSphingolipidSphingolipids are a class of lipids containing a backbone of sphingoid bases, a set of aliphatic amino alcohols that includes sphingosine. They were discovered in brain extracts in the 1870s and were named for the mythological Sphinx because of their enigmatic nature. These compounds play...
storage, a secondary effect of which is increased growth of axons and dendrites. At least one of the diseases in this cluster, torsion dystoniaTorsion dystoniaTorsion dystonia is a disease characterized by painful muscle contractions resulting in uncontrollable distortions. This specific type of dystonia is found in children, with symptoms starting around the ages of 11 or 12. It commonly begins with contractions in one general area such as an arm or a...
, has been found anecdotally to correlate with exceptionally high IQ. Another cluster disrupts DNADNADeoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
repair, an extremely dangerous sort of mutation which is lethal in homozygotes. The authors speculate that these mutations give a cognitive benefit to heterozygotes by reducing inhibitions to neural growth, a benefit that would not outweigh its high costs except in an environment where it was strongly rewarded.
Other scientists gave the paper a mixed reception, ranging from outright dismissal to acknowledgement that the hypothesis might be true and merits further research. The Cochran et al. hypothesis is not widely accepted as true, nor is there consensus that it's false. Present-day knowledge cannot definitively settle the question of whether Ashkenazi Jewish intelligence has a genetic origin.
Other evolutionary theories
Other suggested evolutionary accounts include: a long cultural history encouraging scholarship and learning; a contribution of talent in the study of TorahTorah study
Torah study is the study by Jewish people of the Torah, Hebrew Bible, Talmud, responsa, rabbinic literature and similar works, all of which are Judaism's religious texts...
to social success in Jewish communities; 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; that historic persecution of European Jews fell disproportionately on people of lower intelligence.
Does a group difference in intelligence exist?
One basic question to be answered in assessing a genetic explanation of unusual intelligence in Ashkenazi Jews is whether today's Ashkenazi Jews really do, as a group, have unusual intelligence. Assessing intelligence, especially of ethnic groups, is notoriously difficult and subject to racist and political biasesRace and intelligence
The connection between race and intelligence has been a subject of debate in both popular science and academic research since the inception of intelligence testing in the early 20th century...
.
One observational basis for inferring that Ashkenazi Jews have high intelligence is their prevalance in intellectually demanding fields. From 1901–2010, 21.5% of Nobel prize winners were Jewish, while Jews make up a much smaller fraction of the population of the countries represented. For example, 36% of Nobel prize winners from the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
have been Jewish, while Jews make up 2.1% of the U.S. population. G. Cochran, J. Hardy and H. Harpending additionally cite the disproportionately high percentage of Ashkenazi Chess Grandmasters and Fields Medalists in mathematics. However, such statistics do not rule out factors other than intelligence, such as institutional biases and social networks.
A more direct approach is to measure intelligence with psychometric tests
Psychometrics
Psychometrics is the field of study concerned with the theory and technique of psychological measurement, which includes the measurement of knowledge, abilities, attitudes, personality traits, and educational measurement...
(although the validity of such tests as a measure of intelligence has often been disputed). 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. Some studies have found IQ scores amongst Ashkenazi Jews to be a fifth to one full standard deviation
Standard deviation
Standard deviation is a widely used measure of variability or diversity used in statistics and probability theory. It shows how much variation or "dispersion" there is from the average...
above average in mathematical and verbal tests. However, most studies of Jewish intelligence have used samples which were either poor representations of the whole population or were too small to give reliable results, and some studies from the beginning of the 20th century had found Ashkenazi groups to have below-average intelligence. In reference to the latter, G. Cochran, J. Hardy and H. Harpending argue that it is "a widely cited misrepresentation by Leon Kamin
Leon Kamin
Leon J. Kamin is an American psychologist who chaired Princeton University's Department of Psychology in 1968....
(Kamin, 1974) of a paper by Henry Goddard (Goddard, 1917). Goddard gave IQ tests to people suspected of being retarded, and he found that the tests identified retarded Jews as well as retarded people of other groups. Kamin reported, instead, that Jews had low IQs, and this erroneous report was picked up by many authors including Stephen Jay Gould
Stephen Jay Gould
Stephen Jay Gould was an American paleontologist, evolutionary biologist, and historian of science. He was also one of the most influential and widely read writers of popular science of his generation....
, who used it as evidence of the unreliability of IQ tests (Seligman, 1992)." On the other hand, the validity of IQ tests in general has often been questioned.
Problems with the genetic explanation
Assuming that today there is a statistical difference in intelligence between Ashkenazi Jews and other ethnic groups, there still remains the question of whether the difference is caused by inheritance or environmental factors. The following are specific bases for doubt that genetic inheritance is the cause.Problems found in studies of Ashkenazi genes
Most, though not all, of the Ashkenazi congenital diseases arose from genetic drift after a population bottleneck, and show no evidence of selective pressure of the kind called for in the Cochran, et al. paper. For 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 frequency of this mutation among Ashkenazi Jews today accords with genetic driftGenetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
starting from a population bottleneck
Population bottleneck
A population bottleneck is an evolutionary event in which a significant percentage of a population or species is killed or otherwise prevented from reproducing....
, not with selective pressure favoring its spread.
Though long thought to be a genetic isolate, recent studies have found that modern Ashkenazi Jews are more closely related to other European ethnic groups than to their Middle Eastern forebears. This throws doubt on premise #2 of Cochran et al.
Problems with reproductive advantage
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.It's not clear that mathematical and verbal talent were the prime factors for success in the occupations that Jews were limited to. Social connections, social acumen, willingess to take risks, and access to capital (through inheritance, as above) likely played at least as great a role.
The Talmudic tradition
After the destruction of the Second TempleSecond Temple
The Jewish Second Temple was an important shrine which stood on the Temple Mount in Jerusalem between 516 BCE and 70 CE. It replaced the First Temple which was destroyed in 586 BCE, when the Jewish nation was exiled to Babylon...
in 70 CE
CE
CE, Ce or ce may refer to:* Common Era , secular alternative to Anno Domini * Cerium, chemical element with symbol Ce- Titles :* Chief Executive, administrative head of some regions...
, Jewish culture replaced its emphasis on ritual with an emphasis on study and scholarship. Unlike the surrounding cultures, most Jews, even farmers, were taught to read and write in childhood. Talmudic
Talmud
The Talmud is a central text of mainstream Judaism. It takes the form of a record of rabbinic discussions pertaining to Jewish law, ethics, philosophy, customs and history....
scholarship
Scholarly method
Scholarly method or scholarship is the body of principles and practices used by scholars to make their claims about the world as valid and trustworthy as possible, and to make them known to the scholarly public.-Methods:...
became a leading key to social status.
The emphasis on scholarship came before the Jews turned from agriculture to urban occupations. This suggests that premise #3 of Cochran et al. might have the causal direction backward: mastery of written language due to the Talmudic tradition may have made the Jews well suited for financial and managerial occupations at the time when these occupations provided new opportunities. Similar cultural traditions continue to the present day, possibly providing a non-genetic explanation for contemporary Ashkenazi Jews' high IQs and prevalence in intellectual fields.
See also
- Ashkenazi JewsAshkenazi JewsAshkenazi Jews, also known as Ashkenazic Jews or Ashkenazim , are the Jews descended from the medieval Jewish communities along the Rhine in Germany from Alsace in the south to the Rhineland in the north. Ashkenaz is the medieval Hebrew name for this region and thus for Germany...
- List of Jewish Nobel laureates
- List of Jewish chess players
- Fields MedalFields MedalThe Fields Medal, officially known as International Medal for Outstanding Discoveries in Mathematics, is a prize awarded to two, three, or four mathematicians not over 40 years of age at each International Congress of the International Mathematical Union , a meeting that takes place every four...
- Turing AwardTuring AwardThe Turing Award, in full The ACM A.M. Turing Award, is an annual award given by the Association for Computing Machinery to "an individual selected for contributions of a technical nature made to the computing community. The contributions should be of lasting and major technical importance to the...
- History of the race and intelligence controversyHistory of the race and intelligence controversyThe history of the race and intelligence controversy concerns the historical development of a debate, primarily in the United States, concerning possible explanations of group differences in intelligence...
- Genetic studies on JewsGenetic studies on JewsGenetic studies on the Jews are part of population genetics. This discipline is used to better understand the chronology of migration and thus complements the results provided by history, archeology, language or paleontology. The interest of these studies is to investigate the origins of various...
and Medical genetics of Jewish peopleMedical genetics of Jewish peopleThe medical genetics of Jewish people is the study, screening and treatment of genetic disorders that are more common in particular Jewish populations than in the population as a whole. The genetics of Ashkenazi Jews have been particularly well-studied, resulting in the discovery of many genetic... - Race and intelligenceRace and intelligenceThe connection between race and intelligence has been a subject of debate in both popular science and academic research since the inception of intelligence testing in the early 20th century...
External links
- Researchers Say Intelligence and Diseases May Be Linked in Ashkenazic Genes, The New York Times
- Did Discrimination Enhance Intelligence of Jews?, National Geographic
- "Are Jews Smarter?: What Genetic Science Tell Us", New York Magazine
- The evolution of intelligence: The high intelligence of Ashkenazi Jews may be a result of their persecuted past, economist.com
- Murray, CharlesCharles Murray (author)Charles Alan Murray is an American libertarian political scientist, author, columnist, and pundit working as a fellow at the American Enterprise Institute, a conservative think tank in Washington, DC...
. Jewish Genius, CommentaryCommentary (magazine)Commentary is a monthly American magazine on politics, Judaism, social and cultural issues. It was founded by the American Jewish Committee in 1945. By 1960 its editor was Norman Podhoretz, a liberal at the time who moved sharply to the right in the 1970s and 1980s becoming a strong voice for the...
magazine
- Saletan, WilliamWilliam SaletanWilliam Saletan is the national correspondent at Slate.com. Saletan gained recognition in the fall of 2004 with nearly daily columns covering the ups and downs of the Presidential race. He currently writes the 'Human Nature' column...
. Jewgenics: Jewish intelligence, Jewish genes, and Jewish values, Slate
- Haslinger, Kiryn. "A Jewish Gene for Intelligence?", Scientific AmericanScientific AmericanScientific American is a popular science magazine. It is notable for its long history of presenting science monthly to an educated but not necessarily scientific public, through its careful attention to the clarity of its text as well as the quality of its specially commissioned color graphics...
, 21 September 2005.