Are Jews Smarter?

This story begins, as it inevitably must, in the Old Country.


At some point during the tenth century, a group of Jews abandoned the lush hills of Lucca, Italy, and—at the invitation of Charlemagne—headed for the severer climes of the Rhineland and Northern France. These Jews didn’t have a name for themselves, at first. They were tied together mostly by kinship. But ultimately, they became known as Ashkenazim, a variation on the Hebrew word for one of Noah’s grandsons.


In some ways, life was good for the Jews in this strange new place. They’d been lured there on favorable terms, with promises of physical protection, peaceful travel, and the ability to adjudicate their own quarrels. (The charter of Henry IV, dated 1090, includes this assurance: “If anyone shall wound a Jew, but not mortally, he shall pay one pound of gold . . . If he is unable to pay the prescribed amount . . . his eyes will be put out and his right hand cut off.”) But in other ways, life was difficult. The Ashkenazim couldn’t own land. They were banned from the guilds. They were heavily taxed.


Yet the Ashkenazim did very well, in spite of these constraints, because they found an ingenious way to adapt to their new environment that didn’t rely on physical labor. What they noticed, as they set up their towns, located mainly at the crossroads of trade routes, was that there was no one around to lend money.


So there it was: a demand and a new supplier. Because of the Christian prohibition against usury, Jews found themselves a financially indispensable place in their new home, extending loans to peasants, tradesmen, knights, courtiers, even the occasional monastery. The records from these days are scarce. But where they exist, they are often startling. In 1270, for example, 80 percent of the 228 adult Jewish males in Perpignan, France, made their living lending money to their Gentile neighbors, according to Marcus Arkin’s Aspects of Jewish Economic History. One of the most prolific was a rabbi. Two others were identified, in the notarial records, as “poets.”


Success at money-lending required a different set of skills than farming or any of the traditional trades. Some, surely, were social: cultivating connections, winning over trust (or maybe bullying your way there, Shylock’s awful pound of flesh). It probably required some aggression, because the field was competitive, with Jews suffering so few professional options. But it also required cognitive skills, or something my generation would call numeracy—a fluency in mathematics, a dexterity with numbers—and my grandmother’s generation would call “a head for figures.” If you were Jewish in Perpignan in 1270, and you didn’t have a head for figures, you didn’t stand much of a chance.


Numeracy, literacy, critical reasoning: For millennia, these have been the currency of Jewish culture, the stuff of Talmudic study, immigrant success, and Borscht Belt punch lines.Two Jews, three opinions . . . Keep practicing, you’ll thank me later . . . Q: When does a Jewish fetus become a human? A: When it graduates from medical school.


Of course, there’s another side to this shining coin. Jewish cleverness has also been an enduring feature of anti-Semitic paranoia. In the sixteenth century, Martin Luther said Jewish doctors were so smart they could develop a poison that could kill Christians in a single day—or any other time period of their choosing (and four centuries later, Pravdasuggested Jewish doctors were spies sent to kill Stalin). After the calamities of September 11, one of the creepier conspiracy theories to whip through the Muslim world was the idea that only Jews were cunning enough to have pulled off the hijackings.


Last summer, Henry Harpending, an evolutionary anthropologist at the University of Utah, and Gregory Cochran, an independent scholar with a flair for controversy, skipped cheerfully into the center of this minefield. The two shopped around a paper that tried to establish a genetic argument for the fabled intelligence of Jews. It contended that the diseases most commonly found in Ashkenazim—particularly the lysosomal storage diseases, like Tay-Sachs—were likely connected to and, indeed, in some sense responsible for outsize intellectual achievement in Ashkenazi Jews. The paper contained references, but no footnotes. It was not written in the genteel, dispassionate voice common to scientific inquiries but as a polemic. Its science was mainly conjecture. Most American academics expected the thing to drop like a stone.


It didn’t. The Journal of Biosocial Science, published by Cambridge University Press, posted it online and agreed to run it in its bi-monthly periodical sometime in 2006. The New YorkTimes, The Economist, and several Jewish publications risked their reputations to legitimize it. Today, the paper has a lively presence on the Internet—type “Ashkenazi” into Google and the first hit is the Wikipedia entry, where the article gets pride of place.

Three hares

Image via Wikipedia
The three hares is a circular motif appearing in sacred sites from the Middle and Far East to the churches of southwest England (as the "Tinners’ Rabbits"),[1] and historical synagogues in Europe.[2] It is used as an architectural icon, a religious symbol, and modernly as a work of art[3][4] or a logo for adornment (including tattoos),[5] jewelry and a coat of arms on an escutcheon.[6] It is viewed as a puzzle or as a topology problem or as a visual challenge. It is rendered as a sculpture, in drawing, and in painting.

The symbol features three hares chasing each other in a circle. Like the triskelion[7] the triquetra (and their antecedents, e.g., the Triple spiral and the Yin yang whorl), it has a threefold rotational symmetry. See Frieze group. All of those symbols are interrelated and as such are used in pagan and Wiccan symbolism.[8] Each of the ears is shared by two hares, so that only three ears are shown. It has a number of mystical associations and is associated with fertility and the lunar cycle. When used in Christian churches, it is a symbol of the Trinity. Its origins and original significance are uncertain, as are the reasons why it appears in such diverse locations.[1] That the image's meaning changes depending upon the context and the viewer could be characterized as being analogous to pareidolia[2]; its widespread appeal may be characterized as being a meme.[9][10]

Contents [hide]
1 Origins in Buddhism and diffusion on the Silk Road
2 In Christianity
3 In Judaism
4 As an optical illusion or puzzle
5 Other uses and related designs
6 See also
7 References
8 Further reading
9 External links
[edit]Origins in Buddhism and diffusion on the Silk Road



The spread of the Three Hares symbol between 600 and 1500
The earliest occurrences appear to be in cave temples in China, dated to the Sui dynasty (6th to 7th centuries).[11][12] The iconography spread along the Silk Road,[13] and was a symbol associated with Buddhism.[14] The hares have been said to be "A hieroglyph of 'to be'."[15] In other contexts the metaphor has been given different meaning. For example, Guan Youhui, a retired researcher from the Dunhuang Academy, who spent 50 years studying the decorative patterns in the Mogao Caves, believes the three rabbits image-—"like many images in Chinese folk art that carry auspicious symbolism—represent peace and tranquility."[11][12] See Aurel Stein. The hares have appeared in Lotus motifs.[16]

The Three Hares appear on 13th century Mongol metal work, and on a copper coin, found in Iran, dated to 1281.[17][18][19]

Another appears on an ancient Islamic reliquary from southern Russia. Another 13th or early 14th century Reliquary was from Iran from Mongol rule, and is preserved in the treasury of Cathedral of Trier Germany. On its base, the casket reveals Islamic iconography, and originally featured two images of the three hares. One was lost through damage.[20]

One theory pertaining to the spread of the motif is that it was transported from China across Asia and as far as the south west of England by merchants traveling the silk road. This view is supported by the early date of the surviving occurrences in China. However the majority of representations of the three hares in churches occur in England and northern Germany. This supports a contrary view that the Three Hares are English or early German symbols.[1][11][12][21]

Some claim that the Devon name, Tinners’ Rabbits, is related to local tin miners adopting it. The mines generated wealth in the region and funded the building and repair of many local churches, and thus the symbol may have been used as the miners signature mark.[22] The architectural ornament of the Three Hares also occurs in churches that are unrelated to the miners of South West England. Other occurrences in England include floor tiles at Chester Cathedral,[23] stained glass at Long Melford, Suffolk, and a ceiling in Scarborough, Yorkshire.[1]

[edit]In Christianity

The motif of the Three Hares is used in a number of medieval European churches, particularly in France (e.g., in the Basilica of Notre-Dame de Fourvière in Lyons)[24] and Germany. It occurs with the greatest frequency in the churches of the West Country of England. The motif appears in architectural wood carving, stone carving, window tracery and stained glass. In South Western England there are nearly thirty recorded examples of the Three Hares appearing on 'roof bosses' (carved wooden knobs) on the ceilings in medieval churches in Devon, (particularly Dartmoor). There is a good example of a roof boss of the Three hares at Widecombe-in-the-Moor,[7] Dartmoor, with another in the town of Tavistock on the edge of the moor. The motif occurs with similar central placement in Synagogues.[2] Another occurrence is on the ossuary that by tradition contained the bones of St. Lazarus.[25]

Where it occurs in England, the Three Hares motif usually appears in a prominent place in the church, such as the central rib of the chancel roof, or on a central rib of the nave. This suggests that the symbol held significance to the church, and casts doubt on the theory that they may have been a masons' or carpenters' signature marks.[1] There are two possible and perhaps concurrent reasons why the Three Hares may have found popularity as a symbol within the church. Firstly, it was widely believed that the hare was hermaphrodite and could reproduce without loss of virginity.[26] This led to an association with the Virgin Mary, with hares sometimes occurring in illuminated manuscripts and Northern European paintings of the Virgin and Christ Child. The other Christian association may have been with the Holy Trinity,[26][27] representing the "One in Three and Three in One" of which the triangle or three interlocking shapes such as rings are common symbols. In many locations the Three Hares are positioned adjacent to the Green Man, a symbol associated with the continuance of Anglo-Saxon paganism.[28] These juxtapositions may have been created to imply the contrast of the Divine with man's sinful, earthly nature.[26]

[edit]In Judaism

In Judaism, the "shafan" in Hebrew has symbolic meaning. Although rabbits are listed as a non-kosher animal in the Bible, it can carry very positive symbolic connotations, like lions and eagles. 16th century German scholar Rabbi Yosef Hayim Yerushalmi, saw the rabbits as a symbol of the Diaspora. The replica of the Chodorow Synagogue from Poland (on display at the Museum of the Jewish Diaspora in Tel Aviv) has a ceiling with a large central painting which depicts a double headed eagle holds two brown rabbits in its claws without harming them. The painting is surrounded by a citation from the end of Deuteronomy:

.כנשר יעיר קינו על גוזליו ירחף. יפרוש כנפיו יקחהו ישאהו על אברתו
— Deuteronomy 32:11, The Song of Moses.
This may be translated: "As an eagle that stirreth up her nest, hovereth over her young, spreadeth abroad her wings, taketh them, beareth them on her pinions (...thus is G'd to the Jewish people)."[2]

The hare frequently appears in the form of the symbol of the "rotating rabbits". An ancient German riddle describes this graphic thus:

"Three hares sharing three ears, Yet every one of them has two."[2]

This curious graphic riddle can be found in all of the famous Wooden synagogues from the period of the 17th and 18th century in the Ashknaz region (in Germany) that are on museum display in Beth Hatefutsoth Museum in Tel Aviv, the Jewish Museum Berlin and The Israel Museum in Jerusalem. They also appear in the Synagogue from Horb am Neckar (donated to the Israel Museum). The three animals adorn the wooden panels of the prayer room from Unterlimpurg near Schwäbisch Hall, which may be seen in replica in the Jewish Museum Berlin. They also are seen in a main exhibit of the Diaspora Museum in Tel Aviv. Israeli art historian Ida Uberman wrote about this house of worship: "... Here we find depictions of three kinds of animals, all organized in circles: eagles, fishes and hares. These three represent the Kabbalistic elements of the world: earth, water and fire/heavens... The fact that they are always three is important, for that number . . . is important in the Kabbalistic context".[2]

Not only do they appear among floral and animal ornaments, but they are often in a distinguished location, directly above the Torah ark, the place where the holy scriptures repose.[2]

They appear on headstones in Sataniv (Сатанів), western Ukraine.[29][30] See Galicia (Central-Eastern Europe)[2]

[edit]As an optical illusion or puzzle

The logo presents a problem in topology.[21] It is a strange loop or rendered as a puzzle[31]

Jurgis Baltrusaitis's (1955) Le Moyen-Âge fantastique. Antiquités et exotismes dans l'art gothique [32] includes a 1576 Dutch engraving with the puzzle given in Dutch and French around the image. It notes:

The secret is not great when one knows it.
But it is something to one who does it.
Turn and turn again and we will also turn,
So that we give pleasure to each of you.
And when we have turned, count our ears,
It is there, without any disguise, you will find a marvel.[21]
"These are the oldest known dated examples of the Three Rabbits as a puzzle." One commentator believes its being a puzzle is likely reason for the image's popularity.[21]

One recent philosophical book poses it as a problem in perception and an optical illusion -- an example of contour rivalry. Each rabbit can be individually seen as correct—it is only when you try to see all three at once that you see the problem with defining the hares' ears. This is similar to "The Impossible Tribar" by Roger Penrose,[21] first originated by Oscar Reutersvärd. Compare, M.C. Escher See, Impossible object.

[edit]Other uses and related designs



City of Hasloch's crest
The Community of Hasloch’s arms[33] is described as: Azure edged Or three hares passant in triskelion of the second, each sharing each ear with one of the others, in chief a rose argent seeded of the second, in base the same features three hares. It is said, "The stone with the image of three hares, previously adorned the old village well, now stands beside the town hall."[34] Hasloch is in the Main-Spessart district in the Regierungsbezirk of Lower Franconia (Unterfranken) in Bavaria, Germany.[35]
Hares and rabbits have appeared as a representation or manifestation of various deities in many cultures, including: Hittavainen, Finnish god of Hares;[36] Kaltes-Ekwa, Siberian goddess of the moon; Jade Rabbit, maker of medicine on the moon for the Chinese gods, depicted often with a mortar and pestle;[37][38] Ometotchtli (Two Rabbits,) Aztec god of fertility, etc., who led 400 other Rabbit gods known as the Centzon Totochtin; Kalulu, Tumbuka mythology (Central African) Trickster god; and Nanabozho (Great Rabbit,) Ojibway deity, a shape-shifter and a cocreator of the world.[37][39] See generally, Rabbits in the arts, German Wikipedia
Tinners' Rabbits is the name of a dance of many forms involving use of sticks and rotation of three, six or nine dancers.[40][41]
The hare is rarely used in British armory; but "Argent, three hares playing bagpipes gules" belongs to the FitzErcald family of ancient Derbyshire.[42] Parenthetically, in heraldry the "Coney", that is the rabbit, is more common than the hare.[42]
The French crest of the family Pinoteau—dating from the first Baron Pinoteau (1814–1815) and which includes historian Hervé Pinoteau (former vice president of the Académie Internationale d'Héraldique -- includes three rabbits.[43][44] See generally, Nobility of the First French Empire.
Among hunters, a collection of three hares (“a brace and a half” or tierce) -- or three creatures of any kind, especially greyhounds, foxes, bucks—is called “a leash.”[45][46][47]
The cover art for alternative rock band AFI's album Decemberunderground features three hares, albeit in a different configuration.
[edit]See also

Flag of the Isle of Man
Flag of Sicily, a similar flag also with a triskelion
List of fictional hares and rabbits
Pannonia Film Studio -- The Three Rabbits (A három nyúl), a short animated Hungarian film
Three Rabbit Islands, three uninhabited small islands off the north coast of Sutherland , Scotland in Tongue Bay
Rabbits (film), about three humanoid rabbits in a room written and directed by David Lynch
Rabbit rabbit,rabbit, superstitious periodic mantra
Sator Square, a rotating palendrome meme

Oberlander Jews

Oberlander Jews (also Oberlandish or simply Oberland Jews) are Ashkenazi, Yiddish- and German-speaking Jews originating in the Oberland or higher land western region of Hungary and the district surrounding Bratislava in Slovakia. This is as opposed to Unterlander Jews, who resided in the eastern lower lands on the opposite side of the Danube River and were influenced more by the Hasidic movement.[1]

Many were Haredi while not Hasidic, others were Orthodox while rather contemporary. Most wore contemporary clothing, spoke Hungarian however educated their children within a traditional Jewish religious framework, together with academic subjects as taught in Hungarian.[1] Oberlander Judaism was most similar to classic German pre-emancipation Orthodoxy. One very distinct custom, or minhag, that some Oberlanders adhered to was the wearing of a talis prior to marriage, as German Jews do today. Another is putting on tefilin on the intermediate days of a festival. Oberlander Jews have contributed strongly to present-day Orthodox Jewish communities. Generally, Oberlander Jews were more likely to remain Orthodox than other Ashkenazim after post-World War II immigration to North America[citation needed]. Many of this group have joined Hasidic groups such as Vizhnitz after World War II. Others educated their children in the Lithuanian style yeshiva or in Israel, where they no longer maintain all of the customs and do not speak Hungarian or German. Therefore, being an Oberlander is no longer a significant distinction among Jews, as in pre-World War II Europe.

The intelligence of Ashkenazi Jews

Image via Wikipedia
The intelligence of Ashkenazi Jews has been the subject of study and speculation within the fields of psychometry and evolutionary biology. Psychometric studies have reported a higher than average intelligence quotient among Ashkenazi Jews than among the general population. There has been a broad range of speculation about the possible causes of these findings, as well as a measure of controversy, as the studies touch upon several sensitive subjects such as the possible relationship between race and intelligence, as well as issues of racialism, philo-semitism and anti-semitism.[1]

One highly publicised proposal by Gregory Cochran, Jason Hardy and Henry Harpending, suggests that the Ashkenazi had jobs in which increased IQ strongly favoured economic success, in contrast with other populations, who were mostly peasant farmers.[2]

Contents [hide]
1 Psychometric findings
2 "Natural History of Ashkenazi Intelligence" (Cochran et al, 2005)
3 Other studies
4 Other proposed explanations
5 See also
6 Notes
7 References
8 External links
[edit]Psychometric findings

Cochran et al. write that according to some studies from the 1970s Ashkenazi Jews score 0.75 to 1.0 standard deviations above the general European average. This usually corresponds to an IQ of 112–115. They have high verbal and mathematical scores, while their visuospatial abilities are typically somewhat lower, by about one half a standard deviation, than the European average.[2] More recent studies have found somewhat lower values with a review in 2004 by Richard Lynn stating 0.5 standard deviation.[3] Lynn and Longley in a 2006 review write that the best reading of Jews in Britain is 110 and in the US is 109.5.[4] Brian Ferguson writes that 90% of US Jews are Ashkenazi and that US data usually do not discriminate origin.[5]

[edit]"Natural History of Ashkenazi Intelligence" (Cochran et al, 2005)

The 2005 study "Natural History of Ashkenazi Intelligence" by Gregory Cochran, Jason Hardy, and Henry Harpending at the University of Utah wrote Ashkenazi Jews are greatly overrepresented in occupations and fields with the high cognitive demands. During the 20th century, they made up about 3% of the US population but won 27% of the US science Nobel Prizes and 25% of the Turing Awards. More than half of the world's chess champions are Ashkenazi Jews. The authors argue that non-Ashkenazi Jews do not have high average IQ test scores, nor are they over-represented in cognitively demanding occupations.[2] The study as well as Rushton (1997) argued that despite claims to the contrary, for example in the Mismeasure of Man, also the early IQ testing support a high average Ashkenazi IQ.[6]

The study argues that European Jews were forbidden to work in many of the common jobs of the Middle Ages from 800 to 1700 CE, such as agriculture, and subsequently worked in high proportion in professions 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. Another selection may have been that those with low IQ were unable to perform such professions and drifted away from the Jewish community. Jews rarely married outside of their faith, creating a reproductively isolated population in which this pressure, the authors argue, would be able to influence gene frequency. The authors write that before this time period Jews likely did not have unusual occupations and there is no evidence of high cognitive ability.[2]

Cochran et al. hypothesized that the selective 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, Canavan disease, Gaucher's disease, Niemann-Pick disease, Mucolipidosis type IV, and other lipid storage disorders and sphingolipid diseases. As to how they might affect intelligence, the authors argue that sphingolipid disorders might promote the growth and interconnection of brain cells and that mutations in the DNA repair genes, another cluster of Ashkenazic diseases, may stimulate the growth of neurons.[7] Some of these diseases (especially torsion dystonia) have been associated with high intelligence.[2]

The paper argues that the Parsi in India may be a similar case. It is an endogamous group with a high current economic achievement, a history of trading, business and management, and has a disease pattern that is different from that of their neighbors. [2]

One criticism is that both the concepts of "Ashkenazi Jews" and "intelligence" are socially rather than genetically defined and have no biological basis.[8] In an unpublished critique of the paper, Brian Ferguson writes that all of the basic assumptions of Cochran et al.'s theory are unsupported. For example, he observes that Torah study developed while most Jews were still farmers and that by the second half of the first millennium most Jews were literate in stark contrast to other farming populations. This was an important reason for why Jews could move into more skilled professions. He argues that an environment-only explanation emphasizing that Jews partake of cultural tradition of scholarship and abstract thought can well explain the IQ differences. Ferguson also notes that the paper is not the first to propose that Jews evolved higher intelligence.[5] Steven Pinker has commented that he believes that the core of the hypothesis could be assessed beyond reasonable doubt by a suitable study.[9]

The New York Times described a mixed reaction to the Cochran et al. paper. Steven Pinker said "it's certainly a thorough and well-argued paper, not one that can easily be dismissed outright." Dr. Andrew Clark said that the authors "make pretty much all of the classic mistakes in interpreting heritability". In addition, several raised the possibility of a "founder effect" rather than natural selection being the rationale for the genetic diseases (in disagreement with the paper which dismissed that possibility as statistically unlikely.) Regarding the interpretation of Jewish medieval history, professor of Jewish studies Paul Rose said "I think that some of their conclusions may be right though they still need a lot of work to be persuasive to historians and others."[7]

Botticini and Eckstein (2007) in a study on Jewish history write regarding the Cochran et al. study. that "We do not have a strong view in favor or against this argument. On the one hand, one prediction of our model-individuals with low cognitive skills were pushed out of Judaism once the religion made literacy and education the main requirement for belonging to the Jewish community–may be consistent with this evidence on cognitive abilities. On the other hand, as we emphasize here and in Botticini and Eckstein (2005), the Jewish people left farming and selected into urban, skilled occupations well before any restrictions or prohibitions were imposed on them."[10]

[edit]Other studies

Lynn in his 2006 book Race Differences in Intelligence writes that Israel has an average IQ of only about 95. Lynn explains this by breaking down the Israeli population into three components: 40 percent Ashkenazi Jews with an average IQ of 103; 40 percent Sephardi Jews (Oriental Jewish) with an average IQ of 91; and 20 percent Arab with an average IQ of 86. Lynn suggests these differences could have arisen from selective migration (more intelligent Jews emigrated to Britain and the USA), intermarriage with neighboring populations with different average IQs, selective survival through persecution (European Jews were the most persecuted), and the presence of ethnic non-Jews among the Ashkenazim in Israel as a result of the immigration of people from the former Soviet Bloc countries who posed as Jews.

David and Lynn in a 2007 literature review examined the average IQ of European (largely Ashkenazi) and Sephardic Jews in Israel and found a 14 point lower average score for the Sephardic Jews. The authors argue that this can be explained by the hypothesis of Cochran et al. since Sephardic Jews were allowed to work in a much wider range of occupations and therefore did not come under the evolutionary pressure described in the Cochran et al. study.[11]

A 2010 study by Bray et al. genotyped 471 unrelated Azkhenazi individuals and write that most of the diseases are not under strong positive selection, but rather rose to their current frequency through genetic drift after a population bottleneck. They also write that the Azkhenazi population are less isolated than previously thought with between 35 and 55 percent of the modern Ashkenazi genome coming from European descent.[12]

[edit]Other proposed explanations

A long cultural history encouraging scholarship and learning.[5]
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 Ashkenazi community.[13] Botticini and Eckstein argue that from the end of the second century, Judaism enforced a religious norm requiring Jewish fathers to educate their sons. The high cost of this in subsistence farming communities caused voluntary conversions, explaining a large part of a reduction in the size of the Jewish population from 4.5 million to 1.2 million. As the Jews invested in education, they could then enter skilled occupations.[10]
Cochran et al. write that "Another theory suggests that there was selective breeding for Talmudic scholarship. This seems unlikely to have been an important selective factor, since there weren’t very many professional rabbis, certainly less than one per cent of the population. A selective force that only affects a tiny fraction of the population can never be strong enough to cause important evolutionary change in tens of generations."
However, Cochran et al. write that "A plausible variant of the Talmudic scholarship model suggests that it was like a sexually selected marker and that rich families preferred to marry their daughters to males who excelled (Weyl & Possony, 1963; MacDonald, 1994) so that the payoff to intelligence was indirect rather than direct as we suggest. Without detailed historical demographic information it will be difficult to evaluate this hypothesis."
European Jews' history of persecution selected for high intelligence, leaving a positive effect on the hereditary component of their IQ.[14] Cochran et al. argue that this is unlikely since there are no similar outcome in other groups such as Romani who have faced frequent persecution.
A variant of the above is that selective migration and survival before and during the Holocaust selected for high IQ.[5]
[edit]