Jewish Genius, by Charles Murray

“Jewish Genius,” by Charles Murray — April 2007 [PDF]

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From 800 B.C.E. through the first millennium of the Common Era, we have just two examples of great Jewish accomplishment, and neither falls strictly within the realms of the arts or sciences. But what a pair they are. The first is the fully realized conceptualization of monotheism, expressed through one of the literary treasures of the world, the Hebrew Bible. It not only laid the foundation for three great religions but, as Thomas Cahill describes in The Gifts of the Jews (1998), introduced a way of looking at the meaning of human life and the nature of history that defines core elements of the modern sensibility. The second achievement is not often treated as a Jewish one but clearly is: Christian theology expressed through the New Testament, an accomplishment that has spilled into every aspect of Western civilization.

But religious literature is the exception. The Jews do not appear in the annals of philosophy, drama, visual art, mathematics, or the natural sciences during the eighteen centuries from the time of Homer through the first millennium C.E., when so much was happening in Greece, China, and South Asia. It is unclear to what extent this reflects a lack of activity or the lack of a readily available record. For example, only a handful of the scientists of the Middle Ages are mentioned in most histories of science, and none was a Jew. But when George Sarton put a high-powered lens to the Middle Ages in his monumental Introduction to the History of Science (1927-48), he found that 95 of the 626 known scientists working everywhere in the world from 1150 to 1300 were Jews—15 percent of the total, far out of proportion to the Jewish population.

As it happens, that same period overlaps with the life of the most famous Jewish philosopher of medieval times, Maimonides (1135–1204), and of others less well known, not to mention the Jewish poets, grammarians, religious thinkers, scholars, physicians, and courtiers of Spain in the “Golden Age,” or the brilliant exegetes and rabbinical legislators of northern France and Germany. But this only exemplifies the difficulty of assessing Jewish intellectual activity in that period. Aside from Maimonides and a few others, these thinkers and artists did not perceptibly influence history or culture outside the confines of the Jewish world.

Generally speaking, this remained the case well into the Renaissance and beyond. When writing a book called Human Accomplishment (2003), I compiled inventories of “significant figures” in the arts and sciences, defined as people who are mentioned in at least half of the major histories of their respective fields. From 1200 to 1800, only seven Jews are among those significant figures, and only two were important enough to have names that are still widely recognized: Spinoza and Montaigne (whose mother was Jewish).

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The sparse representation of Jews during the flowering of the European arts and sciences is not hard to explain. They were systematically excluded, both by legal restrictions on the occupations they could enter and by savage social discrimination. Then came legal emancipation, beginning in the late 1700’s in a few countries and completed in Western Europe by the 1870’s, and with it one of the most extraordinary stories of any ethnic group at any point in human history.

As soon as Jewish children born under legal emancipation had time to grow to adulthood, they started appearing in the first ranks of the arts and sciences. During the four decades from 1830 to 1870, when the first Jews to live under emancipation reached their forties, 16 significant Jewish figures appear. In the next four decades, from 1870 to 1910, the number jumps to 40. During the next four decades, 1910–1950, despite the contemporaneous devastation of European Jewry, the number of significant figures almost triples, to 114.

To get a sense of the density of accomplishment these numbers represent, I will focus on 1870 onward, after legal emancipation had been achieved throughout Central and Western Europe. How does the actual number of significant figures compare to what would be expected given the Jewish proportion of the European and North American population? From 1870 to 1950, Jewish representation in literature was four times the number one would expect. In music, five times. In the visual arts, five times. In biology, eight times. In chemistry, six times. In physics, nine times. In mathematics, twelve times. In philosophy, fourteen times.

Disproportionate Jewish accomplishment in the arts and sciences continues to this day. My inventories end with 1950, but many other measures are available, of which the best known is the Nobel Prize. In the first half of the 20th century, despite pervasive and continuing social discrimination against Jews throughout the Western world, despite the retraction of legal rights, and despite the Holocaust, Jews won 14 percent of Nobel Prizes in literature, chemistry, physics, and medicine/physiology. In the second half of the 20th century, when Nobel Prizes began to be awarded to people from all over the world, that figure rose to 29 percent. So far, in the 21st century, it has been 32 percent. Jews constitute about two-tenths of one percent of the world’s population. You do the math.

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What accounts for this remarkable record? A full answer must call on many characteristics of Jewish culture, but intelligence has to be at the center of the answer. Jews have been found to have an unusually high mean intelligence as measured by IQ tests since the first Jewish samples were tested. (The widely repeated story that Jewish immigrants to this country in the early 20th century tested low on IQ is a canard.) Exactly how high has been difficult to pin down, because Jewish sub-samples in the available surveys are seldom perfectly representative. But it is currently accepted that the mean is somewhere in the range of 107 to 115, with 110 being a plausible compromise.

The IQ mean for the American population is “normed” to be 100, with a standard deviation of 15. If the Jewish mean is 110, then the mathematics of the normal distribution says that the average Jew is at the 75th percentile. Underlying that mean in overall IQ is a consistent pattern on IQ subtests: Jews are only about average on the subtests measuring visuo-spatial skills, but extremely high on subtests that measure verbal and reasoning skills.

A group’s mean intelligence is important in explaining outcomes such as mean educational attainment or mean income. The key indicator for predicting exceptionalaccomplishment (like winning a Nobel Prize) is the incidence of exceptional intelligence. Consider an IQ score of 140 or higher, denoting the level of intelligence that can permit people to excel in fields like theoretical physics and pure mathematics. If the mean Jewish IQ is 110 and the standard deviation is 15, then the proportion of Jews with IQ’s of 140 or higher is somewhere around six times the proportion of everyone else.

The imbalance continues to increase for still higher IQ’s. New York City’s public-school system used to administer a pencil-and-paper IQ test to its entire school population. In 1954, a psychologist used those test results to identify all 28 children in the New York public-school system with measured IQ’s of 170 or higher. Of those 28, 24 were Jews.

Exceptional intelligence is not enough to explain exceptional accomplishment. Qualities such as imagination, ambition, perseverance, and curiosity are decisive in separating the merely smart from the highly productive. The role of intelligence is nicely expressed in an analogy suggested to me years ago by the sociologist Steven Goldberg: intelligence plays the same role in an intellectually demanding task that weight plays in the performance of NFL offensive tackles. The heaviest offensive tackle is not necessarily the best. Indeed, the correlation between weight and performance among NFL offensive tackles is probably quite low. But they all weigh more than 300 pounds.

So with intelligence. The other things count, but you must be very smart to have even a chance of achieving great work. A randomly selected Jew has a higher probability of possessing that level of intelligence than a randomly selected member of any other ethnic or national group, by far.

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Nothing that I have presented up to this point is scientifically controversial. The profile of disproportionately high Jewish accomplishment in the arts and sciences since the 18th century, the reality of elevated Jewish IQ, and the connection between the two are not to be denied by means of data. And so we come to the great question: how and when did this elevated Jewish IQ come about? Here, the discussion must become speculative. Geneticists and historians are still assembling the pieces of the explanation, and there is much room for disagreement.

I begin with the assumption that elevated Jewish intelligence is grounded in genetics. It is no longer seriously disputed that intelligence in Homo sapiens is substantially heritable. In the last two decades, it has also been established that obvious environmental factors such as high income, books in the house, and parental reading to children are not as potent as one might expect. A “good enough” environment is important for the nurture of intellectual potential, but the requirements for “good enough” are not high. Even the very best home environments add only a few points, if that, to a merely okay environment. It is also known that children adopted at birth do not achieve the IQ’s predicted by their parents’ IQ.

To put it another way, we have good reason to think that Gentile children raised in Jewish families do not acquire Jewish intelligence. Hence my view that something in the genes explains elevated Jewish IQ. That conclusion is not logically necessary but, given what we know about heritability and environmental effects on intelligence in humans as a species, it is extremely plausible.

Two potential explanations for a Jewish gene pool favoring high intelligence are so obvious that many people assume they must be true: winnowing by persecution (only the smartest Jews either survived or remained Jews) and marrying for brains (scholars and children of scholars were socially desirable spouses). I too think that both of these must have played some role, but how much of a role is open to question.

In the case of winnowing through persecution, the logic cuts both ways. Yes, those who remained faithful during the many persecutions of the Jews were self-selected for commitment to Judaism, and the role of scholarship in that commitment probably means that intelligence was one of the factors in self-selection. The foresight that goes with intelligence might also have had some survival value (as in anticipating pogroms), though it is not obvious that its effect would be large enough to explain much.

But once the Cossacks are sweeping through town, the kind of intelligence that leads to business success or rabbinical acumen is no help at all. On the contrary, the most successful people could easily have become the most likely to be killed, by virtue of being more visible and the targets of greater envy. Furthermore, other groups, such as the Gypsies, have been persecuted for centuries without developing elevated intelligence. Considered closely, the winnowing-by-persecution logic is not as compelling as it may first appear.

What of the marrying-for-brains theory? “A man should sell all he possesses in order to marry the daughter of a scholar, as well as to marry his daughter to a scholar,” advises the Talmud (Pesahim 49a), and scholarship did in fact have social cachet within many Jewish communities before (and after) emancipation. The combination could have been potent: by marrying the children of scholars to the children of successful merchants, Jews were in effect joining those selected for abstract reasoning ability with those selected for practical intelligence.

Once again, however, it is difficult to be more specific about how much effect this might have had. Arguments have been advanced that rich merchants were in fact often reluctant to entrust their daughters to penniless and unworldly scholars. Nor is it clear that the fertility rate of scholars, or their numbers, were high enough to account for a major effect on intelligence. The attractiveness of brains in prospective marriage partners surely played some role but, once again, the data for assessing how much have not been assembled.

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Against this backdrop of uncertainty, a data-driven theory for explaining elevated Jewish IQ appeared in 2006 in the Journal of Biosocial Science. In an article entitled “Natural History of Ashkenazi Intelligence,” Gregory Cochran (a physicist) and Jason Hardy and Henry Harpending (anthropologists) contend that elevated Jewish IQ is confined to the Ashkenazi Jews of northern and central Europe, and developed from the Middle Ages onward, primarily from 800 to 1600 C.E.

In the analysis of these authors, the key factor explaining elevated Jewish intelligence is occupational selection. From the time Jews became established north of the Pyrenees-Balkans line, around 800 C.E., they were in most places and at most times restricted to occupations involving sales, finance, and trade. Economic success in all of these occupations is far more highly selected for intelligence than success in the chief occupation of non-Jews: namely, farming. Economic success is in turn related to reproductive success, because higher income means lower infant mortality, better nutrition, and, more generally, reproductive “fitness.” Over time, increased fitness among the successful leads to strong selection for the cognitive and psychological traits that produce that fitness, intensified when there is a low inward gene flow from other populations—as was the case with Ashkenazim.

Sephardi and Oriental Jews—i.e., those from the Iberian peninsula, the Mediterranean littoral, and the Islamic East—were also engaged in urban occupations during the same centuries. But the authors cite evidence that, as a rule, they were less concentrated in occupations that selected for IQ and instead more commonly worked in craft trades. Thus, elevated intelligence did not develop among Sephardi and Oriental Jews—as manifested by contemporary test results in Israel that show the IQ’s of non-European Jews to be roughly similar to the IQ’s of Gentiles.

The three authors conclude this part of their argument with an elegant corollary that matches the known test profiles of today’s Ashkenazim with the historical experience of their ancestors:

The suggested selective process explains the pattern of mental abilities in Ashkenazi Jews: high verbal and mathematical ability but relatively low spatio-visual ability. Verbal and mathematical talent helped medieval businessmen succeed, while spatio-visual abilities were irrelevant.

The rest of their presentation is a lengthy and technical discussion of the genetics of selection for IQ, indirect evidence linking elevated Jewish IQ with a variety of genetically based diseases found among Ashkenazim, and evidence that most of these selection effects have occurred within the last 1,200 years.

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No one has yet presented an alternative to the Cochran-Hardy-Harpending theory that can match it for documentation. But, as someone who suspects that elevated Jewish intelligence was (a) not confined to Ashkenazim and (b) antedates the Middle Ages, I will outline the strands of an alternative explanation that should be explored.

It begins with evidence that Jews who remained in the Islamic world exhibited unusually high levels of accomplishment as of the beginning of the second millennium. The hardest evidence is Sarton’s enumeration of scientists mentioned earlier, of whom 15 percent were Jews. These were not Ashkenazim in northern Europe, where Jews were still largely excluded from the world of scientific scholarship, but Sephardim in the Iberian peninsula, in Baghdad, and in other Islamic centers of learning. I have also mentioned the more diffuse cultural evidence from Spain, where, under both Muslim and Christian rule, Jews attained eminent positions in the professions, commerce, and government as well as in elite literary and intellectual circles.

After being expelled from Spain at the end of the 15th century, Sephardi Jews rose to distinction in many of the countries where they settled. Some economic historians have traced the decline of Spain after 1500, and the subsequent rise of the Netherlands, in part to the Sephardi commercial talent that was transferred from the one to the other. Centuries later, in England, one could point to such Sephardi eminences as Benjamin Disraeli and the economist David Ricardo.

In sum, I propose that a strong case could be assembled that Jews everywhere had unusually high intellectual resources that manifested themselves outside of Ashkenaz and well before the period when non-rabbinic Ashkenazi accomplishment manifested itself.

How is this case to be sustained in the face of contemporary test data indicating that non-Ashkenazi Jews do not have the elevated mean of today’s Ashkenazim? The logical inconsistency disappears if one posits that Jews circa 1000 C.E. had elevated intelligence everywhere, but that it subsequently was augmented still further among Ashkenazim and declined for Jews living in the Islamic world—perhaps because of the dynamics described by Cochran, Hardy, and Harpending (that is, Oriental Jews were concentrated in trades for which high intelligence did not yield wealth).

Recent advances in the use of genetic markers to characterize populations enable us to pursue such possibilities systematically. I offer this testable hypothesis as just one of many possibilities: if genetic markers are used to discriminate among non- Ashkenazi Jews, it will be found that those who are closest genetically to the Sephardim of Golden Age Spain have an elevated mean IQ, though perhaps not so high as the contemporary Ashkenazi IQ.

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The next strand of an alternative to the Cochran-Hardy-Harpending theory involves reasons for thinking that some of the elevation of Jewish intelligence occurred even before Jews moved into occupations selected for intelligence, because of the shift in ancient Judaism from a rite-based to a learning-based religion.

All scholars who have examined the topic agree that about 80–90 percent of all Jews were farmers at the beginning of the Common Era, and that only about 10–20 percent of Jews were farmers by the end of the first millennium. No other ethnic group underwent this same kind of occupational shift. For the story of why this happened, I turn to a discussion by Maristella Botticini and Zvi Eckstein entitled “Jewish Occupational Selection: Education, Restrictions, or Minorities?” which appeared in the Journal of Economic History in 2005.

Rejecting the explanation that Jews became merchants because they were restricted from farming, Botticini and Eckstein point to cases in which Jews who were free to own land and engage in agriculture made the same shift to urban, skilled occupations that Jews exhibited where restrictions were in force. Instead, they focus on an event that occurred in 64 C.E., when the Palestinian sage Joshua ben Gamla issued an ordinance mandating universal schooling for all males starting at about age six. The ordinance was not only issued; it was implemented. Within about a century, the Jews, uniquely among the peoples of the world, had effectively established universal male literacy and numeracy.

The authors’ explanation for the subsequent shift from farming to urban occupations reduces to this: if you were educated, you possessed an asset that had economic value in occupations that required literacy and numeracy, such as those involving sales and transactions. If you remained a farmer, your education had little or no value. Over the centuries, this basic economic reality led Jews to leave farming and engage in urban occupations.

So far, Botticini and Eckstein have provided an explanatory backdrop to the shift in occupations that in turn produced the selection pressures for intelligence described by Cochran, Hardy, and Harpending. But selection pressure in this classic form was probably not the only force at work. Between the 1st and 6th centuries C.E., the number of Jews in the world plummeted from about 4.5 million to 1.5 million or fewer. About 1 million Jews were killed in the revolts against the Romans in Judea and Egypt. There were scattered forced conversions from Judaism to another religion. Some of the reduction may be associated with a general drop in population that accompanied the decline and fall of the Roman Empire. But that still leaves a huge number of Jews who just disappeared.

What happened to them? Botticini and Eckstein argue that an economic force was at work: for Jews who remained farmers, universal education involved a cost that had little economic benefit. As time went on, they drifted away from Judaism. I am sure this explanation has some merit. But a more direct explanation could involve the increased intellectual demands of Judaism.

Joshua ben Gamla’s ordinance mandating literacy occurred at about the same time as the destruction of the Second Temple—64 C.E. and 70 C.E., respectively. Both mark the moment when Judaism began actively to transform itself from a religion centered on rites and sacrifices at the Temple in Jerusalem to a religion centered on prayer and the study of the Torah at decentralized synagogues and study houses. Rabbis and scholars took on a much larger role as leaders of local communities. Since worship of God involved not only prayer but study, all Jewish males had to read if they were to practice their faith—and not only read in private but be able to read aloud in the presence of others.

In this context, consider the intellectual requirements of literacy. People with modest intelligence can become functionally literate, but they are able to read only simple texts. The Torah and the Hebrew prayer book are not simple texts; even to be able to read them mechanically requires fairly advanced literacy. To study the Talmud and its commentaries with any understanding requires considerable intellectual capacity. In short, during the centuries after Rome’s destruction of the Temple, Judaism evolved in such a way that to be a good Jew meant that a man had to be smart.

What happened to the millions of Jews who disappeared? It is not necessary to maintain that Jews of low intelligence were run out of town because they could not read the Torah and commentaries fluently. Rather, few people enjoy being in a position where their inadequacies are constantly highlighted. It is human nature to withdraw from such situations. I suggest that the Jews who fell away from Judaism from the 1st to 6th centuries C.E. were heavily concentrated among those who could not learn to read well enough to be good Jews—meaning those from the lower half of the intelligence distribution. Even before the selection pressures arising from urban occupations began to have an effect, I am arguing, the remaining self-identified Jews circa 800 C.E. already had elevated intelligence.

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A loose end remains. Is it the case that, before the 1st century C.E., Jews were intellectually ordinary? Are we to believe that the Bible, a work compiled over centuries and incorporating everything from brilliant poetry to profound ethics, with stories that speak so eloquently to the human condition that they have inspired great art, music, and literature for millennia, was produced by an intellectually run-of-the-mill Levantine tribe?

In The Evolution of Man and Society (1969), the geneticist Cyril Darlington presented the thesis that Jews and Judaism were decisively shaped much earlier than the 1st century C.E., namely, by the Babylonian captivity that began with the fall of Jerusalem to the forces of Nebuchadnezzar in 586 B.C.E.

Darlington’s analysis touches on many issues, but I will focus on just the intelligence question. The biblical account clearly states that only a select group of Jews were taken to Babylon. We read that Nebuchadnezzar “carried into exile all Jerusalem: all the officers and fighting men, and all the craftsmen and artisans. . . . Only the poorest people of the land were left” (2 Kings 24:10).

In effect, the Babylonians took away the Jewish elites, selected in part for high intelligence, and left behind the poor and unskilled, selected in part for low intelligence. By the time the exiles returned, more than a century later, many of those remaining behind in Judah had been absorbed into other religions. Following Ezra’s command to “separate yourselves from the peoples around you and from your foreign wives” (Ezra 10:9), only those who renounced their foreign wives and children were permitted to stay within the group. The returned exiles, who formed the bulk of the reconstituted Jewish community, comprised mainly the descendants of the Jewish elites—plausibly a far more able population, on average, than the pre-captivity population.

I offer the Babylonian captivity as a concrete mechanism whereby Jewish intelligence may have been elevated very early, but I am not wedded to it. Even without that mechanism, there is reason to think that selection for intelligence antedates the 1st century C.E.

From its very outset, apparently going back to the time of Moses, Judaism was intertwined with intellectual complexity. Jews were commanded by God to heed the law, which meant they had to learn the law. The law was so extensive and complicated that this process of learning and reviewing was never complete. Moreover, Jewish males were not free to pretend that they had learned the law, for fathers were commanded to teach the law to their children. It became obvious to all when fathers failed in their duty. No other religion made so many intellectual demands upon the whole body of its believers. Long before Joshua ben Gamla and the destruction of the Second Temple, the requirements for being a good Jew had provided incentives for the less intelligent to fall away.

Assessing the events of the 1st century C.E. thus poses a chicken-and-egg problem. By way of an analogy, consider written Chinese with its thousands of unique characters. On cognitive tests, today’s Chinese do especially well on visuo-spatial skills. It is possible, I suppose, that their high visuo-spatial skills have been fostered by having to learn written Chinese; but I find it much more plausible that only people who already possessed high visuo-spatial skills would ever devise such a ferociously difficult written language. Similarly, I suppose it is possible that the Jews’ high verbal skills were fostered, through secondary and tertiary effects, by the requirement that they be able to read and understand complicated texts after the 1st century C.E.; but I find it much more plausible that only people who already possessed high verbal skills would dream of installing such a demanding requirement.

This reasoning pushes me even farther into the realm of speculation. Insofar as I am suggesting that the Jews may have had some degree of unusual verbal skills going back to the time of Moses, I am naked before the evolutionary psychologists’ ultimate challenge. Why should one particular tribe at the time of Moses, living in the same environment as other nomadic and agricultural peoples of the Middle East, have already evolved elevated intelligence when the others did not?

At this point, I take sanctuary in my remaining hypothesis, uniquely parsimonious and happily irrefutable. The Jews are God’s chosen people.

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See also the comments to “Jewish Genius” and Murray’s reply. [PDF]

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To the Editor:

The survival of Judaism despite millennia of oppression continues to confound both the friends and the enemies of the Jews, as well as many Jews themselves, though for different reasons. For Jews and their friends, it is a sign of great good fortune or a confirmation of a special place in God’s universe. For their enemies, it is a problem to be solved. For Charles Murray, apparently, the staying power of the Jews is merely an example of natural selection [“Jewish Genius,” April].

Despite the facetious last sentence of his article (“The Jews are God’s chosen people”), there is no God in his analysis of Jewish survival, only the great secular solvent of Darwinian selection, the tautological insight that hereditable traits contributing to survival will themselves survive and increase over generations. Specifically, in Mr. Murray’s view, it is inherited Jewish intelligence, as selected by pogroms, libels, quotas, and the Holocaust, that has permitted the survival of the Jews and their religion.

The power and novelty of this argument lie in its removal of the burden of understanding anything about what it means to be Jewish. Can there be a more insulting way to look at Jews—not at the content of their character or their tradition but at the fact of their having been genetically sculpted by outside forces? Fortunately for Jews, and for all others whose free will has mattered to them, Mr. Murray’s biology is as failed as his putative generosity.

No religion, after all, can be inherited; any brain can have any thought. Religion is perpetuated not by the transmission of DNA but by persons or groups who embrace a way of life and teach it to their children. For Judaism, moreover, achievement trumps biology. Consider this passage from the Mishnah (redacted in the 2nd century c.e.) discussing a hierarchy for certain privileges: “A Priest has precedence over a Levite; a Levite over an Israelite; an Israelite over a bastard. . . . When? When they are all equal [in learning]. But if the bastard is versed in the law and the High Priest ignorant, the bastard scholar has precedence over the ignorant High Priest.”

Mr. Murray betrays a childish longing for simple explanations, if one that is understandably seductive in an era when Jews have claimed so many of the mountaintops of achievement. It is tempting to tie a bow around Jewish accomplishment by willing it to the next generation as a “genetic inheritance.” But his syllogisms obscure the world as it really is.

Consider that women comprise some 50 percent of the world’s population, but fewer than 5 percent of Nobel Prize winners (one of Mr. Murray’s favorite metrics). Sweden, with only one tenth of a percent of the world’s population, has contributed approximately 5 percent of Nobel laureates. Are Swedes therefore smarter than women? The United States has 5 percent of the world’s population and 21 percent of Nobel winners. Are Americans smarter than Swedes but far less smart than Jews, who while constituting a fraction of a percent of the world’s population can boast of 30 percent of Nobel laureates since 1950?

If only life were this neat. But the fact is that a significant proportion of Jewish Nobel laureates have also been U.S. citizens, and that U.S. citizens of all racial, religious, and ethnic stripes enjoy more access to top research facilities and academic resources than the citizens of other countries. The second most-represented category of Nobel laureates, not surprisingly, is European academics, who have been similarly connected to well-endowed centers of learning.

We forget at our peril that it was not very long ago that basic courses in calculus and physics were not routinely offered to women. Higher math was the property of “male genius”—and white male genius at that. If one hypothesizes that neither “black” nor “female” genius exists, their emergent manifestations will be perpetually exceptionalized, held at bay, and shunted beyond the pale of the rest of the population. If we really “do the math” (as Mr. Murray advises) about past Nobel winners, nothing is as vulgarly simplistic as this Trojan Horse of his, so gaudily adorned to look like revelation.

Robert Pollack
Patricia Williams
Columbia University
New York City

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To the Editor:

We sympathize with the overall themes of Charles Murray’s essay, but we have reservations about some of his scenarios for the evolution of Ashkenazi intelligence. Our own model of elevated Jewish intelligence posits that it is a consequence of Jews’ economic niche in medieval Europe north of the Alps (from around 800 c.e.). Before that period of rapid evolution there is no special sign of unusually high intelligence in the historical record of the Jews. Mr. Murray, following work by Maristella Botticini and Zvi Eckstein, disagrees, and looks back to antiquity for the origins of this phenomenon. There is no obvious critical test to confirm his hypothesis over ours, and we are all reduced to arguing by anecdote.

Mr. Murray suggests that the creation of the Hebrew Bible and, later, of Christian theology as presented in the New Testament are signatures of a population with high intelligence. But while the Bible is indeed a cornerstone of our civilization, is it necessarily evidence of a population with high IQ? Revered documents have come from populations that did not stand out in terms of intelligence—take, as one example, the Book of Mormon and its followers. We would also be inclined to attribute the New Testament mostly to Greeks rather than to Jews.

Another piece of evidence adduced by Mr. Murray is Joshua ben Gamla’s ordinance in the year 64 c.e. mandating community schools for Palestinian Jewish males. But it is not so clear that this had much force. Some literature suggests that it was not widely implemented. (One thinks of our own “No Child Left Behind” law: an earnest statement of good intentions but of little actual consequence.) Certainly there were traditions of literacy among ancient Jews, and the responsibility for it fell more and more to the community over time. But literacy does not require high IQ.

There is a startling absence of any stereotype in classical writings that Jews were “smart.” In Menahem Stern’s comprehensive anthology of classical references to Jews by Greek and Latin authors, not a single one attributes unusual intelligence to them. Finally, the particular alleles (genetic forms) related to intelligence that we think were favored by selection are young, most of them around a thousand years old. By Mr. Murray’s reckoning, they should be much older.

Mr. Murray suggests that “boiling off” was a common phenomenon among the Jews in medieval times—those who were not good at being Jewish fell away and joined the outside community, leaving high intelligence concentrated within. But there is no historical documentation of this among Ashkenazi Jews. If it was a common occurrence, we should expect to find traces of Middle Eastern DNA among the Gentile populations in Poland, Lithuania, and Russia. So far, none has been reported, so we are skeptical of the hypothesis. Within a decade or so, high-resolution genetic data from Eastern Europe and the Middle East should allow a proper test. Indeed, the only real resolution of our differences with Mr. Murray will come from data-driven quantitative models, not from swapping impressions.

There are hints that the selective process that we believe we identified among the Ashkenazim also occurred among the Sephardim of Spain and Portugal, though to a lesser degree. Certainly the experience and achievements of Spanish and Portuguese Jews in London and Amsterdam were similar to those of the Ashkenazim. But Sephardim from other lands show no sign at all of IQ elevation; indeed, this is a serious social and political issue in Israel today.

Gregory Cochran
Henry Harpending
University of Utah
Salt Lake City, Utah

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To the Editor:

Charles Murray puts forward two basic ideas to explain what he asserts is the high native intelligence of Jews. One (as described in an article by Gregory Cochran, Jason Hardy, and Henry Harpending) is the idea of occupational selection, which holds that “the high IQ test scores of Ashkenazim, along with their unusual pattern of abilities, are a product of natural selection, stemming from their occupation of an unusual social niche” over the last millennium. But this is the logical equivalent of asserting that the giraffe has a long neck because its ancestor occupied an environmental niche that strongly selected for long necks, which is the classic fallacy of Jean-Baptiste Lamarck that gives Lamarckianism its name.

Mr. Murray’s second, preferred hypothesis is that Jews are smarter than the average because in ancient times one had to be smart to be a Jew. It is difficult to get past the absurdity of this notion in order to comment on it. It has a companion in the idea one hears voiced from time to time that Christians are more compassionate because one has to be more compassionate to be a Christian. The reasoning in both cases offers little enlightenment.

Daniel N. Haines
New York City

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To the Editor:

It is possible that Charles Murray overanalyzes the issue of elevated Jewish intelligence. In any sample, random inequalities will dictate that one subset will emerge at the high end of a normal distribution. There need not be any special reason for this other than statistical probability and the inevitable results of measurement itself.

To the Jews’ initial skewing toward high intelligence may be added the anthropological phenomenon of human tribalism and the sociological phenomenon of additive advantage. To wit, the rich get richer and the smart get smarter. The Jews may be just the unintended—albeit lucky—inheritors of the initial random inequality and nothing more.

Marc Mayerson
University of California
Los Angeles, California

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To the Editor:

Charles Murray notes that “only about 10-20 percent of Jews were farmers by the end of the first millennium,” the rest having migrated to urban occupations in which intelligence was more of an asset. This raises a different question: how did the Jews survive at all in cities?

Given that disease prevented pre-modern urban populations from replacing themselves and forced cities to rely on a constant replenishment of people from rural areas, one would expect the Jews, intelligent or not, to have dwindled rapidly once they lost their rural base.

Does not Jewish survival suggest that the Jews must have been selected for resistance to disease? And is it not possible that such resistance is related to intelligence? Perhaps research will find that the genes favoring resistance to typhoid are linked to a predisposition toward Tay-Sachs (a signature of Ashkenazi Jews), as well as to enhanced reasoning abilities. If so, “Jewish genius” may be only an accidental byproduct of an evolutionary adaptation to an environment of urban squalor.

David Randall
Brooklyn, New York

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To the Editor:

Charles Murray misses one point in his fascinating article. To cite heredity as a means of explaining why one trait (high intelligence) is more prevalent in one group (Ashkenazi Jews) than in another (the surrounding Gentiles), one does not have to demonstrate that the trait is promoted in the one group; it is enough to show that the other group selects less for it. In other words, the effect of environmental pressures on the intelligence of non-Jews must also be considered.

Consider the reproductive fate of the best and brightest of Christendom in the Middle Ages. Many men of intelligence became priests or monks, a group with a very low rate of reproduction. Many also entered the military, where they were killed in war.

Another avenue that bears exploration is the role of homosexuality. While homosexual Christians could take refuge in the priesthood, homosexual Jews were not released from social pressure to marry and reproduce. If homosexuality is linked in any way to intelligence—as it has been linked to artistic achievement—then here is another factor that might have disfavored the gene pool of Christians.

Jonathan Weinberg
Brooklyn, New York

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To the Editor:

Charles Murray speculates that the intellectual demands that Judaism made upon its adherents caused many Jews of lesser intelligence to fall away from the religion. But one could argue that Jewish history has trended in the opposite direction. Throughout the exile of the past 2,000 years, Jews’ chances for success and even physical survival were far greater when they joined the religion and culture of their host majority. In many periods, it has been precisely those Jews with higher intelligence, and thus a greater capacity for assimilation, who have opted out of the fold.

Elimelech Shalev
Nahariya, Israel

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To the Editor:

Arthur Koestler and others have asserted that a good number of the Ashkenazi Jews of Eastern Europe descended from the Khazars, a Turkic people that adopted Judaism as a state religion around 740 c.e. If this theory is valid, I wonder if it makes idle much of Charles Murray’s speculation about the ancient genetic roots of Jewish intelligence.

Karen D. Nitzschke
Gettysburg, South Dakota

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To the Editor:

In playing up the role of genes, Charles Murray pays insufficient attention to the role of the Jewish tradition itself in nurturing intelligence. Ancient Judaism taught that the written law was incomplete by itself, and that the people’s obligation was to study and develop the oral tradition. This contrasted sharply with other religions in which the law was fixed and its study confined to a clerical elite.

Jonathan Kurtzman
Brookline, Massachusetts

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To the Editor:

Charles Murray discusses the occupations of Ashkenazi Jews in Europe as a factor in their intelligence, but he does not discuss the role of Europe itself.

Despite the many cruelties visited upon the Jews of the continent, European civilization nurtured a creativity unmatched in the rest of the world, as Mr. Murray himself has demonstrated elsewhere. After European Jews were emancipated in the 19th century, what they displayed with special intensity was precisely such creativity. I suspect that there is a direct correlation between the success of a host country and the achievement of its Jews.

Robert W. Wilson
New York City

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To the Editor:

“No other religion [than Judaism] made so many intellectual demands upon the whole body of its believers,” writes Charles Murray. But early Buddhist texts, like the Theravada sutras of the 5th and 6th centuries b.c.e. or the Mahayana writings of the author Nagarjuna (2nd century c.e.), make intellectual demands upon their adherents that are at least as extensive and (harrowingly) complex.

Glenn D. Barnes
Wayne, Pennsylvania

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To the Editor:

Charles Murray’s article has the right balance of hard data and speculation. But he seems to have missed the most obvious (if still somewhat speculative) factor in elevated Jewish intelligence “from the time of Moses.” I refer to the second of the biblical Ten Commandments, which forbade the use of visual and plastic arts and directed the Jews’ energies toward texts. Generally speaking, the latter make far more demands upon intelligence per se than the former. This would also partly explain why to this very day Jews have only average visuo-spatial acuity, as Mr. Murray himself notes in passing.

Sam Lehman-Wilzig
Bar-Ilan University
Ramat Gan, Israel

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To the Editor:

I would add the factor of language to Charles Murray’s consideration of Jewish intelligence. Ashkenazi Jews were one of the only peoples to have been literate in two languages: Hebrew, which was read from right to left and often without vowels, and the local Indo-European language, which would have been read from left to right with vowels.

Reading from left to right, we rely more on our right eye as we move across the page. The right eye, in turn, is controlled by the left side of the brain, the seat of literal-logical intelligence. By the same token, reading from right to left involves more the interpretive-creative right side of the brain. It is no accident, for example, that Hebrew and other languages that go from right to left can do without vowels and have the reader depend on context—interpretive skills—to identify words. (If vowels were removed from English, only context would help determine if ct meant cut orcat.) An impact of the fortuitous but accidental environmental factor of reading both ways might have been to create a new kind of intelligence, one that blended logic and creativity in equal degrees.

Mr. Murray takes note of differences in IQ between Ashkenazi and Sephardi Jews. Indeed, residing in lands where Arabic (read from right to left) was the dominant language, the latter did not have the dual-directional advantage of their Ashkenazi brethren.

Stephen H. Schwartz
New York City

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To the Editor:

The data cited by Charles Murray suggesting that Jews are merely average when it comes to visuo-spatial skills is belied by Jews’ extraordinary historical success in chess. Seven of fourteen chess champions since the late 1800’s have been Jewish (or, as with Garry Kasparov, half-Jewish).

Chris Speck
Durham, North Carolina

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To the Editor:

Charles Murray is on safe ground in testing the Cochran-Hardy-Harpending hypothesis of high Jewish IQ by seeking evidence beyond the Ashkenazim in Europe and going back past the Middle Ages to antiquity. In a review of nearly 100 studies of South Asian/North African IQ, Richard Lynn has shown that although IQ scores of Sephardi Jews are lower on average than those of Ashkenazim, they are higher than those of the populations that surrounded them historically. Clearly we are dealing with something deeply rooted in the Jewish past.

J. Philippe Rushton
University of Western Ontario
London, Canada

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To the Editor:

Charles Murray’s consideration of the historical sources of higher-than-average Jewish intelligence and cultural achievement is the most informed and intelligent on the subject that I know of. That it is written by a non-Jew is, I believe, instructive for many of us who tend to take pride in Jewish achievements. We must always keep in mind that the overwhelming majority of great cultural creators of mankind have not been Jewish, and that achievement is by no means a Jewish monopoly.

We should also be aware that a number of factors—rising rates of intermarriage, the increasing insularity of some religious Jews—raise considerable questions about whether Jewish cultural and creative achievement will be as disproportionately great in the next 200 years as it has been in the previous 200.

Shalom Freedman
Jerusalem, Israel

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To the Editor:

Charles Murray writes that “a group’s mean intelligence,” as measured by IQ tests, “is important in explaining outcomes such as mean educational attainment or mean income.” Twenty years ago, before the economic boom in Ireland, the mean income of Irish people was low. Now it is one of the highest in the world, and the percentage of young people in higher education has risen from 11 percent to over 50.

For various historical reasons, the Irish were unable to realize fully their abilities and intelligence—by which I mean something much more than just IQ. As for IQ tests themselves, while the Irish used to score relatively low, a series of tests carried out by the BBC in 2003 found that they scored higher in IQ and general knowledge than the English, Welsh, and Scots. All in all, it seems that mean IQ, average income, and educational attainment have all risen with a general flowering of the culture.

David Quin
Dublin, Ireland

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To the Editor:

As an Irish Roman Catholic, I enjoyed Charles Murray’s excellent essay on Jewish accomplishment. Am I envious? Not really. After all, the Jews play a useful role in diverting wrath away from the Irish and Scots who have worked their way into so many powerful positions in American life, and have not been found out because of all the eyes fixed on the Jews.

Eoghan Harris
Dublin, Ireland

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To the Editor:

Charles Murray continues to make thoughtful and imaginative contributions on important questions in human biology. It is a lonely road that he travels, one that has exposed him to vituperation from much of the intellectual community. Modern biology is going to force us to examine critically some of the entrenched philosophical notions underpinning Western democracies and to develop guiding principles that are scientifically defensible and allow for the maintenance of cooperative societies.

I suspect that much of the aversion to science that is so widespread in the United States is motivated by fear of what it will force us to recognize and think about. Thanks to Mr. Murray for his courage in continuing to focus his intellect and his pen on the distribution of intelligence in human populations.

Philip Bromberg
University of North Carolina
School of Medicine
Chapel Hill, North Carolina

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To the Editor:

“Jewish Genius” is vintage Charles Murray: it provokes, stimulates, amuses, and challenges while illuminating what many fear to take on.

Sidney Helfant
City University of New York
Brooklyn, New York

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Charles Murray writes:

I am honored that Robert Pollack, director of the Center for the Study of Science and Religion at Columbia University, and Patricia Williams, professor at the Columbia Law School and a MacArthur Fellow, have spent so much effort attacking “Jewish Genius,” but their very eminence makes their letter mystifying. Why do they resort to personal insults? Even more mystifying: why is their letter so heedless of the text of my article?

In their first two paragraphs, they assert that I address how Judaism has survived despite millennia of oppression. But that is not remotely my topic. Then they assert that I attribute that survival to intelligence. As it happens, I do not believe that intelligence explains the survival of Jews and Judaism, but readers of my article would have no way of knowing my opinion on the matter—I never discuss it. Robert Pollack and Patricia Williams first invent my topic and then invent my thesis.

It gets worse. More than half of my article is devoted to discussing the selection factors that may have led to the elevated Jewish IQ that in turn helps explain (and here is my actual topic) disproportionate Jewish accomplishment in the arts and sciences. Yet here is how they summarize my position on the selection factors: “Specifically, in Mr. Murray’s view, it is inherited Jewish intelligence, as selected by pogroms, libels, quotas, and the Holocaust. . . .” Now they have invented my selection factors. I do not even mention libels, quotas, and the Holocaust (it would be odd to say that the Holocaust produced high Jewish intelligence prior to the Holocaust). As for pogroms, I explicitly argue that the winnowing-by-persecution theory, so widely assumed to be the explanation for elevated Jewish IQ, is not likely to have had a major effect. What can have put these selection factors into their heads? How can they ignore the ones I discuss at such length?

In the third and fourth paragraphs of my correspondents’ letter, the indifference to my argument becomes genuinely bizarre. They apparently believe they are disputing me when they write that “religion is perpetuated not by the transmission of DNA but by persons or groups who embrace a way of life and teach it to their children.” But my whole case for elevated Jewish IQ prior to the Middle Ages rests precisely on the centrality of Jewish law, the texts by which Judaism is transmitted, Judaism’s requirement that fathers teach that tradition to their children, the high intellectual demands all this entails, and the implications for the self-selection of people who remain within the community. With all that before their eyes, Robert Pollack and Patricia Williams write that my explanation for elevated Jewish IQ removes “the burden of understanding anything about what it means to be Jewish.” I do not choose the word “bizarre” lightly.

Regarding the question of disproportionate Jewish accomplishment in the arts and sciences, they are not heedless but selective, focusing on Nobel Prizes and conditions achieved by Jews only in the last half-century. Do Jews living today in Europe and the United States “enjoy more access to top research facilities and academic resources than the citizens of other countries”? Yes, and it is a relevant consideration. But the period that I called “one of the most extraordinary stories of any ethnic group at any point in human history” was the 19th century and first half of the 20th century, when Jews were laboring under social and professional discrimination despite legal emancipation. And the comparison group that I used to measure Jewish overrepresentation during that time was not the world population but—stated clearly in the text, hard to miss— the North American and European populations.

But I cannot think that Robert Pollack and Patricia Williams really believe that Jews are not overrepresented at high levels of achievement. Even their own numbers for American and Swedish Nobel Prize winners serve to illustrate how extraordinary the Jewish record has been.

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What a pleasure to turn to the letter, also critical but at a very different level, from Gregory Cochran and Henry Harpending, two of the authors of the article about the source of elevated Ashkenazi IQ that occupied such an important place in “Jewish Genius.” We all agree about the speculativeness of my supplements to their presentation of the Ashkenazi story. With that as the starting point, I have these reactions to their criticisms:

• I see the Hebrew Bible as a massive intellectual achievement, whether judged by its insights into human psychology, complexity of prose, narrative drive, beauty of poetry, or any number of other intellectually demanding criteria. That it is revered is not the point here. Moreover, the Bible was produced not by a single anomalous genius but by uncounted authors over centuries of time—a sign of a culture with unusual human capital. As for the New Testament, unless one wants to argue that Jesus was not the source of his own teachings, and that Paul did not really play the role in formulating Christian theology that he appears to play, I do not see how one avoids concluding that the foundation of the New Testament’s spiritual and intellectual power is Jewish.

• My basis for saying that Joshua ben Gamla’s mandate for universal schooling was widely implemented relies on the scholarship of Maristella Botticini and Zvi Eckstein, and I would have to see the unspecified countervailing evidence before I reassess that position.

• I take issue with the blanket statement that “literacy does not require high IQ.” This is true if literacy is defined as the ability to read and understand the National Enquirer, but not if literacy is defined as the ability to read and understand the Hebrew Bible and rabbinic literature—and that is what it took to be a fully observant Jewish male after the first century c.e.

• When it comes to ancient references to the Jews, I am struck not so much by silence about Jewish intelligence—Greeks and Romans did not readily acknowledge excellence in anyone but themselves, and intelligence itself was not the articulated construct that it is today—as by remarks about Jewish commercial aptitude. From time out of mind, Gentiles have complained about being bested in the marketplace by Jews. This sounds like an IQ-driven phenomenon to me.

Once Messrs. Cochran and Harpending move to their genetic evidence, they are the experts and I am not. I look forward to seeing the results of the analyses that genetic advances are making possible. My falsifiable hypothesis is that today’s Jews who are closest genetically to the Sephardim of the Golden Age of Spanish Jewry (roughly the 10th through the 12th centuries c.e.) will have elevated IQ.

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Daniel N. Haines raises the question (also part of Robert Pollack and Patricia Williams’s critique) of whether the natural-selection argument is tautological. If it is said that natural-selection arguments can lead to just-so stories, then I agree: we observe a distinctive trait today, whether in Jews, men, women, or the Inuit, and then work backward to find a plausible evolutionary explanation for it. But the explanations themselves are causally linear, not circular. To say that being a good Jew entailed meeting certain intellectual demands is a factual statement about the content of Judaism; to say that people who were unable to meet those demands tended to fall away from Judaism is a causal statement about incentives and the human personality; to say that people who possess high IQ are better able to thrive in urban occupations is a causal statement about the source of economic success in urban occupations. Separately, each of these statements lends itself to empirical exploration. Together, they constitute noncircular causal logic.

Marc Mayerson’s point about random inequalities and the subsets they produce certainly applies to all sorts of phenomena. Statisticians armed with such mathematical knowledge have been wreaking havoc with conventional wisdom about things like hitting streaks and “clutch” performances in sports. It is difficult, however, to apply this explanation to a phenomenon like disproportionate Jewish accomplishment, which persists across many generations and extends into diverse fields. The same problem prevents the Matthew Effect (what social scientists, referring to Matthew 25:29, call the rich-getting-richer phenomenon) from explaining Jewish accomplishment. Within a single life, the Matthew Effect can be real. A lucky break early in a career can have cascading positive consequences. Across generations, however, a group had better have a systematic advantage working for it that survives the idiosyncrasies of a particular time or place. The ideal combination is a group genetic advantage plus cultural pressures to marry within the group.

David Randall makes an excellent point about the challenges to survival in the medieval city. I am not competent to comment on his speculations about selection for resistance to disease, but another causal sequence is available: the people with the best chance of escaping and surviving disease in cities were the rich, with their better sanitation, nutrition, living spaces, health care, and options for fleeing a plague. The relationship of IQ to commercial success and of commercial success to better living conditions gave high-IQ urban Jews a significant health advantage that surely contributed to overall reproductive fitness.

Jonathan Weinberg’s hypothesis about the adverse effects of clerical celibacy on Christian IQ is plausible and has often been invoked. I wish someone would subject it to quantitative demographic modeling, but, as far as I know, no one has. Mr. Weinberg’s hypothesis about homosexuality is new to me. I have never seen any data on IQ among homosexuals, so I will have to put it into the category of “what an interesting idea” without being able to take it any further.

I am similarly intrigued by, and equally unable to be helpful about, Elimelech Shalev’s suggestion that success and survival were associated with leaving Judaism, and that in many periods the smartest Jews left the fold. Is it in fact true? I am dubious, but I refer the question to experts in Jewish history.

I do not see how the possible contribution of the Khazars to the Ashkenazim, cited by Karen D. Nitzschke, changes anything. The validity of my speculations depends solely on evidence that Jews in general, not just the Ashkenazim, developed elevated IQ. Whether I am right or wrong is independent of the Khazars.

At last, with Jonathan Kurtzman, a reader returns to a point that I know something about: the roles of nature and nurture in fostering IQ. Unfortunately, it is also a topic that requires a lot of space to explain and document adequately. The abbreviated version is this: a substantial proportion of IQ is shaped by environmental influences, but not the kind of environmental influences that first come to mind. Such things as reading to children, having many books in the house, and valuing education actually have a small causal role. The big factors are genes and the “nonshared environment”—a mélange of poorly understood influences like events in the womb and accidents of upbringing. In this context, the importance of the Jewish tradition in nurturing intelligence (as opposed to being a selection factor for intelligence) is unlikely to be large. But a test of Mr. Kurtzman’s hypothesis is possible if anyone can find the needed data: compare the IQ’s of adults raised in observant and non-observant Jewish homes.

Robert W. Wilson’s suggestion that Jewish achievement is affected by the success of its host country has a distinguished intellectual pedigree in the form of Raphael Patai’s The Jewish Mind (1977), an analysis of what Patai identifies as the six great historical encounters between Jews and other cultures. In my own Human Accomplishment (2003), I argue that the form of individualism fostered by Christianity had a positive effect on Jewish accomplishment—that is, once Christians got around to ending their legal suppression of the Jews.

I must disagree with Glenn D. Barnes’s assertion about the intellectual demands that Buddhism imposes on its adherents, if by adherent one means the average person who considers himself a good Buddhist. During six years of working in Thai villages and living within the Thai community in Bangkok, I met no lay person who knew more than the Buddhist equivalent of Sunday-school stories about the teachings of his religion. The Buddhist texts are indeed as harrowingly complex as Mr. Barnes says, and the practice of Buddhist meditation can be a profound intellectual and spiritual experience, but reading the texts and meditating are optional. Being a Buddhist in good standing is easy.

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Sam Lehman-Wilzig’s point about the Second Commandment’s effect of focusing Jewish intellectual attention on texts is fascinating, and does indeed neatly fit the discrepancy between Jewish visuo-spatial and verbal ability. But in trying to evaluate how much effect the Second Commandment might have had, I think of Islam, which imposed an even more sweeping proscription of images without producing comparable effects. On the other hand, Islam proscribed so many verbal endeavors as well (e.g., realistic fiction) that perhaps it is not a useful comparison.

Stephen H. Schwartz’s hypotheses about the significance of dual literacy in languages that are written from left to right and vice versa, and languages with and without vowels, are also fascinating, especially their codicil about the Sephardi Jews who moved to Arab lands where the second language was also written right to left. I am not competent to discuss the neuroscience of his argument, but the limited effects of shared environment in general (see my response to Mr. Kurtzman) lead me to be cautious about accepting the word “create” in Mr. Schwartz’s statement that using both sides of the brain in this manner would “create a new kind of intelligence.” But we are agreed that the requirements of being a Jew living in Europe could select for that kind of intelligence.

Chris Speck asks how the average visuo-spatial skills of the Jews are to be reconciled with the dominance of Jews in world-class chess. For purposes of illustration, one might think of intellectual skills as moving on a spectrum from purely visuo-spatial through mathematical and logical to purely verbal. Jews have elevated scores not only on measures of verbal aptitude (which includes memory, extremely important at the higher levels of chess), but also on measures of mathematical and logical aptitude, which are extremely important to calculations of lines of play. Jews are just average on the visuo-spatial items in IQ tests that correlate with the ability to visualize chess positions. But “just average” means that the same proportion of Jews will be at the top percentiles on visuo-spatial skills as Gentiles, while higher proportions will be in the top percentiles on the mathematical, logical, and verbal skills that also contribute. Probabilistically, a higher proportion of Jews than Gentiles may be expected to have the complete package of exceptional skills that produces chess champions.

Richard Lynn’s review of studies of Sephardi IQ as cited by J. Philippe Rushton offers a potential strategy for exploring the vexed question of non-Ashkenazi Jews: compare their scores with non-Jews who have surrounded them historically. That work could be extended by calculating not raw IQ means, but ratios of Jewish to non-Jewish IQ’s within culturally meaningful geographic areas. Doing that calculation accurately presents many methodological difficulties, and good data may be too sparse, but the intriguing hypothesis to be explored is that the ratios will be roughly the same everywhere. The estimated Ashkenazi mean of 110 translates to a ratio of 11:10 in Europe and the United States. If non-Ashkenazi Jews with a mean of 100 were historically surrounded by a people with a mean of 91, the ratio would be identical. Since the IQ means of the non-Jewish populations of North African and Middle Eastern countries are estimated to be well below 100, the hypothesis is not implausible on its face.

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Shalom Freedman’s first point is of course correct: Jews are disproportionately represented in the ranks of outstanding achievers but, in raw terms, non-Jews are in the great majority. I proudly join Eoghan Harris in noting that among them are Scots and Irish, and even the occasional Scot-Irish. Mr. Freedman’s worries about intermarriage are justified if the question is the survival of a robust Jewish culture, but less so with respect to IQ. On average, Jews do not marry randomly selected Gentiles, but ones they meet in college or workplace, which in turn means spouses whose own mean IQ is also considerably above the Gentile mean. Increasing cognitive stratification independent of ethnicity or social origins is the ignored story of today’s evolving class structure—the story that the late Richard Herrnstein and I tried to bring to public attention in The Bell Curve (1994).

David Quin’s recounting of the Irish story has many parallels with that of the Jews: the latent ability was always there, but for a long time conditions limited its expression. In earlier decades, Irish potential was hidden by lack of educational opportunities and the overwhelmingly rural character of Ireland. (Everywhere, IQ scores show a marked gradient from rural to urban areas, for reasons related partly to education and partly to the greater intellectual stimulation of urban areas.) But long before the recent Irish economic transformation, the reality of that potential had been proved by the Irish who had emigrated to the United States. As someone who has been visiting Ireland for forty years (my sister married a Limerick man), I should add that I have never doubted Irish verbal ability from the first time I sat in a working-man’s pub and overheard the conversational gymnastics going on around me.

My thanks to Philip Bromberg and Sidney Helfant for their kind words, but I am happy to report that no fortitude was required this time. Unlike so many other fraught topics involving group differences, this one is, or should be, purely celebratory. “Jewish Genius” was wonderful fun to write.