Name: nazis are losers 2007-06-07 1:24 ID:6Wz+rVaB
And a new essay by Greg Cochran:
How the Ashkenazi Got Their Smarts
Ashkenazi Jews have the highest average IQ of any ethnic group. They score 0.75 to 1.0 standard deviations above the general European average, which corresponds to an IQ score around 112-115. . This fact has social significance, because IQ (as measured by IQ tests) is a good predictor of success in academic subjects and many jobs. Jews are just as successful in such jobs as their tested IQ would predict, and are hugely overrepresented in those jobs and accomplishments with the highest cognitive demands. During the 20th century, they made up about 3% of the US population, but won 27% of the US Nobel science prizes and 25% of the ACM Turing awards. They account for more than half of world chess champions.
This is not exactly news. I'm telling you something your grandmother knew. Popular opinion has held that Jews are smart for a long time - although, interestingly, not in Classical times - and such stereotypes are usually decent approximations of the truth.
Ashkenazi Jews have an unusual cognitive ability profile, as well as higher-than-average IQ. They have high verbal and mathematical scores, while their visuospatial abilities are typically somewhat worse (by about half a standard deviation) than the European average. Han Eysenck noted that "The correlation between verbal and performance tests is about 0.77 in the general population, hut only 0.31 among Jewish children. Differences of 10-20 points have been found in samples of Jewish children; there is no other group that shows anything like this size difference. " Their pattern of success is what you might expect from this ability distribution - great success in mathematics and literature, more typical results in painting, sculpture, and architecture.
Just as important, Sephardic and Oriental Jews do _not_ have higher-than-average IQs, nor are they tremendously overrepresented in cognitively demanding fields.
Any attempt at a causal explanation of Ashkenazi cognitive abilities must explain high Ashkenazi IQ, the unusual structure of their cognitive abilities, and the nonexistence of these traits among Sephardic/Oriental Jews and among Jews as a whole in Classical times. It must also be consistent with the neodarwinian synthesis, the historical record, and genetic data.
The natural approach is to look for a historical situation in which natural selection strongly favored this trait constellation. Immediately, we see that conditions among Jews were especially suitable for rapid evolutionary change. They lived in an unusual ecological situation, and they were reproductively isolated.
Reproductive isolation means that there was very little gene flow between the Jews and neighboring non-Jewish populations, very little intermarriage. This is course what the historical record indicates, but the genetic evidence is even stronger. We see that the majority of Y-chromosomes among the Ashkenazi are associated with Mideastern clades; this is enough to show that per-generation gene flow from surrounding Europeans (from males, anyhow) averaged less than 0.5% over many generations. Such reproduction isolation is almost a prerequisite for strong natural selection: if a population undergoing unusual selective pressures mixes heavily with a much larger population experiencing typical selective pressures, nothing happens.
The other important point is that Jews lived unusual lives, compared with most other population. By about 800 AD, almost all of them lived in cities. The great majority of almost every other ethnic group were farmers - they _had_ to be, since in premodern times farmers did not produce much above their own requirements, and it took several farmers to support one city-dweller. To the extent that the demands and rewards of urban life differed from those of farmers, the selective pressures experienced by Jews were unusual.
In earlier times, the great majority of Jews were themselves farmers. This means that in Classical times, they had not yet experienced unusual selective pressures, and in those days nobody thought that they were especially smart. The process that eventually resulted in high Ashkenazi IQ had not yet occurred.
For there to be strong selection for IQ, individuals with high IQs must have had more surviving children than average. Today, of course, that does not happen, but there is reason to think that it was sometimes the case in premodern Europe. In those days, wealthy people had quite a few more surviving children than average, so if high IQ increased income, there could have been selection for IQ in some situations.
The strength of this trend depended very much on the way an individual made a living. A dirt farmer with strong mathematical and verbal talents probably didn't do much better than average, but a merchant with such talents was likely to become wealthy and could raise a large family. In other words, the fitness/IQ derivative (which we will call the IQ elasticity) was not the same for all occupations.
This means that the occupational mix experienced by a population group was very important in determining the selective forces experienced by that population.
The Ashkenazi, in their beginnings in Western Europe, were mostly moneylenders. After they migrated to the Polish-Lithuanian Commonwealth, for a long time most were moneylenders, tax farmers, toll-farmers, and estate managers. They had to manage complex financial transactions, and those who did well made more money and had more children. Prosperous Jews may have averaged twice as many surviving children than poor Jews, and they made their money with their wits, rather than by inheritance or fighting skills, as in most other European elites.
For hundreds of years, _most_ of the Ashkenazi had jobs with high IQ elasticity, while at the same time experiencing very low gene flow with neighboring populations. This situation was unique. There were certainly non-Jewish groups in Europe that had occupations with high IQ elasticity - merchants in Bristol or Rotterdam for example - but they were not reproductively isolated. They kept marrying non-merchants. The Jews of Islam, although reproductively isolated, seem not have had the necessary concentration of occupations with high IQ elasticity. Some had such jobs in some of the Arab world, in some periods, but it seems it was never the case that _most_ did. In part this was because other minority groups competed successfully for these jobs - Greek Christians, Armenians, etc., in part because Moslems, at least some of the time, took many of those jobs themselves, valuing non-warrior occupations more highly than medieval Christians. In fact, to a large extent, and especially during the last six or seven hundred years of relative Moslem decline, the Jews of Islam tended to have 'dirty' jobs. These included such tasks as cleaning cesspools and drying the contents for use as fuel - a common Jewish occupation in Morocco, Yemen, Iraq, Iran, and Central Asia. Jews were also found as tanners, butchers, hangmen, and other disagreeable or despised occupations. I think that such jobs had low IQ elasticity - probably brilliant tanners did not get rich.
Only the Ashkenazi had low gene flow and a preponderance of occupations with high IQ elasticity for hundreds of years. That is enough to have caused the IQ increase that we observe. The narrow-sense heritability of IQ is at least 0.3 - that means if the parents of the next generation average 1 point above the current population average, the next generation (with equal environments) will average 0.3 point higher. Continue this process for 40 generations and you get an increase of 12 points, just about what we see today.
It also explains the pattern of mental abilities we see in Ashkenazi Jews. Verbal and mathematical talent helped medieval businessmen succeed, while spatiovisual abilities were irrelevant.
There have been other causes suggested. One, 'winnowing through persecution", suggests that only the smartest Jews survived persecution. Why this should be so is not clear, particularly there was no similar outcome in other groups such as Gypsies that faced frequent persecution. Another theory suggests that there was selective breeding for Talmudic scholarship. The are two fatal problems with this hypothesis: first, it was wealth that caused increased fertility, not scholarship. Second, there weren't very many rabbis, certainly less than one percent of the population.. A selective force that only affects a fraction of a percent of the population can never be strong, can never cause significant change in tens of generations. One that that affects the top 10 or 20% of the population can.
Albert Einstein said "Things should be described as simply as possible, but no simpler." The same principle must invoked in explaining Einstein himself.
Gregory Cochran
A good bit to think about here, and we'll get back to it. Comments below.
How the Ashkenazi Got Their Smarts
Ashkenazi Jews have the highest average IQ of any ethnic group. They score 0.75 to 1.0 standard deviations above the general European average, which corresponds to an IQ score around 112-115. . This fact has social significance, because IQ (as measured by IQ tests) is a good predictor of success in academic subjects and many jobs. Jews are just as successful in such jobs as their tested IQ would predict, and are hugely overrepresented in those jobs and accomplishments with the highest cognitive demands. During the 20th century, they made up about 3% of the US population, but won 27% of the US Nobel science prizes and 25% of the ACM Turing awards. They account for more than half of world chess champions.
This is not exactly news. I'm telling you something your grandmother knew. Popular opinion has held that Jews are smart for a long time - although, interestingly, not in Classical times - and such stereotypes are usually decent approximations of the truth.
Ashkenazi Jews have an unusual cognitive ability profile, as well as higher-than-average IQ. They have high verbal and mathematical scores, while their visuospatial abilities are typically somewhat worse (by about half a standard deviation) than the European average. Han Eysenck noted that "The correlation between verbal and performance tests is about 0.77 in the general population, hut only 0.31 among Jewish children. Differences of 10-20 points have been found in samples of Jewish children; there is no other group that shows anything like this size difference. " Their pattern of success is what you might expect from this ability distribution - great success in mathematics and literature, more typical results in painting, sculpture, and architecture.
Just as important, Sephardic and Oriental Jews do _not_ have higher-than-average IQs, nor are they tremendously overrepresented in cognitively demanding fields.
Any attempt at a causal explanation of Ashkenazi cognitive abilities must explain high Ashkenazi IQ, the unusual structure of their cognitive abilities, and the nonexistence of these traits among Sephardic/Oriental Jews and among Jews as a whole in Classical times. It must also be consistent with the neodarwinian synthesis, the historical record, and genetic data.
The natural approach is to look for a historical situation in which natural selection strongly favored this trait constellation. Immediately, we see that conditions among Jews were especially suitable for rapid evolutionary change. They lived in an unusual ecological situation, and they were reproductively isolated.
Reproductive isolation means that there was very little gene flow between the Jews and neighboring non-Jewish populations, very little intermarriage. This is course what the historical record indicates, but the genetic evidence is even stronger. We see that the majority of Y-chromosomes among the Ashkenazi are associated with Mideastern clades; this is enough to show that per-generation gene flow from surrounding Europeans (from males, anyhow) averaged less than 0.5% over many generations. Such reproduction isolation is almost a prerequisite for strong natural selection: if a population undergoing unusual selective pressures mixes heavily with a much larger population experiencing typical selective pressures, nothing happens.
The other important point is that Jews lived unusual lives, compared with most other population. By about 800 AD, almost all of them lived in cities. The great majority of almost every other ethnic group were farmers - they _had_ to be, since in premodern times farmers did not produce much above their own requirements, and it took several farmers to support one city-dweller. To the extent that the demands and rewards of urban life differed from those of farmers, the selective pressures experienced by Jews were unusual.
In earlier times, the great majority of Jews were themselves farmers. This means that in Classical times, they had not yet experienced unusual selective pressures, and in those days nobody thought that they were especially smart. The process that eventually resulted in high Ashkenazi IQ had not yet occurred.
For there to be strong selection for IQ, individuals with high IQs must have had more surviving children than average. Today, of course, that does not happen, but there is reason to think that it was sometimes the case in premodern Europe. In those days, wealthy people had quite a few more surviving children than average, so if high IQ increased income, there could have been selection for IQ in some situations.
The strength of this trend depended very much on the way an individual made a living. A dirt farmer with strong mathematical and verbal talents probably didn't do much better than average, but a merchant with such talents was likely to become wealthy and could raise a large family. In other words, the fitness/IQ derivative (which we will call the IQ elasticity) was not the same for all occupations.
This means that the occupational mix experienced by a population group was very important in determining the selective forces experienced by that population.
The Ashkenazi, in their beginnings in Western Europe, were mostly moneylenders. After they migrated to the Polish-Lithuanian Commonwealth, for a long time most were moneylenders, tax farmers, toll-farmers, and estate managers. They had to manage complex financial transactions, and those who did well made more money and had more children. Prosperous Jews may have averaged twice as many surviving children than poor Jews, and they made their money with their wits, rather than by inheritance or fighting skills, as in most other European elites.
For hundreds of years, _most_ of the Ashkenazi had jobs with high IQ elasticity, while at the same time experiencing very low gene flow with neighboring populations. This situation was unique. There were certainly non-Jewish groups in Europe that had occupations with high IQ elasticity - merchants in Bristol or Rotterdam for example - but they were not reproductively isolated. They kept marrying non-merchants. The Jews of Islam, although reproductively isolated, seem not have had the necessary concentration of occupations with high IQ elasticity. Some had such jobs in some of the Arab world, in some periods, but it seems it was never the case that _most_ did. In part this was because other minority groups competed successfully for these jobs - Greek Christians, Armenians, etc., in part because Moslems, at least some of the time, took many of those jobs themselves, valuing non-warrior occupations more highly than medieval Christians. In fact, to a large extent, and especially during the last six or seven hundred years of relative Moslem decline, the Jews of Islam tended to have 'dirty' jobs. These included such tasks as cleaning cesspools and drying the contents for use as fuel - a common Jewish occupation in Morocco, Yemen, Iraq, Iran, and Central Asia. Jews were also found as tanners, butchers, hangmen, and other disagreeable or despised occupations. I think that such jobs had low IQ elasticity - probably brilliant tanners did not get rich.
Only the Ashkenazi had low gene flow and a preponderance of occupations with high IQ elasticity for hundreds of years. That is enough to have caused the IQ increase that we observe. The narrow-sense heritability of IQ is at least 0.3 - that means if the parents of the next generation average 1 point above the current population average, the next generation (with equal environments) will average 0.3 point higher. Continue this process for 40 generations and you get an increase of 12 points, just about what we see today.
It also explains the pattern of mental abilities we see in Ashkenazi Jews. Verbal and mathematical talent helped medieval businessmen succeed, while spatiovisual abilities were irrelevant.
There have been other causes suggested. One, 'winnowing through persecution", suggests that only the smartest Jews survived persecution. Why this should be so is not clear, particularly there was no similar outcome in other groups such as Gypsies that faced frequent persecution. Another theory suggests that there was selective breeding for Talmudic scholarship. The are two fatal problems with this hypothesis: first, it was wealth that caused increased fertility, not scholarship. Second, there weren't very many rabbis, certainly less than one percent of the population.. A selective force that only affects a fraction of a percent of the population can never be strong, can never cause significant change in tens of generations. One that that affects the top 10 or 20% of the population can.
Albert Einstein said "Things should be described as simply as possible, but no simpler." The same principle must invoked in explaining Einstein himself.
Gregory Cochran
A good bit to think about here, and we'll get back to it. Comments below.