On The Formation Of The Ashkenazi

The ancient Jewish population suffered remarkable vicissitudes – the Babylonian exile, the Hellenistic conquest and Hasmonean state, the revolts against the Roman Empire – but most of that history is probably irrelevant to our thesis, except to the extent that it helped create necessary cultural preconditions. Irrelevant because in pre-Diaspora times, the Jews did not occupy an unusual ecological niche nor did they yet exhibit unusual cognitive traits. Most Jews then were farmers, just as in nearly all settled populations, and they must have experienced evolutionary pressures similar to those experienced by other peoples of the region. A fair amount of classical commentary on the Jews has been preserved, and there is no sign that anyone then had the impression that Jews were unusually intelligent. Certain aspects of Jewish culture were probably crucial in setting the stage for this unusual evolutionary phenomenon, but for the most part pre-Diaspora Jewish genetics seems not to have been remarkable in any way. The exact extent of Middle Eastern ancestry of the Ashkenazim is only important to our thesis insofar as it helps us estimate the extent of gene flow between the Ashkenazi and neighbouring populations. In much the same way, the details of the Ashkenazi settlement of and migrations in Europe interest us because of their potential for creating genetic bottlenecks.

The key cultural precondition among the Jews was a pattern of social organization that required literacy, strongly discouraged intermarriage, and that could propagate itself over long periods of time with little change. Literacy (which does not itself require high intelligence) was probably important in the shift from a nation to an urban occupational caste (Botticini & Eckstein, 2002), acting as an entree to many urban professions in which Jews, at first, had no special biological advantages.

After the Bar-Kochba revolt in AD 135, most Jews lived outside Israel. They were concentrated in the Parthian (later Sassanid) empire, and in the eastern half of the Roman Empire, but there was a substantial population of Roman Jews, along with other poorly documented western settlements such as Cologne. After the Moslem conquests, the great majority of Jews lived under Islamic rule.

The Ashkenazim, the Jews living north of the Alps and Pyrenees, appear in the historical record in the eighth and ninth centuries. Their origins are misty. There are three different threads that may have led to the foundation of the Ashkenazi Jews, but their relative importance is unclear.

The first possibility is that the Ashkenazim – or some fraction of them – had already lived in France and the Rhineland for a long time, perhaps going back to Roman times. We know that there were Jews in Cologne around AD 300 (Williams, 2002), and that there were Jews living in France under the Merovingian monarchs (Gregory of Tours, 1982) in the fifth and sixth centuries. However, King Dagobert of the Franks ordered that the Jews convert, leave or face execution in his lands in 629. This conversion edict may have pushed them out of most of France. Certainly we hear little about French Jews for the next 150 years or so. The size, even the existence of this population is uncertain.

The second thread involves Jewish merchants originating from the lands of Islam, as far as Palestine and Iraq. The Carolingian kings encouraged and protected these merchants, who brought luxury items such as silks and spices from the East according to Agobard of Lyons (Ben-Sasson, 1976). A few such traders served as interpreters on diplomatic missions: one brought Charlemagne an elephant from Haroun Al-Rashid.

The third thread, generally thought to be the best supported, is that most of the founding Ashkenazi population migrated from southern Europe, especially Italy. There are accounts about particular individuals and families moving there from Italy; for example the Kalonymus family is said to have migrated to Mainz from Lucca in Italy in 917 (Weinryb, 1972; Ben-Sasson, 1976; Ankori, 1979; Barnavi, 1992).

When we first see them in the historical record, the Ashkenazim were long-distance merchants who traded with the Moslem world. This is the beginning of an occupation pattern that is very different from those of other Europeans and from those of other Jewish groups, as well. The majority of Jews had already given up agriculture (Botticini & Eckstein, 2002), but the Jews of Islam, although urban, mostly worked in various crafts. The Ashkenazim, from their beginnings and for a long time, seldom had such jobs. This pattern is detailed in Gross (1975, p. 147): ‘Two entirely different patterns in the practice of crafts and their place in Jewish life and society are discernible throughout the Middle Ages. One characterizes the communities in countries around the Mediterranean, including in the south those in the continents of Asia and Africa, and in the north extending more or less to an imaginary demarcation line from the Pyrenees to the northern end of the Balkans. The other, in the Christian countries of Europe, was more or less north of the Pyrenees–Balkans line,’ and (p. 151) ‘North of the Pyrenees and in the Balkans crafts played a very small role as a Jewish occupation, from the inception of Jewish settlement there.’

The Ashkenazi population, established in northern France by the early 900s, prospered and expanded. They settled the Rhineland and England after the Norman Conquest. At first they were international merchants who acted as intermediaries with the Moslem world. As Moslems and Christians, especially Italians, increasingly found it possible to do business directly, Ashkenazi merchants moved more and more into local trade. When persecution began to be a serious problem and the security required for long-distance travel no longer existed, the Ashkenazim specialized more and more in one occupation, finance, left particularly open to them because of the Christian prohibition of usury. The majority of the Ashkenazim seem to have been money-lenders by AD 1100 (Arkin, 1975; Ben-Sasson, 1976), and this continued for several centuries. Such occupations (sales, trade, finance) had high IQ demands, and we know of no other population that had such a large fraction of cognitively demanding jobs for an extended period.

In some cases, we have fairly detailed records of this activity. For example (Arkin, 1975, p. 58), concerning the Jews of Roussilon circa 1270: ‘The evidence is overwhelming that this rather substantial group of Jews supported itself by money lending, to the virtual exclusion of all other economic activities. Of the 228 adult male Jews mentioned in the registers, almost 80% appear as lenders to their Christian neighbors. Nor were loans by Jewish women (mostly widows) uncommon, and the capital of minors was often invested in a similar manner. Moreover, the Jews most active as moneylenders appear to have been the most respected members of the community.’

The Jews in this period were prosperous. Ben-Sasson points out (p. 401) that ‘. . . Western Europe suffered virtual famine for many years in the tenth and eleventh centuries, there is no hint or echo of this in the Jewish sources of the region in this period. The city dweller lived at an aristocratic level, as befitted international merchants and honored local financiers.’ Their standard of living was that of the lower nobility (Roth, 2002).

Although prosperous, they were not safe. The first major crisis was the First Crusade, resulting in the death of something like a quarter of the Jews in the Rhineland. Religious hostility, probably exacerbated by commercial rivalries, increased, manifesting itself in the form of massacres and expulsions culminating in the expulsion of the Jews from most of Western Europe. They were expelled from England in 1290, from France in 1394, and from various regions of Germany in the 15th century. The expulsions had greater effect in the long run than massacres and persecutions. Jewish population growth rates were high due to prosperity and distaste for family limitation; so numbers tended to recover from attacks after a generation or two. But the potential for such population recovery decreased as Jews were excluded from more and more of Western Europe.

Many of the Jews moved east, first to Austria, Bohemia and Moravia, then to the Polish–Lithuanian Commonwealth. The Polish rulers welcomed Jewish immigrants who could help modernize and reconstruct the country, which had been devastated by Mongol raids. Jews were welcome as urban investors and initiators of trade. Other skilled immigrants were also welcome, but some of those groups brought political risks, particularly the Germans through their connection with the Teutonic Knights. The Jews were politically neutral and therefore safe.

As they had in Western Europe, the Jews of Poland had a very unusual occupational profile. The very first to immigrate were mainly moneylenders, but that soon changed. They became tax-farmers, toll-farmers, estate managers, and they ran mills and taverns. According to Weinryb (1972), in the middle of the fourteenth century ‘about 15 per cent of the Jewish population were earners of wages, salaries and fees. The rest were independent owners of business enterprises.’ They were the management class of the Polish–Lithuanian Commonwealth. Besides literacy, success in those specialized occupations depended upon skills similar to those of businessmen today, not least the ability to keep track of complex transactions and money flows.

Eventually, as the Ashkenazi population of the Polish–Lithuanian Commonwealth increased, more and more Jews became craftsmen – there are after all only so many managerial and financial slots. Still, for 800–900 years, from roughly AD 800 to AD 1650 or 1700, the great majority of the Ashkenazi Jews had managerial and financial jobs, jobs of high complexity, and were neither farmers nor craftsmen. In this they differed from all other settled peoples of which we have knowledge.

[Ashkenazi] Jews who were particularly good at these jobs enjoyed increased reproductive success. Weinryb (1972, see also Hundert, 1992) comments: ‘more children survived to adulthood in affluent families than in less affluent ones. A number of genealogies of business leaders, prominent rabbis, community leaders, and the like – generally belonging to the more affluent classes – show that such people often had four, six, sometimes even eight or nine children who reached adulthood. On the other hand, there are some indications that poorer families tended to be small ones. It should also be added that overcrowding, which favours epidemics, was more prevalent among the poorer classes. In short, the number of children surviving among Polish Jews seems to have varied considerably from one social level to another.’ He goes on to suggest that wealthier Jews were less crowded as they lived in bigger houses, they could keep their houses warmer, they could afford wet-nurses, and they had better access to rural refugia from epidemics. As an example, in a census of the town of Brody in 1764 homeowner households had 1.2 children per adult member while tenant households had 0.6.


Ankori, Z. (1979) Origins and history of Ashkenazi Jewery (8th to 18th century). In Goodman, R. M. & Motulsky, A. G. (eds) Genetic Diseases among Ashkenazi Jews. Raven Press, New York, pp. 19–46.

Arkin, M. (ed.) (1975) Aspects of Jewish Economic History. The Jewish Publication Society of America, Philadelphia.


Barnavi, E. (ed.) (1992) A Historical Atlas of the Jewish People. Alfred A. Knopf, New York.

Ben-Sasson, H. (1976) A History of the Jewish People. Harvard University Press, Cambridge.


Botticini, M. & Eckstein, Z. (2002) From Farmers to Merchants: A Human Capital Interpretation of Jewish Economic History. URL: http://www.cepr.org/pubs/dps/DP3718.asp.


Gregory of Tours (1982) The History of the Franks. Penguin Books, New York.

Gross, N. (1975) Economic History of the Jews. Schocken Books, New York.


Hundert, G. D. (1992) The Jews in a Polish Private Town. Johns Hopkins University Press, Baltimore, MD.


Roth, N. (2002) Medieval Jewish Civilization: An Encyclopedia. Routledge Encyclopedias of the Middle Ages V.7. Routledge, London.


Weinryb, B. D. (1972) The Jews of Poland, a Social and Economic History of the Jewish Community in Poland from 1100–1800. The Jewish Publication Society of America, Philadelphia.


Williams, M. (2002) The Jews among the Greeks and Romans. The Johns Hopkins University Press, Baltimore, MD.

-- Gregory Cochran , Jason Hardy , Henry Harpending

from "Natural History Of Ashkenazi Intelligence"

Quoted on Mon Jun 4th, 2012