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The gene detective

BMJ 2008; 336 doi: (Published 13 March 2008) Cite this as: BMJ 2008;336:586

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Ashkenazi Gene Pool

Dear Sir,

It is most unlikely that there were only 1,000 Ashkenazi Jews, as Professor Cedar accepts, around the year 1000 C.E. (i.e. merely some 200- 300 families). I doubt very much that it could have been such a low number though there must have been at an earlier time - possibly a few hundred years earlier. It is known that about that year, the great Rabbi Gershom together with a 'synod' of rabbis in Mainz in the Rhineland, produced a series of famous edicts - perhaps the best known of which was a ban on polygamy (theoretically allowed by the Bible). Only Ashkenazim (European Jews) accepted this edict and the rest of world Jewry continued with the practice of polygamy when and where it was allowed– albeit rarely. I have seen it estimated that, at the time, Ashkenazim only constituted some 15% of world Jewry (these proportions were due to be reversed over the course of subsequent centuries). It seems inconceivable that a synod of rabbis of that stature could be gathered from a mere 1,000 Jews, nor that world Jewry could only have amounted to some 7,000 at the time. We know that the bloody rampage of the First Crusade in 1096 claimed more than 5,000 Jewish victims in the communities along the Rhine alone (‘Germany’, Stuart Cohen (ed.), 1974, p.5.). I have actually seen it estimated that at that time world Jewry numbered between 750,000 and 1,500,000, suggesting a total of at least 100,000 Ashkenazim (Cecil Roth, ‘The European Age in Jewish History’ in “The Jews, Their History”, Louis Finkelstein (ed.) 1972, p. 231). This estimate is supported by this statement in the ‘Jewish Encyclopaedia’ online at; It has been estimated that during the five centuries from 1000 to 1500, 380,000 Jews were killed during the persecutions, reducing the total number in the world to about 1,000,000

Nevertheless, whatever the number of Ashkenazi Jews was around the year 1000 C.E., it is now clear that they did not differ all that much in their gene makeup from other Jews elsewhere in the world, in spite of the genetic diseases specific to their descendants. Thus we find the following statement :- ‘Several lines of evidence support the hypothesis that Diaspora Jews from Europe, Northwest Africa, and the Near East resemble each other more closely than they resemble their non-Jewish neighbours’ (“Jewish and Middle Eastern non-Jewish populations share a common pool of Y-chromosome” Santachiara-Benerecetti, A. Oppenheim, M. A. Jobling, T. Jenkins, H. Ostrer, and B. Bonné-Tamir M. F. Hammer, A. J. Redd, E. T. Wood, M. R. Bonner, H. Jarjanazi, T. Karafet, S. doi:10.1073/pnas.100115997 PNAS 2000;97;6769-6774; originally published online May 9, 2000). Interestingly, this is a conclusion reached regarding the remarkable similarity between the gene patterns of fingerprints among Ashkenazi, Sephardi, Yemenite and Oriental Jews. In other words, despite their wide dispersal in many parts of the world for centuries, there is clear evidence of the Eastern Mediterranean pool of genes amongst practically all present day Jews. (L.Sachs quoted in P.V.Tobias, “Race, Religion and Culture”, Jewish Quarterly, Vol 9:4, 1971/2, p.9.)

Murray Freedman MA, B.Ch.D, (retired dentist)

Competing interests: None declared

Competing interests: No competing interests

17 March 2008
Murray P. Freedman
Leeds LS17 8DY