Y-chromosomal Aaron - Other Carriers of The DNA

Other Carriers of The DNA

Following the discovery of the very high prevalence of 6/6 CMH matches amongst Cohens, others were quick to look for it, and often to see it as a signpost for possible Jewish ancestry, though the chromosome itself is not exclusive to Jews.

News of 6/6 matches in the Lemba of Southern Africa were seen as confirming a possible Jewish lineage (Thomas MG et al. 2000); possible links were discussed between the Jews and the Kurds; and some suggested that 4/4 matches in non-Jewish Italians might be a genetic inheritance from Jewish slaves, deported by Emperor Titus in large numbers after the fall of the Temple in AD 70, some of whom were put to work building the Colosseum in Rome.

Such speculation was to some extent tempered when it was realised that Haplogroups J1 and J2 represented at least two different lineages which could be associated with the CMH, (the Italians mostly belong to Haplogroup J2); and that individuals with at least 5/6 matches for the original 6 marker Cohen Modal Haplotype occur widely across the Middle East, with significant frequencies in various Arab populations mainly with J1 Haplogroup, "that are not traditionally considered admixed with mainstream Jewish populations" – notably Yemen (34.2%), Oman (22.8%), Negev (21.9%), and Iraq (19.2%); and amongst Muslim Kurds (22.1%), Bedouins (21.9%), and Armenians (12.7%).

On the other hand, Jewish populations were found to have a "markedly higher" proportion of full 6/6 matches, according to the same (2005) meta-analysis, compared to these non-Jewish populations, where "individuals matching at only 5/6 markers are most commonly observed".

The authors nevertheless warn that "using the current CMH definition to a infer relation of individuals or groups to the Cohen or ancient Hebrew populations would produce many false-positive results," and note that "it is possible that the originally defined CMH represents a slight permutation of a more general Middle Eastern type that was established early on in the population prior to the divergence of haplogroup J. Under such conditions, parallel convergence in divergent clades to the same STR haplotype would be possible."

Y-DNA patterns from around the Gulf of Oman were analysed in more detail by Cadenas et al. in 2007. The detailed data confirms that the main cluster of haplogroup J1 haplotypes from the Yemen appears to be some genetic distance different from the CMH-12 pattern typical of Eastern European Ashkenazi Cohens.