Re: Ancient Ashkenazic DNA Admixture #dna #israel #announcements


Adam Cherson
 

A follow-up on the matrilineal discussion for those with an interest in the scientific literature on the subject: there are two classic studies on the mtDNA groupings of Ashekanizic and non-Ashkenazic Jews: 1): 'The Matrilineal Ancestry of Ashkenazi Jewry: Portrait of a Recent Founder Event' (2005): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1380291/   and 2) 'Counting the Founders: The Matrilineal Genetic Ancestry of the Jewish Diaspora' (2008): https://doi.org/10.1371/journal.pone.0002062       

The second of these papers concludes as follows:

"The phylogenetic approach taken in the current study of most non-Ashkenazi Jewish communities, coupled with a previous study on Ashkenazi Jews, reveals the mechanisms involved in the formation of the various extant patterns of mtDNA haplotype variation of the Jewish Diasporas, and taken together provides a nearly comprehensive picture of the maternal genetic landscape of the entire Jewish population. Some of the communities reveal strong founder effects, while in others an abundance of maternal lineages is evident. Mechanisms, such as recruitment of maternal lineages from host populations, including their occasional historic long-distance transfer to new settlements, have been likely operative. Taken together, these studies show that while the founding event for each community may have had an important role in shaping their current genetic structure, other factors related to migration and survival of founding lineages, are responsible for the assembled list of remnant lineages, stressing once again the importance of an interdisciplinary approach in the reconstruction of demographic histories of extant populations." p13 [Emphasis added]

Another more recent paper takes a contrary view, suggesting a European origin for the predominant Ashkenazim matrilneal lines: 'A Substantial Prehistoric European Ancestry Amongst Ashkenazi Maternal Lineages' (2014): DOI: https://doi.org/10.1038/ncomms3543 stating: "Overall, we estimate that most (>80%) Ashkenazi mtDNAs were assimilated within Europe. Few derive from a Near Eastern source, and despite the recent revival of the ‘Khazar hypothesis’, virtually none are likely to have ancestry in the North Caucasus. Therefore, whereas on the male side there may have been a significant Near Eastern (and possibly east European/ Caucasian) component in Ashkenazi ancestry, the maternal lineages mainly trace back to prehistoric Western Europe. These results emphasize the importance of recruitment of local women and conversion in the formation of Ashkenazi communities, and represent a significant step in the detailed reconstruction of Ashkenazi genealogical history." p.2. [Emphasis added]

The earlier paper from 2005 had concluded that these Ashkenazic maternal lineages were Near Eastern in origin. How should we in the lay, general public interpret this apparent conflict as to the origins of these maternal lineages?

I believe there is a substantial risk in using modern samples to imply pre-historic origins. In my view it is not possible to look at modern populations and infer their geographic origins from 10-20 thousand years ago: to do so convincingly requires in my view DNA samples from 10-20 thousand years ago. Furthermore, our contemporary bias is to draw a solid line between the Near East and Europe, whereas in Mesolothc times, this entire region seems to have been more of a cline, both genetically and culturally. For these reasons I choose to hold my conclusions in abeyance regarding the ancient origins of the Ashkenazic matrilineages, until such time as more ancient DNA can shed light on the subject. As to the other finding, that there has been a significant amount of 'recruitment' of local women in the formation of the Ashkenazic population, there is no disagreement between the papers, and I believe the modern dna evidence can and does support this finding.


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Adam Cherson

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