06 December 2008

DNA: Sephardic ancestry study update, link

Here's the link to read the abstract for the original article in The American Journal of Human Genetics (4 December 2008) on which the New York Times' Sephardic DNA story was based.

Among the authors of "The Genetic Legacy of Religious Diversity and Intolerance: Paternal Lineages of Christians, Jews, and Muslims in the Iberian Peninsula," are the well-known Kohanim DNA project initiator Karl Skorecki (Molecular Medicine Laboratory, Rambam Health Care Campus, Haifa) and population geneticist and author/co-author of several major Jewish DNA studies Doron M. Behar (Rappaport Faculty of Medicine and Research Institute, Technion-Israel Institute of Technology, Haifa), in Israel.

The abstract reads (I have added paragraph breaks):

Most studies of European genetic diversity have focused on large-scale variation and interpretations based on events in prehistory, but migrations and invasions in historical times could also have had profound effects on the genetic landscape.

The Iberian Peninsula provides a suitable region for examination of the demographic impact of such recent events, because its complex recent history has involved the long-term residence of two very different populations with distinct geographical origins and their own particular cultural and religious characteristics —North African Muslims and Sephardic Jews.

To address this issue, we analyzed Y chromosome haplotypes, which provide the necessary phylogeographic resolution, in 1140 males from the Iberian Peninsula and Balearic Islands. Admixture analysis based on binary and Y-STR haplotypes indicates a high mean proportion of ancestry from North African (10.6%) and Sephardic Jewish (19.8%) sources.

Despite alternative possible sources for lineages ascribed a Sephardic Jewish origin, these proportions attest to a high level of religious conversion (whether voluntary or enforced), driven by historical episodes of social and religious intolerance, that ultimately led to the integration of descendants.

In agreement with the historical record, analysis of haplotype sharing and diversity within specific haplogroups suggests that the Sephardic Jewish component is the more ancient.

The geographical distribution of North African ancestry in the peninsula does not reflect the initial colonization and subsequent withdrawal and is likely to result from later enforced population movement—more marked in some regions than in others—plus the effects of genetic drift.

Those of a scientific mind may be interested in the study's supplemental material here. Scroll down to page 28 to see the specific Sephardic Jewish information, but also note the inclusion of other familiar haplogroups in the other geographical categories. I'm not a scientist, but wonder why only eight markers were tested for Sephardic Jewish, while the other categories tested 18 markers. I'm sure someone will provide that information soon.

Readers may be interested in this New York Post article on the increasing popularity of DNA testing among Latinos and the findings. Do read the comments to the story by readers and also by FamilyTreeDNA founder/CEO Bennett Greenspan, who is quoted in the story.

Although FamilyTreeDNA offers links to many complete studies on its study page, this new study has not yet been added, but I believe it will soon appear.

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