Sunday, November 16, 2014

Jewish DNA

The Institute for Sefardic and Anousim Studies at Netanya Academic College sponsored a lecture by Bennett Greenspan on "DNA of the Jewish People: Ashkenazim, Sefardim, Anousim."  It was well-attended by an enthusiastic audience and this is my summary.  Bennett Greenspan is an expert on the subject of Jewish genealogy, having had geneaology as a hobby since he was a child.  His official position is in political science, but he has founded with others the company called "Family Tree DNA," that does DNA sequence analyses for a fee in order to determine markers that could provide genealogical information about people's ancestry (see for more information).
In the nuclei of human cells there are 23 pairs of chromosomes and within these chromosomes are sequences of DNA that constitute  distinct human gene sequences (the genome) that code for specific human characteristics (the phenotype), such as eye color, hair color, skin color etc.  There are many ways of analysing the DNA sequences, but the most common are (i) the Y-chromosome, the male sex chromosome, to analyse for patrilineal sequences and (ii) the mitochondrial (mt) DNA, which is an extranuclear piece of DNA that is passed down from mother to child (of both sexes) and can be analyzed for matrilineal descent.  From sequence analyses of these sources it is possible to characterize the genetic composition of any given individual in terms of common genetic markers (called haplogroups) found in different groups of humans.  So for example people from the Middle East commonly have a haplogroup marker labeled J that is found commonly in Arabs and Jews, while people from other regions of the world (Europe, China) have other common markers.  By comparing the range of markers found in a given individual or groups of individuals (for statistical analysis) it is possible to characterize the genetic profile of a given genealogical group. 
Of course, after many thousands of years of human evolution there has been much mixing of human genes pools and consequently there are very few "pure" genetic profiles.  But, the composition and distribution of various markers can be used to characterize specific groups.  In Jewish genealogy, the first such characterization was that of Cohanim, the priestly caste, that is unique in that it requires both female descent from a Jew and male descent from a Cohen. In the first such study reported in the prestigious British science journal Nature in 1997 by Dr. Karl Skorecki of the Technion, 188 Jewish males were asked to contribute some cheek cells from which their DNA was extracted for study. Participants from Israel, England and North America were asked to identify whether they were a Cohen, Levi or Israelite.  The results of the analysis of the Y chromosome markers of the Cohanim and non-Cohanim were indeed significant, a particular marker was detected in 98.5 percent of the Cohanim, and in a significantly lower percentage of non-Cohanim.
More recent studies reported in 2010 analysed the total genome, or nuclear DNA content, rather than analyzing only the male Y chromosome or the female mitochondrial DNA, to assess similarities. The results obtained in these studies provide a statistical probability of nearness of relationship.  The results of two independent studies (see M. Balter, Science 328, 1342, 2010) were consistent, showing that Jews from the three main Diaspora groups: Ashkenazi Jews (of European origin), Sephardi Jews (of Spanish origin) and Oriental Jews (of Middle Eastern origin), showed closer genetic relationships than comparison to non-Jewish groups of the same geographic region.  Further, the European Jews showed greater similarities to Cypriot and Druze groups than to other European groups (see also my blog article Family ties 13/8/10).  
There is a view, expressed originally by Arthur Koestler in his book "The Thirteenth Tribe" (1976) that European Jews were mainly descended from converts of central Asian origins, specifically the Khazars, a Turkic tribe that was converted to Judaism in the 8th century.  This concept was expanded on recently (2008) by Tel Aviv University historian Shlomo Sands in "The invention of the Jewish people."   These can be seen as attempts by left-wing ideologues to justify their view that the Jews have no legitimate claim to the land of the Middle East and hence allows them to oppose Israel but support the claims of the Palestinians.  All genetic studies carried out so far refute these views and support the conventional view that the main Jewish groups are related to each other and not to Turkic tribes and that all Jewish groups do in fact have an origin in the Middle East.
These genetic findings have great significance for those people who we call Bnei Anousim or descendents of the Secret Jews, who were forcibly converted to Christianity by the Church in Spain and Portugal, and were persecuted as New Christians (or conversos) by the Inquisition, but who clung throughout the centuries to their ancient customs, often in ignorance of their meaning.  All over the Spanish and Portuguese world individuals are waking up to the fact that they now have the freedom to pursue their own destiny and their own heritage.  Many are contacting Bennett and his company to have their genetic profile tested to see if they may have markers indicating that they are indeed of Jewish origin.  In this way, in the long term, thousands of people who were forcibly denied their identity will hopefully be able to return to the Jewish people. 
For background on DNA sequencing analysis please see my lectures at and for a history of the study of DNA please see


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