Studies point to a common genetic basis for the Jews of the world, but is that the whole story?
The hunt for the Jewish genome began immediately with the publication of the results of the mapping of the human genome. There is no doubt that the characterization of the genome of the Jewish people arouses special curiosity and is of historical importance. Has a people that has existed for thousands of years, exiled from its homeland and spread everywhere but jealously guarding its heritage and religion, also guarded its genetic heritage? Over the years, the phenotypic characterizations of the Jewish "race" have proliferated, in very negative anti-Semitic stereotypes, in countless cartoons and even in computer games. On the other hand, quite a few people believe that the Jews are endowed with extraordinary qualities of creativity and excellence and that their contribution to the advancement of humanity is much greater than their relative share in the population.
But do the historical facts show that the Jews are a "race" or a people? Will the genome tell the story of the Jewish people, their origins and migrations? Are there genes that characterize people of Jewish origin?
Clues to the existence of genes that characterize Jewish populations can be obtained from genetic diseases that are common mainly among Jews, such as Tay-Sachs and breast cancer. However, it is difficult to draw clear conclusions from the results of the studies so far, and it is now accepted to assume that DNA tests alone do not reflect the true story. The variation in DNA between the Jews is very great, and in contrast there are genetic similarities between Jews and people considered non-Jews. Therefore, alongside the scientific factors, social, cultural and behavioral factors must also be taken into account.
And yet, what is the sequence of genes, or the primordial genotype from which the "Jewish race" developed? The human genome contains 22 pairs of autosomal chromosomes, two sex chromosomes (XX in women and XY in men) as well as mitochondrial DNA. The genetic heritage of men is measured according to the Y chromosome found only in males and passed from father to son, while that of women is tested according to mitochondrial DNA, which is passed from the mother to all her offspring. From these tests it became clear that the ancient origin of 80% of Jewish men is from the Middle East. In contrast, the population of Jewish women is more heterogeneous, although at least 50% also come from the Middle East. And here the question arises: "Who are these genes that were characterized as belonging to the ancient fathers and mothers of the primary Jewish dynasty? The story of Ruth the Moabite raises a question - was she a convert and great-grandmother of King David whose lineage is considered the most central. Is it possible to conclude from this that the genotype of Ruth the Moabite convert also became part of the Jewish nuclear genome?
The continued hunt for the Jewish genome is getting more and more complicated. It is commonly thought that the modern Jewish population comes from two large groups that separated from each other many years ago into Ashkenazim and non-Ashkenazim, or Sephardim. This division is somewhat simplistic, relying on the fact that the Ashkenazim originate from northern and eastern Europe, while the Sephardi originate from Spain and the countries of the Near East. This division is done mainly for reasons of convenience, but it is clear that these groups are not homogeneous. The Jews migrated from land to land and from country to country and their gene pool therefore changed according to the routes of their migrations and migrations. Indeed, from time to time studies are published showing surprising connections between groups of Jews who are geographically far apart. Advanced technologies, such as a review of the entire genome, are increasingly confirming the conclusion that the Jewish populations from Europe and the Middle East have common genes originating from a Jewish population that lived in the Near East 3000 years ago and then the split occurred and each population inherited genes from the environment in which they lived.
If so, although there is some common genetic basis for the Jewish people, there is still room to ask whether Jewish identity is determined by genetics or by cultural-ethnic identity.
on the notebook
Professor Bracha Reger, Emeritus Professor of Microbiology and Immunology at the Faculty of Health Sciences at Ben Gurion University, President of Ort Israel and Chairman of the Academic Council of Ort Israel. Served as the chief scientist of the Ministry of Health and was a member of the Council for Higher Education.
And more on the subject
Genetic ancestry, Jewish. Behar D. and Skorecki K. in Encyclopedia Judaica, second edition, vol.7 pp. 450-458
Legacy: a genetic history of the Jewish people. Harry Oster, Oxford University Press, USA; 1st edition, May 2, 2012
North African Jewish and non-Jewish populations form distinctive, orthogonal clusters. Campbell et al. in PNAS, August 6, 2012 DOI: 10.1073/pnas.1204840109