Genetic link found among ‘kohanim’
JEWS of the priestly tribe (kohanim) – both Ashkenazi and Sephardi – have been found to share a variation of the Y chromosome, linking them as descendants of Aaron the High Priest who lived 3,300 years ago.
This astonishing finding was reported was the result of a study conducted by Prof. Karl Skorecki, a senior nephrologist at Rambam Hospital in Haifa and head of molecular medicine at the Technion’s medical school, along with colleagues in Haifa, London and Arizona. Their peer-reviewed study finding was published yesterday in the scientific correspondence column of the prestigious the British science journal Nature.
The researchers took samples of genetic material from unrelated Jewish men in the three countries, and asked them whether they were from the priestly tribe. Tissue was taken by swabbing the inside of their cheeks.
The phenotypes of 188 secular and religious Jews who said they were kohanim were found to be very different from those who said they were not. Skorecki told The Jerusalem Post that the researchers did not identify kohanim according to their names (such as Cohen or other names of kohanim such as Rappaport or Shapiro), but by asking them to state if they were kohanim.
Skorecki, who is himself a kohen, said that the idea for the study came to him when he was attending synagogue services and saw another kohen being called up to the Torah for the first aliya.
“I looked at him and noted we didn’t look alike, but that nevertheless, according to tradition, we both descended from the priestly tribe. I wanted to know if it were possible to find a genetic connection.”
Based on surveys of Jewish gravestones, about 5 percent of the seven million male Jews around the world belong to the priestly tribe. This means 350,000 men, or about 100,000 to 120,000 in Israel alone.
The priesthood performed major Jewish rituals from the time of Aaron (the brother of Moses, who headed the Levite tribe) and received fixed portions of the sacrifices in the First and Second Temples.
Since the destruction of the Temple, the priesthood – handed down from father to son – has bound its members by certain obligations, such as keeping ritually pure at a distance from the dead and not marrying a divorcee.
Skorecki, along with Sara Selig and Shraga Blazer at the Technion and Robert and Neil Bradman, P.J. Waburton, Monica Ismajlowicz and Michael Hammer of London’s University College and the University of Arizona, found a preponderance of the YAP, DYS19B haplotype in kohanim of both Ashkenazi and Sephardi origin (as well as a few Yemenites), but not in the non-kohanim. This served as further evidence that the Jewish priesthood predated the division of world Jewry into these two major ethnic groups over 1,000 years ago.
Any differences in the gene structure would reflect molecular-biological changes due to mutations; these are useful in calibrating the rate of mutations in the genes and observing human molecular evolution, he added.
The Y chromosome, carried only by men, is passed patrilineally; mitichondrial DNA is transmitted by the mother’s X chromosomes.
“The Y chromosome is not very important; half of the world’s population manages fine without it. But it can provide some anthropological information,” Skorecki explained.
He added that it was impressive how the characteristic Y chromosome was passed down to today’s kohanim despite periods of assimilation over the millenia. Even secular Jews seem to know if they are of the priestly tribe, says the professor. But he added that if the trends of secularism, assimilation and intermarriage continue in the Diaspora, the number of Jews with this priestly haplotype will probably decline.