Wednesday, February 23, 2005

Kohanim genetic link

A rabbi is trying to use genetic research to prove a common ancestral link between different Jewish populations:

Does modern genetic research support the belief that all Jews share a common ancestry?

The answer is yes, according to Rabbi Yaakov Kleiman, director of the Center for Kohanim in Jerusalem’s Old City.

According to Jewish tradition, Jacob was the progenitor of the Children of Israel, known later as the Jewish People. Today, after a long period of exile, Jews live on five continents and have taken on the outward appearance of their host nations.

“So,” asks Rabbi Kleiman, “if a Moroccan Jew looks nothing like his Polish counterpart, who’s to say they’re related?”

The answer to this question begins in a Toronto synagogue, where Dr. Karl Skorecki, a nephrologist at the University of Toronto and a kohen (a member of the Jewish priestly class), observed another kohen of Sephardic background being called to the Torah.

Skorecki, a Jew of European descent, considered his own fair complexion, light hair and eye colour, compared with the dark skin, hair and eyes of his fellow kohen. He then recalled the Torah passage that states that all kohanim are descendants of Aaron the high priest.

Perplexed, he decided to investigate whether, despite outward differences, kohanim have a common genetic background. Skorecki conducted a study along with Dr. Michael Hammer of the University of Arizona. Together, they sampled a group of self-identified kohamim (priests), and analyzed their Y-chromosomes.

Their hypothesis was that since kehuna (priesthood) is patrilineal, the Y-chromosome of kohamin might contain a common “marker” (genetic sequence).

Indeed, this marker was found. The study showed that both Ashkenazic and Sepharadic kohanim have a very high percentage of one particular marker: YAP-. This marker, along with another group of markers found in follow-up studies, have come to be known as the “cohen modal haplotype” (CMH) – the standard genetic signature of the Jewish priestly family.

The results of this study intrigued Rabbi Kleiman, himself a kohen and the co-director of the Center for Kohanim, which was established to promote identity and knowledge among kohanim and increase commitment to their heritage.

Now, the belief that all kohamin have common genes was supported by cutting-edge scientific research.

“But it goes even further,” says Rabbi Kleiman. “Subsequent studies that track the rate of mutations on the Y-chromosome indicated that CMH started approximately 106 generations ago. This takes us back to the end of the Egyptian exile – right around the birth of Aaron the cohen.”

Rabbi Kleiman was so impressed by the research findings that he followed the growing trail of genetic research further back, to Abraham, Isaac and Jacob, searching for a genetic pattern common to all Jews.

“This too, has now been found,” he says. “According to the latest findings, all Diaspora Jewish communities share the “cohen modal haplotype,” but in lower percentages than are found in Kohanim.

“This is because ‘kohen’ is a genetic definition based on father-to-son inheritance. But ‘Jewish’ is more universal, since Judaism accepts converts.”

Rabbi Kleiman notes that further research indicates that all Jews, no matter where they live today, exhibit the genetic markers shared by other people native to the Middle East region – an indication that today’s Jews originated from the ancient Hebrews in this region.

What do these findings signify for kohanim and Jews?

“It’s a sanctification of God’s name,” Rabbi Kleiman says. “It strengthens the faith of those who believe with cold hard science. It’s an indication that the line of tradition has never been lost. Ultimately, the Torah promises that just as we will be scattered to the ends of the earth, so too, we will be gathered together at the end of days. Now we can track this promise in the genetic code itself.”

Kleiman is now investigating communities in the Diaspora who claim a connection to the Jewish people.

“Some of the findings are quite positive. The Cochin Jews of India have been found to have the genetic markers of the ancient Hebrews, indicating a very low rate of intermarriage over the centuries. Ethiopian Jews, though, show markers more similar to their North African neighbours. But there’s an African tribe called the Lemba, who claim to come from the ancient Hebrews, and they do have such a genetic connection.”

“Genetics is no replacement for tradition,” Rabbi Kleiman says. “But if someone is interested in being tested for ‘Jewish-ness’ or ‘kohen-ness,’ he’s welcome to contact the Center for Kohanim and we’ll do our best to help.”

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