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Biology 103
2003 Second Paper
On Serendip

The Kohen Gene

Talia Liben

In a world where Jews have assimilated so much into other cultures, is it possible to trace the lineage of an elite group of Jewish men all the way back to a man who lived three-thousand and five-hundred years ago? According to Karl Skorecki, a scientist at the Israel Institute of Technology in Haifa, and Michael Hammer, a geneticist from the University of Arizona at Tuscan, the possibility is alive (1).

In Jewish tradition, as written in the Hebrew Bible, the Children of Israel were split into three groups. The Kohanim (the singular is simply Kohen) were the priests. The first Kohen was Moses' brother, Aaron, and all Kohanim since then are said to be descendants of Aaron. The second group was the Levis, of which Moses himself was a part of, and the third group was compiled of the remaining eleven tribes (of which ten have said to be "lost"), simply called the Israelites.

Since the Kohanim were the priests among the Jewish people, their duties were the holiest and most important. They were in charge of the sacrifices brought to the Temple, and thus had the most intimate relationship with God, aside from the prophets such as Moses. After the destruction of the Second Temple in 70 C.E., and thus the secession of sacrificial offerings, the role of the priests became ceremonial. However, despite the fact that their strict duties do not apply today, all Kohanim, according to Jewish tradition, must still obey many commandments that pertain directly to them. The hope is that one day, a new Temple will be built, and their service will be required once again (1).

According to Jewish tradition, the role of each individual (Kohen, Levi, or Israelite) is passed down patrilineally from father to son. In traditional and orthodox Judaism, a woman is known as "the daughter of a Levi" (if her father is a Levi) until she marries, and then she is "the wife of a Levi." So, the concept of a "kohen gene" can only pertain to Jewish men who have not converted into the faith (1).

A gene is a sequence of DNA that is used by cells to create protein. It has all of the information needed to make a protein. It knows when to make these protein and where to begin and end. The functions of a cell are then carried out by the proteins. When someone speaks about a gene for eyes, he is talking about the gene that codes for the protein that is the pigment for the eye color (2). A gene is a "functional and physical unit of heredity passed from parent to offspring" (3).

Since genes are hereditary, the question among certain scientists, and many Jews, became an interesting one; whether or not it is possible to have a gene that marked Kohanim throughout the centuries. In January of 1997, after working on the project for over four years, Hammer and Skorecki found that the priestly lineage can indeed be traced all the way back to Aaron, the first High Priest of Israel.
Jews are split in two by another category, aside from tribal divisions. Those born in, or whose ancestors came from, Europe, are called Ashkenazi Jews. Those from Spanish and Middle Eastern countries are called Sephardi Jews. The researchers discovered that the gene was found in Jewish Kohanim of both Sephardi and Ashkenazi lineage (4).

The two scientists tested genetic samples from the inside of the cheeks of unrelated Jewish men. These men came from three different nations Israel, North America, and Britain (3). There were 188 men in the original testing who believed that they were descendents of the line of Kohanim. The majority of these men had genetic phenotypes that genetically differed from those of the men who did not believe themselves to be Kohanim. The Y-chromosome YAP, DYS19B haplotype is passed down from father to son, and it is the genetic marker that was found in 98.5% of the Kohanim (4).

There are several implications of these findings. Besides being a biological proof of events and traditions that have remained alive for 3, 500 years, Michael Hammer says, "it's a beautiful example of how father to son transmission of two things, one genetic, one cultural, gives you the same picture" (5). It also shows that the wives of these Kohanim have remained extremely faithful to their husbands. More than 90% of the Kohanim ultimately tested share the same genetic markers. Dr. David Goldstein said that "even a low rate of infidelity would have dramatically lowered the percentage" (6).

The prevalence of this gene in Kohanim is convincing evidence of the existence of The Temple and the priests as described in the Bible. An estimated 5% of the Jewish males in the world (by 1997 when the study was done) have the y-chromosome gene in them, and are therefore Kohanim. The fact that the gene was found in men of both Ashkenazi and Sephardi lineage is interesting, because it means that the priesthood is older than the division of the Jewish people into these two groups. It is a division that transpired during the Middle Ages, over a thousand years ago (4). This also refutes the possibility that Ashkenazi Jews did not descend from the ancient Hebrews, but were a part of a Turkish-Asian empire from before the tenth century. The empire was said to have converted en masse to Judaism (7).

Using the tools available, researchers are now searching for the "ten lost tribes" who were uprooted from the now State of Israel by the Assyrians. DNA can now be used to "discover historical links to the Jewish people" (7). In an attempt to learn whether or not they are truly Kohanim, many Jews have tried to get tested for the common y-chromosome.

Is it possible that the preponderance of this genetic marker among self-claimed Kohanim is a fluke? The Levis is also a tribal group which is passed down from father to son. Yet, when Levis were tested for a common gene, there was no genetic marker found. Is it possible that these scientific findings could cause rifts among nations or religions? Can biological proof of an old-age tradition truly exist without a doubt? And does it really matter?.

Work Cited

1) Cohen, Debra Nussbaum "Kohen Gene Pioneers Fear Misuse" 1997



4) Jeffrey, Grant "A Genetic Trace is Found Linking Kohanim Worldwide"

5) Hammer, Professor Michael, New York Times, 1997

6) Goldstein, Dr. David, Oxford University Science News, 1998

7) Kleiman, Rabbi Yaakov, "The DNA Chain of Tradition: The Discovery of the "Cohen Gene""

8) Jewish Post, "Scientists Discover Chromosome Similarity of Jewish Priests" 1997


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