The Cohen Gene: Scientific and Halakhic Perspectives

This past week, Yeshiva University's Torah U'Maddah Project continued its Fall 1997 evening lecture series with a panel presentation that caught the attention of many Yeshiva University students. The presentation, entitled "The Cohen Gene: Scientific a nd Halakhic Perspectives," drew nearly 200 attendees. A mixture of YU and Stern students, high school students, and quite a few Cohanim gathered in Weissberg Commons to hear the three hour lecture.

Authorities in the fields of genetics and Halakha respectively, were the evening's speakers. Dr. Neil Bradman, chairman of the Center for Genetic Anthropology at the University College London, England, presented the audience with the most signif icant and recent genetic research conducted in the field of "Jewish genetics." The entire Cohen Gene research project was arguably Bradman's brainchild. Rabbi Moshe Tendler, who holds the Isaac and Bella Tendler Chair in Medical Ethics and is a Rosh Yeshiva at Yeshiva University, then spoke about some of the Halakhic issues that pertain to Cohanim today and their relevance to Bradman's recent genetic research.

Dr. Feit, a professor of Biology at YU and mentor to many current and former pre-med students, began the evening by expressing his and the entire scientific community's interest in genetics and specifically the Cohen gene research project. He then intr oduced Dr. Bradman, the evening's first speaker.

Scientific Perspective

It is the "patrilineal nature of Jewish Priesthood," according to Dr. Bradman, that aroused his interest and the interest of several other geneticists. Knowing that portions of man's genetic makeup are passed strictly from father to son - namely, the Y chromosome, which causes maleness - they set out to determine whether that chromosome might contain special features that would link all Cohanim to each other and set them apart from Levites and Israelites, other historical status divisions within the Jewish people.

It was only within the last three or four years that differences between different Y-chromosomes became evident and only very recently that a difference between the Y-chromosomes of many Cohanim and Y-chromosomes of others became apparent. Dr. B radman explained that Y-chromosomes, like all chromosomes, are made up of many fragments of DNA. Certain fragments of DNA in the chromosome, called markers, distinguish chromosomes from each other. If a father has a specific marker on his Y-chromosome, t hen his son will have the same Y-chromosome marker, barring a significant mutation.

Two markers that were identified on the Y-chromosome of many Cohanim were isolated. They became known as "YAP negative," a gene lacking the YAP sequence commonly found on the Y chromosome, and "DYS19," a microsatellite repeat in the DNA sequenc e of the chromosome. Dr. Bradman asserted that a unique chromosomal marker was not only identified, but the frequency of that chromosomal marker within a large sample of Ashkenazic and Sephardic Cohanim was significantly higher than the frequency of that same chromosomal marker within a large sample of Ashkenazic and Sephardic non-Cohanim.

Dr. Bradman frequently emphasized that he had done a population study, and although it did show a statistically significant difference between the Y-chromosomes found in a population of Cohanim and the Y-chromosomes found in a population of non- Cohanim, "the results were not something that enabled us to tell anything about a particular individual." Since many Cohanim did not have the Y-chromosome markers while some Israelites and Levites did have the Y-chromosome mark ers, the individual Cohen or non-Cohen status of Jewish males cannot be unequivocally determined by current testing methods.

The final part of Dr. Bradman's presentation included the newest results of research he has conducted. These newest studies involved the finding of new markers on the special Y-chromosome, and also involved research on the genes of Levites. The results were favorable for Cohanim, but not for Levites, who were shown to be "a very heterogeneous group."

Halakhic Perspective

Before Rabbi Tendler presented the Halakhic sources relevant to the evening's topic, he began his lecture by emphasizing that "the Cohen is an essential part of our religious life. Without a Cohen, you couldn't redeem your first bo rn, you couldn't eat your food, and there would be chaos in the synagogue when it came to calling people up to the Torah."

He then explained how Halakha sanctions modern-day Cohanuth without proof of patrilineal heritage through the use of a Halakhic concept called Chezkath Cahuna. This means that a person's claim to be a Cohen is enough to give one the Halakhic status of a Cohen if the claim cannot be disputed.

The dissenting views among Achronim were then explored in several Halakhic sources as to the status of modern-day Cohanim. Some insisted that we should consider a modern-day Cohen a Saphek Cohen, or Cohen of do ubtful status, because no proof exists as to his lineage. Others insisted that because of Chezkath Cahuna, we can consider a Cohen a Vadai Cohen, or Cohen of certain status, in all respects. Because of the short time allowed f or this very broad topic, Rabbi Tendler did not offer concrete Halakhic conclusions to this issue but did offer some of the practical Jewish laws that would be affected by this rabbinic disagreement, such as the Priestly blessing, redemption of the first born, and taking Challah.

Rabbi Tendler concluded that because genetics cannot give concrete evidence for an individual's patrilineal heritage, the status of a modern-day Cohen cannot be changed. However, when asked if Halakha would use concrete genetic evidence i f it could be provided, he answered, "Yes, just like DNA identification is used by Halakha to determine parental status." When asked if such evidence will likely be provided, Rabbi Tendler seemed skeptical.

Joshua Cypess, the educational coordinator of the lecture and of future Torah U'Maddah lectures, remarked, "If there was any place that this topic had to be discussed, it was surely Yeshiva University. We provided a detailed scholarly lecture in Maddah , and at the same time had Rav Tendler give a shiur on the topic as well. After all, this is what YU and Torah U'Maddah are really about."