Can the “Jewish gene” prove who is Jewish and who is not?
Rabbi Dr Akiva Tatz, however, maintains that there is a recently discovered gene that while not yet solid enough to base a firm Jewish identity on, is prevalent among Ashkenazi Jews, and has some “fascinating consequences”.
Tatz discussed the ramifications of this recent discovery and other issues surrounding Jewish genetics with students at Hatzolah House in Sydenham last Wednesday. He was invited by The Arch and the South African Union of Jewish Students.
Having practised as a doctor in South Africa and the United States, Tatz moved to Israel, where he practised in hospital and general medicine in Jerusalem, and engaged in a number of years of Talmudic study, later teaching Jewish thought and medical ethics in Jerusalem.
For years, the debate around the existence of a Jewish gene has raged amongst researchers, with some flatly denying that there is any basis to such a theory. According to Tatz, while this field might still be in relative infancy, there is more to discover about ourselves as Jews than we previously thought, and genetics makes it possible.
“You don’t need to be a doctor or medical student to know that medicine is going very strongly in the direction of genetic bases,” says Tatz. “Almost every journal published nowadays has at least one article about genetic sequences, and medicine today almost doesn’t move without genetic studies.”
The role of genetic identification within Judaism can be difficult to pin down, he says. According to the Talmud, if a body or part of a body is found and it cannot be identified, if there is a unique feature from which it can be assumed who the person was, it is good enough.
The question, however, is what is considered unique. “The Talmud doesn’t say, and doesn’t give any statistics,” says Tatz. “From the 16th century, halachic authorities have tried to define it. They said that if the uniqueness of the feature was one in a thousand, that was good enough.
“However, genetic identification is much more accurate. Better, but not absolute. Major rabbinic figures in this field have said that if we need to identify someone and have positive genetic identification and some other piece of surrounding evidence, it is halachically acceptable.”
Tatz explains that experts in Jewish genealogy and history have determined that 40% of all Ashkenazi Jews are descended from just four Jewish women who left the Middle East more than 1 000 years ago and settled in Europe.
He says mitochondrial DNA, the genetic material present in cellular bodies called mitochondria, is inherited exclusively from a person’s mother. Therefore genetic markers in this DNA can be traced back many generations to determine a person’s maternal ancestors with a high degree of certainty.
“We have about 20 000 to 30 000 genes. The human genome is found in the nucleus of the cell, in the mitochondria, which contains 25-30 genes. Uniquely, these are inherited only from the mother.
“It so happens that in this DNA, there is a unique Jewish feature. And it just so happens that you are Jewish because your mother is. The two match up perfectly.”
Tatz stressed, however, that this research has not made it enough to prove Judaism just by doing a genetic test. Not yet. Still, it has already had major consequences the world over.
“The evidence suggests that most Ashkenazi Jews are descended from men who came from Israel before the time of the Roman exile, and Roman women who converted to Judaism at the time. It turns out that Ashkenazi Jews are far more closely related to Tuscan Italians than to other Jews from other parts of the world.”
Another case cited is that of the Lemba, an ethnic group native to Zimbabwe and South Africa. This group has some religious practices and beliefs similar to those in Judaism, which they say were transmitted by oral tradition.
“The Lemba tribe have a story of descending from King Solomon through Africa, and claim to be Jewish,” says Tatz. “A number of them do, in fact, have the gene. Although the research needs to be carried further, the case may have some standing thanks to the evidence so far.”
Another application of genetics to identify Jews is effecting an extremely painful and bitter story developing in Israel. In the 1950s, Yemenite Jews were brought to Israel and settled in tent camps around the country. Living under such conditions, many of their babies fell ill, and were taken to Israeli hospitals, where many disappeared.
“When the parents came for their child, they were told it had died, and where it had been buried,” Tatz says. “The accusation is that the hospitals sold the babies, or gave them away to Holocaust-survivors without children. Since then, commission after commission has been set up to bring the situation to a close, but it has never been resolved.”
Last month, the Israeli Knesset passed a law allowing for the graves to be opened and for genetic analysis to be carried out on the remains. “Within a couple of weeks, perhaps once and for all, this will be laid to rest,” says Tatz. “Unfortunately, it’s not simple, as in Israel people are not buried in coffins. The graves of these babies are small, and the ground shifts. It’s not clear exactly where each individual child is located, but there is great hope that this scar on modern Israeli history may be resolved.”
The practice of tracing genetic genealogy amongst Jews is not necessarily new. One example is that of the lineage of Kohanim, and their descendants today.
“A Kohen gene has been said to exist in certain men claiming to be Kohanim. Before, they were believed only on the basis of their own testimony,” says Tatz. However, a very high percentage of people claiming descent have a unique Y-chromosomal polymorphism, which suggests that all Kohanim on the earth today descended from one man who lived about 2 000 years ago.
“Thanks to genetic research, we can tell how closely related any two human beings are on earth. A recent study found that any two Jews on earth are 10 times more closely related than any two random people living in New York.”