AUGUST 17, 2001	| current issue | back issues | subscribe |

Studies Casting New Light On Origin of Europe's Jews

Stanford's Risch Puts Mythic Theory To Rest

By DAVID POLLACK

Recent genetic testing methods are producing scientific evidence that is clarifying the origins of Ashkenazi Jewry.

Dr. Neil Risch, a researcher at the Department of Genetics at Stanford University, is at the forefront of a field that has brought evidence that may help to break the deadlock between historians who argue over the history and makeup of Ashkenazi Jewry.

"There has been a lot of debate about Ashkenazi history," Dr. Risch said. "There is a period of about 1,000 years, before the people settled in Eastern Europe, that's missing from the record."

Among the theories seeking to explain the origins of the Ashkenazim is a theory propagated by the late writer Arthur Koestler. Koestler contended that the predecessors of Ashkenazi Jews did not originate in Palestine, but rather in Khazaria, a medieval empire populated by a people of Turkish stock whose nobility converted to Judaism. In "The Thirteenth Tribe: The Khazar Empire and its Heritage" (Random House, 1976) Koestler stated that "the majority of ... world Jewry might be of Khazar and not of Semitic origin," a passage that has led some reviewers of the book to question the historical rights of Jews to Israel.

But while Koestler argued that traditional historians were motivated by an "obvious intent to avoid upsetting believers in the dogma of the Chosen Race," geneticists such as Dr. Risch defend the traditional history of Jewish origin. "If you made a [genetic] map of Europe and the Middle East and you put Ashkenazi Jews on it," Dr. Risch said, "they would not end up in Turkey or in the middle of Europe, but in the Mediterranean."

In order to make determinations such as these, Dr. Risch studies the mutated genes that cause some of the diseases commonly found in the Ashkenazi Jewish population. In 1995, he and a team of other researchers investigated the history of idiopathic torsion dystonia, a movement disorder that affects the Jewish population at a much higher frequency than it does any gentile population.

Using the family history of his patients and a dating technique called linkage disequilibrium analysis, Dr. Risch determined that the mutation arose less than four centuries ago in present-day Lithuania and Byelorussia. In the paper, Dr. Risch notes that the mutation "first appeared approximately 350 years ago ... [and] that the carriers preferentially originate from the northern part of the historic Jewish Pale of settlement."

The fast proliferation of the disease, Dr. Risch argues, can be explained by the migratory patterns of the population. "Our data from that study," he said, "suggests that there was a 'bottleneck' during the period of time that the Ashkenazi Jews went into Lithuania.... It could either be that the mutation first arose at that time, or, more likely, that it was carried by somebody who, by chance, had a lot of children."

Accepting the latter scenario, Dr. Risch rejects the possibility that the Khazar migration could have brought the mutation — which, according to Dr. Risch's study, now exists at a frequency "between 1 in 6,000 to 1 in 2,000 in Ashkenazi Jews" — in the population. "I'm not sure I would make that argument," Dr. Risch said. "The timing is wrong. The mutation that causes torsion dystonia entered the Ashkenazi population 400 or 500 years ago at the most, rather than the much earlier time that the Khazars probably migrated."

Dr. Risch's more recent work in the field provides further evidence in support of the traditional theory of Jewish history. In a study published in April of last year, Dr. Risch and another team of researchers analyzed two mutations that cause Gaucher disease, a storage disorder that is more widespread in the Jewish population than is dystonia.

Finding that the mutations had a longer history than that which causes dystonia, Dr. Risch also noted that the disease is not restricted to the Jewish population. "We dated one mutation to the period of time that the Ashkenazi population probably first coalesced as a distinct group, 1,100 or 1,200 years ago," Dr. Risch said. "We also have evidence that the other mutation actually predates the formation of the Ashkenazi Jews because it exists in non-Jews also. It has a reasonable frequency in the Portuguese community and exists in many Caucasian groups."

To Dr. Risch, these facts place the antecedents of today's Ashkenazi Jewish population in Central Europe, and not Khazaria, during the Middle Ages. "My interpretation is that this evidence is more in line with the founding of the Ashkenazi population in Central Europe," he said. "The Khazar contribution to the Ashkenazi gene pool is probably not that significant."

Dr. Harry Ostrer, a researcher in the Department of Genetics at New York University Medical School, contends that the Ashkenazi Jewish population is undoubtedly closer to other Jewish populations, at least genetically, than it is to non-Jewish groups outside the Middle East. In a June study of Y-chromosome haplotypes, or genetic markers transmitted on the male line, Dr. Ostrer and a team of researchers concluded, "Despite their long-term residence in different countries and isolation from one another, most Jewish populations [are] not significantly different from one another at the genetic level."

Another finding of Dr. Ostrer's study is that while the Ashkenazi Jews are not very close genetically to European gentiles, they are genetically close to some Arab groups. Reinforcing this evidence is a study by Aravinda Chakravarti, director of the McKusick-Nathans Institute of Genetic Medicine at Johns Hopkins University, who found that a certain genetic mutation causing deafness, DFNB1, affects Jews, Palestinians and other groups of the Mediterranean. Recognizing the historical ramifications of this study, Dr. Ostrer pointed out that Jews and Palestinians probably had common ancestors not so long ago. "It's commonly believed among historians that many of the people that became Palestinian Arabs were once Jewish," he said.

The researcher went on to underscore the social irony of such a situation. "The Arabs don't happen to 'remember' that anymore," he said, pointing to the hostilities of Arab groups toward Israel. He was also able, however, to see the situation from the opposite perspective. "Conversely, maybe if the Israelis 'remembered' [that the Arabs used to be Jews], they'd be nicer to them."