Monday, February 06, 2006

Our Four Mothers

Most of us are far more drawn to news about science than we are to science. When James D. Watson's The Double Helix was published in 1968, I gobbled it up, fascinated not by the details about the mystery of the genetic code but by the details of competition among scientists who understood that the first to resolve the mystery would win the Nobel Prize and earn lasting fame. Francis Crick and Watson came in first, with Rosalind Franklin perhaps unfairly deprived of her share.

The scientific breakthrough was epic and what has ensued is breathtaking. While doubtlessly scientists competed and played games before Watson and Crick, their story serves as a marking point in the marketing of scientific achievement. For all of their brainpower, great scientists are human and they aren't any more immune than the rest of us from the foibles that are inherent in the species. Grandeur and greed can be found under one scientific tent.

There is rivalry and back-stabbing, public relations and exaggerated claims and, as the recent South Korean cloning scandal shows, at times there are claims that are fabrications. More commonly, there is a rush to publish findings that need additional examination, findings that may be challenged or altered by new research.

Which brings up the claim or news - proclaimed nearly everywhere in oversimplified fashion, including on the front page of the New York Times "Week in Review" - that nearly half of all Ashkenzai Jews are descended from four mothers whose antecedents were likely in the Near East. Even if they weren't Sarah, Rifkah, Leah and Rachel, for traditionalists it is good to know that the "four mothers" concept somehow has been validated. It is even more comforting to know that we aren't descended from apes, although I am certain that primatologists would insist that first came the monkeys and then came the mammas.

I have read the American Journal of Human Genetics report on "The Matrilineal Ancestry of Ashkenazi Jewry: Portrait of A Recent Founder Event." Twenty scholars, an astounding number, are listed as responsible for the report, with Professor Richard Villems of the University of Tartu in Estonia identified as the key contact. We are witness to the globalization of science. I contacted Dr. Villems and he was helpful and modest, saying that the findings are largely the handiwork of Doron M. Behar of the Technion in Haifa.

Another interesting point: The Journal notes that it received the report on September 28, 2005, accepted it for publication on December 6, 2005 and published the electronic edition (which is what I have) on January 11, 2006. I wonder whether there was a rush to publish before the findings were adequately peer reviewed, particularly by geneticists who might take issue with what has been claimed. This is not a gratuitous question because there apparently is disagreement, as I shall indicate, on one crucial point.

The report that a substantial proportion of Ashkenazim have distinctive maternally-transmitted DNA identified as four subgroups of the K family is apparently beyond challenge, although the sample size strikes me as too small to support what is being claimed. In addition, because there are open questions regarding the other half of Ashkenazim, the total picture is somewhat blurred. What is claimed for the K cluster is that in the course of the Jewish migration from the Near East into the Roman Empire and then into the Rhine Basin, there was a genetic "founder event" or "bottleneck" that triggered significant contraction in the maternal genetic composition.

A founder event is defined as "the establishment of a new population by a few original founders (in an extreme case, by a signal fertilized female) which carry only a small fraction of the total genetic variation of the parental population." As Professor Villems wrote to me, this means that some genetic mechanism had by chance favored four variants of maternal lineages. We aren't told why or how this occurred. Indeed, as the report notes, "the question of a founding event in the maternal history of Ashkenazi Jews" is in dispute, with some geneticists "reaching the conclusion that there is little evidence for such an event." The time and place of this claimed founder event is inevitably uncertain, which supports the conclusion that while researchers can with confidence report on contemporary genetics, when they reach way back into history they are on slippery ground.

Likely, in due course the report about these four mothers will be qualified and refined as additional research is conducted. We will learn more about the past than we now know, but all of the research in the world will not uncover all historical secrets and genetic research is, in an important sense, historical research.

The intriguing thing is what such research can tell us about the recent past and contemporary Jewish life, whether it can shed light on the incidence of intermarriage and its impact on the genetic composition of Jews. We might also wonder whether the key role played by women in the genetic transmission among Ashkenazi Jews provides support for the halachic concept that the transmission of Jewish identity is via mothers.

Genetics is a risky subject and not primarily from a purely scientific standpoint. Jews know how attitudes toward genetics can breed racism and other evils. Experts in this growing field should ponder whether all of life's mysteries merit resolution. Likely, though, genetic research will continue at a rapid pace because it is triggered in large measure by the ambition of truly bright scientists.

As war is too serious a business to be left entirely to generals, genetics is too serious a business to be left entirely to scientific specialists. As additional research is conducted, hopefully there will be discourse as to how to proceed and this will include ethicists, theologians, sociologists and experts from other disciplines whose views should be taken into account when scientists determine how to proceed.