Arizona Daily Wildcat
Research of Y chromosome unraveling biblical legend
Genetic research on the Y chromosome may help answer questions of biblical significance related to the Jewish Diaspora, or dispersion of the Jewish people.
Michael Hammer, a UA associate research scientist in the Arizona Research Laboratory has been performing studies on the Y chromosome which, in theory, is passed unchanged from father to son.
Occasionally, mutations occur which are inherited by subsequent generations, allowing researchers to construct a kind of family tree that can be used to trace the origin of a people.
Hammer and other researchers have used this information to compare genetic data from Jewish groups to host populations.
In a seminar hosted by Sisterhood, an auxiliary of Temple Emanu-El, 225 N. Country Club Road, Hammer presented his findings to about 85 members of the Tucson Jewish community Sunday.
In the lecture, Hammer said that his findings suggest that the Cohanim - a priestly class of Jews who are said to be descendants of Aaron, brother of Moses - have to a great extent retained their genetic diversity.
Hammer and his colleagues surveyed a group of men in the United States who regarded themselves as Cohanim and compared their Y chromosomes to non-priestly class Jewish men.
"This pattern held no matter which community of Jewish men we surveyed," he said.
Matt Kaplan, an ecology and evolutionary biology graduate student, who has been processing a large amount of the genetic samples, said that the research is in accordance with biblical theories.
"It certainly is consistent with biblical timing, at least with the Cohanim," he said.
Hammer said that his research suggests that the world's Jewish populations closely resemble Syrians, Palestinians and Lebanese, indicating a common ancestry originating in the Middle East about 4,000 years ago.
Genetic evidence also suggests that the Jewish people have retained their biological diversity separate from host populations - showing low rates of intermarriage.
Hammer said that his research is now focusing on understanding the evolutionary reasons for the high occurrence of rare genetic diseases - such as Tay Sachs, an inherited lipid-metabolism disease affecting children - in Jewish populations.
Hammer said that it is possible that a powerful, affluent Jews - such as a rabbi - who had these genetic defects early in Jewish history contributed it to the gene pool in the form of several offspring.
Kaplan said that the higher occurrence of certain diseases in Jewish populations may have also come about because their persecution throughout history may have brought about conditions that promoted inbreeding.
"Although there are taboos against marrying family, if you go back a few generations everyone is family and that kind of inbreeding can reduce diversity," Kaplan said.
Men in attendance at Sunday's seminar were invited to participate in Hammer's study.
They were given a questionnaire to fill out, asking questions about their Jewish background and were then asked to provide a cheek cell sample, collected by rubbing the inside of the mouth with a brush.
The samples, Kaplan said, will have the DNA extracted and then put into the appropriate group, based on the specific mutation.
Kaplan said that those wishing to know their personal information can request it.
Dana Adler, a member of Sisterhood, said she was impressed by the presentation but regretted that women were unable to participate.
Hammer said it is easier to study male genetic data and that is why his study has focused on men but he plans to include women in future studies.
Adler said Hammer did an excellent job of simplifying material that can be very confusing.
"I was just engrossed with what he was saying," she said.