As Diaspora Jews increasingly assimilate and intermarry with gentiles, and their
Israeli counterparts marry Jews whose forebears came from the four corners of
the earth, a window of opportunity to study Jewish genetics is gradually
closing.
In another generation or two, it may be possible only to know
whether one bears a “Jewish genome” rather than identify the different genetic
threads that once bound them together.
For more than 100 years, both Jews
and non-Jews have been trying to find out whether Jews are a religious group, a
people or even a race. Some were motivated to use this information as a basis for
discrimination or even murder, others to boast about supposed superior
intellectual abilities and a disproportionately large number of Nobel Prize
laureates.
Jews with a family history of chronic or genetic diseases
wanted to know if they were likely to contract them or pass them on to their
children and grandchildren. The higher prevalence of Tay-Sachs, Gaucher and
Canavan’s disease among Jews is well known, but some experts claim certain
psychiatric, metabolic and oncological diseases are also more common among
them.
Now, Prof. Harry Ostrer has produced a 264-page, English-language
volume melding together science, history and biography to better understand the
complex subject. Titled Legacy: A Genetic History of the Jewish People,
the $25 hardcover book was published by Oxford University Press.
A Jewish
medical geneticist at Yeshiva University’s Albert Einstein College of Medicine,
Ostrer is also director of genetic and genomic laboratories at Montefiore
Medical Center in New York. Almost two years ago, he was named to the Forward 50
list of “people who have made an imprint in the past year on the ways in which
American Jews view the world and relate to each other.”
A physics
graduate of the Massachusetts Institute of Technology who received his MD from
Columbia University College of Physicians and Surgeons, Ostrer trained in
pediatrics and medical genetics at Johns Hopkins University and molecular
genetics at the US National Institutes of Health.
Before joining
Einstein, he spent 21 years as professor of pediatrics, pathology and medicine
and director of the human genetics program at New York University’s School of
Medicine.
While he has spent much of his career investigating the genetic
basis for a variety of rare diseases from color vision deficiencies and
thalassemia to sex development disorders – even going to the Far East to test
Cambodian and Thai citizens for mutations that disrupt their blood – Ostrer has
put a special emphasis on population genetics among Diaspora Jews, collaborating
and competing with research groups in Israeli centers and others
abroad.
He co-established with Israeli-born Einstein researcher Dr. Gil
Atzmon the Jewish HapMap Project on genomes of contemporary Jewish Diaspora
groups (Hap refers to haplotype – a group of genes inherited together by an
organism from a single parent).
The book is divided into six large
chapters – “Looking Jewish,” “Founders,” “Three Genealogies,” “Tribes,” “Traits
and Identity” – plus 277 references. In the first chapter, he describes the work
a century ago of Dr. Maurice Fishberg, a young Russian-Jewish immigrant
physician in New York City, who “grappled with the issues of Jewish origins,
identity and traits” in a series of articles that he made into a book: The Jews:
A Study of Race and Environment.
A one-time coal miner, the physician
became chief medical examiner of new immigrants for United Hebrew Charities and
then a physical anthropologist who confronted American supporters of restricting
immigration who claimed the Jews brought in communicable diseases, especially
tuberculosis. But his maps proved that the prevalence of TB was significantly
lower in the lower Manhattan districts where Jewish immigrants congregated than
in all other districts, apparently due to their better hygiene and eating habits
due to kashrut.
But he also found that “mental retardation, mental
diseases...called hysteria and neurasthenia,” diabetes and “amaurotic family
idiocy,” now known as Tay-Sachs disease, were more common among Jews, leading
him to wonder about their heredity. Fishberg decided to become a physical
anthropologist to measure and compare physical shapes such as head shape (using
calipers) and pigmentation to scientifically determine “racial
characteristics.”
Researchers after him postulated that humans originated
in Africa, and that over the millennia, their migration out of the continent led
to genetic differentiation in which those with lighter skin, hair and eyes were
more likely to survive in cooler climates and passed on their genes to produce
new races.
“Viewed in the context of Jewish history,” Ostrer wrote, “the
genetic makeup of contemporary Jewish populations has been influenced by the
geographic origins of a relatively small number of founders... Following the
destruction of the Jewish kingdoms more than 2,000 years ago, the Jews became a
migratory people who established communities throughout the world. Some of these
communities retained their continuity over long periods of time.
“Within
those communities, Jews were linked by religion, customs, marriage and language.
The designation ‘Jewish’ was limited by Jewish law to those whose mothers were
Jewish. Entry [into] the community was possible through religious conversion,
but this was not common. Jewish identity was maintained within these communities
up to the present day.”
Ostrer noted that Jews today can be designated
according to where their forebears lived for many centuries as “Middle Eastern”
(Mizrahi); Sephardi (originating in Spain and Portugal until the end of the 15th
century); Ashkenazim, who moved from Italy and crossed the Alps and settled in
the Rhineland and then other places in Europe; and North African Jews, who lived
along the coast for over two millennia after being exiled after the destruction
of the two Temples, mixed with surrounding populations.
All this shaped
the face of world Jewry.
DR. CHAIM SHEBA, the pioneering Israeli
geneticist who was surgeon-general of the Israel Defense Forces and Health
Ministry director-general (after whom Sheba Medical Center at Tel Hashomer was
named) is lauded in the book for his work to determine whether Jews constituted
a single homogeneous group or a series of genetically related groups.
He
found that eating ful (fava beans) and certain anti-malaria medications can
cause terrible anemias in certain people due to G6PD deficiency caused by genes
that are found in certain non-Ashkenazi Jews, Greeks and African Americans. This
led to Sheba becoming “the original force behind the concept of ‘Jewish genetic
disease.’” The work of the past four decades has provided a basis for Sheba’s
observations that “Jews from different Diaspora groups had different disease
susceptibilities.” Other researchers identified the higher rate of Neimann-Pick,
Canavan’s and Gaucher’s diseases among Jews of specific origins.
Ostrer
explained that in recent years, a method known as “coalescence,” that estimates
when a mutation occurred in populations based on the observation that DNA is
inherited in “blocks.” If people who have the same mutation share a large block,
the mutation arose from a recent founder, but if the block is short, the founder
lived long time ago. Thus this technique is similar to carbon dating for
archeology.
The author discusses the two breast/ovarian cancer mutations,
BRCA1 and BRCA2, which do not cause most cases but are likelier in Ashkenazi
Jews. He mentions that Rosalind Franklin, a young Orthodox Jewish scientist,
discovered the structure of DNA with Watson and Crick in 1953, but unlike them,
did not live to receive the Nobel Prize they did because she died at 37 of
ovarian cancer caused by the mutant gene.
Also mentioned is the
University of Washington’s superb geneticist Prof. Mary-Claire King, who studies
the genetics and interaction of genetics and environmental influences on human
conditions such and is known for three major achievements – identifying the
BRCA1 mutation, showing that humans and chimpanzees are 99 percent genetically
identical; and applying genomic sequencing to identify victims of human rights
abuses. King is a frequent visitor to Israel and collaborates regularly with
Israeli scientists, including Sha’are Zedek Medical Center’s chief of medical
genetics, Prof. Ephrat Levy-Lahad (whose work is also mentioned in the
volume).
The genetic link between members of the Jewish priestly tribe
(Kohanim) through their paternally inherited Y chromosome, proven by geneticists
Michael Hammer, Luca Cavalli-Sforza, Rambam Medical Center and Technion Prof.
Karl Skorecki and others is described in detail as well.
Ostrer said that
his Jewish HapMap Project in New York City has so far shown “in exquisite detail
what had been conjectured for a century. Jewish populations from the major
Jewish Diaspora groups – Ashkenazi, Sephardic and Mizrahi – form a distinctive
population cluster that is closely related to Semitic and European populations.
Within this larger Jewish cluster, each of the Jewish populations formed its own
subcluster.”
A high degree of mixing of Ashkenazi, Sephardi, Italian and
Syrian Jews caused them to become more closely related to each other than they
were to Middle Eastern, Iraqi and Iranian Jews. This genetic split seemed to
have occurred about 2,500 years ago.
The author uses his observations to
refute theories that Ashkenazi Jews are descendants of converted Khazars, a
semi-nomadic people living in medieval Eurasia who welcomed Jews to their midst.
He also reports that in addition to southern Europeans, the closest genetic
neighbors to most Jewish groups were the Palestinians, Israeli Beduin and Druse.
“The genetic clusters formed by each of these non-Jewish Middle Eastern groups
reflects their own histories of marrying within the group,” he said.
The
issue of “Jewish intelligence” that seems to come up every time members of the
“Chosen People” are awarded Nobel Prizes continues to be debated. There are
those who contend there is a genetic basis for IQ and those who claim it comes
from studiousness, from Torah learning and from the fact that Jews were held
back by discrimination from joining the top ranks of the arts and sciences but
rushed in after emancipation.
“Breeding, selection and education may all
have contributed to Jewish intellectual accomplishment, but so, too, did being
in the right place at the right time,” and showing that they were worthy of
emancipation by excelling.
The belief that Jews constitute a religious,
rather than ethnic or racial group in the US and other Western countries is
widespread.
“Jewish” was never a category for race in the US Census,
Ostrer notes, even though genetic studies “would seem to refute
this...
Jewishness at a genetic level can be characterized as a tapestry
with the threads represented as shared segments of DNA and no single thread
required for composition of the tapestry,” he writes.
Genetic analysis of
Jews have high stakes, since being Jewish not only decides who belongs to the
family and can take part in Jewish life and earn Israeli citizenship but also
“touches on the heart of Zionist claims for a Jewish homeland in
Israel.”
Ostrer concludes his fascinating book by saying that much about
Jewish genetics remains unknown but will probably be discovered in the next few
decades as more is learned about susceptibility to diseases, origins and
genetics of positive traits.
“With Jews and non-Jews alike wanting to
know about their origins, ancestors and relatives, it will take its place in the
formation of group identity alongside shared spirituality, shared social values
and a shared cultural legacy.”