A just-published, “definitive” study of Jews of North African origin has set
their place on the genetic map of the Jewish Diasporas. This completes research
of contemporary Jewish populations following previous work on Ashkenazim,
Sephardim and Mizrahi Jews who originated in Europe and the Middle
East.
The study – led by Prof. Harry Ostrer of the departments of
pathology, genetics and pediatrics at the Albert Einstein College of Medicine at
New York’s Yeshiva University, was just published online in the Proceedings of
the US National Academy of Sciences.
The researchers analyzed the genetic
make-up of 509 Jews from 15 populations compared with genetic data on 114
individuals from seven North African non-Jewish populations.
North
African Jews are the second largest Jewish Diaspora group. Until now, how they
are related to each other, to other Diaspora groups and to their non-Jewish
North African neighbors had not been well defined.
The study also
included members of Jewish communities in Ethiopia, Yemen and
Georgia.
The findings support the historical record of Middle Eastern
Jews settling in North Africa during classical antiquity, converting non-Jews to
Judaism and marrying local populations, thereby forming distinct populations
that stayed largely intact for more than two millennia.
“Our new findings
define North African Jews, complete the overall population structure for the
various groups of the Jewish Diaspora and enhance the case for a biological
basis for Jewishness,” said Ostrer, an Einstein physician who is director of
genetic and genomic testing for the division of clinical pathology at nearby
Montefiore Medical Center. Ostrer noted that obtaining a comprehensive genetic
fingerprint of various Jewish subpopulations can help reveal genetic links to
heart disease, cancer, diabetes and other common diseases.
In a previous
genetic analysis, the researchers showed that modern-day Sephardi (Greek and
Turkish), Ashkenazi (Eastern European) and Mizrahi (Iranian, Iraqi and Syrian)
Jews originating in Europe and the Middle East are more related to each other
than to their contemporary non-Jewish neighbors, with each group forming its own cluster within the larger
Jewish population.
In addition, each group showed Middle-Eastern ancestry
and varying degrees of mixing with surrounding populations.
Two of the
major Jewish populations – Middle Eastern and European Jews – were found in the
Einstein study to have diverged from each other about 2,500 years
ago.
North African Jews exhibited a high degree of endogamy – a term that
refers to marriage within their own religious and cultural group – in accordance
with their community’s custom.
Two major subgroups within this overall
population were identified – Moroccan/Algerian Jews and Djerban
(Tunisian)/Libyan Jews. The two subgroups varied in their degree of European
mixture, with Moroccan/Algerian Jews tending to be more related to Europeans,
which most likely resulted from the expulsion of Sephardi Jews from Spain during
the Inquisition starting in 1492.
Ethiopian and Yemenite Jewish
populations also formed distinctive genetically linked clusters, as did Georgian
Jews.
The Jerusalem Post asked for comments on the paper from Prof. Karl
Skorecki, a leading genetics researcher and nephrologist – kidney care
specialist –at Haifa’s Rambam Medical Center who has done pathfinding work on
the ancient links of the Priestly Tribe and Y chromosomes.
“This
Einstein-led research is definitive,” said Skorecki, a modern- Orthodox Jew who
said he is closely familiar with the paper and the “superb researchers” involved
in it.
“One of its great strengths is the interdisciplinary
collaboration, including among other experts such as historians. The context of
historical expertise greatly enhances the ability to understand and draw
inferences from the genetic analysis,” Skorecki said.
“This paper
continues the team’s excellent work in the past few years on DNA markers across
the entire genome. The second largest Diaspora community, from North Africa, was
missing. The various Jewish communities share with each other and have a great
deal of overlap.”
Skorecki said he did not work with the team this time,
but has before. “A monopoly is not good,” he said. “It’s better for many
different groups from different parts of the world to work independently and
even competitively perform similar research, as it adds to credibility and
confidence.”
Jews who were forced out of Spain and Portugal in the late
15th century moved eastward to Bulgaria, Turkey and Saloniki, but also to
Morocco in North Africa.
“This is clear. There is very interesting
genetic consistency and a confirmation of history that we have obtained from
archival historical records. Using genetics can also be a historical tool,” the
Rambam expert said.
“When one looks for geneticbased predisposition to
diseases, it’s important to know to what other population the given group is
genetically related, in this case, the non-Jews in the same area. The new
findings show that there was not much Jewish admixture with the local non-Jewish
population in North Africa. Compared to the variation of the worldwide
population, Jewish communities were quite different. They mostly married among
themselves, with not enough mixing with the non- Jewish group to make it
possible to separate the DNA.
One can see that there is shared Jewish
ancestry of Near East origin among Ashkenazim and other Jews who had been
separated for thousands of years.”
Skorecki, who is also at the Technion-Israel Institute of Technology in Haifa, noted that new studies, such
as a major one a few weeks ago from University College London researchers in the
American Journal of Human Genetics, have shown that the general population in
Ethiopia has the most diverse structure in the world.
“There was a great
deal of diversification, so it’s a great place to study genetics,” said
Skorecki.
“Many researchers,” he continued, “believe that humans
originated in more than one place, but contemporary humans probably descend
mostly from humans from northeast Africa, such as Ethiopia.
“I, like
them, think that they were dark skinned, and as they moved, their skin color
evolved to adapt to their environment,” said Skorecki.
His own research
group at Rambam and others are currently involved in studying the whole genome
of three billion letters.
Now Jewish samples are being studied for whole
genome sequences – every single letter of the bases making up pairs in the DNA –
which will provide even more insight on human health.
Skorecki believes
the non-Jewish academic world is interested in Jewish genetics as scholars of
history. Probably, the Jewish connection to the Bible also interests them, he
said.
There is similar international interest in the people of Iceland
and their diseases, just as there is in the Druse who often marry their first
cousins, and Ashkenazi Jews who married among themselves for many
centuries.
“One can understand their genetic structure and then learn a
lot about health. Everything is headed towards whole genome studies,” said
Skorecki.
A “personalized medicine initiative” based at the Weizmann
Institute of Science in Rehovot and coordinated by Nobel Prize laureate Prof.
Aaron Ciechanover, also of the Technion, is using modern technologies to get samples and understand
genomes and proteins,” said the Rambam researcher.
Having two adult
children who married Sephardi Jews, Skorecki said there is currently a “|window
of opportunity” to do Jewish genetic research as Jewish/non-Jewish and Sephardi/
Ashkenazi intermarriage occurs. Assimilation in the US is high, but “in Israel,
we welcome the coming together of descendants of separate Jewish communities and
their marriage in Israel. Scientists in my grandchildren’s generation will say
they are just Jews.”