GENETICS AND THE JEWISH IDENTITY
by Diana Muir Appelbaum And Paul S. Appelbaum Md

The Jerusalem Post
February 12, 2008, Tuesday

HIGHLIGHT: Studies show not only that almost all Jewish populations
have origins in the Middle East but that the DNA of Jews from almost
every corner of the Diaspora is more similar to that of other Jews
than to any other population. What the studies cannot tell us though
is who is a Jew. Diana Muir Appelbaum is the author of Reflections
in Bullough’s Pond: Economy and Ecosystem in New England (University
Press of New England 2000 and is working on a book on nationalism.

Paul S. Appelbaum is the Elizabeth K. Dollard Professor of Psychiatry
Medicine and Law at Columbia University and writes about the ethics
of genetic testing and research.

The Book of Exodus specifies that the male descendants of Aaron
the brother of Moses should constitute the Jewish priesthood – the
kohanim – "for all time." Jewish tradition holds that the status of
kohen has been faithfully passed from father to son for more than 3
300 years. In 1997 the world was amazed to learn that the old Bible
story had found new and very persuasive scientific support.

Seemingly out of the blue a group of genetics researchers announced
that they had evidence to support that story. The group led by
Israeli researcher Dr. Karl Skorecki himself a kohen reported that the
evidence was in the DNA of one of the 46 chromosomes that each kohen
carries. Skorecki realized that Y chromosomes which confer male sex are
passed down just as the status of kohen is from father to son. And like
all chromosomes the Y always displays a pattern of mutations called a
"haplotype" that varies across family groups and therefore can be used
to trace descent. Thus any haplotypes that were on Aaron’s Y chromosome
ought to appear with only minor changes in all of his descendants
including modern kohanim if they were in fact Aaron’s offspring. In
other words kohanim should share a common genetic signature.

And so they do. A distinctive haplotype now known as the "kohen modal
haplotype was found in 45 percent-61% of Ashkenazi kohanim, 56%-69%
of Sephardi kohanim and 10%-15% of other male Jews. The haplotype is
estimated to be between 2,100 and 3,250 years old, a time range that
includes the biblical period.

Only a decade since that study was published, it is hard to recover
the surprise with which the world greeted the findings. Skepticism
over the historicity of the Bible had led to widespread doubt that
Jews descended from the ancient Israelites, let alone that the kohanim
descended from the biblical Aaron. More recent data suggest that the
percentage of kohanim with the telltale haplotype may be somewhat
lower than the initial estimates. But the fidelity of transmission
of kohanic identity is nonetheless remarkable.

What about the Levi’im?

The obvious next step was to ask whether the DNA of the Levi’im
also shows descent from a single ancestor. According to the Bible,
all Levi’im, who had a separate ritual role in the ancient Temple,
descend from Jacob’s son Levi. However, Y chromosome haplotypes of
the Levi’im have proven much more diverse than those of kohanim.

Although a haplotype common to 52% of Ashkenazi Levi’im was found,
the origins of this genetic marker appear to derive from central Asia
– not the Middle East – and it is essentially absent from Levi’im of
Sephardi descent.

Where did that central Asian haplotype come from? Most Jews are vaguely
aware of the Khazars; their king plays the role of interlocutor
in Yehuda Halevi’s 12th-century defense of Jewish doctrine, The
Kuzari. The Khazars, however, were not a mere literary device. They
were a real people with a major kingdom north of the Caspian Sea,
and in the eighth or ninth century the Khazar leaders and some of the
people converted to Judaism. After the 10th century, they disappear
from history. The common ancestor of the Ashkenazi Levi’im who carry
this particular haplotype lived less than 2,000 years ago. A good
guess is that at roughly the time the Khazar kingdom disappeared,
a very small number of closely related individuals with the tradition
of being Levi’im, or perhaps only a single male, came from the general
region of the Khazar kingdom to join the then-small Ashkenazi community
in Europe. If this is so, it may indicate that the Khazar Jews had
created a native class of Levi’im.

Jews and their neighbors: The Diaspora

Genetic researchers have not neglected more than 90% of Jews who are
neither kohanim nor Levi’im. They began with good reason to suspect
that a great deal of mixing had taken place during the millennia of
dispersion. People had noticed, after all, that the pale-skinned
redheads common in Lithuanian Jewish communities do not look much
like petite, dark-haired Jews from Yemen. It was assumed that Jews
were bound more by tradition than by genetic kinship, that in the
distant past Jewish men had followed opportunity to some far-off
city, married local girls, persuaded them to separate the meat and
milk dishes and founded new Jewish communities. Moreover, it was
believed non-Jewish ancestors had continued to mix into the Jewish
community. The idea that the traditional story – Jews driven into
exile faithfully marrying only fellow Jews – might be largely true
was startling. And yet, so it seems.

There were, of course, times and places where significant numbers of
people converted to Judaism. But in the centuries since the beginnings
of European Jewry, the best available estimate is that a mere 0.5%
of new material entered the gene pool of Ashkenazi Jews in each
generation. This is part of a picture of remarkable Jewish genetic
continuity emerging from research labs at a dizzying rate.

More studies have been carried out on the genetic history of the
Jews than on most ethnic groups, perhaps because there are so many
Jewish doctors to take advantage of the fabled willingness of Jews to
participate in research. These studies not only show that almost all
Jewish populations have origins in the Middle East, but that the DNA
of Jews from almost every corner of the Diaspora is more similar to
that of other Jews than to any other population. When compared with
non-Jewish groups, the closest match is with the Muslims of Kurdistan,
not with the European peoples alongside whom Ashkenazi Jews lived
for centuries or the Arab neighbors of many Sephardi populations.

Other groups with histories of ancient migrations do not have the same
degree of continuity. Hungarians are known to have originated on the
Eurasian steppe and moved westward in a migration many centuries long,
arriving in the Carpathian basin about 995 CE. They speak a language
from the steppe, take pride in their history of migration and military
conquest and expected that genetic research would demonstrate their
central Asian origins. The evidence to date, however, has shown a
varying but quite small element of central Asian ancestry in Hungarian
populations, along with great similarities between Hungarians and their
Slavic and German neighbors. This does not mean that the Hungarians
with Slavic ancestry are not real Hungarians. Rather, Hungarian culture
has been so powerfully attractive that for many centuries people of
Slavic, Germanic and other ancestry elected to join the Hungarian
people. Ironically, the genetic distinctiveness of the Jews in part
may reflect the unattractiveness of joining a religious minority that
was oppressed and impoverished through much of its history.

Jews and their neighbors: The Middle East

With Jews looking increasingly like a relatively cohesive population
largely of Middle Eastern origin, the logical next question is how
close a genetic relationship exists with other Middle Eastern groups.

A study of Israeli Jews and Palestinian Arabs published in 2000 by
Israeli researchers revealed what the authors described as a relatively
recent common ancestry." It was greeted with euphoric proclamations
that Palestinians and Jews are brothers. A closer look at the details
of the study gives reason for pause.

The researchers compared Jews and Palestinians to a sample of people
from Wales. When compared with the Welsh Jews and Palestinians
did indeed look similar as they probably would if contrasted
with Trobriand Islanders. When the same research team conducted
a follow-up study comparing Jews and Palestinian Arabs to Kurds
Armenians Turks Syrians Jordanians Lebanese and Beduin they saw a very
different picture. Although all Middle Eastern populations have broad
similarities Jews were found to be more closely related to groups
in the north of the Fertile Crescent (Kurds, Turks and Armenians)
than to their Arab neighbors.

This could mean that Jews Kurds Armenians and Anatolian Turks all carry
the genetic markers of ancient indigenous populations of the Fertile
Crescent while Palestinian Arabs and Beduin may largely descend from
the Arab conquerors with their distinctive genetic signifiers. Genetics
may eventually provide answers to such questions as what proportion
of Palestinian ancestry arrived via earlier or later migrations. So
far we have only partial explanations.

One of the most compelling studies compared the small Samaritan
population in Israel with Druse Palestinians and Jews from various
parts of the Diaspora. The results appear to corroborate the
traditional Samaritan belief that they have lived in Samaria since
antiquity and are closely related to the Jews. Only four Samaritan
family lineages survive but of those four male lines three carry the
kohen modal haplotype while the fourth the Cohen family of priests
does not. The data indicate that the Samaritans generally married
other Samaritans. Y chromosome DNA shows the Samaritan male line to
have "a much greater affinity" to Jews than to the Palestinian Arabs
who have surrounded them since the Arab conquest.

Studies of Jewish women

The ease of tracing male lineages with the Y chromosome accounts for
the large body of research that uses exclusively male populations.

However another technique allows equivalent explorations of the female
line. Every cell of our bodies contains mitochondria small organelles
that generate energy from food. Each mitochondrion harbors its own
circular strand of DNA which both sexes inherit from their mothers
and which is passed on only by women to the next generation.

The utility of mitochondrial DNA (mtDNA) studies is demonstrated by
recent findings concerning one of the least known Jewish groups: the
Bene Israel descendents of 6 0 Jews "discovered" on the west coast
of India by Jewish traders from Baghdad in the 1830s. They carry the
kohen modal haplotype along with other Middle Eastern genetic markers
and have substantial mtDNA found only in the Indian population among
whom they lived – always keeping the Sabbath – for hundreds perhaps
thousands of years. From the genetic evidence it looks as though a
small group of Jews all or mostly male arrived on the Indian coast
married local women and built a Jewish community.

Studies of mitochondrial DNA suggest that Jewish communities were
often founded by very small numbers of women. One study demonstrates
that 27% of Moroccan 41.3% of Bene Israel and 51.4% of all Georgian
Jews are descended from a single female ancestor in each community.

The matriarch of 41.3% of the Bene Israel came from a local Indian
family. We do not know the origins of that founding mother of the
Georgian Jewish community or even whether she was born to a Jewish
family only that she carried a distinctive haplotype found in an area
stretching from Sicily to the Caucasus to Iraq.

The Bukharan Persian Ethiopian Iraqi and Ashkenazi Jewish communities
all have unusually small numbers of maternal ancestors. This could
reflect communities founded by tiny numbers of Jewish women willing
to travel with their husbands to far-off lands or situations like
the Bene Israel’s where a community was founded at least in part by
a small number of women who married Jewish men and lived as Jews.

A bit of light recently has been thrown on part of this picture by a
study of the mtDNA of Ashkenazi women close to half (42%) of whom are
descended from one of just four matriarchs. The distinctive complete
sequence haplotypes carried by descendents of these four women are
almost unknown in other populations except occasionally in Jewish
communities that trace their origin to the expulsion from Spain. The
evidence indicates that these four female ancestors most probably
originated in the Levant perhaps accompanying their husbands from
the Middle East to their new homes. Even Samaritan mtDNA has been
examined showing distinctive patterns about equally different from
Jewish and Palestinian comparison groups and hence with somewhat more
mixing than in the male line.

Genetics of the "lost tribes"

Jews and Christians alike have an endless fascination with stories
of the "lost tribes" of Israel turning up in odd parts of the world.

Witness the recent enthusiasm about the Bnei Menashe in the hills of
eastern India. Few such groups have been studied by geneticists but
when they are the results can be remarkable.

Perhaps the most surprising story in Jewish genetics involves the
Lemba a Bantu-speaking people of about 50 0 living in southern East
Africa. Their appearance and lifestyle are largely similar to other
Bantu-speaking groups with a few notable exceptions: They practice
circumcision have a ritualized slaughter procedure for animals avoid
eating pigs and have a strong tradition that their ancestors migrated
from "Sena in the north by boat." When westerners came into contact
with the Lemba and noticed the similarity of their customs to Jewish
practices they wondered whether "Sena" might be Sana in Yemen and
whether the Lemba were of Jewish descent.

A British anthropologist arranged for genetic testing of members of the
tribe finding that 10% of Lemba men carry the kohen modal haplotype on
their Y chromosomes. Even more impressive the Lemba have a priestly
clan whom they call the Buba. Fully 52% of Buba men who were tested
bear that same marker of kohanic descent. Although mtDNA testing has
not yet taken place it seems likely that the origins of at least some
portion of the tribe date back to the arrival on African shores of
male Jews and their subsequent marriage to local women. Only vestigial
Jewish traditions were maintained among a population that is animist
and Christian in practice. In no sense – cultural or halachic – can
the Lemba be considered Jews today. But their story demonstrates the
power of DNA to elucidate the probable history of many populations.

Genetics and identity

What genetic data cannot tell us is who is a Jew. The answers to
that question are variously halachic political and cultural. On a
purely technical level there is no genetic screen that can sort Jews
from non-Jews. Population differences do not translate into reliable
tests of individual lineage. What genetics can tell us is something
about where our ancestors came from – no more. It cannot tell us who
we are. Nor can it tell us who we want to become as individual Jews
or as a Jewish people. As new data emerge from genetics laboratories
though we are likely to learn a great deal more about the history of
our people.

From: Emil Lazarian | Ararat NewsPress