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Genetics And The Jewish Identity

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  • Genetics And The Jewish Identity

    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
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