[Paleopsych] Reuters: Study Finds Why Jewish Mothers Are so Important
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Study Finds Why Jewish Mothers Are so Important
Filed at 12:21 p.m. ET
WASHINGTON (Reuters) - Four Jewish mothers who lived 1,000 years
ago in Europe are the ancestors of 40 percent of all Ashkenazi Jews
alive today, an international team of researchers reported on
The genetic study of DNA paints a vivid picture of human evolution
and survival, and correlates with the well-established written and
oral histories of Jewish migrations, said Dr. Doron Behar of the
Technion-Israel Institute of Technology, who worked on the study.
The study, published in the American Journal of Human Genetics,
suggests that some 3.5 million Jews alive today all descended from
For their study, Behar and geneticist Karl Skorecki, with
collaborators in Finland, France, Estonia, Finland, Portugal,
Russia and the United States sampled DNA from 11,452 people from 67
``All subjects reported the birthplace of their mothers,
grandmothers, and, in most cases, great-grandmothers,'' they wrote
in their report.
They looked at mitochondrial DNA, which is found in cells, outside
the nucleus and away from the DNA that carries most genetic
instructions. Mitochondrial DNA is passed down virtually unchanged
from mother to daughter, but it does occasionally mutate, at a
Researchers can use this molecular clock to track genetic changes
through time, and used it, for instance, to compute when the
``ancestral Eve'' of all living humans lived -- in Africa, about
180,000 years ago.
Now they have found four ancestral Jewish mothers.
``I think there was some kind of genetic pool that was in the Near
East,'' Behar said in a telephone interview.
``Among this genetic pool there were four maternal lineages, four
real women, that carried the exact specific mitochondrial DNA
markers that we can find in mitochondrial DNA today.''
They, or their direct descendants, moved into Europe.
``Then at a certain period, most probably in the 13th century,
simply by demographic matters, they started to expand
dramatically,'' Behar said.
``Maybe it was because of Jewish tradition, the structure of the
family that might have been characterized by a high number of
But these four families gave rise to much of the population of
European Jews -- which exploded from 30,000 people in the 13th
century to ``something like 9 million just prior to World War II,''
The Nazis and their allies killed 6 million Jews during the war,
but there are now an estimated 8 million Ashkenazi Jews, defined by
their common northern and central European ancestry, cultural
traditions and Yiddish language.
Behar said as they sampled people from Ashkenazi communities around
the world, the same mitochondrial genetic markers kept popping up.
They did not find the markers in most of the non-Jewish people they
sampled, and only a very few were shared with Jews of other origin.
This particular study does not provide a direct explanation for
some of the inherited diseases that disproportionately affect Jews
of European descent, such as breast and colon cancer, because most
diseases are caused by mutations in nuclear DNA, not the DNA
studied by Behar's group.
These genes are believed to date from a ``bottleneck'' phenomenon,
when populations were squeezed down from large to small and then
expanded again. Behar and Skorecki's team have found what is known
as a ``founder effect'' -- when one or a small number of people
have a huge number of descendants.
What the study also shows, Behar said, is that Jewish mothers are
highly valued for a good reason. ``This I could tell you even
without the paper,'' he said.
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