Newsgroup: it.politica.internazionale
Titolo: Study finds why Jewish mothers are so important (Reuters)

E'uno studio analogo a quelli fatti da Cavalli-Sforza. Ma il risultato 
ha delle implicazioni demografiche a lungo raggio.
Cmq. complimenti alle mamme Askhenazi :)
Am.
 Study finds why Jewish mothers are so important
By Maggie Fox, Health and Science Correspondent  Fri Jan 13, 12:25 PM 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 Friday.
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 four 
women.
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 populations.
"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 known rate.
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."
SETTLING EUROPE
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 children."
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," Behar said.
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.


Cut
Tu come stai col tuo pedegre'.
Saluti Cad Ali'
--------------------------------
Inviato via 
http://arianna.libero.it/usenet/

 
1. Si scrive 'pedigree', e non sono un cane
3. Non sei una mamma askhenazi
Sorry,
Am.