Atlantis Online
March 29, 2024, 06:07:12 am
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Comet theory collides with Clovis research, may explain disappearance of ancient people
http://uscnews.sc.edu/ARCH190.html
 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

New Light on Origins of Ashkenazi in Europe

Pages: [1]   Go Down
  Print  
Author Topic: New Light on Origins of Ashkenazi in Europe  (Read 161 times)
0 Members and 37 Guests are viewing this topic.
Ian Nottingham
Superhero Member
******
Posts: 3441



« on: April 18, 2008, 01:19:18 pm »

New Light on Origins of Ashkenazi in Europe
 
By NICHOLAS WADE
Published: January 14, 2006
A new look at the DNA of the Ashkenazi Jewish population has thrown light on its still mysterious origins.

Until now, it had been widely assumed by geneticists that the Ashkenazi communities of Northern and Central Europe were founded by men who came from the Middle East, perhaps as traders, and by the women from each local population whom they took as wives and converted to Judaism.

But the new study, published online this week in The American Journal of Human Genetics, suggests that the men and their wives migrated to Europe together.

The researchers, Doron Behar and Karl Skorecki of the Technion and Ramban Medical Center in Haifa, and colleagues elsewhere, report that just four women, who may have lived 2,000 to 3,000 years ago, are the ancestors of 40 percent of Ashkenazis alive today. The Technion team's analysis was based on mitochondrial DNA, a genetic element that is separate from the genes held in the cell's nucleus and that is inherited only through the female line. Because of mutations - the switch of one DNA unit for another - that build up on the mitochondrial DNA, people can be assigned to branches that are defined by which mutations they carry.

In the case of the Ashkenazi population, the researchers found that many branches coalesced to single trees, and so were able to identify the four female ancestors.

Looking at other populations, the Technion team found that some people in Egypt, Arabia and the Levant also carried the set of mutations that defines one of the four women. They argue that all four probably lived originally in the Middle East.

A study by Michael Hammer of the University of Arizona showed five years ago that the men in many Jewish communities around the world bore Y chromosomes that were Middle Eastern in origin. This finding is widely accepted by geneticists, but there is less consensus about the women's origins.

David Goldstein, now of Duke University, reported in 2002 that the mitochondrial DNA of women in Jewish communities around the world did not seem to be Middle Eastern, and indeed each community had its own genetic pattern. But in some cases the mitochondrial DNA was closely related to that of the host community.

Dr. Goldstein and his colleagues suggested that the genesis of each Jewish community, including the Ashkenazis, was that Jewish men had arrived from the Middle East, taken wives from the host population and converted them to Judaism, after which there was no further intermarriage with non-Jews.

The Technion team suggests a different origin for the Ashkenazi community: if the women too are Middle Eastern in origin, they would presumably have accompanied their husbands. At least the Ashkenazi Jewish community might have been formed by families migrating together.

Dr. Hammer said the new study "moves us forward in trying to understand Jewish population history." His own recent research, he said, suggests that the Ashkenazi population expanded through a series of bottlenecks - events that squeeze a population down to small numbers - perhaps as it migrated from the Middle East after the destruction of the Second Temple in A.D. 70 to Italy, reaching the Rhine Valley in the 10th century.

But Dr. Goldstein said the new report did not alter his previous conclusion. The mitochondrial DNA's of a small, isolated population tend to change rapidly as some lineages fall extinct and others become more common, a process known as genetic drift. In his view, the Technion team has confirmed that genetic drift has played a major role in shaping Ashkenazi mitochondrial DNA. But the linkage with Middle Eastern populations is not statistically significant, he said.

Because of genetic drift, Ashkenazi mitochondrial DNA's have developed their own pattern, which makes it very hard to tell their source. This differs from the patrilineal case, Dr. Goldstein said, where there is no question of a Middle Eastern origin.
Report Spam   Logged

Share on Facebook Share on Twitter

Ian Nottingham
Superhero Member
******
Posts: 3441



« Reply #1 on: April 18, 2008, 01:25:33 pm »

Great article, Mario, I just posted it under "Human Genetics."
Report Spam   Logged
Mario Dantas
Superhero Member
******
Posts: 1376


WWW
« Reply #2 on: May 01, 2008, 06:40:00 pm »


Ian,

I found days ago something related...

http://education.guardian.co.uk/higher/medicalscience/story/0,,505080,00.html

M
Report Spam   Logged

Ian Nottingham
Superhero Member
******
Posts: 3441



« Reply #3 on: May 13, 2008, 02:38:54 am »

Thanks, Mario!

In search of Eve's daughters


Professor Bryan Sykes says most Europeans are descended from just seven women. James Meek asks him if he's serious - and finds out why racists are seizing on the theory

Special report: the ethics of genetics

Monday June 11, 2001
The Guardian


Bryan Sykes is the opposite of a racist. It is not just that he doesn't believe in the concept of race. He feels he has proved, scientifically and to his own satisfaction, that race - in Britain, in Europe, in the world - is a myth. There are only individuals. "We are not a race at all," he says. "We've been mongrels for 10,000 years and it has done us a lot of good."

Sykes, 53, is not the first or only scientist to have used DNA to explore the migrations of our ancestors across the globe over tens of thousands of years. But he has gone further than any other in popularising, and now commercialising, the research. His new book, The Seven Daughters Of Eve - elaborating his theory that 95% of present-day Europeans can trace their ancestry back to just seven individual women - is distributed with a discount voucher attached. Buyers will get £50 off the £150 cost of a DNA test which will tell them which of the seven women they are descended from - which "clan", as Sykes puts it, they belong to.

When I first read about the work of researchers such as Sykes, seeking by studying mutations in a particular kind of human DNA to study how long people had lived in a particular place, I wondered whether it wasn't the kind of science that might be misused. I imagined some Dr Strangelove of genetics, striving to prove, scientifically, that his "people" - Serbs? Croatians? Gypsies? - were there millennia before someone else's "people".

When I meet him in the sunny courtyard of Oxford University's institute of molecular medicine, where he is professor of human genetics, the question melts away. Neither of us has come across such a thing. Indeed, on the science level, the opposite seems to be happening. In Europe, the work of Sykes and his colleagues has shown that the concept of separate races collapsed when the DNA evidence was studied. Descendants of the founder mothers are jumbled together higgledy-piggledy, from Siberia to County Cork. Sykes places the home of one of the seven daughters in present-day Syria. Although Sykes maintains that the seven daughters really existed, between 45,000 and 10,000 years ago, in his book he fabricates names and life histories for them, as a way of cutting through the fog of races, populations and peoples. "It was partly as a reaction to the way population genetics has always been done, which is to ignore the effects of individuals, and to just classify the human race into a number of so-called 'populations'," he says. "There isn't any genetic basis for the racial classifications that have existed."

It's reassuring. Then, a few days after our meeting, I discover by chance that Sykes's work is already being misused by racists: not in the Balkans but in Britain. In the wake of the Oldham riots, I browse through the British National Party website, where there is a page of audio and video clips. One of the audio files is a recording of a confrontation on air, in April, between a liberal presenter on a Dundee radio station and Phil Edwards, the BNP press officer.

Countering the presenter's assertion that "being British is a bastardisation", Edwards says: "We are formed from closely related tribes of white European people. It is not colour, it is race, it is genetics. If you take for instance the work of Professor Sykes at Oxford University. He has sampled 6,000 blood samples of people whose maternal grandmothers were born in the UK, right? And he has found that 99% of those people have got the identical DNA to the DNA in the neolithic burial grounds at places all over the UK, people who lived here eight, 10,000 years ago. So don't give me this offensive business about saying we're a bastardised people."

Sykes can't be held responsible for the deliberate distortion of his work. Yet it sharpens the question as to the motives of the people sending in DNA samples for analysis to Sykes's company, Oxford Ancestors - now coming in at the rate of almost 100 a day, many from the US. What are they looking for?

"The quite remarkable thing is that if people find themselves in the same clan as somebody else - and I've observed this - they do feel quite closely connected with them, more than they otherwise would," says Sykes. "It is not going to be because they have the same DNA. I think it is partly because they feel connected back to the same woman, which they are."

Sykes's book portrays a Europe without races. Indeed, at the end, he reveals a bigger picture; each of the seven daughters can trace her ancestry back still farther, to 100,000 years ago, to a single maternal ancestor from Africa. Surely that should allow the racists no foothold? And yet, somehow, it does. The danger is that in setting up the vision of a Europe founded by seven women, whose genes 95% of us carry, Sykes is unintentionally promoting a them-and-us image. You have the Euro-DNA, or you don't. You carry the genetic badge of a vaguely defined and, as it happens, largely white-skinned continent, or you don't.

The particular kind of DNA Sykes works with is a powerful scientific tool. It has proved that Polynesia was colonised from east Asia, not South America. It has proved that all modern human beings are descended from a single, relatively recent ancestor in Africa, that we're not descendants of the Neanderthals and that the influx of migrants from the Near East, bringing agriculture to Europe in Neolithic times, was smaller than used to be thought. It may yet show - this is Sykes's current project - the extent of Anglo-Saxon spread into present-day Britain, and help explain why we now speak English and not some Welsh-Cornish amalgam. But it has its limits, limits that the media - encouraged by Sykes - have been inclined to ignore.

Sykes studies a tiny percentage of human DNA known as mitochondrial DNA, or mDNA, which unlike most of our genes does not get jumbled up between mother and father from generation to generation. MDNA is passed on unchanged from mother to child, time after time, over thousands - in fact, millions - of years. This extraordinary property means that we do, indeed, carry within us a piece of information passed on directly from a maternal ancestor who lived in the world while the Ice Age was at its height.

By comparing mutations in mDNA, which occur spontaneously every 10 millennia or so, it is possible to draw conclusions about the movements of large groups of people over time. It is also possible to identify "clusters" of present-day people with similar sets of mutations, which can be traced back to putative single maternal ancestors in the distant past. That is how Sykes has come up with his seven daughters. He has given them imaginary names and worked out where and when they were likely to have lived.

There is Ursula, from 45,000 years ago, in present-day Greece; Xenia (25,000, the Caucasus); Helena (20,000, the north-east Pyrenean foothills); Tara (17,000, Tuscany); Velda (17,000, the Basque region); Katrine (15,000, northern Italy) and Jasmine (10,000, the Euphrates valley).

And yet how relevant is mDNA to human identity? The truth is, hardly at all. If Oxford Ancestors reports that you belong to the "Helena clan", it means that you probably share with 47% of modern Europeans a single maternal ancestor living 20,000 years ago.

In his book, Sykes recounts the story of the Iceman, the 5,000-year-old corpse found frozen in the Alps in 1991, and how his lab was able to use mDNA analysis to dispel suspicions that the body was actually a South American mummy placed in the mountains as a hoax. In response to journalists' queries, he then went further, providing the media with an Irish management consultant from Dorset, Marie Moseley, who had "exactly the same DNA as the Iceman". In fact, she didn't - she had the same mDNA as the Iceman, along with millions of other people around the world.

So does the science back up the seven daughters theory? Sykes freely concedes that his biographies of the daughters are fantasy. But the latest research may even undermine the central theme of the book. The resonant figure of seven women as the founding mothers of 95% of present-day Europeans stems from research published in a 1996 paper in the American Journal of Human Genetics. A follow-up paper on the same topic, published last year, comes up with the rather less magical figure of 11, representing only 76% of present-day Europeans.

Sykes was one of 37 scientists involved in the research which produced that paper. The leading scientist was Martin Richards, then working alongside him at Oxford, now of Huddersfield University. He is reluctant to comment on Sykes's theory, saying that he hasn't seen the book. But what about the seven daughters? "To say that Europeans had seven maternal ancestors is not very meaningful," he says. "It just depends how far you want to go back in time. The problem with Bryan's seven is that we now know that very few of them would actually have been living in Europe - most of them probably lived in the Middle East.

"What I think is really interesting is which of our ancestors actually migrated into Europe, and when, and how we can use that information to help archaeologists reconstruct the past. We have done quite a lot of work on that now, and we know that there were considerably more than just seven women involved."

• The Seven Daughters of Eve is published by Bantam, priced £18.99
« Last Edit: May 13, 2008, 02:39:29 am by Ian Nottingham » Report Spam   Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by EzPortal
Bookmark this site! | Upgrade This Forum
SMF For Free - Create your own Forum
Powered by SMF | SMF © 2016, Simple Machines
Privacy Policy