WASHINGTON (AP) â€” Four out of five of the men in Europe shared a common male ancestor that lived as a primitive hunter on a wild continent some 40,000 years ago, researchers say.
In a study appearing Friday in the journal Science, researchers say that an analysis of a pattern found in the Y chromosome taken from 1,007 men from 25 places in Europe shows that about 80 percent of Europeans arose from the Paleolithic people who first migrated to Europe.
Peter A. Underhill, a senior researcher at the Stanford Genome Technology Center in Palo Alto, Calif., and co-author of the study, said the research supports conclusions from archaeological, linguistic and other DNA evidence about the settlement of Europe by ancient peoples.
``When we can get different lines of evidence that tell the same story, then we feel we are telling the true history of the species,'' said Underhill.
Underhill said the researchers used the Y chromosome in the study because its rare changes establish a pattern that can be traced back hundreds of generations, thus helping to plot the movement of ancient humans.
The Y chromosome is inherited only by sons from their fathers. When sperm carrying the Y chromosome fertilizes an egg it directs the resulting baby to be a male. An X chromosome from the father allows a fertilized egg to be female.
The Y chromosome has about 60 million DNA base pairs. Changes in those base pairs happen infrequently, said Underhill, but they occur often enough to establish patterns that can be used to trace the ancestry of people.
He said researchers looking at the 1,007 chromosome samples from Europe identified 22 specific markers that formed a specific pattern. Underhill said the researchers found that about 80 percent of all European males shared a single pattern, suggesting they had a common ancestor thousands of generations ago.
The basic pattern had some changes that apparently developed among people who once shared a common ancestor and then were isolated for many generations, Underhill said.
This scenario, he said, supports other studies about the Paleolithic European groups. Those studies suggest that a primitive, stone-age human came to Europe, probably from Central Asia and the Middle East, in two waves of migration beginning about 40,000 years ago. Their numbers were small and they lived by hunting animals and gathering plant food. They used crudely sharpened stones and fire.
About 24,000 years ago, the last ice age began, with mountain-sized glaciers moving across most of Europe. Underhill said the Paleolithic Europeans retreated before the ice, finding refuge for hundreds of generations in three areas: what is now Spain, the Balkans and the Ukraine.
When the glaciers melted, about 16,000 years ago, the Paleolithic tribes resettled the rest of Europe. Y chromosome mutations occurred among people in each of the ice age refuges, said Underhill. He said the research shows a pattern that developed in Spain is now most common in northwest Europe, while the Ukraine pattern is mostly in Eastern Europe and the Balkan pattern is most common in Central Europe.
About 8,000 years ago, said Underhill, a more advanced people, the Neolithic, migrated to Europe from the Middle East, bringing with them a new Y chromosome pattern and a new way of life: agriculture. About 20 percent of Europeans now have the Y chromosome pattern from this migration, he said.
On the Net:
Science magazine: http://www.eurekalert.org
Paleolithic art: http://www.paleolithic.com/index.html