1 February 2010
Skeleton of western man found in ancient Mongolian tomb
DNA extracted from a gentleman whose skeleton lay in one of more than 200 tombs recently excavated at a 2,000-year-old cemetery in western Mongolia pegs him as a descendant of Europeans or western Asians. Yet he still assumed a prominent position in ancient Mongolia's Xiongnu Empire, say geneticist Kyung-Yong Kim of Chung-Ang University in Seoul, South Korea, and his colleagues.
On the basis of previous excavations and descriptions in ancient Chinese texts, researchers suspect that the Xiongnu Empire - which ruled a vast territory in and around Mongolia from 209 BCE to 93 CE - included ethnically and linguistically diverse nomadic tribes. The Xiongnu Empire once ruled the major trading route known as the Asian Silk Road, opening it to both Western and Chinese influences. Researchers have yet to pin down the language spoken by Xiongnu rulers and political elites, says archaeologist David Anthony of Hartwick College in Oneonta, N.Y. But the new genetic evidence shows that the 2,000-year-old man "was multi-ethnic, like the Xiongnu polity itself," Anthony remarks.
This long-dead individual possessed a set of genetic mutations on his Y chromosome, which is inherited from paternal ancestors, that commonly appears today among male speakers of Indo-European languages in eastern Europe, central Asia and northern India, Kim's team reports. The same man displayed a pattern of mitochondrial DNA mutations, inherited from maternal ancestors, characteristic of speakers of modern Indo-European languages in central Asia, the researchers say. "We don't know if this 60- to 70-year-old man reached Mongolia on his own or if his family had already lived there for many generations," says study coauthor Charles Brenner, a DNA analyst based in Oakland, Calif. Two other skeletons from the Xiongnu cemetery in Duurlig Nars show genetic links to people who live in northeastern Asia, according to Kim's team.
The Duurlig Nars man's genetic signature supports the idea that Indo-European migrations to northeastern Asia started before 2,000 years ago. This notion is plausible, but not confirmed, says geneticist Peter Underhill of Stanford University. Further investigations of Y chromosome mutation frequencies in modern populations will allow for a more precise tracing of the Duurlig Nars man's geographic roots, Underhill predicts.
Scholars have long sought to trace the origin and spread of related languages now found in Europe, India and other parts of Asia. One hypothesis holds that Indo-European languages proliferated via several waves of expansion and conquest by nomads known as Kurgans who had domesticated horses and thus could travel long distances. In this scenario, Kurgans left a homeland north of the Black Sea, in what's now Russia, around 6,400 years ago.
Another view holds that farmers from ancient Turkey spread Indo-European tongues as they swallowed up one parcel of land after another, beginning around 9,000 years ago. Since 1978, discoveries of 2,400- to 4,000-year-old mummified corpses with European features in northwestern China, not far from Mongolia, have fueled the Kurgan hypothesis. Add to those discoveries a report by geneticist Christine Keyser of the University of Strasbourg in France and her colleagues: they found that nine of 26 skeletons previously excavated at 11 Kurgan sites in northeastern Russia possess a Y chromosome mutation pattern thought to mark the eastward expansion of early Indo-Europeans. That same genetic signature characterizes the Duurlig Nars man.
Kim's group plans to extract and study DNA from additional Duurlig Nars skeletons. For now, Anthony remarks, "this new study from Mongolia is important because it adds one more point of light to a largely dark prehistoric sky."
Source: ScienceNews (29 January 2010)