|Ancient DNA Tells Tales from the Grave|
By Nancy Touchette
July 25, 2003
DNA from a 2,000-year-old burial site in Mongolia has revealed new information about the Xiongnu, a nomadic tribe that once reigned in Central Asia. Researchers in France studied DNA from more than 62 skeletons to reconstruct the history and social organization of a long-forgotten culture.
The researchers found that interbreeding between Europeans and Asians occurred much earlier than previously thought. They also found DNA sequences similar to those in present-day Turks, supporting the idea that some of the Turkish people originated in Mongolia.
The research also provides glimpses into the Xiongnu culture. Elaborate burials were reserved for the elite members of society, who were often buried with sacrificial animals and humans at the time of burial. And relatives were often buried next to each other.
“This is the first time that a complete view of the social organization of an ancient cemetery based on genetic data was obtained,” says Christine Keyser-Tracqui of the Institut de Médecine Légale in Strasbourg, France. “It also helps us understand the history of contacts between the Asiatic and European populations more than 2,000 years ago.”
The necropolis, or burial site, was discovered in 1943 by a joint Mongolian-Russian expedition in a region known as the Egyin Gol Valley of Mongolia. Skeletons in the site were well preserved because of the dry, cold climate. The researchers estimated that the site was used from the 3rd century B.C. to the 2nd century A.D.
The researchers were able to figure out how various skeletons may have been related by analyzing three different types of DNA. They used mitochondrial DNA, which is inherited only from the mother, Y-chromosome DNA, which is passed from father to son, and autosomal DNA (that is, everything but the X and Y chromosomes), which is inherited from both mother and father.
Most scientists had previously thought that people from Asia mixed with Europeans sometime after the 13th century, when Ghengis Khan conquered most of Asia and parts of the Persian Empire. However, Keyser-Tracqui and her coworkers detected DNA sequences from Europeans in the Xiongnu skeletons.
“This suggests that interbreeding between the European and Asian people in this part of the world occurred before the rise of the Xiongnu culture,” says Keyser-Tracqui.
The oldest section of the burial site contained many double graves. This may reflect the ancient practice of sacrificing and burying a concubine of the deceased along with horses and other animals. This practice, reserved for the more privileged members of society, was apparently abandoned—later sections of burial site revealed no double graves.
The most recent sector of the necropolis contained only the remains of related males, a burial grouping that had never been seen before.
Skeletons from the most recent graves also contained DNA sequences similar to those in people from present-day Turkey. This supports other studies indicating that Turkish tribes originated at least in part in Mongolia at the end of the Xiongnu period.
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