The Silk Road has long been known as a trade route that connected different cultures, and one area now known as the Xinjiang Uyghur Autonomous Region was a meeting point for people with varied traditions, languages, and agricultural practices. Hundreds of mummified human remains that date back thousands of years have been discovered in the Tarim Basin, one part of that region, in recent decades. Though these remains are from 2000 BCE to 200 CE, their wool garments and physical appearance seem 'Western' and other artifacts of theirs have indicated they produced wheat, barley, and kefir cheese, and raised sheep, goat and cattle in a barren desert. This evidence has confounded scientists who have wondered about the origins of these Tarim Basin mummies. Were they descendants of migrants from the Black Sea? Or, maybe they had ties to farmers that lived in what is now Iran. But, the answer might be something else entirely.
An international team of researchers has now examined genomic sequences from the DNA of the oldest of the Tarim Basin mummies, from about 2100 to 1700 BCE, as well as DNA from five people who were recovered from a nearby area called Dzungarian Basin, and who date back to about 3000 to 2800 BCE. The researchers were surprised by what they found. The work has been reported in Nature.
The researchers found that these mummified people were not newcomers to the area where they were found. They seem to be the direct descendants of a large population of people that are known as Ancient North Eurasians (ANE) and who mostly disappeared as the last ice age ended. Genetic material from these people still survives in the indigenous people of Siberia and the Americas, whose DNA may have a proportions as high as 40 percent. But the people in Tarim Basin had not mixed with anyone else who has lived during the Holocene. Their ancestry may have undergone a long and extreme bottleneck before they settled in the Tarim Basin.
The individuals from the Dzungarian Basin were descendants of both local populations and Western steppe herders. It's notable that the Tarim Basin people had no evidence of genetic admixture even though the populations around them mixed extensively. The researchers noted that their culture does not seem to have been isolated either; they knew about other groups' cuisines, cultures, and technologies.
“Despite being genetically isolated, the Bronze Age peoples of the Tarim Basin were remarkably culturally cosmopolitan; they built their cuisine around wheat and dairy from the West Asia, millet from East Asia, and medicinal plants like Ephedra from Central Asia,” explained a co-corresponding study author Christina Warinner, a professor of Anthropology at Harvard University and research group leader at the Max Planck Institute for Evolutionary Anthropology.
Sources: Max Planck Institute for Evolutionary Anthropology, Nature