DNA research reveals details about human past from mummies

Since its discovery, the ancestry of hundreds of mummified bodies buried in boats in an inhospitable desert region of northwestern China has confused and divided archaeologists.

Found in Xinjiang’s Tarim Basin, primarily in the 1990s, the mummies’ bodies and clothing are remarkably intact despite being up to 4,000 years old. Naturally preserved by the dry desert air, her facial features and hair color can be seen clearly.

Their Western looks, felted and woven wool garments, and the cheese, wheat, and millet found in their unusual tombs suggested that they were long-distance shepherds from the West Asian steppe or migrant farmers from the mountains and desert oases of Central Asia.

Dry desert air preserved the bodies, with hair and facial features clearly visible / Wenying LJ Xinjiang Institute of Cultural Relics and Archeology

However, a new study by Chinese, European and American researchers that analyzed the DNA of these 13 mummies, sequencing their genomes for the first time, painted a different picture. Their analysis suggested that the remains belonged not to newcomers but to a local group descended from an Asian Ice Age population.

“Mummies have long fascinated scientists and the public since their original discovery. In addition to being remarkably preserved, they were found in a highly unusual context and exhibit many distant cultural elements,” said Christina Warinner, associate professor of anthropology at Harvard University.

“We found strong evidence that they really do represent a highly genetically isolated local population,” added Warinner, who is also head of the microbiome science group at the Max Planck Institute for Evolutionary Anthropology and author of the study published in the journal Nature on Wednesday. ).

“In contrast to their genetic isolation, however, they appear to have openly embraced new ideas and technologies from their herders and farming neighbors, while developing unique cultural elements shared by no other group,” she said.

The researchers analyzed genetic information from the oldest mummies in the Tarim Basin – dating from 3,700 to 4,100 years old – along with sequenced genomes from the remains of five people from the Dzungarian Basin, further north, in the Xinjiang Uyghur Autonomous Region, in China. Dating back between 4,800 and 5,000 years ago, they are the oldest human remains found in the region.

amazing crossroads

Ancient DNA can provide powerful evidence about people’s movements at a time when written records or other clues are scarce, said Vagheesh Narasimhan, an assistant professor at the University of Texas at Austin who has worked on genetic samples from the Central Asian region. He was not involved in the study and called the research “exciting.”

The research found that mummies in the Tarim Basin showed no signs of mixing (a scientific term for having babies) with other groups living at the same time. The mummies were direct descendants of a group that was already widespread during the Ice Age, but had largely disappeared by the end of that age – about 10,000 years ago.

Called the Ancient North Eurasians, remnants of this hunter-gatherer population survive only a fraction in the genomes of today’s populations, with indigenous peoples in Siberia and the Americas having the largest proportions known. It was unexpected to find them in the Tarim Basin and dated from these years.

The other genetic samples from the far north in Xinjiang showed that the people they came from mixed extensively with different Bronze Age populations in the region, making it remarkable that mummies from the Tarim Basin were so genetically isolated.

A DNA analysis of the remains suggests that the mummies were not newcomers to the region and were descended from Ice Age hunter-gatherers / Wenying LJ Xinjiang Institute of Cultural Relics and Archeology

Although remote now, in the Bronze Age “this was a region of incredible crossroads. There was a vibrant mix of North, South, East and West that goes back 5,000 years,” said Michael Frachetti, professor of anthropology at the University of Washington in Saint Louis, who did not participate in the study.

“It makes it all the more paradoxical in a way that you have a strongly integrated community from a cultural perspective, but it still retains some very, very iconic and unique components of its own local ideology, local culture, local funeral traditions, as well as a apparently unmixed genetic profile that goes even further back to primordial ancestry from deep times.”

Narasimhan said it is possible for a population to be genetically isolated, but also culturally cosmopolitan.

“It is not necessary for genetics to always go hand in hand with cultural or linguistic exchange,” he said. “People can always adopt new techniques, whether agricultural or metallurgical from other groups, or change their funeral practices and so on, without population movement or turnover.”

While the DNA study reveals tantalizing details about the mummies, it’s unlikely to be the last word on their origins. The study looks at mummies found at a single site and it’s not clear whether sequencing a broader range of sites in the Tarim Basin could result in the discovery of different genetic ties, Narasimhan said.

Frachetti said ancient genetic samples from this region are still relatively rare, and it’s possible they could find other genetic influences from the Himalayas or Tibet.

Although previous work has shown that mummies lived on the edge of a desert oasis, it is still unclear why they were buried in boats covered in cattle skins with oars on their heads – a rare practice not seen elsewhere in the region and perhaps the best associated with the Vikings.

“They bury their bodies in boats and no one else does. This means that where this tradition comes from remains one of the biggest enigmas of this desert population, who must be the last community in the world to do this,” said Farchetti.

Translated text. Read the original in English.