'Culturally cosmopolitan' Bronze Age mummies found in China have surprising origins
Mummies were found buried in boats, with leather and wool clothing, and even cheese necklaces.
Researchers have sequenced the genome of the mysterious Tarim Basin mummies for the first time, in an effort to understand the origins of these fascinating people.
The Tarim Basin mummies are a collection of hundreds of exceptionally preserved remains, up to 4,000 years old, found buried in the desert in Western China. Scientists had assumed they were migrants to the region because of their cosmopolitan style — they were buried in boats, wearing western-style felted clothing, and holding agricultural products such as wheat and cheese.
"What we ultimately found was something that was very surprising, and I have to say, completely unexpected," said study co-author Christina Warinner. "It's not that frequently where we look at a set of data and think, 'Wow, that was not something I expected at all.'"
The surprise was that despite their cosmopolitan accoutrements, these people were in fact Indigenous to the area but genetically isolated from other neighbouring communities.
The results were published in the journal Nature.
Exceptionally well preserved, down to their DNA
These hundreds of mummified bodies date back from 2,000 BC to 200 AD, and were originally discovered by European explorers in the 1900s. The dry and salty desert led to them being immaculately preserved.
"These people are so well preserved that we can see the tattoos on their faces. We can see the woollen clothing that they're wearing," said Warinner, a professor of anthropology at Harvard University and a group leader at the Max Planck Institute for Evolutionary Anthropology.
The items they were buried with were also well preserved, such as wheat, barley, millet, and even kefir cheese. "One mummy famously had clumps of cheese arranged as a kind of necklace," she said.
That high level of preservation extended to their DNA. Using cutting-edge genetic technology, the team was able to sequence the genomes of 13 individuals who lived between 4,100 and 3,700 years ago. They compared this data to hundreds of both ancient and modern genomes to better understand where this population came from.
"There were three main hypotheses," said Warinner. "They each proposed that it was a group from far to the West —hundreds, if not thousands of kilometres to the West, ultimately, that had migrated either quickly or slowly to the region."
But their results showed no ancestry from any of the western groups that had been proposed. Instead, the findings suggest they were direct descendants of an Ice Age population that was Indigenous to Northern Eurasia 9,000 years ago.
"Like many things in archeology, it solves one mystery but raises so many more," said Warinner.
Culturally cosmopolitan and yet genetically isolated
Warinner said this result is particularly interesting because it contrasted so strikingly with their clear influences from far-flung cultures.
"So while they were very genetically isolated and did not inter-marry with any of the neighbouring groups that completely surrounded them, they borrowed ideas and cultural elements from all of these groups," said Warinner. "They adopted dairying practices and made cheeses. They learned how to farm both wheat from the west and millet from the east…. They seem to have been very culturally cosmopolitan."
This area where the mummies were found is now "one of the harshest places on Earth," said Warinner, however thousands of years ago it would have been a lush river oasis.
Snow melt from mountains to the North would have led to large, vast rivers flowing through the area . However, because of the lack of geographic features constraining these rivers, they were prone to sudden shifts, which could be the reason behind this populations' demise.
"They lived there and thrived when it was this riverine oasis, and when the river moved, they were suddenly stranded in the middle of the desert."
Next Warinner would like to learn more about how communities were interacting along these rivers at the time.
"Genetics can't fully explain that process. That's something really where we have to rely on the archeology to help us understand what happens when people with such different lifestyles meet and interact," she said.
Produced and written by Amanda Buckiewicz.