How Denisovans Survived and Thrived on the ‘Roof of the World’

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Denisovans survived and thrived on the high Tibetan Plateau for more than 100,000 years, according to a new study that deepens scientific understanding of the mysterious ancient human first identified in 2010.

The researchers analyzed thousands of animal bone fragments discovered in the Baixia Karst Cave, 3,280 meters above sea level near the city of Xiahe in China’s Gansu Province—one of only three known places where extinct humans lived. Their work revealed that Denisovans were capable of hunting, butchering and processing a variety of large and small animals, including woolly rhinoceroses, blue sheep, wild yaks, marmots and birds.

The team of archaeologists working in the cave also discovered a fragment of a rib bone in a layer of sediment dating back between 48,000 and 32,000 years, making it the youngest of a handful of known Denisovan fossils — evidence that the species existed more recently than scientists previously thought.

Because of the scarcity of fossil evidence, details about how ancient human ancestors lived have been scarce. But New study Archaeologists reveal that the Denisovans who lived in the Baishiya Karst Cave had an incredible ability to adapt, surviving in one of the most extreme environments on Earth during warmer and colder periods, and taking advantage of the diverse animal resources available in the grassy landscape.

“We know that Denisovans lived and inhabited the cave and the Tibetan Plateau for a long time, and we really want to know how they lived there? How did they adapt to the environment?” said Dongguo Zhang, an archaeologist and professor at Lanzhou University in China and co-lead author of the study published Wednesday in the journal Nature.

“They used all these animals available to them, which means their behavior is flexible,” Zhang added.

The rib belongs to a Denisovan who likely lived at a time when modern humans were spreading across Eurasia, said study co-author Frido Welker, an associate professor in the Molecular Paleoanthropology Group at the Globe Institute at the University of Copenhagen. Future research at the site and region could shed light on whether the two groups interacted there, he added.

“This puts this fossil and the layer (of sediment) in a context where we know that humans were likely present in the wider region, which is interesting,” he added.

Denisovans were first identified a little over a decade ago in a laboratory using DNA sequences extracted from a small fragment of finger bone. Since then, fewer than a dozen Denisovans have been found. Denisovan fossils They have been found all over the world.

Most of these remains were found in Denisova Cave in the Altai Mountains of Siberia, hence the group’s name. Later genetic analysis revealed that Denisovans, like Neanderthals, had once interbred with modern humans. Traces of Denisovan DNA found in modern humans suggest that this ancient species may have once lived across much of Asia.

However, it It wasn’t until 2019 Researchers say they have identified the first Denisovan fossil outside a cave of the same name.

A jawbone with teeth found by a monk in the Baixia Karst Cave, a sacred site for Tibetan Buddhists, dates back at least 160,000 years and contains the molecular signature of Denisovan man. The discovery of DNA from sediments at the site has led to Published a year laterprovided further evidence that Denisovan humans once lived in this area.

In 2022, scientists identified Age discovered in a cave in Laos As with the jawbone, it was not possible to extract DNA from the tooth, so the researchers instead studied microscopic remains of proteins, which are better preserved than DNA, although less informative.

The study, published Wednesday, examined more than 2,500 animal bones recovered during excavations at Baishia Cave in 2018 and 2019.

Most of the pieces were too small to be identified with the naked eye, so the researchers turned to a relatively new technique known as zooarchaeology by mass spectrometry (ZooMS), which allows scientists to extract valuable information from specimens that might have been overlooked in the past.

Based on small differences in the amino acid sequence of collagen preserved within the bones, ZooMS helped researchers determine what type of animal the bones belonged to.

In addition to large and small herbivores, the analysis revealed carnivores such as hyenas. Some of these animals, such as the blue sheep, are still common in the Himalayas today.

Many of the bones showed cut marks indicating that Denisovans were processing animals for their hides, meat and bone marrow. Some of the bones were also used as tools, according to the study.

Taken together, the diversity of animal species found suggests that the area around the cave was dominated by grassland landscapes with some small forested areas—similar to today, although Zhang noted that most of the animals living there today are domesticated yaks and goats.

During the painstaking process of sorting the bones, which took several months, the team was able to identify the rib bone fragment, which was 5 centimeters long. However, the protein information was not clear enough to immediately identify the species of human it belonged to. Further analysis of the preserved ancient proteins, led by Welker, revealed that it was a Denisovan.

The rib bone came from a layer of sediment from which the team had previously extracted Denisovan DNA, and Zhang said the researchers are trying to recover DNA from the new specimen. That process could provide more detailed genetic information about the rib’s owner and the broader Denisovan population that once lived in the area.

With so little known about Denisovans, “every discovery is of great importance,” and the zooarchaeological analysis conducted by the authors of the new study was “particularly useful,” said archaeologist Samantha Brown, head of the junior group for paleoproteomics at the University of Tübingen in Germany, who worked on the Denisovan cave remains.

“The young age of the fossil is certainly surprising,” said Brown, who was not involved in the research. “In this time period we have evidence that modern humans occupied sites all the way to Australia. This really opens up conversations about the possibility that these groups interacted with modern humans moving into Asia and the Pacific, but more evidence is likely needed to understand the nature of these interactions.”

Work is continuing at the Baixia Karst Cave, she said, and Zhang is excavating another Paleolithic site in an area likely inhabited by Denisovans or modern humans who came after them.

In contrast to Denisova Cave, which was occupied by early modern humans, Neanderthals, and Denisovans, current evidence suggests that Denisovans were the only human group to have lived in the Baixia Karst, Zhang said. That makes the Tibetan Plateau—an area called the “Roof of the world“- a site of particular importance in the quest to answer many remaining questions about who the Denisovans were, what they looked like, how they disappeared and their place in the human family tree.