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Denisovans survived and thrived on the high-altitude Tibetan Plateau for more than 100,000 years, according to a new study that deepens scientific understanding of the enigmatic ancient humans first identified in 2010.
Researchers analyzed thousands of animal bone fragments discovered in the Baishiya Karst Cave, 3,280 meters above sea level near the city of Xiahe in China’s Gansu province – one of only three places where the missing people were known to have lived. Their work revealed that the Denisovans could hunt, butcher, and process a variety of large and small animals, including woolly rhinoceros, blue sheep, wild yaks, marmots, and birds.
The team of archaeologists working in the cave also discovered a rib bone fragment in a layer of sediment dating between 48,000 and 32,000 years ago, making it the youngest of the few known Denisovan fossils – a clue that the species was around more recently than scientists used to think.
Due to the lack of fossil evidence, details of how these archaic human ancestors lived have been scarce. But the new study reveals that the Denisovans living in the Baishiya Karst Cave were incredibly resilient, surviving in one of Earth’s most extreme environments during warmer and colder periods and maximizing the diverse animal resources available in the grassland landscape. .
“We know that the Denisovans lived, occupied the cave and this Tibetan plateau for such a long time, we really want to know, how did they live there? How did they adapt to the environment?” said Dongju Zhang, an archaeologist and professor at Lanzhou University in China and co-author of the study published Wednesday in the journal Nature.
“They used all these animals at their disposal, so their behavior is flexible,” Zhang added.
The rib belonged to a Denisovan, which likely lived at a time when modern humans were spreading across the Eurasian continent, said study co-author Frido Welker, an associate professor in the Biomolecular Paleoanthropology Group of the Globe Institute at the University of Copenhagen. He said future research at the site and in the region could shed light on whether the two groups interacted there.
“It puts this fossil and the (sediment) layer in a context where we know that in the wider region people are likely to be present, and that’s interesting,” he said.
Denisovans were first identified just over a decade ago in a laboratory using DNA sequences extracted from a small fragment of finger bone. Since then, less than a dozen Denisovan fossils have been found worldwide.
Most of them were found in Denisova Cave in the Altai Mountains of Siberia, so the group got their name. Genetic analysis then revealed that Denisovans, like Neanderthals, had once interbred with modern humans. Traces of Denisovan DNA found in modern humans suggest that the ancient species once lived in much of Asia.
However, it wasn’t until 2019 that researchers identified the first Denisovan fossil from outside the amer cave.
A toothed jawbone found by a monk in Baishiya Karst Cave, a sacred site for Tibetan Buddhists, dates back at least 160,000 years and contained a Denisovan molecular signature. The discovery of DNA from sediment at the site, published a year later, provided more evidence that the Denisovans had once called the area home.
In 2022, scientists identified a tooth discovered in a cave in Laos as Denisovan, a clue that placed the species in Southeast Asia for the first time. As with jawbone, DNA cannot be extracted from the tooth, so the researchers studied the microscopic remnants of proteins, which preserve better than DNA, though are less informative.
The study published Wednesday examined more than 2,500 animal bone fragments obtained during excavations at Baishiya Cave in 2018 and 2019.
Most of the fragments were too small to be identified by 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 can have been overlooked in the past.
Based on small differences in the amino acid sequence of the collagen preserved within the bone, ZooMS helped researchers determine what type of animal the bones belonged to.
As well as large and small herbivores, the analysis revealed carnivores such as hyenas. Some of the animals, such as the blue sheep, are still common in the Himalayas today.
Many of the bones had cut marks indicating that the Denisovans were processing the animals for their skins as well as their meat and bone marrow. Some bones were also used as tools, according to the study.
Together, the variety of animal species found suggests that the area around the cave was dominated by a grassy landscape with some small patches of forest—similar to today, although Zhang noted that most of the animals living there today are ungulates. and domesticated goats.
During the painstaking process of categorizing the bones, which took several months, the team identified the rib bone fragment, which is 5 centimeters long. However, the resolution of the protein information was not clear enough to immediately determine which type the man belonged to. Further analysis of the preserved ancient proteins led by Welker revealed that it was Denisovan.
The rib bone came from a sediment layer from which the team had previously extracted Denisovan DNA, and Zhang said researchers are trying to recover DNA from the new specimen. This process can provide more detailed genetic information about the rib’s owner and the wider Denisovan population that once lived in the area.
With so little information about the Denisovans, “every discovery is of great importance,” and the zooarchaeological analysis conducted by the authors of the new study was “particularly detailed,” said archaeological scientist Samantha Brown, a leader of the new Paleoproteomics group at the University German of Tübingen. who worked on the remains from Denisova Cave.
“The new age of the fossil was definitely surprising. In this time period we have evidence of modern humans occupying countries as far away as Australia. “This really opens up conversations about the possibility that those groups interacted as modern humans moved into Asia and the Pacific, but more evidence is likely needed to understand the nature of those interactions,” said Brown, who was not involved. in research.
Work continues at Baishiya Karst Cave, and Zhang is excavating another Paleolithic site in the region that the Denisovans or the modern people who came after them may have occupied, she said.
Unlike Denisovan Cave, which was occupied by early modern humans and Neanderthals as well as Denisovans, current evidence suggests that Denisovans were the only group of people living in Baishiya Karst Cave, Zhang said. This makes the Tibetan Plateau – an area nicknamed the “roof of the world” – a particularly significant place in the quest to answer the many remaining questions about who the Denisovans were, what they looked like, how they became extinct and their place in people. family tree.
