A new study that expands scientific knowledge of the mysterious ancient humans initially discovered in 2010 indicates that Denisovans lived and prospered on the high-altitude Tibetan plateau for over 100,000 years.

Thousands of animal bone fragments that were discovered at Baishiya Karst Cave, 3,280 meters above sea level, close to the Chinese city of Xiahe in Gansu province—one of only three locations where it is known that extinct humans formerly resided—were examined by researchers. According to their research, Denisovans were able to hunt, kill, and prepare a variety of large and small animals, including as birds, woolly rhinoceros, blue sheep, wild yaks, and marmots.

The rib bone fragment, the oldest of the few known Denisovan fossils, was found by the archaeology team at the cave in a layer of sediment that dates back between 48,000 and 32,000 years. This discovery suggests that the species was more recent than previously believed.

The lack of fossil evidence has left us with few details about the lives of these prehistoric human forebears. However, the new research shows that the Denisovans who inhabited Baishiya Karst Cave were extraordinarily hardy, managing to thrive in one of the harshest habitats on Earth during both warmer and colder seasons while making the most of the variety of animal resources found in the grassland area.

“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?” stated Dongju Zhang, a co-lead author of the study that was published in the journal Nature on Wednesday and an archaeologist and professor at Lanzhou University in China.

Zhang continued, “They used all these animals available to them, so that means their behavior is flexible,”

According to research coauthor Frido Welker, an associate professor at the University of Copenhagen’s Biomolecular Paleoanthropology Group at the Globe Institute, the rib belonged to Denisovan, who most likely lived at the period when modern humans were spreading throughout the Eurasian continent. He noted that more studies in the area and at the location might clarify whether or not the two groups interacted there.

He found it fascinating that “it does put this fossil and the (sediment) layer in a context where we know in the wider region humans were likely to be present.”

A Series of Hints from Denisovan

DNA sequences taken from a little piece of finger bone were used in a lab setting to identify Denisovans for the first time a little over ten years ago. Less than a dozen Denisovan fossils have been discovered globally since then.

The majority of them were discovered in Denisova Cave in the Siberian Altai Mountains, which is how the group earned its name. Subsequent genetic studies demonstrated that Denisovans and Neanderthals had interbred with contemporary humans. Denisovan DNA traces discovered in modern humans imply that the extinct species most likely once inhabited most of Asia.

But it wasn’t until 2019 that scientists discovered the first Denisovan fossil outside of the cave with the same name.

At least 160,000 years ago, a monk discovered a jawbone with teeth at Baishiya Karst Cave, a sacred site for Tibetan Buddhists. The jawbone had a Denisovan molecular signature. More proof that Denisovans had formerly lived in the region was provided by the discovery of DNA from silt at the location, which was reported a year later.

Scientists discovered a tooth in a Laos cave that they recognized as belonging to the Denisovan species in 2022. This discovery put the species for the first time in Southeast Asia. Since it was not possible to extract DNA from the tooth, as was the case with the jawbone, scientists looked instead at the minute remains of proteins, which survive better than DNA but are less instructive.

More than 2,500 pieces of animal bone that were found during 2018 and 2019 digs at Baishiya cave were evaluated in the study, which was published on Wednesday.

Given that the majority of the fragments were too minute to identify by eye, the researchers used a relatively new method called Zooarchaeology by Mass Spectrometry (ZooMS), which enables them to glean important information from specimens that may have previously gone unnoticed.

ZooMS assisted the researchers in identifying the type of animal Baishiya’s place in the Denisovan narrative based on subtle variations in the amino acid sequence of collagen preserved inside the bone.

The research identified carnivores such as hyenas in addition to large and small herbivores. In the Himalayas today, certain species are still common, such the blue sheep.

Cut markings on many of the bones indicated that the Denisovans were processing the animals for their hides in addition to their meat and bone marrow. According to the study, some bones were also utilized as instruments.

Overall, the variety of animal species discovered indicates that the region surrounding the cave was primarily covered in grasslands with a few tiny forested patches. This is comparable to the area today, though Zhang pointed out that the majority of the animals residing there now are domesticated goats and yaks.

The five-centimeter-long piece of rib bone was discovered by the scientists during the arduous, multi-month process of classifying the bones. Nevertheless, the protein information’s resolution was insufficiently clear to identify the type of human it had belonged to right away. Welker conducted additional study on the surviving ancient proteins, which identified it as Denisovan.

The scientists had previously collected Denisovan DNA from a layer of sediment from which the rib bone originated, and Zhang stated that they are attempting to recover DNA from the new specimen. The owner of the rib and the larger Denisovan community that formerly inhabited the region may be better understood genetically thanks to that approach.

Because there is so little known about the Denisovans, “each discovery is of major importance,” and the zooarchaeological analysis done by the authors of the new study was “particularly insightful,” according to Samantha Brown, an archaeologist and junior group leader for paleoproteomics at the University of Tübingen in Germany who has worked with Denisova Cave remains.

“The young age of the fossil was definitely surprising. At this time period we have evidence for modern humans occupying sites all the way (to) Australia. This really opens up conversations about the possibility of those groups interacting as modern humans moved into Asia and the Pacific but more evidence will likely be needed to understand the nature of those interactions,” said Brown, who was not involved in the research.

Zhang is excavating a second paleolithic site in the area that may have been inhabited by Denisovans or later modern people, while work at Baishiya Karst Cave is still ongoing, she said.

Current evidence indicates that Denisovans were the only human group to exist at Baishiya Karst Cave, unlike Denisova Cave, which was inhabited by Neanderthals, early modern humans, and Denisovans, according to Zhang. Because of this, the Tibetan plateau, sometimes referred to as “the roof of the world,” is an especially important location in the hunt for the answers to the numerous unanswered questions regarding the identity of the Denisovans, their appearance, their disappearance, and their position on the human family tree. The bones were legitimate.

The role of Baishiya in the Denisovan narrative

The investigation uncovered carnivores like hyenas in addition to big and small herbivores. Even now, the Himalayas remain home to several of the animals, such the blue sheep.

The Denisovans were processing the animals for their hides in addition to their meat and bone marrow, as evidenced by the cut marks on many of the bones. The research also found that certain bones were utilized as instruments.

Although Zhang pointed out that the majority of the animals residing there now are tamed yaks and goats, the diversity of animal species discovered collectively indicates the area surrounding the cave was dominated by a grass landscape with some minor woodland sections — similar to today.

The five-centimeter-long piece of rib bone was discovered by the scientists during the arduous, multi-month process of classifying the bones. Nevertheless, the protein information’s resolution was insufficiently clear to identify the type of human it had belonged to right away. Welker conducted additional study on the surviving ancient proteins, which identified it as Denisovan.

The scientists had previously collected Denisovan DNA from a layer of sediment from which the rib bone originated, and Zhang stated that they are attempting to recover DNA from the new specimen. The owner of the rib and the larger Denisovan community that formerly inhabited the region may be better understood genetically thanks to that approach.

Because there is so little known about the Denisovans, “each discovery is of major importance” and the zooarchaeological analysis carried out by the new study’s authors was “particularly insightful,”  according to Samantha Brown, an archaeologist and junior group leader for paleoproteomics at the University of Tübingen in Germany who has worked with Denisova Cave remains.

“The young age of the fossil was definitely surprising. At this time period we have evidence for modern humans occupying sites all the way (to) Australia. This really opens up conversations about the possibility of those groups interacting as modern humans moved into Asia and the Pacific but more evidence will likely be needed to understand the nature of those interactions,” said Brown, who was not involved in the research.

Zhang is excavating a second paleolithic site in the area that may have been inhabited by Denisovans or later modern people, while work at Baishiya Karst Cave is still ongoing, she said.

Current evidence indicates that Denisovans were the only human group to exist at Baishiya Karst Cave, unlike Denisova Cave, which was inhabited by Neanderthals, early modern humans, and Denisovans, according to Zhang. Because of this, the Tibetan plateau, sometimes referred to as “the roof of the world,” is an especially important location in the hunt for the answers to the numerous unanswered questions regarding the identity of the Denisovans, their appearance, their disappearance, and their position on the human family tree.