Originally published 2021-12-08.
In November 2021 a team led by archaeologist Katerina Douka of the University of Vienna announced the oldest Denisovan fossils yet identified: three small bone fragments, about 200,000 years old, from the deepest layers of Denisova Cave in the Altai Mountains of southern Siberia. The study, published in Nature Ecology & Evolution with Samantha Brown as first author, also showed for the first time that the stone tools and butchered animal bones in those layers were left by Denisovans themselves.
Here is how the fragments were found, why they matter, and how our picture of the Denisovans has changed since.
Who were the Denisovans?
Denisovans are an extinct group of archaic humans, close relatives of the Neanderthals. They are named after Denisova Cave, which itself takes its name from Denis, an 18th-century hermit said to have lived there. Scientists first recognised them in 2010, not from a skeleton but from DNA extracted from a child's finger bone, known as Denisova 3, that had been excavated in 2008. Its genetic code did not match either modern humans or Neanderthals.
Genetic studies show that Denisovans and Neanderthals were more closely related to each other than either was to us. Estimates vary, but one places the split between the Denisovan and modern human lines at roughly 800,000 years ago, and the Denisovan–Neanderthal split at roughly 640,000 years ago.
Calling them a "sub-species" or simply our "ancestors" can mislead. They were a sister population that lived alongside early modern humans and Neanderthals, and they did interbreed with both. In 2018 researchers even identified a bone fragment from the cave belonging to a girl whose mother was a Neanderthal and whose father was a Denisovan.
How three tiny bones were found among thousands
Most bones from Denisova Cave are broken into pieces too small to identify by eye. The team screened about 3,800 of these fragments, each 4 cm or smaller, using a technique called ZooMS, or zooarchaeology by mass spectrometry. It reads the collagen protein in bone, which differs slightly between animal groups, so researchers can sort human fragments from bison, horse or deer without destroying much material.
Five fragments matched the human collagen profile. Four of them still held enough ancient DNA to reconstruct their mitochondrial genomes: three were Denisovan, and one was Neanderthal. Douka described the result as a deliberate gamble that paid off: "We specifically targeted these layers where no other human fossils were found before, and our strategy worked." Brown put it more bluntly to the Max Planck Institute: "Finding one new human bone would have been cool, but five? This exceeded my wildest dreams."
What the layers reveal about Denisovan life
Because the new bones came from layers with stone tools and food waste, the researchers could link that debris directly to Denisovans. Before this, it was not certain who had made the oldest artefacts in the cave.
The animal remains show a varied diet built on hunting. Denisovans took bison, roe and red deer, gazelle, saiga antelope and woolly rhinoceros, and they made tools from stone gathered near the Anui River below the cave. The cave sits at the mouth of a valley close to water, a good spot for watching and ambushing game. Neanderthals appear at the site later, around 130,000 to 150,000 years ago, and the two groups seem to have used the cave at different times over a very long period.
Correcting some common claims
"Denisovans lived 200,000 to 400,000 years ago." That range circulated in early coverage, but the fossil evidence points to a much later span. These fragments are the oldest Denisovan fossils known, at about 200,000 years. Other remains from the same cave are much younger, and current estimates place Denisovans in Asia from roughly 200,000 until at least around 50,000 years ago, possibly later.
"Only six Denisovan fossils were known." In 2021 that was roughly right: a handful of teeth and bone pieces from Denisova Cave, plus a jawbone from Baishiya Karst Cave on the Tibetan Plateau. That cave is a Buddhist holy site, and the jaw was reportedly found there by a monk in 1980; a 2019 study dated it to more than 160,000 years ago. Today the list is longer.
"The world was much hotter then, which is why they could live in Siberia." Not quite. Reporting on the study described the climate when these three individuals lived as warm but broadly comparable to today's, with broad-leaved forest and open steppe around the cave. The Altai went through many warm and cold phases over the long period people used the cave, so the evidence points to an adaptable population rather than one that could only survive in a hothouse world.
Denisovan DNA in people today
The Denisovans did not simply vanish. Their genes survive in living populations, especially in Asia and Oceania. People in Melanesia, including Papua New Guinea, as well as Aboriginal Australians and Philippine Negrito groups carry roughly 5% Denisovan DNA. Many Tibetans carry a version of a gene called EPAS1, inherited from Denisovans, that helps them live at high altitude where oxygen is scarce.
That pattern suggests Denisovans once lived over a wide area of mainland and island Asia, meeting and mixing with modern humans as they spread east.
The Denisovans get a face
For years scientists knew Denisovan genes better than their bodies. That has started to change:
- Laos, 2022: a tooth from Tam Ngu Hao 2 cave, likely between about 164,000 and 131,000 years old, was assigned to Denisovans on the basis of its shape.
- Taiwan, 2025: a jawbone dredged from the seabed of the Penghu Channel was identified through ancient proteins as belonging to a male Denisovan.
- China, 2025: the Harbin skull, a nearly complete cranium more than 146,000 years old that had been named Homo longi in 2021, was shown through protein and mitochondrial DNA evidence to be Denisovan. Geneticist Qiaomei Fu summed it up: "After 15 years, we give the Denisovan a face."
The Harbin skull is strikingly complete and massive, with a wide, low face and a prominent brow ridge, giving a first real look at what these people were like. Tiny fragments from Siberia started that journey, and they remain the oldest firm evidence of Denisovans so far.
Sources: Max Planck Institute: Molecular analysis reveals the oldest Denisovan fossils; ScienceAlert; Denisovan; National Geographic, 18 June 2025.
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