The greatest mystery of human evolution, which emerged 15 years ago from a 60,000-year-old little finger bone, finally began to unravel in 2025.
Analysis of DNA extracted from the fossil electrified the scientific community in 2010 when it revealed a previously unknown human population that in the distant past met and interbred with our own species, Homo sapiens. This enigmatic group became known as the Denisovans after Denisova Cave in the Altai Mountains of Siberia, where the little finger was found.
Despite intimate knowledge of the genetic makeup of this population, traces of which millions of people carry today, scientists knew nothing about how the Denisovans came about, or where they lived, or why they disappeared. The discovery and the questions it sparked galvanized a generation of geneticists, archaeologists and paleoanthropologists.
Some of that work paid off this year, and scientists finally put a face to the Denisovan name by extracting new clues from another well-known fossil: a prehistoric human skull that didn’t seem to fit any known group. Now, other pieces of the puzzle began to fall into place.
View from Denisova Cave in the Altai Mountains of southern Siberia. – Zoonar GmbH/Alamy Stock Photo
DNA extracted from a little finger bone unearthed in the cave has revealed the first known Denisovan. -Eddie Gerald/Alamy Stock Photo
Enter “Dragon Man”
When the skull came to light in Harbin, northeastern China, in 2018, after being hidden for storage at the bottom of a well for decades, some scientists suspected it might be Denisovan.
DNA sequences from the group were detected in the genomes of present-day Asians but not Europeans, suggesting that this region was where Denisovans predominated.
Based on its distinct shape, the researchers assigned the skull to a new species they named Homo longi, or “Dragon Man.” About a dozen Denisovan fossils that have been identified since 2010 using DNA were too small and fragmentary to warrant an official species name.
Obtaining ancient DNA from the skull, which was estimated to be 146,000 years old, was key to understanding whether there was a link between Dragon Man and the Denisovans. However, it turned out to be complicated.
A team led by Qiaomei Fu, a geneticist and professor at the Institute of Vertebrate Paleontology and Paleoanthropology, part of the Chinese Academy of Sciences in Beijing, tested six bone samples from Dragon Man’s only surviving tooth and from the petrous bone of the skull, a dense piece at the base of the skull that is often a rich source of DNA in fossils. However, the tests did not yield results.
But Fu, who as a young researcher had been part of the team at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, that first discovered the Denisovans, reported in June that her team was able to recover Denisovan genetic material from an unexpected source: the dental calculus of Dragon Man—the grime left on the teeth preserves DNA from the hard mouth over time.
That information was not a slam dunk result. The genetic material the researchers found was mitochondrial DNA, which, unlike nuclear DNA, is inherited only through the maternal line, providing an incomplete picture of an individual’s genomic ancestry. This discovery potentially meant that Dragon Man could have been a mixture of two species, something that is not unprecedented. In 2018, scientists revealed a fossilized bone from Denisova Cave that belonged to a girl with a Neanderthal mother and a Denisovan father.
However, the team also recovered protein fragments from the petrous bone samples, which – although less detailed than the DNA – suggested that the Dragon Man skull belonged to a Denisovan population.
Together, the two lines of evidence “cleared up some of the mystery surrounding this population,” Fu told CNN in June when the research was published. “After 15 years, we know the first Denisovan skull.”
The DNA discovery makes Homo longi likely to become the official name for about a dozen Denisovan fossils, Chris Stringer, a paleoanthropologist and research leader in human evolution at the Natural History Museum in London, said in an email.
Ryan McRae and Briana Pobiner, paleoanthropologists at the Smithsonian’s National Museum of Natural History, agreed, though they said the name Denisovan will likely persist as a popular name, just as most people call Homo neanderthalensis today.
“While more work needs to be done to build the body of evidence and give scientists a more complete view of Denisovan anatomy, habitat and behavior, being able to link complete fossils with molecular evidence is a huge step forward,” McRae and Pobiner wrote in an annual list of the top stories in human evolution.
Additional evidence could be at hand, waiting to be identified, the researchers suggest, and with it 2026 could be set for more groundbreaking revelations.
With molecular evidence now linking the Dragon Man skull to the Denisovans, it is easier for paleoanthropologists to identify other potential Denisovan remains, including these skulls discovered in China. – Guanghui Zhao
A portrait of a Denisovan
A fossil skull, with its telltale bumps and ridges, can reveal a lot about what an individual looked like, according to John Gurche, a paleoartist who creates reconstructions of ancient human ancestors for museums including the Smithsonian and the American Museum of Natural History. He recreated Dragon Man’s face for National Geographic.
Assuming the Dragon Man skull belonged to a typical Denisovan individual, the scientists said the ancient man would have had pronounced brow ridges, large teeth and would not have had our high foreheads. But if she was dressed in modern clothes, this prehistoric relative may not have attracted many eyes on a subway train.
Gurche said he uses the known relationships between soft tissue and bone in humans and monkeys to recreate facial features such as the width of the eyeball, the dimensions of the nasal cartilage and the thickness of the soft tissue in some parts of the face. More challenging were features about which the skull “offers little information,” including the shape of the lips and ears and the placement of the hair.
With molecular evidence now linking Dragon Man to the Denisovans, it will be easier for paleoanthropologists to identify other potential Denisovan remains, including skull fossils from sites in China that have long defied classification.
More revelations may come from another skull fossil discovered in China in 2022 that has not been formally described in the scientific literature. It is the third skull discovered at the site known as Yunxian in China’s Hubei province and is believed to be around 1 million years old. The other two skulls were found in 1990.
A digital reconstruction published in September of the site’s second skull, which was badly crushed, suggested it was an early ancestor of the Dragon Man, meaning the lineage may have originated much earlier than previously thought.
The researchers’ larger analysis, based on the reconstruction and more than 100 other skull fossils, also pushes back the chronology of the appearance of species like our own, Homo sapiens and Homo neanderthalensis, by a significant 400,000 years.
However, the findings have drawn some skepticism. More details about the third Yunxian skull would allow the team to test the accuracy of the reconstruction and its placement in the human family tree.
Scientists used digital techniques to reconstruct a crushed skull. – Jiannan Bai/Xijun Ni
The oldest genome raises new questions
A 200,000-year-old tooth similar in appearance to the molar still attached to the skull of Dragon Man could be set to shake up what is known about Denisovans and the wider human family tree next year and beyond. Researchers found the tooth during an excavation of Denisova Cave in 2020.
Stéphane Peyrégne, a researcher at the Max Planck Institute for Evolutionary Anthropology, and his colleagues have since analyzed the molar and recovered from it the complete genome of a Denisovan—a highly detailed set of genetic information that can reveal genetic diversity and past evolution.
This is only the second time scientists have succeeded in sequencing a “high coverage” genome from a Denisovan fossil – the first was from the finger fossil that revealed the existence of the Denisovans.
The scientists shared the genome analysis in October on what is known as a preprint server, which allows the study’s authors to post early versions of their work online and is being reviewed by other researchers. Peyrégne declined to comment on the paper until it is officially published next year. Stringer described the findings as “very important.”
The genome allows further investigation of Denisova biological traits that may influence human health today. For example, a study published in August suggested that a Denisovan gene variant involved in the production of mucus and saliva may have helped Homo sapiens adapt to new environments.
The new genome is also much older than the first and allows geneticists to probe deeper into Denisovan history and reconstruct the relationships between the various ancient populations.
The genome represents a Denisova man who lived in a small group 200,000 years ago in Denisova Cave. Analysis of the group showed that not only did his ancestors apparently interbreed with early Neanderthals, but the individual also had ancestors from an unknown “super archaic” group for which there is currently no ancient DNA match.
The Smithsonian’s McRae said traces of these “phantom lines” have also been found in the DNA of modern humans, and scientists aren’t sure who they are. They may represent other extinct hominins such as Homo erectus or Homo floresiensis, sometimes known as the “hobbit”.
“Or, they could represent hominins that we really haven’t found in the fossil record. They’re ghosts until we have somewhere to track them,” he said by email.
Discovering the identity of this group will be a new mystery for human evolution experts to ponder in 2026.
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