The fossil is only about 4.5 centimeters long, a broken piece of the radius near the elbow. But for scientists trying to reconstruct the Denisovans, it fills an enormous anatomical blank.
Until now, researchers had never identified a Denisovan radius — one of the two long bones of the forearm. The ancient humans were discovered through DNA from a pinkie bone, and most of their known anatomy has come from teeth, jaws and, more recently, a skull and two leg bones. The latter were reported just last month and suggest, judging from the leg bones’ size, that Denisovans were extremely tall by ancient standards. One individual may have stood close to 1.9 meters, or 6 feet 3 inches, and weighed about 91 kilograms (around 200 lbs).
Now two studies published in Nature describe the radius alongside skull fragments, teeth, stone tools and tens of thousands of animal bones from Bianfu Cave in Yunnan Province in southwestern China. The forearm bone belonged to an adult or near-adult Denisovan who lived roughly 142,000 to 134,000 years ago. Its unusual combination of Neanderthal-like and modern-human-like features offers the clearest glimpse yet of what a Denisovan arm was built like.
And because bones record how muscles pulled on them and how joints carried loads, there’s a lot of information that scientists can piece together to infer things like Denisovan arm biomechanics.
Building a Denisovan body one bone at a time
Researchers recovered this Denisovan forearm bone alongside fossils and stone tools from Bianfu Cave in China’s Yunnan Province. Credit: Song Xing, Institute of Vertebrate Paleontology and Paleoanthropology.
Denisovans entered science in 2010 in an unusual way. Researchers identified the population from DNA recovered from a single pinky finger rather than from a recognizable skeleton or some morphologically distinct body part. Since then, fossils have appeared across Asia, but the record remains remarkably sparse.
A major breakthrough came in 2025, when proteins and mitochondrial DNA linked the massive Harbin, or “Dragon Man,” skull from northeastern China to Denisovans. The skull showed a broad face, prominent brow ridge and large braincase, finally giving the lineage something approaching a face.
The new radius begins filling in the body below it.
The preserved section includes part of the radial head, where the forearm meets the elbow, and the radial tuberosity, where the biceps tendon attaches. The bone has a relatively large joint surface, more reminiscent of Neanderthals, while its overall external shape and the geometry of its neck align more closely with modern humans.
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Its biceps attachment also appears oriented differently from that of most modern humans, with implications for the now extinct human species’ biomechanics. Moving the attachment farther around the radius can increase the biceps’ leverage during supination, the motion that rotates the forearm so the palm faces upward. For the same muscle size, such a configuration could potentially produce greater rotational force.
That does not mean Denisovans necessarily had exceptionally muscular arms. That may well have been the case, but the fragment cannot inform us about muscle mass or overall strength. Instead, it shows that their limb anatomy followed its own combination of traits rather than simply matching Neanderthals, their closest known evolutionary relatives.
Intriguingly, this is not the first time a Denisovan limb bone has looked surprisingly modern. A 2019 analysis of the Denisovan pinkie bone found that its dimensions fell within modern human variation and differed from Neanderthal fingers. The new radius strengthens the idea that Denisovan postcranial anatomy may have been more human-like in some respects than their close genetic relationship with Neanderthals might suggest.
Proteins identified the owner
The researchers found the radius at Bianfu Cave alongside two pieces of skull and four teeth. The seven fossils may represent at least four individuals, ranging from a child about 5½ years old to adults.
Unfortunately, DNA is not available to clarify things. The cave’s age and relatively warm conditions have destroyed it.
“These conditions were unsuitable for DNA preservation,” geneticist Qiaomei Fu of the Chinese Academy of Sciences told Scientific American.
Instead, the researchers turned to ancient proteins, which can survive much longer than DNA and still preserve clues about a fossil’s species, evolutionary relationships and even, in some cases, biological sex.
Researchers searched more than 60,000 bone fragments for pieces that looked potentially human, narrowed the collection to 22 candidates and then examined preserved proteins with mass spectrometry. Three fragments — the radius and two skull pieces — proved human. Detailed protein analysis linked those bones and two teeth to Denisovans.
All five carried a collagen variant known from other Denisovan fossils, and protein-based evolutionary trees placed them with Denisova 3, the Siberian individual whose genome helped define the lineage. Proteins from two teeth also showed they came from males.
The two skull fragments measure 7.6 and 10 millimeters thick, placing their cranial vault thickness closer to several archaic humans, including Homo heidelbergensis and Middle Pleistocene populations from East Asia, than to a typical modern human skull.
The arm belonged to a hunter
Besides the exceedingly rare Denisovan fossils, the Chinese scientists excavating Bianfu Cave also found numerous artifacts, which were probably made by the elusive lineage.
Archaeologists recovered 1,366 stone artifacts, including flakes, scrapers, notches and choppers. Denisovans apparently favored quick, economical toolmaking, often taking locally available stone, knocking off usable flakes and doing relatively little additional shaping. They also used animal bones as tools.
Animal remains like Deer and wild cattle dominated the assemblage. Cut marks, impact scars and broken bones show that people butchered carcasses in the cave and smashed bones to extract marrow. They most likely deliberately hunted animals rather than scavenging leftovers from other predators.
“We have many sites, but we often don’t know who is the maker of these tools,” archaeologist Hao Li told National Geographic. At Bianfu, fossils and artifacts occur together closely enough to make the Denisovan connection unusually persuasive.
“I am fascinated by the insights into the technology used by Denisovans,” evolutionary geneticist Svante Pääbo, who was not involved in the research, told National Geographic. “It is wonderful that we are finally getting some direct insights into how they lived.”
For a human lineage first discovered as a sequence of DNA letters, Bianfu Cave brings the Denisovans another step closer to becoming people we can actually picture.
Both studies appeared in the journal Nature: one on the ancient proteins preserved in the fossils and another on Denisovan subsistence at Bianfu Cave.
