Denisovans, an enigmatic group of ancient humans, were initially recognized solely through their DNA, but now they have a distinct appearance.

With molecular data, Qiaomei Fu and her team at the Institute for Vertebrate Paleontology and Paleoanthropology have validated long-held suspicions among researchers.

This aligns with additional evidence that Denisovans were robust and heavyset. “I believe we observe individuals weighing around 100 kg of lean body mass: a truly massive individual,” stated Bens Viola, who was not part of the research team from the University of Toronto, Canada.

Denisovans were first discovered in 2010 in the Denisova Cave in Siberia’s Altai Mountains, where researchers found fragments of an unknown ancient hominin’s finger bone. The preserved DNA concluded that it was neither modern humans (Homo sapiens) nor Neanderthals (Homo neanderthalensis), but rather an entirely new species.

Moreover, genetic findings indicated that Denisovans interbred with contemporary humans. Today, populations in Southeast Asia and Melanesia carry up to 5% of Denisovan DNA, signifying their earlier presence in Asia.

Following these revelations, researchers commenced their quest for Denisovan fossils in both fieldwork and museum collections. Several fossils have since been discovered, with a notable mandible found in the Baishaya Karst Cave on the Tibetan Plateau, confirmed through fossil and DNA protein analysis from surrounding sediments. Recently, a jawbone recovered from the Peng Channel off Taiwan’s coast was also confirmed as Denisovan through preserved proteins.

Nevertheless, there remained frustrating gaps, as all confirmed Denisovan fossils obtained via molecular evidence were small, leading to limited insight. Conversely, more complete fossils from Asia were considered candidate Denisovan remains, yet none yielded molecular evidence.

Fu and her team aimed to extract preserved DNA or proteins from the human skull discovered in Harbin, northeastern China. This skull, kept under wraps for decades, was first described in 2021 and is notably large and robust, characterized by prominent brow ridges and brain size similar to modern humans. It has been dubbed Homo longi—or Dragon Man—by its discoverer.

“My impression is that this specimen is representative of what we would expect Denisovan to be, in both size and context,” Viola remarked.

Fu noted that recovering preserved molecules from the Harbin skull was an arduous task. While her team struggled to obtain DNA from the bones, they successfully retrieved 95 proteins, including three variants unique to Denisovans.

Seeking further evidence, Fu turned to dental calculus, a hardened plaque that forms on teeth, which yielded mitochondrial DNA inherited from its maternal lineage. Although she described the quantity as “small,” it was sufficient to confirm the specimen as Denisovan.

“It’s an astonishing outcome, and the efforts made were commendable,” said Saman Subroun from the National Research Centre in Burgos, Spain. “I believe many researchers tend to overlook dental calculus in genetic studies.”

With the identification of the robust Harbin skull as Denisovan, the long-suspected notion of their substantial size is now validated.

“There was a clue,” Brown noted.

The reason for their size remains unclear. Neanderthals’ robust build is linked to the cold climates of Europe and West Asia where they thrived. While Denisovan sites, including Denisova Cave and the Tibetan Plateau, were also cold, others were tropical. “We need to contemplate the implications of this,” Viola stated.

It’s possible that Denisovans varied over time. The fragments from Denisova Cave suggest two distinct groups existed: one from 217,000 to 106,000 years ago and another from 84,000 to 52,000 years ago. The Harbin skull dates back at least 146,000 years, with Fu discovering that its proteins and mitochondrial DNA align with the older group. Nevertheless, we’ve yet to locate any large Denisovan fossils in contemporary times, leaving their full appearance uncertain.

“Numerous different groups inhabited the landscape independently, often isolated from each other for tens of thousands of years,” Viola remarked. We should not presume they all bore a similar appearance.