'Dragon Man,' a mysterious new human species found in China, could be a closer relative of ours than Neanderthals

• Anthropologists found a 146,000-year-old human ancestor called Homo longi, or "Dragon Man," in China.
• These hunter-gatherers were widespread in the region and may have interbred with ancient humans.
• New research suggests Homo longi could be more closely related to modern humans than Neanderthals.

About 146,000 years ago, a hunter died in the forests of what is now northern China. His skull remained almost perfectly preserved in sediment until bridge builders in Harbin found it in 1933.

At that time, Harbin was occupied by Japan, so a Chinese worker hid the skull in an abandoned well, where it remained for 85 years. The worker told his grandson about the hidden bone, now known as the Harbin cranium, and three years ago it finally made its way to anthropologists at the Hebei GEO University.

A trio of papers published Friday reveal that the skull belonged to a previously unknown species of human ancestor, called Homo longi.

"Because the Harbin fossil is so well preserved and informative, it is one of the most important finds so far for the last 500,000 years of human evolution," Chris Stringer, an anthropologist at the Natural History Museum in London who co-authored the studies, told Insider.

Stringer's team nicknamed this new hominin species "Dragon Man," after the province where it was found: Heilongjiang, which translates to "dragon river."

According to the new research, "Dragon Man" could be the closest known relative of modern humans - closer than Neanderthals, the group to which that title previously belonged.

'Dragon Man' might have interbred with ancient humans

According to the new studies, the Harbin cranium came from a 50-year-old male. The analysis also showed that Homo longi had a brain size comparable to that of modern humans, though parts of its skull resemble those of more ancient hominins.

As shown in the video below, Homo longi's skull is massive and has a flatter shape, with square eye sockets, thick eyebrow ridges, and oversized teeth. These are characteristics more typical of Neanderthals, and they suggest that "Dragon Man" was relatively large. From the skull's size, researchers think the species had adapted to survive in harsh environments.

"Like Homo sapiens, they hunted mammals and birds, and gathered fruits and vegetables, and perhaps even caught fish," Xijun Ni, a paleoanthropologist at the Hebei GEO University who co-authored the studies, said in a release.

During the period 146,000 years ago, known as the Middle Pleistocene, various human ancestors crossed back and forth between Africa, Asia, and Europe. Modern humans were already living in western Asia, including the Arabian Peninsula, so in their eastern migration, they could have crossed paths with the "Dragon Man."

"We don't know if this population survived long enough to meet Homo sapiens, but they may well have done. If Neanderthals could interbreed with modern humans, then I'm sure that the Harbin group could too," Stringer said.

Humanity's closest relative?

To determine whether Homo longi was more like Homo sapiens or Neanderthals, the researchers measured more than 600 parts of the Harbin skull, then compared the data to 95 other hominin skulls. A computer analysis revealed that "Dragon Man" was likely closer on the evolutionary tree to modern humans than to Neanderthals - meaning the species shared a more recent common ancestor with us.

"We found our long-lost sister lineage," Ni said.

Stringer thinks that Homo longi - along with other hominin fossils previously found in China that had not been assigned a species - is part of a distinct population of human ancestors that thrived in East Asia during the Middle Pleistocene.

However, Ian Tattersall, an anthropologist with the American Museum of Natural History who was not involved in the research, told Insider that he's unsure Homo longi is really a sister lineage to modern humans. That's because skulls from Homo sapiens have distinct foreheads, and the bones that make up the face are retracted from the forehead, Tattersall said. He thinks "Dragon Man" is missing that characteristic.

"I'd reserve judgement on the claim of a particularly close relationship with Homo sapiens," he said.

Tattersall said he doesn't have a problem with assigning the skull to a new species, though.

'Dragon Man' could be a Denisovan

It's possible, Stringer said, that Homo longi is actually a member of the Denisovan population - a human ancestor that lived in Asia from 500,000 to 30,000 years ago. If that were the case, he added, "then we know that they did interbreed with both Neanderthals and our species, and some of the Harbin group's DNA could still be in some Homo sapiens populations today."

To investigate that possibility, researchers could collect ancient DNA from the skull for further testing.

"But as the extraction process is somewhat destructive, it needs to be considered very carefully for this precious fossil," Stringer said.