An ancient skull unlike any human ever seen is baffling scientists and could rewrite the story of our evolution

• An ancient skull found in China is like nothing scientists have ever seen. 
• The teen's head shape doesn't fit with any of the early human relatives seen to date. 
• If it is an undiscovered human ancestor, it could rewrite the story of human evolution.

An ancient skull is baffling scientists because it looks unlike any known human ancestor.

The mystery 300,000-year-old skull of a child aged between 12 and 13 years old was first uncovered in Hualongdong in East China in 2019, alongside a leg bone.

Researchers think the individual, known only as HDL 6, is a mix between modern humans and an unknown hominin that existed in China at that time, Science Alert reported Monday.

The skull has facial features that are similar to early modern humans, which scientists think began to branch away from another human ancestor known as Homo erectus between 750,000 to 550,000 years ago.

But its limbs, skull cap, and recessed chin "seem to reflect more primitive traits," Xiujie Wu, a paleontologist from the Chinese Academy of Sciences and co-authors wrote in an analysis of the bones published July 31. 

These features are closer to a Denisovan's facial structure, a now-extinct branch of East Asian hominins that split from Neanderthals about 400,000 years ago.

This strange skull shape has "never been recorded in late Middle Pleistocene hominin fossil assemblages in East Asia," scientists said in a recent analysis. 

It is possible that the finding could rewrite what we know of human lineages in the area. It suggests Denisovan, Homo erectus, and this new lineage which is "phylogenetically close" to us may have co-existed in East Asia, per Science Alert. 

Human history is messier than we thought

This isn't the first time human remains have shaken up the neat evolutionary path that is thought to have led to humans.

Many of us have been taught that Homo sapiens emerged from Homo erectus in Sub-Saharan Africa about 200,000 years ago.

But the reality seems to be a lot more messy. Archaic Homo sapien fossils often carry a mixture of old facial structures and modern features so that timeline can be a bit more blurry than school books would have us think.

That's the case, for instance, of remains found in Morocco in 2017 dated about 300,000 years ago with Homo sapiens-like features, suggesting humans may have emerged much earlier than previously thought.

Findings of archaic human remains in Israel and Greece over the past few years dating back about 200,000 years also suggested human ancestors may have left Africa a lot earlier than previously thought. 

There's also paleontological and genetic evidence that suggests ancient humans interbred with their cousins the Neanderthals and Denisovans, further complicating the bloodlines.

If proven correct, the East Asia findings could add another branch of "presapiens specimen," bringing more insight into the human tree of life.