New ‘Dragon Man’ Skull Could Represent Humanity’s Closest Ancestor

Scientists have announced that a fossil discovered and hidden away 85 years ago may represent humanity’s closest known relative on our ancestral family tree. The skull, dubbed “Dragon Man” for the Dragon River near where it was discovered, is thought to be more closely related to humans than Neanderthals, who are typically considered our closest known relative.

According to scientists, this skull (shown above) displays a mixture of features common to Neanderthal and Homo sapiens. If I’m being honest, it just looks like a Neanderthal skull to me. The prominent brow ridge is an easy distinction between Neanderthals and ourselves, but I’m not much good at subtle differences in bone morphology.

I had an idea for how to make it easier to see the distinction. Here’s an identical picture of the same skull with a red line drawn down the image. The red line is perfectly straight. It is positioned directly next to the farthest edge of the brow ridge. I’ve combined the image from the new paper with a previous image comparing Homo sapiens (left) and Neanderthals (right) and drawn the same line in the same way down the photos of all three skulls.

The line descending from the brow ridge on the Neanderthal skull crosses the lower jaw with seven pixels of material to the left. The Dragon Man brow ridge line crosses with 10 pixels to the left. Our imaginary brow ridge line splits the human skull with 21 pixels on the right. I don’t know what the actual measurement differences are in millimeters, but we don’t need them to show you the difference. This skull is a midpoint between Neanderthal/Denisovans and ourselves.

Cell writes:

It differs from all the other named Homo species by presenting a combination of features, such as long and low cranial vault, a wide and low face, large and almost square orbits, gently curved but massively developed supraorbital torus, flat and low cheekbones with a shallow canine fossa, and a shallow palate with thick alveolar bone supporting very large molars.

The proposed name for the new species is Homo longi. The skull has a fascinating history. A worker in the city of Harbin found the skull in 1933. It’s thought he recognized he had an important scientific discovery, but the authors of the papers discussing it speculate that he may have been ashamed at working for the Japanese. The man who found the fossil hid it in a well for 85 years before telling his family about it shortly before his death, in 2018.

Pro Tip: If you have a hidden family treasure, do not wait 85 years to tell your family.

In recent decades, we’ve learned more about a race of humans called the Denisovans. We have only a handful of Denisovan bones — Neanderthal remains are much more plentiful — but we’ve learned enough to determine that they contributed to the genome of Micronesia and that their existence overlapped with Neanderthals. We have direct evidence of Neanderthal-Denisovan interbreeding, so we know these two groups of humans had contact with each other.

The researchers argue that Homo longi fits into the Denisovan lineage. The Harbin skull is said to be quite similar to an earlier fossil, Dali Man, as well as to the Jinniushan woman.

If Homo longi is established as being part of Dali Man’s family tree, it would typically lead to the species being named as Homo dali instead of Homo longi. Our efforts to precisely determine the relationships between archaic human fossils is limited by the difficulty of recovering DNA, the paucity of the fossil record, and the fact that ancient groups of Homo interbred multiple times.

In this case, there’s a puzzle to be solved between the genetic relationship between Denisovans and Neanderthals versus Denisovans and humans. This fossil has morphological similarities to our own species, but Denisovans and Neanderthals were more closely related to each other than to us.

One thing we do know is that we don’t yet have the full story of humanity’s emergence as a species. There’s an unknown hominin ancestor who contributed to Denisovan DNA but split off from modern humans over a million years ago. A paper published last year found evidence for a ‘ghost’ hominin contribution — a species we haven’t yet found — in African genomes. Sub-Saharan Africans are also known to have the lowest percentage of Neanderthal DNA, while Europeans have the most. It’s hard to solve a puzzle when you don’t have all the pieces. Discoveries like the Harbin skull should help us see the picture a bit more clearly.

Feature image by Qiang Ji, Wensheng Wu, Yannan Ji, Qiang Li, Xijun Ni.