15 hours ago
We finally know what an ancient species of human looked like
It's said that were you to meet a suited and well-coiffured male Neanderthal on the train, you'd easily mistake him for a fellow commuter. Face-to-face with Dragon man, however, you'd be forgiven for changing carriages. His head has been described as massive and his teeth enormous, and you could prop a book on his brow ridges. His brain was as big as a modern human's – but a different shape. New research links him to a handful of bone fragments dubbed 'Denisovan', an elusive East Asian being. Dragon man has finally put a face on the last of three human species that co-existed for many thousands of years – the others being Neanderthals, and us.
Dragon man has finally put a face on the last of three human species that co-existed for many thousands of years – the others being Neanderthals, and us
The breakthrough is due to cutting-edge science and two, largely Chinese, teams, analysing DNA and proteins. But like all good fossils, Dragon man has a curious backstory. It begins in 1933, when north-east China was under Japanese occupation. An unnamed labourer, it's said, found a skull when working on a bridge near Harbin City. Perhaps aware of the great interest shown in Peking man, whose fossil remains had only recently been found, he took the traditional Chinese route and hid his treasure down an abandoned well. There it stayed until shortly before his death, when his family learned of it. Word got out, and in 2018 Qiang Ji, professor of palaeontology at Hebei GEO University, persuaded the owners to donate the skull to his institution's geoscience museum.
The skull's secret hiding place might have saved it from disappearing into the black market for fossils and antiquities. Whatever really happened, it was exceptionally well preserved and obviously ancient: but almost nothing else was known about it. The immediate questions were: where was it found, and how old was it? With studies comparing its chemistry to geological layers and to other fossils of known age, scientists were able to confirm that it probably had come from the area of the Harbin bridge, where locals have long collected animal fossils thrown up by underwater sand-mining. Uranium isotope dating pointed to an age of at least 146,000 years – contemporary with Neanderthals.
At the same time, starting in 2010 with no more than a tooth and a finger bone excavated in a Siberian cave called Denisova, scientists had identified a new type of human. Further finds across East Asia have since included pieces of a rib and two jaws, and a few teeth and undistinguishable scraps. When the Harbin skull was announced, some scientists inevitably wondered if it too might be Denisovan, but there was no evidence to back the idea. One of the teams studying it suggested it could be yet another species, which they named Homo longi – after Long Jiang, or Dragon River.
The condition of the Harbin skull is so good, linking it to any known group of early humans would be a great advance. The new studies claim to have proved such a link – with Denisovans. In one study, lead author Qiaomei Fu and colleagues report that they were unable to find any surviving DNA in the skull. They had more luck with calculus (fossil dental plaque) on the skull's one tooth, recovering mitochondrial DNA (mtDNA) from what they say is Dragon man himself. This most closely matches known Denisovan mtDNA.
In the other study, Fu led a different team applying proteomics – analysing ancient proteins, which offer less detail than DNA, but can survive from a greater age. Here again they found a match unique to Denisovans. All three approaches – skull shape, mtDNA and proteins – point to the existence of three human groups existing at this time. The evolutionary relationships between them remains unclear, but they are known to have mated with each other: modern Europeans have a small amount of Neanderthal DNA, and people in South-East Asia, Aboriginal Australia and Pacific islands retain a little DNA from Denisovans.
The quest to understand what these three ancient species looked like and how they behaved – early Homo sapiens, Neanderthals and Denisovans, or what some are now saying we must call Homo longi – is quite literally a journey into our identity. Knowing where the Harbin skull fits in will inspire a rush of new research. Some will dispute the claimed Denisovan matches: they look pretty convincing to me, but it must be admitted that the sciences are entering new ground.
On that count, the apparent success of the proteomics and of extracting relevant mtDNA from calculus will spur others to apply the techniques to already known Asian fossils (including skulls), several of which have been suspected as Denisovan. It should also lead to more excavation, the only route to insights into these humans' lives. Dragon man may look scary, but his face at the top of funding proposals could work wonders.
