An ancient human fossil discovered in China that is unlike any other hominid ever discovered has been detailed by a global team of scientists.
It suggests that our current model of the human family tree requires an additional branch because it does not resemble the lineage that split to create Neanderthals, Denisovans, or us.
2019 saw the discovery of the jaw, cranium, and limb bones of this unclassified human, known as HLD 6, in Hualongdong, East Asia. Since then, scientists at the Chinese Academy of Sciences (CAS) have had difficulty tracing the remains’ pedigree.
The hominin’s face resembles the contemporary human lineage’s facial anatomy, which diverged from Homo erectus as far ago as 750,000 years ago. The person’s lack of a chin, however, more closely resembles that of a Denisovan, an extinct species of prehistoric human in Asia that diverged from Neanderthals more than 400,000 years ago.
Researchers at CAS believe they have discovered an entirely new lineage, a hybrid between the branch that gave rise to modern humans and the branch that gave rise to other ancient hominins in the area, like Denisovans. They are working with researchers from China’s Xi’an Jiaotong University, the UK’s University of York, and Spain’s National Research Center on Human Evolution.
In the past, it has been difficult to classify all of the Pleistocene hominid fossils discovered in China. Because of this, such remains are frequently dismissed as minor variations on the direct path to modern mankind; for instance, as an ancient example of a Homo sapien or an advanced version of Homo erectus.
However, this very straightforward and linear interpretation is debatable and not generally accepted. While Homo erectus did live on in Indonesia for around 100,000 years, the recently discovered bones in East China are more similar to other, more recent lineages of hominid.
The existence of a fourth lineage of hominins during the Middle to Late Pleistocene has already been demonstrated by genomic analyses of Neanderthal bones found in Europe and western Asia.
But the fossil record never formally identifies this missing group.
Perhaps the recently discovered human remains in China are the final puzzle piece.
While the 12- or 13-year-old’s fossilized jaw and skull have current human-like features, the limbs, skull cap, and jaw “seem to reflect more primitive traits,” according to the analysis’s authors.
Their findings make it more difficult to get to current humans. Instead, the mix of physical traits revealed in this prehistoric hominid suggests that three lineages coexisted in Asia: the lineage of Homo erectus, the Denisovan lineage, and this other lineage that is “phylogenetically close” to us.
Although Homo sapiens didn’t first come in China until about 120,000 years ago, it appears that some of our “modern” traits were present here much earlier. The last common ancestor of modern humans and neanderthals may have emerged in southwest Asia before migrating to all continents.
More archaeological study will now be required to verify that notion.
The study was published in the Journal of Human Evolution.
