An ancient hominin skull discovered in north-east China is offering new information about human evolution and changing our understanding of the origin of our species.
The fossil human cranium, thought to belong to a male about 50 years old, was found in 1933 during the construction of a bridge over the Songhua River, in Harbin City. Now the skull has been reanalysed by a team led by Professor Qiang Ji from the Hebei GEO University, in collaboration with Professor Chris Stringer at the Natural History Museum.
The skull’s exact find spot is unknown, but analysis of sediments trapped inside the skull have confirmed that it came from a rock formation dated to the Middle Pleistocene, 125,000 to 800,000 years ago, while uranium series dating has revealed that fossil itself is at least 146,000 years old. This date makes it contemporary with several other human species that coexisted in Asia, Europe, and Africa more than 100,000 years ago.
The cranium is larger than that of Homo sapiens and all other known species of archaic humans, and has a large brain capacity that is within the range of modern humans. The skull displays a combination of primitive and modern characteristics, including a long and low braincase lacking the globular shape found in H sapiens, and a low face with delicate cheekbones that more closely resembles modern humans. The unique combination of traits has been used to support the argument for recognising the cranium as a new species of Homo.
A key part of the research involved phylogenetic analyses, which use mathematical techniques to explore the relationships between different species or organisms. This analysis suggests that the cranium and several other Middle Pleistocene human fossils from China represent a new sister group for H sapiens that is closer to modern humans than Neanderthals (Homo neanderthalensis), who were previously believed to be our closest relatives. On this basis, some of the researchers have suggested that the skull represents a new species of the Homo genus and have called it Homo longi (‘Dragon Man’), after the name often given to Heilongjiang province where it was found: ‘Long Jiang’, meaning ‘dragon river’.
The family tree of human lineages created by the team predicts that the common ancestor of Homo longi and Homo sapiens lived c.950,000 years ago, and that both species had a common ancestor with Neanderthals over 1 million years ago. This would mean that H sapiens split from Neanderthals around 400,000 years earlier than previously thought. However, there is still a question mark hanging over these predicted dates, as they are currently not supported by predictions based on DNA analysis.
It is also unclear whether the Harbin skull does belong to a new species, as Professor Chris Stringer has pointed out similarities to another fossil skull found at Dali, also in China, in 1978. He said, ‘While I agree that the Harbin group warrants a distinct species name, I would prefer to place the Harbin and Dali fossils together as H daliensis’. Despite these differences of opinion, Stringer describes the fossil as ‘a remarkable new piece in the jigsaw of human evolution’.
The research has recently been published in three papers in the journal The Innovation.