Two hominid skulls discovered in China show mixed features of different species

Virtual reconstruction of the two skulls found in China (Image courtesy Xiujie Wu)
Virtual reconstruction of the two skulls found in China (Image courtesy Xiujie Wu)

An article published in the journal “Science” describes the study of two incomplete skulls dated between 105,000 and 125,000 years discovered in the Henan province in eastern China. An international team examined the fragments found describing the mixed characteristics that put together those of various species of hominids. An intriguing hypothesis is that these are the mysterious Denisovans, of which very few bones were found. Unfortunately the attempt to recover DNA fragments failed.

The discovery of the skulls began in December 2007, when the archaeologist Zhan-Yang Li was completing an excavation in the city of Lingjing. By a lucky chance, at the last moment he found stone tools and decided to keep digging for two more days. It was the last morning when his team discovered a skull fragment that convinced the archaeologists to return to the city for six more seasons. The result was the discovery of 45 more fragments that formed the two partial skulls.

The lack of face and jaws don’t allow a comprehensive study but the parts found still made it possible to examine the two skulls and to assess the similarities with the various species of hominids existing at the time the two individuals lived. Both skulls have prominent brow ridges and inner ear bones similar to those of Neanderthals and different than those of Homo sapiens. One skull has a brain volume of about 1,800 cubic centimeters, very large for both Neanderthals and modern humans but with bone  characteristics on the back similar to those of Neanderthals.

The situation is complicated by the presence of other features different from those of European and Middle Eastern Neanderthal. Their brow ridges are thinner and the skull bones are less strong, more like those of the early modern humans and some other Asian fossils. At the same time, their features are too modern for them to be older hominids such as Homo erectus or Homo heidelbergensis.

The paleoanthropologist Xiu-Jie Wu, one of the authors of the research, thinks that this might be an archaic human species previously unknown that survived in the Far East 100,000 years ago. These hominids may have interbred with other species ending up having mixed characteristics. Increasingly in recent paleoanthropological research crossbreedings were detected among various species of hominids so this hypothesis makes sense.

Another intriguing hypothesis is that the two skulls belong to Denisovans, hominids of which so far only very few bones have been found. According to paleoanthropologist Jean-Jacques Hublin the mix of characteristics found in the two skulls matches what we can expect from Denisovans although they were found at 4,000 kilometers from the bones attributed to this species.

The paleogeneticist Qiaomei explained that she attempted to extract DNA from three fragments of the skulls but without success. Genetic techniques have made leaps forward in recent years but recovering DNA fragments from such ancient bones is always a problem and the results are highly dependent on their conservation status. The attempts involve the destruction of tiny pieces of bone so if the first ones fail it’s unlikely that they try again. This will make it difficult to figure out who the people who inhabited those lands over 100,000 years ago were.

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