An international team of researchers has discovered an early human skull that is unlike any other in the fossil record. Their analysis suggests that this skull may represent a new branch in the evolutionary tree.
The skull, which includes a nearly complete jaw and partial cranium, was found in Hualongdong, a region near the Yangtze River in east China. It is estimated to be 300,000 years old, which coincidentally is the same age as the oldest-known skull of a modern human.
However, this skull does not belong to the modern human species. It shares some similarities with modern humans, such as a flat face, but it lacks a “true chin,” leading researchers to believe it may belong to an earlier human species like homo erectus.
The scientists note that while the face of the skull resembles modern humans, the jaw and top of the head exhibit more primitive traits.
Further analysis revealed that the skull displays a combination of features found in homo sapiens, homo erectus, and the Denisovans. The Denisovans are an early human species closely related to Neanderthals.
After attempting to classify the bones under one of these known species, the researchers are now considering the possibility that the Hualongdong skull may represent a new species of early human, filling a missing link in the evolutionary chain.
The study, published in the Journal of Human Evolution last week, highlights the discovery of other enigmatic early human fossils in China in recent years.
These fossils are often considered transitional forms on the evolutionary path to known species. However, the increasing number of these mysterious bones is challenging the idea that our understanding of human evolution is complete.
For instance, a skull found in Harbin, northern China, is believed to represent a new species of human, although not all scientists agree on its classification.
Comparisons between the Harbin skull, the Dali Man, and the Hualongdong skull led researchers to suggest that these fossils could potentially form a new sister lineage to homo sapiens.
In addition to fossil comparisons, genetic testing has also supported this theory. A 2014 study sequencing the genome of a Neanderthal woman found the presence of genes from various early human species, including an unknown ancestor.
A possible model of gene flow in early humans.
Nature
Since the Hualongdong skull is believed to be from a 12 to 13-year-old individual, its unique features were initially attributed to its young age