A fossilized jawbone discovered in a cave in eastern China bears a curious mix of ancient and modern features, according to a detailed analysis that compares it with dozens of other human specimens. The finding, published in the Journal of Human Evolution, indicates that the 300,000-year-old bone could have belonged to an as-yet undescribed species of archaic human1.
Scientists excavating a cave called Hualongdong, located in Anhui province in eastern China, have unearthed remains of 16 individuals that date to around 300,000 years ago2. Several fragments belong to the skull of a 12-to-13-year-old juvenile.
Xiujie Wu, a palaeoanthropologist at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, and her colleagues first described the skull in 20192. But in 2020, while sifting through trays of animal bones found in the cave, they identified a fragment of a mandible — the lower part of the jaw — that could be another piece of the same skull.
The discovery has enabled a more detailed analysis of where the Hualongdong people fit on the human family tree. The mandible has a mixture of both modern and archaic features. For example, the bone along the jawline is thick, a feature shared with early human species, such as Homo erectus. It also lacks a true chin, the presence of which is a key feature of Homo sapiens. But the side of the mandible that attaches to the upper jaw is thinner than those of archaic hominins and more reminiscent of that of modern humans.
Ancient and modern
The analysis deepens the mystery of which ancient human species inhabited the region during the Middle to Late Pleistocene epoch, a period spanning almost 800,000 years that preceded the end of the last Ice Age, around 12,000 years ago.
A digital comparison of the newly uncovered mandible with 83 other jawbones confirmed a strange mix of ancient and modern anatomical features. Wu and her colleagues used juvenile and adult bones from Neanderthals (Homo neanderthalensis), which lived in Eurasia until 40,000 years ago, H. sapiens from around the world, and H. erectus, a species whose range extended from eastern Africa to the southeast Asian islands of Indonesia between 1.9 million and 250,000 years ago.