Fossils of previously unknown human ancestor discovered in China

A team of researchers led by the Chinese Academy of Sciences has recently analyzed the fossilized jawbone, partial skull, and leg bones of a hominin who lived about 300,000 years ago in what is now eastern China. 

The remains, discovered in Hualongdong, China in 2019, belonged to a 12- or 13-year-old individual. 

Previously unknown hominins 

According to the experts, the fossils possess features that do not match those of previously identified ancestors of modern humans (Neanderthals and Denisovans). This suggests that the remains belong to a previously unknown human lineage combining features of both Pleistocene hominins and modern humans. 

By conducting a morphological and geometric assessment of the fossils, the researchers found that the jawbone exhibited unique features, including a triangular lower edge, a unique bend, and no chin. 

Traits of modern humans

Although the hominin resembled modern humans to a certain degree, it seemed to be more closely related to older species from the Middle Pleistocene period (770,000 to 126,000 years ago), particularly Homo Erectus. 

The fact that such a peculiar combination of features has never before been observed in hominins from East Asia provides evidence that traits found in modern humans had already started to emerge as early as 300,000 years ago.

Possible coexistence of three lineages

The analysis of the skull – which a previous research team had found to be the first-ever human skull from Middle Pleistocene discovered in southeastern China – revealed that the facial bones were more similar to those of modern humans than the jawbone was. 

This unique combination of features suggests the possible coexistence of three lineages in Asia during the Middle Pleistocene: Homo Erectus, Denisovan, and a third lineage that seems to be a step closer to Homo sapiens.

Further research is needed 

Further research is needed to clarify how the discovery of this specimen challenges previous understandings of the evolutionary patterns leading to modern humans, as well as the geographic distribution of hominin species across various parts of the globe during the Pleistocene. 

Moreover, by comparing these fossils with other unidentified Pleistocene hominin bones discovered during excavations in other parts of the world, scientists plan to assess whether any of these bones might belong to the newly discovered species, which still awaits its official scientific name.

More about human ancestors

Human ancestors refer to the species in the human lineage that have come before Homo sapiens, the species to which all modern human beings belong. This lineage stretches back millions of years.

One well-known human ancestor is Homo neanderthalensis (Neanderthals), who lived around 400,000 to 40,000 years ago. Another is Homo erectus, which lived from about 1.9 million to 110,000 years ago.

Going further back, the Australopithecines, like Australopithecus afarensis (famously represented by the fossil named “Lucy”), lived between about 4 million and 2 million years ago.

A direct ancestor of Australopithecines was Australopithecus anamensis, a species that lived about 4.2 to 3.9 million years ago.

Australopithecus anamensis is significant because it provides a link between the more ancient Ardipithecus group of hominins from about 4.4 million years ago and the later Australopithecus afarensis. 

There’s some evidence that A. anamensis and A. afarensis might have coexisted for a short period, showcasing the intricate and sometimes overlapping timeline of hominin evolution.

Sahelanthropus tchadensis is an extinct hominid species and is one of the oldest known early human ancestors. The primary specimen, a nearly complete cranium nicknamed “Toumaï” (meaning “hope of life” in the local Goran language), was discovered in 2001 in the Djurab Desert in northern Chad.

The fossils of Sahelanthropus tchadensis are dated to be about 7 million years old, placing them in the Late Miocene epoch.

The study of human evolution is a complex and ever-changing field as new discoveries continue to reshape our understanding of where we come from.

The study is published in the Journal of Human Evolution.

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By Andrei Ionescu, Earth.com Staff Writer

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