For decades, scientists believed that the inner ear formation was peculiar to Neanderthals, the closest extinct relatives of humans. But a re-examination of remains of an archaic human skull surprised researchers with inner ear formation, much like that of Neanderthals. The fossilized human skull was found in 1970s during excavations at the Xujiayao site in northern China.

Neanderthals

Arrangement of semicircular canals was long used to identify Neanderthals

With this finding, theories of inter-breeding between archaic humans and Neanderthals have gained more weight. Erik Trinkaus, an anthropology professor at the Washington University in St. Louis, said that it only adds to the confusion of theories that try to explain the human origins, inter-breedings and migration patterns. Later phases of human evolution were like a labyrinth of people in different geographies and biology.

The study will appear in the forthcoming issue of the journal Proceedings of the National Academy of Sciences. Researchers conducted a micro-CT scan of the ancient human skull. Researchers were expecting the scan to show a temporal labyrinth like the one found in modern humans. But what the study revealed was typical to Neanderthals.

The semicircular canals are a fluid-filled sensing system they help people maintain balance. For example, when you are running, or turning the head from one side to another or while bending over. A specific arrangement of these semicircular canals has been used as a marker to differentiate Neanderthals from archaic and modern humans.

A contact between Neanderthals and archaic humans can’t be ruled out

But the latest discovery raises the question whether that specific arrangement of semicircular canals is really unique to Neanderthals. The skull examined in this study, Xujiayao 15, was unearthed along with other human bones and teeth. All these fossils had the characteristics of non-Neanderthal archaic humans. Trinkaus said broader implications of this finding are still unclear.

Neanderthals came into existence about 400,000 years ago, and disappeared from Earth about 30,000 years ago. Presence of a Neanderthal characteristic in a non-Neanderthal sample may be an evidence of contact between Neanderthals in Eurasia and archaic humans in China.