Researchers Find Ancient Human Skull with Inner Ear Structure Unique to Neanderthals

Researchers have found a unique inner ear formation in a 100,000-year-old human skeleton that was earlier thought to be present only in Neanderthals.

The study, conducted by researchers at the Washington University in St. Louis, was based on CT scans of a fossilized bone found in 1970s. The ancient bone was found at the Xujiayao site in China's Nihewan Basin.

Neanderthals are the ancient cousins of humans that separated from the primate line about 400,000 years ago. The group then moved to Eurasia and completely disappeared from the world about 30,000 years ago.

The discovery of ear structure associated with Neanderthal in ancient human remains might hint at inter-breeding between the two groups. However, researchers maintain that they still don't know about the broader implication of the study results.

For the study, researchers analyzed interior configuration of the temporal bone. They found that the inner-ear structure resembled that of a Neanderthal than ancient humans.

"We were completely surprised," said Erik Trinkaus, PhD, a physical anthropology professor at Washington University in St. Louis. "We fully expected the scan to reveal a temporal labyrinth that looked much like a modern human one, but what we saw was clearly typical of a Neandertal. This discovery places into question whether this arrangement of the semicircular canals is truly unique to the Neandertals."

The semi-circular canals in ears, the researchers explained, are remnants of fluid-filled system that helps humans maintain balance.

The inner-ear structure has been used by other researchers as a marker to identify human remains from Neanderthals and other hominid skeletons.

Xujiayao 15, the skull that was used in the study, was found along with teeth and bones. According to researchers, the bones were thought to have come from early non-Neanderthal form of late archaic humans.

Trinkaus said that the new study adds to the existing research on human evolution and migration patterns.

"The study of human evolution has always been messy, and these findings just make it all the messier," Trinkaus said in a news release. "It shows that human populations in the real world don't act in nice simple patterns.

The study is published in the journal Proceedings of the National Academy of Sciences. Xiu-Jie Wu, Wu Liu and Song Xing of the Institute of Vertebrate Paleontology and Paleoanthropology, Beijing, and Isabelle Crevecoeur of PACEA, Université de Bordeaux are other authors of the study.