100,000-year-old human skull found in China with 'unique' ear provides further evidence that interbreeding wiped out Neanderthals
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Re-examination of a 100,000-year-old human skull found 35 years ago in Northern China suggests they were closer than thought in physiology to Neanderthals.
A study has revealed the surprising presence of an inner-ear formation long thought to occur only in Neanderthals.
And it lends further credence to the theory that Neanderthals were wiped out through interbreeding with other humans.
A skull in China has been found with a trait once thought unique to Neanderthals. The Xujiayao 15 temporal bone is shown here with the extracted temporal labyrinth, an inner-ear formation thought long gone by 100,000 years ago. It is also shown with its position in the temporal bone
HOW NEANDERTHALS WERE WIPED OUT BY INTERBREEDING
They are often depicted as dim-witted evolutionary losers, but Neanderthals were not driven to extinction by their lack of brains, a previous study by the University of Colorado Museum and Leiden University suggests.
Instead, it is more likely that they disappeared 40,000 years ago because of interbreeding and assimilation with our early modern human ancestors, scientists believe.
An analysis of archaeological evidence dating back 200,000 years stripped away some of the myths surrounding Neanderthals and revealed they were more advanced and sophisticated than has widely been thought.
The differences between the two human sub-species are not enough on their own to account for the demise of the Neanderthals, said the US and Dutch researchers.
Interbreeding could be one reason why Neanderthals vanished, according to the scientists. They were not so much driven to extinction as assimilated.
Evidence of the two mixing can be seen in the fossil record. Some human-like characteristics have been found in late Neanderthal fossils, and conversely, Neanderthal features have been seen in early specimens of modern humans in Europe.
Study co-author Erik Trinkaus, PhD, a physical anthropology professor at Washington University in St. Louis, said the discovery 'places into question' how humans from the Pleistocene period (2.6 million to 11,700 years ago) dispersed.
'It suggests, instead, that the later phases of human evolution were more of a labyrinth of biology and peoples than simple lines on maps would suggest,' he said.
The study in the Proceedings of the National Academy of Sciences is based on recent micro-CT scans of a fossilised human skull found during 1970s excavations at the Xujiayao site in China's Nihewan Basin.
'We were completely surprised,' Trinkaus contiued.
'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 Neanderthal.'
Instead the researchers found an arrangement of semicircular canals in the ear that places into question whether this was unique to Neanderthals.
The presence of this particular arrangement of the semicircular canals in the temporal labyrinth had previously been considered enough to securely identify fossilised skull fragments as being from a Neanderthal.
This pattern is present in almost all of the known Neanderthal labyrinths. It has been widely used as a marker to set them apart from both earlier and modern humans.
The discovery the later humans have the same trait, however, could now call into question whether other fossilised remains truly belonged to Neanderthals.
And it also raises more questions about where Neanderthals lived, as previously they were thought to live almost entirely in Europe
This diagram of the inner-ear shows the temporal labyrinth in yellow. The presence of this arrangement of canals had previously been thought enough to confirm a skull as belonging to a Neanderthal, but that now appears to not be the case and suggests they may have interbred with early humans
A previous study by the University of Colorado Museum and Leiden University said it was likely that Neanderthals (stock image shown) disappeared 40,000 years ago because of interbreeding with our early modern human ancestors, based on analysis of archaeological evidence dating back 200,000 years
The skull at the centre of this study, known as Xujiayao 15, was found along with an assortment of other human teeth and bone fragments, all of which seemed to have characteristics typical of an early non-Neanderthal form of late archaic humans.
Trinkaus, who has studied Neanderthal and early human fossils from around the globe, said this discovery only adds to the rich confusion of theories that attempt to explain human origins, migrations patterns and possible interbreedings.
'The study of human evolution has always been messy, and these findings just make it all the messier,' Trinkaus said.
'It shows that human populations in the real world don't act in nice simple patterns.'
Trinkaus also explains how migration patterns between Eastern Asia and Western Europe took thousands of years to play out, further complicating matters.
'This study shows that you can't rely on one anatomical feature or one piece of DNA as the basis for sweeping assumptions about the migrations of hominid species from one place to another,' he concluded.
The discovery of this skull in Asia, rather than Europe, also raises more questions about where Neanderthals lived, as previously they were thought to live almost entirely in Europe. Shown is a map of their distribution in the times they were believed to inhabit Earth
The skull at the center of this study, known as Xujiayao 15, was found along with an assortment of other human teeth and bone fragments, all of which seemed to have characteristics typical of an early non-Neanderthal form of late archaic humans (stock image shown)
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