Discovery of Neandertal trait in ancient skull raises new questions about human evolution

Jul 07, 2014
The Xujiayao 15 late archaic human temporal bone from northern China, with the extracted temporal labyrinth, is superimposed on a view of the Xujiayao site. Credit: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Science

Re-examination of a circa 100,000-year-old archaic early human skull found 35 years ago in Northern China has revealed the surprising presence of an inner-ear formation long thought to occur only in Neandertals.

"The discovery places into question a whole suite of scenarios of later Pleistocene population dispersals and interconnections based on tracing isolated anatomical or in fragmentary fossils," said study co-author Erik Trinkaus, PhD, a physical anthropology professor at Washington University in St. Louis.

"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."

The study, forthcoming in the Proceedings of the National Academy of Sciences, is based on recent micro-CT scans revealing the interior configuration of a temporal bone in a fossilized human skull found during 1970s excavations at the Xujiayao site in China's Nihewan Basin.

Trinkaus, the Mary Tileston Hemenway Professor in Arts & Sciences, is a leading authority on early human evolution and among the first to offer compelling evidence for interbreeding and gene transfer between Neandertals and modern human ancestors.

His co-authors on this study are 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.

This shows the Xujiayao 15 temporal bone, with the extracted temporal labyrinth and its position in the temporal bone. Credit: Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Science

"We were completely surprised," Trinkaus said. "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."

Often well-preserved in mammal skull fossils, the semicircular canals are remnants of a fluid-filled sensing system that helps humans maintain balance when they change their spatial orientations, such as when running, bending over or turning the head from side-to-side.

Since the mid-1990s, when early CT-scan research confirmed its existence, the presence of a particular arrangement of the in the temporal labyrinth has been considered enough to securely identify fossilized skull fragments as being from a Neandertal. This pattern is present in almost all of the known Neandertal labyrinths. It has been widely used as a marker to set them apart from both earlier and modern humans.

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-Neandertal form of late archaic humans.

Discovery of Neandertal trait in ancient skull raises new questions about human evolution
Schematic of the inner-ear showing temporal labyrinth in yellow. Credit: Wikipedia

Trinkaus, who has studied Neandertal 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.

While it's tempting to use the finding of a Neandertal-shaped labyrinth in an otherwise distinctly "non-Neandertal" sample as evidence of population contact (gene flow) between central and western Eurasian Neandertals and eastern archaic humans in China, Trinkaus and colleagues argue that broader implications of the Xujiayao discovery remain unclear.

"The study of 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.

"Eastern Asia and Western Europe are a long way apart, and these migration patterns took thousands of years to play out," he said. "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."

Explore further: Dizzying heights: Prehistoric farming on the 'roof of the world'

More information: Temporal labyrinths of eastern Eurasian Pleistocene humans, PNAS, www.pnas.org/cgi/doi/10.1073/pnas.1410735111

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User comments : 6

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Torbjorn_Larsson_OM
4.2 / 5 (5) Jul 07, 2014
Trinkaus is odl school paleoanthropologist and a multiregionalist. [ http://en.wikiped...Trinkaus ] Typically old school would take a unique specimen and make a sweeping, extraordinary claim without having the requisite extraordinary evidence.

As here.

""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.""

Said by Trinkaus, apparently without noting the irony.

So, meh.
verkle
1 / 5 (12) Jul 07, 2014
There will continue to be only questions raised and answers not found when scientists continue to pursue just the theory of evolution. Thinking out of the box of evolution is necessary.

Vietvet
4.7 / 5 (12) Jul 07, 2014
There will continue to be only questions raised and answers not found when scientists continue to pursue just the theory of evolution. Thinking out of the box of evolution is necessary.



Didn't think it was possible but you get dumber with every post.
JVK
1 / 5 (11) Jul 07, 2014
"...you can't rely on one anatomical feature or one piece of DNA..."

You can rely on the fact that nutrient-dependent pheromone-controlled amino acid substitutions differentiate cell types and link ecological variation to ecological adaptations without all the pseudoscientific nonsense of evolutionary theories. If cause and effect were not so clearly linked via animal models to humans, theorists might continue to try to make their case.

http://www.ncbi.n...24693353

"... the model represented here is consistent with what is known about the epigenetic effects of ecologically important nutrients and pheromones on the adaptively evolved behavior of species from microbes to man. Minimally, this model can be compared to any other factual representations of epigenesis and epistasis for determination of the best scientific 'fit'."
Captain Stumpy
4.5 / 5 (8) Jul 08, 2014
You can rely on the fact that nutrient-dependent pheromone-controlled amino acid substitutions differentiate cell types and link ecological variation to ecological adaptations without all the pseudoscientific nonsense of evolutionary theories
@jk
not according to YOU! as you've said before
Mutations are pathological; they do not create new species
& according to you
In my model, selection of nutrients and their metabolism to species-specific pheromones enables speciation
as well as when I asked
DOES your model make any changes to the nucleotide sequence of the genome of an organism, virus, or extrachromosomal genetic element?
This is a yes or no answer
THIS is the DEFINITION of MUTATION- to which you answered
YES!
--Thanks for asking
thus, according to the above, your model CANNOT ENABLE SPECIATION NOR CREATE NEW SPECIES because, by your own admission, your model creates mutations, and therefore cannot do what you say it can do

sorry mensa-boy, YOU LIE
cantdrive85
1.3 / 5 (13) Jul 08, 2014
Discovery of Neandertal trait


I knew there was an explanation for Cap'n Stupid...

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