US NewsNearly 240,000-year-old ancient teeth could reveal previously unknown human ancestor from Southern China
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Scientists are taking a closer look at a set of ancient teeth, first discovered in the 1970s but thought to have originated more than 200,000 years ago, under the suspicion that they could reveal a previously unknown human relative.
The four teeth were first discovered in the Yanhui Cave, located in Southern China's Tongzi county, between 1972 and 1983.
At the time, they were classified as Homo erectus, a primitive human species that could walk upright and dates back 1.8 million years ago.
Now, a team of researchers from the Centro Nacional de Investigacion sobre la Evolucion Humana (CENIEH) believe the teeth could have originated from either Homo erectus or their more advanced counterpart, Neanderthals, or possibly some other mysterious, hybrid group.
Ancient teeth hint at mysterious human relative
The find adds to a growing number of fossils from China that don't fit neatly in the existing human family tree.
To come to this conclusion, the researchers used modern methods like geometric morphometrical analysis, which primarily examines the change of shape, and Micro-Computed Tomography, or x-ray imaging in 3D.
Researchers said the teeth can be dated back to approximately 172,000 to 240,000 years ago.
As part of their analysis, they compared the Tongzi teeth to hominims from the same chronological period - the later part of the Middle Pleistocene epoch - and the surrounding areas of East Asia, according to the study.
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While they looked at many comparative samples, the researchers are unsure just who exactly the teeth belong to.
In an attempt to pinpoint their origin, researchers looked at the structures and patterns of the Tongzi teeth, according to.
They also compared the teeth to modern-day tooth samples from East Asia, as well as other regions including West Asia, Africa and Europe.
It proved to be even more puzzling, when they discovered the dentine, or tissue below the enamel, didn't appear to have the same crinkles found in Homo erectus, National Geographic reported.
Instead, the teeth had more simple features akin to those in Neanderthals, but they still weren't a perfect match.
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One possible theory is that the teeth could originate from the Denisovan ancestry, a mysterious hominim population that split off from the Neanderthals about 400,000 years ago.
The teeth had some similarities to tooth fossils from the Denisovans, but they weren't located in the same place in the mouth, making it hard to reach a definite conclusion.
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'An abundant amount of genetic information has been collected from the Denisovans but there are very few fossil remains,' CENIEH explained.
'Therefore, both their physical appearance and their identification in the fossil record remain a mystery.'
Another possibility could be that the teeth came from a hybrid of two different hominims.
For example, if the Denisovans crossed paths with Homo erectus, they could have interbred to create the group that produced this particular teeth sample, National Geographic noted.
Until they can get their hands on more fossilized evidence, the origination of the teeth remains unclear, however.
'More genetic and fossil discoveries would be necessary to evaluate the taxonomy of the non-erectus populations of the Middle Pleistocene, such as the Tongzi hominids, which could be good candidates for the Denisovan ancestry,' said Maria Martinon-Torres, one of the co-authors of the study.
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