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Discovery in a cave in Laos could reveal more about the greatest mystery of human evolution

2022-05-18T06:03:20.274Z


An enigmatic tooth unearthed from a remote cave in Laos could belong to the Denisovan group of prehistoric hominins


New similarity between Neanderthals and humans discovered 0:54

(CNN) -

A tooth unearthed from a remote cave in Laos is helping to outline an unknown chapter in human history. Researchers believe the tooth belonged to a young woman who lived at least 130,000 years ago and was likely from the Denisovans. , an enigmatic group of early humans first identified in 2010.

The lower molar is the first fossil evidence placing Denisovans in Southeast Asia and may help unravel a puzzle that has long preoccupied experts on human evolution.

The only definitive Denisovan fossils were found in North Asia, in the Denisovan cave of the same name in the Altai mountains of Siberia, Russia.

Genetic evidence, however, links archaic humans more closely to places much farther south, in what is now the Philippines, Papua New Guinea, and Australia.

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"This shows that Denisovans were probably also present in South Asia. And it supports the results of geneticists who say that modern humans and Denisovans could have been found in Southeast Asia," said study author Clément Zanolli, a researcher in paleoanthropology at the CNRS, the French National Center for Scientific Research and the University of Bordeaux.

Archaeologists discovered the tooth at a location known as Cobra Cave, 260 kilometers (160 miles) north of the Lao capital Vientiane, where they began digging in 2018.

The study, published in the journal Nature Communications on Tuesday, estimated the molar to be between 131,000 and 164,000 years old, based on analysis of cave sediments, dating of three animal bones found in the same layer, and the age of the rock covering the fossil.

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The tooth was unearthed from a cave in Laos and belonged to a woman who lived at least 131,000 years ago.

“Teeth are like the black box of an individual.

They retain a lot of information about their life and biology.

Paleoanthropologists have always used them, you know, to describe species or distinguish between species.

So for us paleoanthropologists (teeth) are very useful fossils," Zanolli said.

Comparison with archaic human teeth

The researchers compared the tooth's cusps and grooves with other fossilized teeth belonging to archaic humans and found that they did not resemble teeth belonging to Homo sapiens or Homo erectus, an archaic human who was the first to walk upright whose remains have been found throughout Asia.

The cave find most closely resembled a tooth found in a Denisovan mandible found on the Tibetan Plateau in Xiahe County, Gansu Province, China.

The authors said it was possible, though less likely, that it could have belonged to a Neanderthal.

"Think of it (the tooth) as traveling through (a) valley between mountains. And the organization of these mountains and valleys is very typical of a species," Zanolli explained.

Analysis of some protein in the enamel of the tooth suggested that it belonged to a woman.

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Denisovan DNA lives on in some humans because, once our Homo sapiens ancestors encountered Denisovans, they had sex with them and gave birth to babies, something geneticists call admixture.

This means that we can look back into human history by analyzing current genetic data.

"Mixing" was thought to have occurred more than 50,000 years ago, when modern humans moved out of Africa and likely encountered Neanderthals and Denisovans.

But pinpointing exactly where it happened has proven difficult, particularly in the case of the Denisovans.

Definitely Denisovan?

Any addition to the scant hominid fossil record from Asia is exciting news, says Katerina Douka, assistant professor of archaeological sciences in the department of evolutionary anthropology at the University of Vienna.

She was not involved in the investigation.

He says he would have liked to see "more and more evidence" that the tooth was definitely Denisovan.

"There are a number of assumptions that the authors accept to confirm that it is a Denisovan fossil," he adds.

"The reality is that we can't know if this single, poorly preserved molar actually belonged to a Denisovan, a hybrid, or even an unknown group of hominins. It could very well be a Denisovan, and I'd love it if it was a Denisovan, because right?" Would that be great? But more reliable evidence is needed."

In considering the Lao tooth to be Denisovan, the researchers in this study relied heavily on a comparison with the Xiahe jaw, Douka said.

However, the jawbone, though many thought to be Denisovan, was not a closed case.

No DNA has been recovered from the fossilized jaw, only evidence of "thin" protein, she added.

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"Anyone working on this hominin group, where many big questions remain, wants to add new points to the map. The difficulty lies in reliably identifying any fossil as a Denisovan," he said.

"However, this lack of robust biomolecular data significantly reduces the impact of this new finding and is a reminder of how difficult it is to work in the tropics."

It's hard to get DNA out of that weather

The study authors said they plan to try to extract ancient DNA from the tooth, which, if possible, would provide a more definitive answer, but the warm weather suggests that might be a long shot.

The research team also plans to continue excavating the site after a pandemic hiatus, hoping for more discoveries of ancient humans who lived in the area.

"In this kind of environment, DNA is not well preserved, but we will do our best," said study co-author Fabrice Demeter, an assistant professor at the Lundbeck Foundation Center for GeoGenetics in Denmark.

ArcheologyToothGeneticsHominids

Source: cnnespanol

All news articles on 2022-05-18

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