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Siberian Caves Provide New Insight Into Mysterious Extinct Human Species

New fossils would be especially welcome, as we know almost nothing about the physical appearance of Denisovans, aside from them having rather chunky teeth.

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The entrance to Denisova Cave, which contains evidence of previous habitation by extinct human species, in the Anui River valley in the Altai mountains of Siberia, Russia, is shown in this image released on Jan. 30, 2019. VOA

Scientists using sophisticated techniques to determine the age of bone fragments, teeth and artifacts unearthed in a Siberian cave have provided new insight into a mysterious extinct human species that may have been more advanced than previously known.

Research published Wednesday shed light on the species called Denisovans, known only from scrappy remains from Denisova Cave in the foothills of the Altai Mountains in Russia.

While still enigmatic, they left a genetic mark on our species, Homo sapiens, particularly among indigenous populations in Papua New Guinea and Australia that retain a small but significant percentage of Denisovan DNA, evidence of past interbreeding between the species.

Fossils and DNA traces demonstrated Denisovans were present in the cave from at least 200,000 to 50,000 years ago, and Neanderthals, a closely related extinct human species, were present there between 200,000 and 80,000 years ago, the new research found. Stone tools indicated one or both species may have occupied the cave starting 300,000 years ago.

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Bone points and pierced teeth, sampled for radiocarbon dating from the early Upper Paleolithic layers of Denisova Cave in Siberia, Russia, are shown in this photo provided Jan. 30, 2019. VOA

Scientists last year described a Denisova Cave bone fragment of a girl whose mother was a Neanderthal and father a Denisovan, evidence of interbreeding. The girl, nicknamed “Denny,” lived around 100,000 years ago, the new research showed.

Pendants made of animal teeth and bone points from the cave were determined to be between 43,000 and 49,000 years old. They may have been crafted by Denisovans, suggesting a degree of intellectual sophistication.

“Traditionally these objects are associated in Western Europe with the expansion of our species, and are seen as hallmarks of behavioral modernity, but in this case Denisovans may be their authors,” said archaeological scientist Katerina Douka of the Max Planck Institute for the Science of Human History in Germany.

Our species arose in Africa roughly 300,000 years ago, later spreading worldwide. There is no evidence Homo sapiens had reached Denisova Cave when these objects were made.

Denisovans are known only from three teeth and one finger bone.

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“New fossils would be especially welcome, as we know almost nothing about the physical appearance of Denisovans, aside from them having rather chunky teeth,” said geochronologist Zenobia Jacobs of the University of Wollongong in Australia.

“Their DNA in modern Australian Aboriginal and New Guinean people tantalizingly suggests they may have been quite widespread in Asia, and possibly even southeast Asia, but we need to find some hard evidence of their presence in these regions to flesh out the full story of the Denisovans,” added University of Wollongong geochronologist Richard “Bert” Roberts.

The research was published in the journal Nature. (VOA)

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New Virus Can Spread Through Human Contact: China

China: Possible That New Virus Could Spread Between Humans

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Security guards stand in front of the closed Huanan wholesale seafood market, where health authorities say a man who died from a respiratory illness had purchased goods from, in the city of Wuhan, Hubei province, China. VOA

The possibility that a new virus in central China could spread between humans cannot be ruled out, though the risk of transmission at the moment appears to be low, Chinese officials said Wednesday.

Forty-one people in the city of Wuhan have received a preliminary diagnosis of a novel coronavirus, a family of viruses that can cause both the common cold and more serious diseases. A 61-year-old man with severe underlying conditions died from the coronavirus on Saturday.

While preliminary investigations indicate that most of the patients had worked at or visited a particular seafood wholesale market, one woman may have contracted the virus from her husband, the Wuhan Municipal Health Commission said in a public notice.

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Commuters wear protection masks inside a subway train in Hong Kong, China. VOA

The commission said the husband, who fell ill first, worked at the Huanan Seafood Wholesale Market. Meanwhile, the wife said she hasn’t had any exposure to the market.

It’s possible that the husband brought home food from the market that then infected his wife, Hong Kong health official Chuang Shuk-kwan said at a news briefing. But because the wife did not exhibit symptoms until days after her husband, it’s also possible that he infected her.

Chuang and other Hong Kong health officials spoke to reporters Wednesday following a trip to Wuhan, where mainland Chinese authorities briefed them on the outbreak.

The threat of human-to-human transmission remains low, Chuang said, as hundreds of people, including medical professionals, have been in close contact with infected individuals and have not been infected themselves.

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She echoed Wuhan authorities’ assertion that there remains no definitive evidence of human-to-human transmission.

The outbreak in Wuhan has raised the specter of SARS, or severe acute respiratory syndrome. SARS is a type of coronavirus that first struck southern China in late 2002. It then spread to more than two dozen countries, killing nearly 800 people. (VOA)