Tuesday , March 2 2021

New dates were reduced when Denisovans and Neandertals crossed paths



The mysterious ancient hominids known as Denisovans and their evolutionary cousins, the Neanderthals, frequented a southern Siberian cave starting off surprisingly long, there were two new studies.

Tests for visits to these cave populations in Denisova, which began about 200,000 years ago for Neanderthals and possibly 300,000 years ago by Denisovans, appear on January 31 Nature.

It was known that the members of the two extinct hominid species had occupied the cave of Siberia at some points during the Stone Age. But the new evidence offers the best aspect until the time Denisovans and Neandertals reached the site, and how the two hominid species could have interacted, including interbreeding.

In a new study, a team led by geoarchaologist Zenobia Jacobs found that Denisovans occupied the cave of Siberia for only 55,000 years ago, while a second investigation, led by archaeologist Katerina Douka, placed the # 39; Denisovan's last stand at the site at approximately the same stage. As for the Neanderthals, the last inhabitants of the cave of Denisova approximately 97,000 years ago, estimates of the Jacobs group.

"Now it seems that the Denisovans can be located on the site for about 300,000 years ago up to about 50,000 years ago, with Neanderthals there for intermediate periods," says Chris Stringer, paleoanthropologist, of the Natural History Museum in London, who did not participated research But it is still uncertain whether hominid fossils in the cave are derived from individuals who died during periodic occupations or whose remains were transported to the site, for example, by carnivores, he says.

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Suggestions from other researchers that the Denisovans survived in South Siberia until maybe 30,000 years ago could not be verified in new studies.

Jacobs, from the University of Wollongong in Australia, and colleagues generated dates for 103 samples of sediment from the cave of Denisova that has given stone tools and hominid fossils. Early estimates were based on calculations of when the sediment had been exposed recently to sunlight. The oldest Denisovan fossil, a molar tooth, came from sediments dated 300,000 years ago. But this fossil may have been deposited initially in sediments above where it was finally found, causing the tooth considerably less than 300,000 years old, says the Jacobs team.

Douka, from the Max Planck Institute for the Science of Human History in Jena, Germany, and colleagues estimated ages for four Denisovans, three Neanderthals and three other hominids whose fragmentary remains are They found the Denisova Cave. The team incorporated age estimates for fossils and new and previously collected sediments, information on original fossil positions when excavated and comparisons of mitochondrial DNA extracted from fossils.

So far, the ages of Neanderthal fossils in northeastern Asia have been scarce and suggestive of a relatively late presence of the Stone Age. "We did not wait [Denisova Cave] Neanderthals go back about 120,000 years ago, but the sediment that contains the Neanderthal DNA dates back to 200,000 years, "says Douka. This genetic evidence goes a bit closer to the estimates of when Neanderthals go First arrived in the cave of Siberia based only on fossils. The relatively warm temperatures apparently encouraged the Neanderthals to walk north to the cave of Denisova, researchers say.

Scientists knew that the arrival of the Neanderthals in the cave led to the intertwining with Denisovans. In August 2018, the researchers reported that a girl represented by DNA removed from a snippet dug into the cave of Siberia had a Denisovan father and a Neanderthal mother, the only hybrid of the first generation of its type never found (SN: 15/09/18, p. 9).

The Douka team estimates that the hybrid girl lived between 79,300 and 118,100 years ago, before a previous estimate and alignment with the ages of the other Neanderthal fossils in the cave. Appointment estimates are not accurate enough to determine whether Denisovans and Neanderthals occupied the cave at the same time. But the family of the girl should have lived near the cave, if not, while Denisovans was there, the suspects of Douka.

His team also estimates that the animal teeth pendants and bones that were previously unearthed in the Denisova cave are from 43,000 to 49,000 years ago. Although these artefacts have traditionally been linked to the Stone Age Homo sapiensRussian archaeologists from the Douka team consider the Denisovans as the potential creators of these findings. The investigations of Denisova Cave, which began 40 years ago, have not yielded H. Sapiens fossils or DNA.

H. Sapiens He lived in other parts of Siberia about 45,000 years ago, but (SN: August 29, 14, p. 8). Since Denisovans did not do more than 52,000 years in the new studies, "my money would be in the first modern humans," as Stringer claims, the creators of the slopes and points of Denisova Cave.

But it would not be surprising if they were Denisovans and H. Sapiens These devices were formed, writes archaeologist Robin Dennell of the University of Sheffield in England in a comment published in the same issue of Nature. Interbrebre between H. SapiensNeanderthals and Denisovans could have been more common than scientists. In addition to previous tests of crossbreeding between Neanderthals and Denisovans in the cave, Neandertals and H. Sapiens It is known that they have intervened in the rest of Eurasia.


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