A massive, remarkably complete skull from China may reveal the long-awaited face of a Denisovan.
shijun ne
Written by Ann Gibbons
Nearly 90 years ago, Japanese soldiers occupying northern China forced a Chinese man to help build a bridge over the Songhua River in Harbin. While his companions weren’t searching, he found a treasure: a remarkably complete human skull buried in the riverbank. He wrapped the heavy skull and hid it in a well to prevent the Japanese supervisors from finding it. Today, the skull has finally been removed from its lair and given a new name: Dragon Man, the newest member of the human family, which lived more than 146,000 years ago.
In three papers in a one-year-old magazine Cooperat, paleontologist Qiang Ji of Hebei GEO University and his team Summon new species Mostly. (lang It means dragon in Mandarin.) They also claim that the new species belongs to the sister group of h. healthyand so on and so on Human relatives of Neanderthals. Other researchers question the idea of a new species and the team’s analysis of the human family tree. But they suspect that the large skull has an equally exciting identity: they think so The long-awaited Denisovan skull, an elusive human ancestor from Asia best known for its DNA.
Marta Mirazon Lar, a paleoanthropologist at the University of Cambridge, who was not involved in this work, says she is “skeptical of the statements about the missing lineage of the man’s sister”. But she and others were thrilled with the discovery. “It’s a wonderful skull,” said paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology, “I think it’s the best Denisovan skull ever.”
The amazing skull was revealed by the descendants of the bridge builder, who recovered it from the crater after being told by their grandfather on their deathbed. They donated it to Hebei Jiu University’s Museum of Earth Sciences. But before Ji asked him exactly where he found the fossil, the man died, leaving researchers unsure of the geological context.
Without a geological context, Ji hired several researchers to date the skull. Griffith and Nathan University and chronologist Rainer Groen and colleagues linked strontium isotopes in sediments capped in nasal cavities to a specific layer of sediment around the bridge, which they dated Between 138,000 and 309,000 years ago. Uranium-series bone dating puts the minimum age at 146,000 years.
Next, the researchers tried to identify the skull. The paleoanthropologist Xijun Ni of the Chinese Academy of Sciences and Hebei GEO University, who led the effort, was at first baffled: The massive skull had a brain similar to that of modern humans. But it cannot be a member of h. healthy Because it has larger square eye sockets, thick forehead edges, a wide mouth and a massive molar.
Ni, who is also a paleontologist who studies dinosaur and primate fossils, used computational statistical methods to construct and analyze a data set of more than 600 skull features, such as measurements of their height and eyebrow size, as well as the presence or absence of traits such as wisdom teeth. Compare 55 features of 95 skulls, jaws or other fossilized teeth of the genus turn from all over the world. The computer model sorted the fossils into family trees and found that the tree that best matched the data contained four main groups. The new skull was hatched into a cluster of several skulls from the middle Pleistocene in China, the period from 789,000 to 130,000 years ago when different lineages of humans coexisted.
Within the Chinese group of fossils, the new skull was more closely related to the jawbone than to the Xiahe Cave on the Tibetan Plateau. The proteins in this jawbone As well as ancient DNA in the sediments of the cave, strongly suggests that he was a Denisovan, a relative of Neanderthals who lived in Denisova Cave in Siberia from 280,000 to 55,000 years ago, leaving traces of his DNA in modern humans. To date, the only Denisovan fossils that have been clearly identified are pinkie bones, teeth, and a few skull bones from Denisovan Cave. But the large, “odd” new molar matches Denisova’s molars, says Bence Viola, a paleoanthropologist at the University of Toronto who analyzed them with Hublin.
The authors of the article admit that this discovery could be Denisovans. “I think they’re probably Denisovans,” says Chris Stringer, a paleoanthropologist at the Natural History Museum in London and co-author of two of the papers, directly.
But the team has not yet attempted to extract ancient DNA or proteins from the skull or molars to test the idea. Meanwhile, their analysis showed that the Chinese group of fossils was closer to the oldest h. healthy Ni says that Neanderthals who lived at the same time. “Neanderthals are generally believed to belong to an extinct lineage closer to our own species. However, our discovery indicates that the new lineage we identified includes Mostly is the actual sister group of h. healthy. “
While other researchers have been amazed at the skull’s size and completeness, many are critical of the analysis. “When I saw this analysis, I almost fell off a chair,” Hublin says. They wonder how the skull is so closely related to the Xiahe jawbone that there are no overlapping features to compare as the skull does not have a jawbone. DNA research also shows that modern humans are more closely related to Neanderthals than to Denisovans. If the Xiahe jawbone was indeed Denisovans, then the closest relative of the new skull was probably Neanderthals, not Neanderthals. h. healthy. “It is too early to name a new species, especially a fossil without context, with inconsistencies in the data set,” said Maria Martinon Torres, a paleontologist at CENIEH, the National Center for Research on Human Evolution in Spain.
For now, the paper’s authors say they don’t want to risk destroying teeth or other bones to get their DNA or protein. But other researchers hope the work will be done soon. For example, Viola says he hopes that one day I will be able to “finally look into the eyes of a Denisovan.”
