125,000 years old refugee camp?

[Hervé]

Early human fossils suggest intermixing (http://www.livescience.com/58087-patchwork-early-human-fossils-discovered.html)

Charles Q. Choi Live Science (http://www.livescience.com/58087-patchwork-early-human-fossils-discovered.html)
Thu, 02 Mar 2017 14:03 UTC


http://www.livescience.com/images/i/000/089/993/original/early-human-skull-1.jpg?interpolation=lanczos-none&downsize=:1400
Two partial skulls (shown here in a digital reconstruction) of an early human were discovered at an archaeological site (shown here) in Xuchang in central China.Credit: Xiu-Jie Wu


Fossils unearthed in China appeared to be strange patchworks of extinct and modern human lineages, with the large brains of modern humans; the low, broad skulls of earlier humans; and the inner ears of Neanderthals, a new study reported.

These new fossils suggest that far-flung groups of ancient humans were more genetically linked across Eurasia than often previously thought, researchers in the new study said.
"I don't like to think of these fossils as those of hybrids," said study co-author Erik Trinkaus, an anthropologist at Washington University in St. Louis.

"Hybridization implies that all of these groups were separate and discrete, only occasionally interacting. What these fossils show is that these groups were basically not separate. The idea that there were separate lineages in different parts of the world is increasingly contradicted by the evidence we are unearthing."
Modern humans first appeared in Africa (http://www.livescience.com/44988-humans-dispersed-earlier-than-thought.html) about 150,000 to 200,000 years ago, and recent archaeological and genetic findings suggest that modern humans first migrated out of Africa (http://www.livescience.com/56188-humans-left-africa-due-to-earth-wobbles.html) starting at least 100,000 years ago.

However, a number of earlier groups of so-called archaic humans left Africa beforehand; for instance, Neanderthals (http://www.livescience.com/28036-neanderthals-facts-about-our-extinct-human-relatives.html) lived in Europe and Asia between about 200,000 and 40,000 years ago.

The fragmentary nature of the human fossil record has made it tricky to determine the biology of the immediate predecessors of modern humans in eastern Eurasia, Trinkaus said. Unearthing details from this region could shed light on an otherwise poorly understood aspect of human evolution (http://www.livescience.com/474-controversy-evolution-works.html), yielding insights into how modern and archaic humans interacted, he added.

In the new study, scientists analyzed fragments of two human skulls that lead study author Zhan-Yang Li, an archaeologist at the Chinese Academy of Sciences in Beijing, unearthed during fieldwork in the city of Xuchang in central China between 2007 and 2014. The fossils are about 105,000 to 125,000 years old, the researchers said.

Back when these ancient humans lived, the site where they were found was a spring-fed lake amid a mosaic of open grasslands and some forests, said study co-author Xiu-Jie Wu, a paleoanthropologist at the Chinese Academy of Sciences. Researchers found fossils of more than 20 other mammal species there, including those of rhinos, deer, horses, gazelles and rodents, and about one-sixth of these bones had cut marks, suggesting that humans preyed on them, Wu told Live Science.

The partial human skulls combined the features seen in different groups of humans across Eurasia. Like early modern humans, these skulls had large brains (http://www.livescience.com/32142-are-big-brains-smarter.html) and modest brow ridges, the researchers said. However, like earlier humans from eastern Eurasia, the skulls had low, broad brain-cases. In addition, the semicircular canals in the skulls' inner ears and the arrangement of the rear portion of the skulls more closely resembled the features of Neanderthals from western Eurasia, the scientists said.

This collection of features in central China suggests that populations of humans across Eurasia were more connected with each other more than previously thought, Trinkaus said.
"We're seeing a general interconnectedness of all these populations across the Old World," Trinkaus told Live Science.

"Features that we might normally think of [as] belonging to one region or another do appear across the whole range of populations, although the frequency at which those features appear may differ across regions."
Fieldwork in this region will hopefully unearth the complete skull (showing the face) and teeth of these ancient humans, "so we can tell what they looked like," Wu told Live Science.

The scientists detailed their findings (http://science.sciencemag.org/cgi/doi/10.1126/science.aal2482) in the March 3 issue of the journal Science.

[Hervé]

Researchers discover ancient skulls that may belong to Deniso­vans (http://www.sciencemag.org/news/2017/03/ancient-skulls-may-belong-elusive-humans-called-denisovans)

Ann Gibbons Science (http://www.sciencemag.org/news/2017/03/ancient-skulls-may-belong-elusive-humans-called-denisovans)
Fri, 03 Mar 2017 18:36 UTC


https://www.sott.net/image/s19/381500/large/online.jpg (https://www.sott.net/image/s19/381500/full/online.jpg)
Fossil fragments (yellow) were put together with their mirror-image pieces (purple) to visualize the skull of an archaic human who lived in eastern China. © Z. Li et al.


Since their discovery in 2010, the ex­tinct ice age humans called Deniso­vans have been known only from bits of DNA, taken from a sliver of bone in the Denisova Cave in Siberia, Russia. Now, two partial skulls from eastern China are emerging as prime candidates for showing what these shadowy people may have looked like.

In a paper published this week in Science, a Chinese-U.S. team presents 105,000- to 125,000-year-old fossils (http://science.sciencemag.org/content/355/6328/969) they call "archaic Homo." They note that the bones could be a new type of human or an eastern variant of Neandertals. But although the team avoids the word, "everyone else would wonder whether these might be Denisovans," which are close cousins to Neandertals, says paleo­anthropologist Chris Stringer of the Natural History Museum in London.

The new skulls "definitely" fit what you'd expect from a Denisovan, adds paleoanthropologist María Martinón-Torres of the University College London—"something with an Asian flavor but closely related to Neandertals." But because the investigators have not extracted DNA from the skulls, "the possibility remains a speculation."

Back in December 2007, archaeologist Zhan-Yang Li of the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing was wrapping up his field sea­son in the town of Lingjing, near the city of Xuchang in the Henan province in China (about 4000 kilometers from the Denisova Cave), when he spotted some beautiful quartz stone tools eroding out of the sedi­ments. He extended the field season for two more days to extract them. On the very last morning, his team discovered a yellow piece of rounded skull cap protruding from the muddy floor of the pit, in the same layer where he had found the tools.

The team went back for another six sea­sons and managed to find 45 more fossils that fit together into two partial crania. The skulls lack faces and jaws. But they include enough undistorted pieces for the team to note a close resemblance to Ne­andertals. One cranium has a huge brain volume of 1800 cubic centimeters—on the upper end for both Neandertals and moderns—plus a Neandertal-like hollow in a bone on the back of its skull. Both cra­nia have prominent brow ridges and inner ear bones that resemble those of Neander­tals but are distinct from our own species, Homo sapiens.

However, the crania also differ from the western Neandertals of Europe and the Middle East. They have thinner brow ridges and less robust skull bones, similar to early modern humans and some other Asian fossils. "They are not Neandertals in the full sense," says co-author Erik Trinkaus, a paleoanthropologist at Washington Univer­sity in St. Louis in Missouri.


https://www.sott.net/image/s19/381502/medium/China_20cave_20map.png (https://www.sott.net/image/s19/381502/full/China_20cave_20map.png)
Two ancient crania were unearthed about 4000 kilometers from Denisova Cave at the site of Lingjing in Henan province in China. © A. Caudra/Science


Nor are the new fossils late-occurring representatives of other archaic humans such as H. erectus or H. heidelbergensis, two species that were ancestral to Nean­dertals and modern humans. The skulls are too lightly built and their brains are too big, according to the paper.

The skulls do share traits with some other fossils in east Asia dating from 600,000 to 100,000 years ago that also defy easy classification, says paleoanthropologist Rick Potts of the Smithsonian Na­tional Museum of Natural History in Washington, D.C. Those features include a broad cranial base where the skull sits atop the spinal column and a low, flat plateau along the top of the skull. The Lingjing crania also resemble another archaic early human skull that dates to 100,000 years ago from Xujiayao in China's Nihewan Ba­sin 850 kilometers to the north, according to co-author Xiu-Jie Wu, a paleoanthropologist at IVPP.

Wu thinks those fossils and the new skulls "are a kind of unknown or new ar­chaic human that survived on in East Asia to 100,000 years ago." Based on similari­ties to some other Asian fossils, she and her colleagues think the new crania repre­sent regional members of a population in eastern Asia who passed local traits down through the generations in what the re­searchers call regional continuity. At the same time, resemblances to both Nean­dertals and modern humans suggest that these archaic Asians mixed at least at low levels with other archaic people.

To other experts, the Denisovans fit that description: They are roughly dated to ap­proximately 100,000 to 50,000 years ago, and their DNA shows that after hundreds of thousands of years of isolation, they mixed both with Neandertals and early modern humans. "This is exactly what the DNA tells us when one tries to make sense of the Denisova discoveries," says paleoanthropologist Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany. "These Chinese fossils are in the right place at the right time, with the right features."

But Wu and Trinkaus say they can't put fossils in a group defined only by DNA. "I have no idea what a Denisovan is," Trinkaus says. "Neither does anybody else. It's a DNA sequence."

The only way to truly identify a Den­isovan is with DNA. IVPP paleogeneticist Qiaomei Fu says she tried to extract DNA from three pieces of the Xuchang fossils but without success.

Regardless of the new skulls' precise identity, "China is rewriting the story of human evolution," Martinón-Torres says. "I find this tremendously exciting!"