They remain one of the most difficult groups of people to have ever lived on Earth. Evidence from DNA traces left by Denisovans suggests that they lived on the Tibetan plateau, probably traveled to the Philippines and Laos in South Asia, and may have made their way to northern China more than 100,000 years ago. They also interbred with modern humans.
But what the Denisovans looked like or how they lived remained a mystery. Only a jaw fragment, a few bone fragments, and a tooth or two provide any evidence of their physical characteristics.
Their DNA, first found in samples taken from the Denisova cave in Siberia in 2010, provides much of our knowledge about their existence.
But recently, scientists have located a strong candidate for the species to which Denisovans may belong. This homo talli – or “Dragon Man” – from Harbin in northeastern China. This key fossil consists of a nearly complete skull with a skull as large as that of a modern human and a flat face with delicate cheekbones. Dating suggests it is at least 150,000 years old.
“Now the Denisovans homo talli species,” Prof Xijun Ni of the Chinese Academy of Sciences in Beijing said last week. “The latter is characterized by a broad snout, thick brow ridges over its eyes and large tooth sockets.”
Possible Denisovan-homo talli The connection is one of the recent developments of researchers studying these humans with whom they studied. homo sapiens We have shared the planet for hundreds of thousands of years. It is even thought that they may play a key role in our own evolution.
Scientists in Tibet have discovered a Denisovan gene in the local population, the result of the two species interbreeding in the distant past. Most importantly, this gene has been shown to help modern men and women survive at high altitudes.
Also Denisovan-homo talli The connection was also traced to the Tibetan plateau, where scientists began studying the jawbone, which was originally found in a remote cave 3,000 meters (10,000 ft) above sea level by a Buddhist monk who kept it as a relic.
It turned out that the bone did not belong to a modern human. However, it was only when researchers began examining the cave where the jawbone was first discovered that they found that the sediments there were rich in Denisovan DNA. It was also determined that the fossil itself contained proteins that pointed to the origin of Denisovans.
Janet Kelso from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, said, “This is the first time a Denisovan fossil has been found outside Sibera, and this was very important.” “Equally intriguing was that the jawbone had teeth similar to those found in bones. homo talli. “So I think the evidence suggests a connection between the skull and the Denisovans.”
This view was supported by Prof Chris Stringer of the Natural History Museum in London. “Evidence supports the idea that Denisovans were members of a group” homo talli But we still don’t have absolute proof. But I believe this will happen in time.”
A big problem for researchers was that DNA had not yet been found in Chinese fossils. homo talliStringer added. “Their genes did not survive the passage of time. However, the use of proteomics techniques can provide important new data. “These focus on the fossil’s proteins, which survive much longer than its DNA and can tell us much more about the species.”
Recent research also suggests that these humans may have played an important role in the evolution of our own species.
The influence of the Denisovan gene found in Tibetans today provides an example. But Denisovan DNA has also been found in other modern populations, including people in New Guinea, northern Australia and the Philippines, and appears to help them fight infections from diseases such as malaria.
Relating to: Where did they all go? How did Homo sapiens become the last remaining human species?
Stringer said Denisovans settled in areas covering a very variable geography. “Some were hot and low-lying, some were cold and mountainous. They represented a wide variety of habitats, from the Tibetan plateau to islands such as Sulawesi. [in Indonesia].”
In contrast, Neanderthals, the third largest group of humans to have evolved over the last several hundred thousand years, confined themselves to the cooler climates of a region stretching from Europe east to southern Siberia.
They did not expand from this relatively uniform environment. Scientists now ask: Are the richly diverse homelands adopted by Denisovans a sign that they had more diverse and adaptive behaviors than Neanderthals?
homo sapiens it also appears to have mated with Denisovans on more than one occasion. “There is actually good evidence that some modern humans interbred multiple times with genetically distinct Denisovans,” Kelso said. “This suggests that the two groups coexisted for a long time, with some studies suggesting that the last contact occurred as recently as 25,000 years ago.”
Most importantly, by this time Neanderthals were already extinct.
The research conducted by Ni and Stringer also shows that one of the three main groups of humans that evolved at this time, homo sapiens And homo talli The group was probably the last to split off on divergent evolutionary paths, about a million years ago, with Neanderthals branching off even earlier.
However, DNA analysis points to more recent divergence dates. homo sapiens The split first is therefore a very important question for future research, Stringer said.
“How often our paths cross after this crossroads is now a subject of intense scientific interest,” he added. “We have a lot to learn.”