Neanderthals and Denis could live tens of thousands of years apart, scientists report in two papers Nature1,2.
Long-awaited studies are based on the analysis of bones, artifacts and sediments from the Denis cave in southern Siberia, which is littered with old human remains. They provide the first detailed history of 300,000 years of occupation of various groups of ancient people.
"Now we can tell the entire story of the whole cave, not just pieces," says Zenobia Jacobs, a geochronologist at the University of Wollongong, Australia, who led one of the studies.
Ancient human hotspot
Soviet archaeologists began to uncover the story of Denis Cave at the foot of Mount Altai in the early 1980s. Since then, scientists have found fragmentary remains of nearly a dozen old people in place. The cave became world-renowned in 2010, after analyzing DNA from a small hominine finger bone, it was found that the creature differs from modern humans and Neanderthals3. She belonged to a formerly unknown hominine group, later named Denisovans.
Another DNA sequence in the bone remains of the cave found that the Denis were a sister group of Neanderthals and may have lived through Asia – where they met the ancestors of some people living there4.
Last year, another magnificent discovery emerged: DNA analysis of the long bone fragment revealed the first known "hybrid" of two ancient human groups, a woman named Denny, whose mother was Neanderthal and Denisovane5.
Most cave remains are more than 50,000 years old in radiocarbon dating technology that is used on organic materials, and efforts to use other methods at the date of the sediments where the remains are buried have been hampered by the lack of a good map of the geological layers of the cave. Many scientists fear that cave disasters, such as animal groves, hide the content so that they stay and artifacts already sit in sediments of similar age.
In order to overcome these challenges, scientists led by Jacobs and Wollongon, geochronologist Richard Roberts, used a dating technique that determines when the individual grains of soil were last exposed to light1. This allowed them to identify areas of the cave in which the soil was disturbed, so neighboring grains returned to wild data. They could then omit these areas when dating sediments in the same geological layer as hominin remain and tools.
The first signs that the cave occupied any ancient population are stone tools – excavated in the early 1980s – about 300,000 years old. But scientists could not find out if they were Denis or Neanderthals. Denisovan Cave remains (including some of the DNA that poured into the soil) 200,000 years ago and 55,000 years ago, while the oldest Neanderthal remains are about 190,000 years old and the youngest date about 100,000 years ago.
Scientists can not tell exactly where the groups lived together or if they ever shared a cave. The existence of a hybrid – who lived about 100,000 years ago – means that these groups had to live close enough to meet them at that time. In addition, Denny's father wore a source of Neanderthal origin, suggesting that his ancestors had previously joined Neanderthals.
Who was here?
Homo sapiens he could also live in a cave, researchers say. Bone tags and instruments – similar to those made by modern people in Europe – from the younger cave layers date back to 49,000 to 43,000 years, says a team led by archaeologists Katerina Douka at the Max Planck Institute for Human History Jena, Germany and Tom Higham at Oxford University in the UK Nature paper2.
Scientists dated one hominine bone about 46,000 to 50,000 years ago, but could not get any DNA to investigate which species it belonged to.
No other H. sapiens the remaining of this period, known as the early Upper Palaeolithic, were found in Denis Cave or in the wider Altai region. For this reason, the Russian archaeologists who led the excavation of the site claimed that the Denizs created artifacts that are more sophisticated than older stone tools. But Higham would want to see more evidence before linking artifacts to a group. "It is possible that the Denizs could do the upper Palaeolithic." It is possible that the Russians are right, and now we can not be sure of the evidence we have, "he says.
Hybrids similar to Denny are other suspects, says archaeologist Robin Dennell of the University of Exeter in the UK and author of an accompanying studio essay6.
It is also possible that everyone who created artifacts was influenced by contact H. sapiens, he says. "I would be very surprised if the Original Upper Palaeolithic in Denis was made Denisovans or Neanderthals without the benefit of our kind."
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