Denisov's cave in southern Siberia has been home to Neanderthals and Denisovs for thousands of years, but questions remain about the timing of their stay. A pair of new studies traces the history of the archaic human occupation on the spot, showing who lived there and when, including a possible era when the two extinct species hung out together.
In two publications, published today in the journal Nature, the updated dates for filling the cave with Denisova with Neanderthals and Denisovets are presented. A new study suggests that Denisovans – related species of Neanderthals – made this cave their home for a longer period than Neanderthals, having first examined the cave 287,000 years ago. Neanderthals arrived at the site about 140,000 years ago, possibly sharing space with Denisov for thousands of years. This is another evidence that Neanderthals and Denisovans interbred – and that this mixing took place in or near Denisova.
For the past 40 years, archaeologists and paleontologists have carefully screened Denisov’s cave, pulling out various animal and Neanderthal bones. But the real bomb appeared in 2010 with the discovery of a finger bone from previously unknown human species, the so-called Denisovites. Genetic analysis shows that Denisovites were related species of Neanderthals, but almost everything else in them remains a mystery, for example, when they first appeared on the scene and when they became extinct.
Denisova Cave, located at the foot of the Altai Mountains in southern Siberia, is thus an important resource for improving our understanding of not only Denisovites, but also Neanderthals. And perhaps our own view Homo sapiens– although, oddly enough, the cave did not bring any evidence that anatomically modern people had ever lived in it. For Neanderthals and Denisov, however, Denisov’s cave served as an important refuge for vast areas of time.
Indeed, a huge amount of time. We are not talking about a thousand years here or a thousand years there. Rather, we are talking about hundreds of thousands of years of occupation. Scheduling events, such as when the cave was first occupied and by whom, was tough, in part because of the large size of the cave and its complex sediment layers; The cave stratigraphy covers both the Siberian period of the Middle Paleolithic (between 340,000 and 45,000 years ago) and the period of the initial Upper Paleolithic (approximately 45,000– 40,000 years ago).
Scientists also faced the limitations of radiocarbon dating, which can go away only 50,000 years ago. The cave was settled much longer, which required the use of less reliable methods of dating and, as a result, the establishment of unconvincing or contradictory terms.
To overcome these obstacles and limitations, an interdisciplinary team of researchers from around the world, including from Russia, Britain, Australia, Germany and Canada, spent the last five years analyzing the bones and artifacts found in Denisov's cave. The researchers used several dating methods, both well-proven and the most modern, and statistical methods to date thousands of objects in place, which allows them to make the most accurate and detailed timeline of human activity in Denisov's cave.
The first study, conducted by Zenobia Jacobs and Richard Roberts of the University of Wollongong in Australia, presented new dates for cave deposits in the Denisova Cave. To date these deposits, and as a result, the bones and artifacts inside, the researchers used a relatively new method, called stimulated luminescence, in which scientists can tell when the last time a mineral grain, such as quartz, was exposed to sunlight. Dates of 103 sediment deposits covering 280,000 years of cave history have been provided.
The results of this work showed that Denisovtsy occupied the cave for the first time about 287,000 years ago and continued to live in the cave until 55,000 years ago. Neanderthals arrived at the cave about 193,000 years ago, and they continued to live there until 97,000 years ago, covering 96,000 years. The bones of 27 animals, including mammals and fish, and 72 plant species were also analyzed, indicating a changing climate in the region during the millennial occupation of the cave. At times, the region was relatively warm, with forests of deciduous trees, but sometimes it was a harsh and desert habitat in the tundra-steppe zone.
The main conclusion of the study of Jacobs and Roberts is the assumption that the Denisovites and Neanderthals sat down together in a cave. Now, perhaps, the two species did not share the space at the same time, but the latest data shows that they probably did. In an astounding discovery obtained last year, a group of scientists, some of whom are co-authors of this new study, discovered genetic evidence of a hybrid archaic hominin called Denisov II, who lived in a cave 90,000 years ago – a girl with Denisovsky dad and a Neanderthal mom.
These data, along with other areas of research, suggest that the two species intersect regularly, and that this was not an isolated case.
The second study, conducted by Katerina Douka from the Institute of Human History of them. Max Planck in Germany proposed new dates for the Neanderthal and Denisov fossils, as well as teeth points and bone points found at the site. The Duki team used several methods to indirectly and directly date thousands of bone fragments and artifacts, including radiocarbon dating and dating in a series of uranium, which take advantage of known radioactive decay rates.
“This is the first time that we can confidently assign an age for the entire archaeological sequence of the cave and its contents,” said Tom Higham, an archaeologist at Oxford University and co-author of the new study.
The oldest fossil in Denisovan assumes that this group was present on the site 195,000 years ago, whereas all Neanderthal fossils, including Denisov II, were dated from 80,000 to 140,000 years ago. The youngest Denisovan fossil was from 52,000 to 76,000 years ago.
"The Douka newspaper is exciting because we knew that Neanderthals and Denis had used Denisov’s cave, and that the two groups interbred in or near it, but we didn’t know much about how long each group visited the cave or the time span during which the two groups intersected using the cave, ”said Gizmodo Sharon Browning, professor of biostatistics at the University of Washington, who did not participate in the new study.
Many dates given in the Duki article had large margin of error, which is a consequence of complex stratigraphy (for example, fears that some elements move to lower stratigraphic layers) and unwillingness to go beyond the limits of available data. But although some estimates present “considerable uncertainty and the possibility of visiting any of the groups that were sooner or later, but left no trace found,” Browning said that these results still “help establish a plausible usage model over time.”
Artifacts found at the site, such as bone points, punctured teeth and pendants, were dated from 49,000 to 43,000 years ago, and are currently the oldest artifacts ever discovered in northern Eurasia, according to Douka. The trouble is that these dates are thousands of years after the last evidence of human occupation appeared in the cave.
“On the basis of modern archaeological data, we can assume that these artifacts are associated with the Denisov population,” the authors of the study suggested. "At present, it is impossible to determine whether modern anatomically humans were involved in their production, since the fossil of modern humans and the genetic evidence of such antiquity had not yet been identified in the Altai Territory."
Denisovans were probable producers of these items, because this is the simplest explanation, given that the Neanderthals had long since left the cave, and, according to a new study, there is no evidence in the cave that modern people exist. But anthropologist Chris Stringer from the Museum of Natural History in the UK is not sure that these items belonged to Denisovites.
"My money would have been in the early modern people who could be mapped elsewhere on this date, for example, in Ust-Ishim in Siberia, but the authors of the Douka newspaper quite surprisingly claim that it is very economical to assume that Denisovanians were responsible, although Denisovs are not yet known as late as in the sequence, ”said Stringer. Gizmodo"Only more discoveries and more research can resolve this issue satisfactorily."
Stringer said he liked two new studies, saying that they "introduce the newest dating methods to stratigraphy, paleoclimatic recordings and human fossils," but he said that there are still many unsolved problems. For example, it is likely that some, if not all, of the bones were dragged into the cave by carnivorous animals that hunted people, he said, or that the bones have shifted dramatically over the years from their original resting place, dropping the dating. to a large extent.
"But at face value, it seems that Denisovites can be placed at least intermittently, in place for about 250,000 years, from about 300,000 years to about 50,000 years ago, and Neanderthals are also there for periods of time," – he said. Stringer. “The classes seem to be concentrating during warmer periods, confirming the view that Denisov’s cave probably was on the northern borders of the occupation for both these groups of people.
The fact that Neanderthals and Denisovs were present at the same time greatly complicates the unraveling of what people are responsible for which elements of archeology — perhaps, DNA sediment research will ultimately help to better compare their presence in the cave. ”
These uncertainties and large error fields are undoubtedly frustrating, but these two documents help to remove most of the uncertainty. Over time, we steadily get a clearer picture of the archaic human occupation in the cave of Denisov. And damn it, it's always exciting.[Nature, Nature]