Inside the Denisova Cave in Siberia Jun 23, 2021 20:16:42 GMT
Post by Admin on Jun 23, 2021 20:16:42 GMT
"Just collecting hundreds of samples from all three chambers in the cave, and documenting their precise locations, took us more than a week, but we obtained a comprehensive set of samples spanning more than 300,000 years of Siberian history," Professor Jacobs said.
The new study builds on the detailed timeline obtained from optical dating of the Denisova Cave sediments at UOW, published in Nature in 2019.
"The chronology generated previously for the cave sediments allowed us to choose the best places to collect the DNA samples and make the most of the extraordinary insights from sediment DNA," Professor Jacobs said.
At the Max Planck Institute for Evolutionary Anthropology in Leipzig, Ph.D. student Elena Zavala, the study's lead author, extracted and sequenced small traces of ancient human and animal mitochondrial DNA from the huge collection of samples.
"These efforts paid off and we detected the DNA of Denisovans, Neanderthals and ancient modern humans in 24 percent of the samples," she said.
When matching the DNA profiles with the ages of the layers, the researchers found the first humans to visit the site were Denisovans about 250,000 years ago, followed by Neanderthals about 200,000 years ago. Only Neanderthal DNA was found in sediments deposited between 130,000 and 80,000 years ago. Denisovans who came back after this time carried a different mitochondrial DNA to Denisovans who were there earlier, suggesting a different population had arrived in the region.
Modern human DNA first appears in the Initial Upper Palaeolithic layers, which contained pendants and other ornaments made from animal bones and teeth, mammoth ivory, ostrich eggshell, marble and gemstones. "This provides not only the first evidence of modern humans at the site, but also suggests that they may have brought new technology into the region with them," Ms Zavala said.
The scientists also found animal DNA in nearly all samples, and identified two time periods when changes occurred in both animal and human populations. The first, around 190,000 years ago, coincided with a shift from relatively warm to relatively cold conditions, when hyaena and bear populations changed and Neanderthals first appeared in the cave.
The second major change occurred between 130,000 and 100,000 years ago, along with a shift in climate from relatively cold to relatively warm conditions. During this period, animal populations changed again, Denisovans vanished, and Neanderthals were left as the only human occupants of the cave.
"The coincidence of these population turnovers with climatic transitions between interglacial and glacial periods suggests that environmental factors played a key role in shaping the human and faunal history of this region," Professor Roberts said.
Professor Matthias Meyer, leader of the Advanced DNA Sequencing Techniques group at the Max Planck Institute for Evolutionary Anthropology and senior author of the new study, said: "Being able to generate such dense genetic data from an archaeological site is like a dream come true. There is so much information hidden in sediments—it will keep us and many other geneticists busy for a lifetime."
New studies reveal deep history of archaic humans in southern Siberia
More information: Pleistocene sediment DNA reveals hominin and faunal turnovers at Denisova Cave, Nature. doi.org/10.1038/s41586-021-03675-0