Deep in southern Siberia there is an invaluable place in understanding our history as human beings. Denisova Cave, where archaeologists found the finger phalanges of a girl in 2008 redrawn our evolutionary family tree. DNA analysis from this bone fragment revealed the presence of a hitherto unknown human species. Denisovans appeared in our evolutionary family tree.
Previous fossil finds confirmed the existence of Neanderthals, while artifacts from smaller layers indicated that modern humans lived there as well. This makes Denisovans Cave the only place where Denisovans, Neanderthals, and modern humans have resided.
The site has a major role, however the story of Denisova Cave is based only on a handful of bone fragments and objects. Recently, however, a whole new layer of information is available. New developments in archaeology – the study of fossil DNA – make it possible to map human DNA from soil.
That’s exactly what Elena Zavala, a doctoral candidate at the Max Planck Institute for Evolutionary Anthropology, and her team did. They took 728 soil samples from different layers of the cave, and looked for the presence of human and animal DNA. “Honestly, I didn’t know what to expect,” Zavala says. “The technology is completely new and has not been used much. The conditions in Denisova Cave with a low, almost constant temperature are very favorable, so we were hoping for a good result. The first data, for the animal’s fossil DNA, immediately showed that the dating of our samples was correct.
In the end, 175 samples were found to contain mitochondrial DNA from one of the three hominin species. This type of DNA does not come from the cell nucleus, but from the mitochondria in our cells, and it is easy to detect. Based on previous finds, we already had an approximate sketch of the history of habitation in Denisova Cave. “This picture is now more accurate,” Zavala says. “As far as Denisovans and Neanderthals are concerned, the data is in line with fossil finds, but we now know better who was in the cave complex and when.”
Fossil bone fragments, while important, only show part of the story. Based on the artifacts found, it is suspected for some time that modern humans also visited Denisova Cave. Its existence is confirmed by fossil DNA, Zavala said. “Archaeological material from the younger strata has already indicated this trend, but we now know for sure that the first modern humans appeared about 45,000 years ago, much earlier than was thought.”
Conversely, DNA from soil samples also provides more certainty about who exactly were the makers of the artifacts from the different strata, Zavala explains. Two prominent elements. Artifacts found in the middle Paleolithic (250,000-170,000 years ago) can now be said to have been made primarily by Denisovans, although this is only certain if they have been discovered at other sites confirming this. Little can be said with certainty about the discoveries in the younger classes, but they coincide with the arrival of modern humans. This at least indicates that they brought the technology with them.
DNA from modern humans as well as from Neanderthals and Denisovans has been found in those younger strata. Did these three types of people bump into each other? It’s a great question, Zavala says, but it remains unanswered for now. The time period that this layer spans is very large. They may have been there in different seasons, perhaps hundreds of years between them. To provide a definitive answer, you still need bone or DNA fragments from the cell nucleus. The only thing we can say for sure is that this possibility exists.
In the video below you can see what the cave looks like from the inside.