As far as caves go, Siberia's Denisova Cave is a super prominent one, the place where scientists confirmed the existence of a species of hominins (we're one, as are Neanderthals) known as the Denisovans. But the prehistoric treasures the cave has given up have been few—just eight bone fragments and teeth of Denisovans and Neanderthals. The dirt just gave up a whole lot more. A new study that makes use of a revolutionary archaeological tool that recovers human DNA without the presence of bones managed to craft a 300,000-year history of the cave's occupants. Researchers extracted mitochondrial DNA from soil samples dating from 300,000 to 20,000 years ago. What they found: Denisovans solely occupied the cave from 250,000 to about 170,000 years ago, a much earlier presence than fossils indicate, per Haaretz.
Neanderthals then enter the mix, with both groups occupying the site at times, though from about 130,000 to 100,000 years ago, only Neanderthal DNA was detected. While no fossils of modern humans were found in the cave, their DNA does appear in soil dated to around 45,000 years ago. Denisovans appear to have vanished around 60,000 years ago, followed by Neanderthals around 40,000 years ago. "I cannot think of another site where three human species lived through time," lead author Elena Zavala of Germany's Max Planck Institute for Evolutionary Anthropology tells Science. In the end, hominin DNA was found in 175 of 728 soil samples, which senior author Matthias Meyer describes as "like a dream come true." The research, published Thursday in Nature, is "the most comprehensive study yet of ancient DNA extracted from sediment at any single site in the world," researchers write at the Conversation. (Read more discoveries stories.)