This Tooth Once Belonged To A Member Of A Mysterious Species Of Humans That We Know Almost Nothing About

This tooth is one of just four fossils we have from the Denisovans, a mysterious people with which we interbred. No wonder they want to photograph it from every angle. Slon et al/Science Advances

A molar from Denisova Cave, Siberia, comes from the mysterious people to which the cave gives its name, increasing the number of Denisovan fossils to just four. Moreover, while the other fossils are of similar ages, this one is substantially older. Given their role in our evolution, the tooth is one of the most precious artifacts known to science.

In March 2010, an approximately 40,000-year-old finger bone fragment was found in Denisova Cave. Although the cave was at times occupied by both Neanderthals and modern humans, DNA showed that this was a new species, or at least a previously unknown subspecies of humanity. Comparison of this DNA with that of people living today showed the Denisovans interbred with our ancestors, and Melanesians and Indigenous Australians have inherited 2-5 percent of their genome from these encounters.

That's an important part of the human heritage to come from a group about which we know so little – just one finger bone, two molars, and some DNA fragments from cave sediments. Now in Science Advances, first author Dr Viviane Slon of the Max Plank Institute for Evolutionary Anthropology and colleagues have announced the extraction of DNA from a molar found in 1984, showing it too came from a Denisovan. The different branches of humanity that occupied the cave had teeth too similar to determine their origins from shape alone.

Other Denisovan fossils were dated as between 30,000 and 50,000 years old, or lack a clear date. The new find, however, came from a much deeper layer in the cave, indicating the owner lived much earlier. Based on radiothermoluminescence dating of the layer in which it was found, the molar was 128,000-227,000 years old, a figure broadly supported by the genetic clock of its mitochondrial DNA.

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