Since 2008, when their fragmentary fossils first turned up in a Siberian cave, the Denisovans have been the most mysterious branch of the human family tree. The archaic humans, like Neanderthals, lived at the same time as early Homo sapiens but have been extinct for tens of thousands of years.
For nearly a decade, we’ve known Denisovans from only one site, which yielded just a shard of finger bone and a few teeth from four individuals — and ancient DNA extracted from the scant remains.
