DNA from just a single cave in Siberia revealed that it had been occupied by two archaic human groups that had interbred with the newly arrived modern humans. This included both the Neanderthals, whom we knew about previously, and the Denisovans, who we didn’t even know existed and still know little about other than their DNA sequences. The DNA also revealed that one of the Denisovans had a Neanderthal ancestor a few hundred generations back in his past…
Now, the same cave has yielded a bone fragment that indicates the interbreeding may have been common. DNA sequencing revealed that the bone fragment’s original owner had a mom that was Neanderthal and a father who was Denisovan. The fact that we have so few DNA samples from this time and that one is the immediate product of intermating gives us a strong hint that we should expect more examples in the future.
The Denisova Cave sits within Russia near its borders with China, Kazakhstan, and Mongolia. It appears to have conditions that favor the preservation of ancient DNA, as bones from the site have yielded high-quality genomes from both Neanderthals and Denisovans. It does not seem to have favored the preservation of skeletons themselves, as most material has been fragmentary; all we know about the appearance of Denisovans comes from a molar and a small finger bone, though dating indicates they occupied the cave more than 30,000 years after the Neanderthal.
Fascinating stuff…even if you’re already beyond fundamentalist fairy-tales.