DNA shows girl had one Neanderthal, one Denisovan parent

Enlarge / Excavations in the Denisova Cave. (credit: IAET SB RAS, Sergei Zelensky)

One can be forgiven for thinking that the first modern humans who ventured out of Africa stumbled into a vibrant bar scene. 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.

But in almost all of these cases, the ancestry seems to have come from a single exchange of chromosomes many generations prior. There was little indication that the interbreeding was frequent.

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.

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