When my labmate first showed me this paper, we marveled at the sheer number of authors. By my count, this work is credited to 56 scientists with 21 different affiliations (including UC Berkeley) in 7 countries. I don’t even know how to count the number of PI’s here; clearly it was a huge undertaking.

But now, knowing what they actually accomplished, I’m almost surprised that it took only 56 people. They sequenced over 4 billion base pairs, using three samples of bone from Neanderthals that have been dead for about 40,000 years. Most of the bones used were found in the Vindija cave site in northern Croatia.

The results tell us about the relationship between humans and Neanderthals during the late Pleistocene era: between the time when they split into two separate species (400,000 years ago) and when Neanderthals disappeared (30,000 years ago). Human subjects with European or East Asian ancestry had significantly more genes in common with the Neanderthals, compared to people from South or West Africa. This means that about 80,000 years ago, sometime after humans migrated out of Africa, they must have come into close contact with Neanderthals—close enough to interbreed and leave Neanderthal genes in the DNA of non-African modern humans.