David Reich: commitment

Transcript context

…The reason I ask is that Aristarchus, the ancient Greek, had the heliocentric theory because he had deduced how far the Earth is from the sun and noticed other things. But it was not adopted, because his fellow Athenians were like, “Look, if we believe that the Earth revolves around the sun, for it to be the case that we don’t see relative movement of the stars to the Earth, the only possible explanation is that the stars are so far away that it is just incomprehensible and implausible.” So the heliocentric theory was dismissed. What I’m trying to ask is, what is the equivalent here of “for this to work, the stars have to be so far away that it’s inconceivable,” where actually the stars are so far away? Maybe we should adopt the implausible implication that this theory gives us. That’s a great question. I think we have to assume that there’s a linkage between the cultural transformations in Africa and Eurasia at this time, and that’s not something the community has really put together with the genetic data. There’s this thread in the genetics about substructure in Africans, and then there’s this whole world based on ancient DNA, and they’ve never been put together. Nobody’s put together the now extensive work on modern human substructure with the extensive work based on ancient DNA of archaic human relationships to modern humans. If you put them together, you realize they line up in terms of their time of substructuring. I don’t know if that’s improbable. It seems parsimonious to me. It also seems significant that different groups of humans at this time were capable of adopting Stone Age technology. Once one group had figured it out, the genetic difference between different human lineages was not so big that you could not show people how to use stone tools.…

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