Re: European Middle Plesitocene (via Twitter):
Maybe a dumb question....how do you know Neandergenes derive from Africa vs. f.e. recent Africa and Neandergenes both derive from Atapuerca?
Not a dumb question at all. I discussed this exact issue with David Reich last week. There is no strong fossil argument for an African ancestor at that time, Europe and West Asia are anatomically and archaeologically just as plausible. My inclination is to suspect Africa because of the deep genetic variation still retained in that population, but that variation could have been retained in other ways – particularly since every scenario of human origins now must involve population mixture.