Haven't read the paper yet, this just got posted, but its a topic I've been thinking about recently.
Do you think/have you considered the roll of the Toba volcano and the subsequent genetic bottleneck in the lack of diversity?
Could we be looking out a scenario where we see Out of Africa movement spreading out across the land, followed by this disaster resulting in just a few isolated groups.
From these multiregional survivors spring forth our limited, albeit present, diversity - ie the "races".
Just musing without any research. Thought I'd throw it out there.
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