How Jared Diamond relates sexual selection to geographic differences seen in humans?
My reading of the original edition, back in 1994 or so, is a bit vague in memory, but I felt that Diamond was heavy handedly molding pre-history into a pastiche of environmental determinism, in order to sell books. As determinists do, he danced with the chicken-or-egg problem of assigning causality, and came down, so lightly and gingerly on the side of environment, that critics were never really able to pin it on him. Diamond would seem to say that environmental pressures shaped sexual selection by weeding out morphological differences that don’t confer advantages in the climates to which proto-humans were trying to adapt. The people who settled Europe became light skinned and blonde, first, perhaps, because melanin wasn’t needed in northern climes as skin protection, but once blue eyes became established along with that, blue eyed blondes became desireable alleles in the European population, to the point they became prominent in some areas. Can he “prove” that? No. But he can point to
