Classical natural selection, which depends on the very slow process of random mutation, with environmental selective pressures then acting over generations to favour certain mutations above others, requires long periods of time. It is just about conceivable that this operated in the ancient Greek situation, since this arose on the back of the incursion of a new population into the central Mediterranean at this time, with a different gene pool. In that sense this change is quite different from those that came afterwards in modern Europe.
