What is the reason for the nose structure differences between Caucasoid and Negroid types?
In general, the Caucasoid nose is narrow, thin and high - almost continuing downward from the forehead. On the other hand, the Negroid nose is broad, flat and low.
Is there an anthropological explanation for that?
I mean is it the climate differences in Europe and Africa that caused those differences?
And all other races fall somewhere along the line between those two.