/sci/ - Science & Math

Why do certain races, such as the negro, have more dimorphic features? You can see it in both the negro man and negro woman.

Negore men have large penises, broad shoulders more muscle mass etc and negro women have larger asses and hips etc.
Asians are the polar opposites of that, often looking like children and whites are in the middle.

What about the African continent caused the negro to develop like this?