Any person, lineage, race adjusts to the challenges presented to it. The biggest challenge beeing nature.
Thats why people have white skin or black skin or in between as they simply adapted to the sun. No magic to it.
In many big international cities today you see a very large variety of people from different racial backgrounds.
Quiet interesting. Brings some problems for the invidual as he has to implement different traits and match it with his society. thats for that..
The notion that blacks are bigger has not much base checking all data available. The myth, Im sure, has some base.
That base is in my opionion: Darker appears bigger to the eye espacially in contrast to white.
Next is that when you take 100 white people in scandinavia outside into the cold you will get probably 99 shrivelled up dicks.
Take 100 blacks in central africa outside and you will get 99 good hanging full of blood flaccids.
People who think that someone decided to give a specific race some advantages just because they are preferred by someone are plain stupid.