Nature endowed Negros with a relatively large penis size to compensate for their relatively small brain size.
It was essential to the survival of the negro race in prehistoric times to procreate as quickly and effectively as possible, because the male members of any given tribe would often be at risk of getting killed off during an excursion into the African wilderness, as their lack of intelligence would often have them charging at a heard of elephants armed with nothing more than shoddy spear, a small shield, a painted face, and, yes, a massively large swinging penis.
It's why prehistoric Africa soon transitioned from a Hunter/Gatherer society into solely a Gatherer society. Black men were simply too stupid to hunt and had to rely on women for their survival, which remains largely true today.
Furthermore, it's no wonder why the zenith of the African race is the African American. The African American has contributed more to world society in 100 years than the native African has in 100,000. And why is this?
Because the African American has white in him.