You know what I might consider scientific evidence is the geographical location of said race in determining penis size. Honestly, in an environment in which survival is key to any race, or ethnicity, the penis may grow through evoluation to insure pregnancy. Perhaps procreation is a way for the race to survive. Now, if I were in Africa, and lions were casually looking at me like they do all the time, until they bite off your dick, I would need to be equipped to procreate effectively to insure the survival of my species. Maybe that is the key to the herald of the ebony penis.
Although I have heard stories that not all black penis' are extraordinary, but I am trying to figure out why I care. I am Greek and Italian, and I have huge hands. I don't fear for lack in the department, but it seems my theory may fall short in my own physiology. Considering there are no lions corralling the landscape of Greece, OR Italy.
The devil's advocate would tell me that if a lion or any another instinctively driven animal were to try to eat my butt, I would want the smallest penis possible, so that it would not be the target of said animals razor sharp claws. Because let's face it, if I want to get eaten by a lion, I hope he doesn't go for my junk first. I would rather him eat my throat, or suffocate me, which seems to be the main focus of their attacks. Yeah, they suffocate their victims. At least lions do, Hyenas like to eat their victims alive. Hence, the penis people eating theory above.