Why haven't the 1 billion plus in black Africa advanced to the "Stone Age"?

Like as making anything to sell, cars, airplanes, ships, food exports, electronics and on and on. No don't blame the "White man" for that stealing that from them. Gold and diamonds are just trinkets. Why do we expect more from our blacks here in the USA? Yes "cry-baby" to Yahoo.. "Rick Shaw" said the obvious, he made me feel bad about reality.