Why is it that 90% of Africa, is so backward in Technology?

Yes I know there are more than 50 countries in Africa and over 1 Billion people there, so why are they so primitive? It is said that human life started in Africa 56,000 years ago, so what happened? They produce nothing except more Africans. Don't give me this a "Rant" and cry-baby to Yahoo, just answer my question if you can come up with something other than "White people stole their gold and diamonds", those are just trinkets.