Why hasn't the continent of Africa been as resilient as the continent of Europe?

Both of these continents have had many trials and tribulations. Europe has been constantly invaded, the Black plague, the Dark Ages, numerous mive wars, and limited resources. Even with all of that Europe has always bounced back stronger, more intelligent, and unified. Africa has been invaded, Aids epidemic, and droughts. However Africa has always had numerous valuables such as the Nile and Diamonds. Yet, except for Northern Africa which is dominated by Arabs, It seems to never get back on it's feet. Why hasn't the continent of Africa been as resilient as the continent of Europe?