Many African countries are currently in the bottom parts of socioeconomic rankings like [GDP per capita](http://en.wikipedia.org/wiki/List_of_countries_by_GDP_%28PPP%29_per_capita), [life expectancy](http://en.wikipedia.org/wiki/List_of_countries_by_life_expectancy), [literacy](http://en.wikipedia.org/wiki/List_of_countries_by_literacy_rate), [HDI](http://%5BHDI%5D%5B1%5D,), etc. Some of them possess a decent amount of natural resources and relatively low population burden, so this is disappointing.

Are there historical reasons for this to have happened? And yes, I know there are poor countries everywhere, but there seems to be an unusually high concentration of them especially in the Sub-Saharan region. And before colonization is brought up as a factor, let me remind you the United States is a former British colony.