I think there's more to it than just skin colour. Black people in my opinion are naturally more violent and animalistic, to a degree I think they're lesser evolved. I think this relates to the fact that Black males are said to produce 3 to 19% more of the sex hormone testosterone than Whites or East Asians; it's thought high testosterone levels are linked to aggression and criminal behaviour. Credence to this is 40% of the male prison population in the US is black, over 75 per-cent of Gun-crime committed in the UK is by young blacks, and 1 in 3 young black males is unemployed in the UK; it’s also been noted that blacks tend to have lower IQ levels. (Look at the world IQ map)
Also, when you start looking at countries/areas inhabited by black people, be it the ghettos of American, East London, South Africa, or the usual third-world dumps, you start to notice that crime, unemployment and poverty are all quite prevalent.