What's interesting is that you do see this behavior from white people--in the UK, where liberalism has worked the same cultural damage on the white underclass. It's not behavior limited to blacks, but is seen in any group raised and nurtured with liberal principles.
Socialism will most likely be the thing that sends Europe and the rest of the world into the tank, but it does not appear to have led to violent crime in European countries.
http://en.wikipedia.org/wiki/List_of_countries_by_intentional_homicide_rate