Yet fertility rate in South Sudan is a staggering 4.9 vs 1.8 in USA.
http://www.gapminder.org/ for best perspectives on all this
The second half of this may be BS but the difference in Africa from 1950-2010 is staggering. https://en.m.wikipedia.org/wiki/Total_fertility_rate#/media/...
PS: For comparison the baby boomers are from US fertility rates over 3.5 in the late 1950's. http://www.prb.org/publications/datasheets/2012/world-popula...