1. They have.
2. Sub-Saharan Africa doesn't have the required plants & animals that are needed to jump from a hunter gather society to an agricultural one.
If you stuck stone age White people in Africa they would likely be in a similar state. 
Oh hey you're back ya little shitter. Wasn't your last account suspended for telling someone to kill themselves?
This looks like a ban dodge. Some one should really report that. 
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When you can't argue you tell people to kill themselves multiple times.

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