We don't know what color the original Africans were. They may have had lighter skin and straighter hair than present day Africans, and got darker while everybody else got lighter.
Good point. The 'stay-at-home' Africans may have gone through their own series of changes that were different than those that affected the 'out-of-Africans.' The sub-Saharan Africans are the most 'different' from all the other people outside that region.
Yes, that's what the article I found assumes. The earliest humans (pre-modern man), were lighter skinned but had much more hair. As the amount of hair decreased, the skin darkened to reduce overall UV exposure. The mechanism was intense UV sunlight destroying vitamin B (folic acid) in lighter skinned, pregnant women's bodies, thus causing neural tube defects in babies.
Note: apparently there are documented cases of white women using tanning salons while pregnant and having NTD babies possibly due to the reduced B. The bad thing is that B is most important in the early stages of a PG, before it becomes obvious. Yikes!
The African Bushmen are physically different than all other humans on earth. The females have an 'apron' over the genetial area and the males have a semi-erect penis. Also, the Bushmen are lighter skinned, have some features resembling Mongoloids and their children even have 'Mongoloid spots' which is common among the Asians of today. (The 'spots' disappear with age on all)