Afrikaaners live at a latitude where "light" skin can be maintained - they are hardly Central Africans.
The vitamin D thing kept human beings from living North of the 30th parallel until they had developed a way to acquire sufficient Vitamin D from a very, very, very extensive fish diet. Eskimos are among those who developed such a diet - including the eating of raw sea mammal livers - a major source of Vitamin D. Quite possibly their darker skinned offspring didn't die in infancy from rickets. As far as Arawaks being lighter than Central Africans, it is suggested that the Arawaks are recent arrivals to their present territory, plus they, like all other persons of predominantly American Indian ancestry, are of mixed European/Indian descent.
Again, there's a lot of this stuff on the net.
"The vitamin D thing kept human beings from living North of the 30th parallel until they had developed a way to acquire sufficient Vitamin D from a very, very, very extensive fish diet."
Fine, let's look at somebody else. The descendants of the Spaniards and other Europeans in the tropics in places like Cuba, Puerto Rico, Mexico or Peru have lived there for as long as 500 years. They have maintained their light skin.
More recently.......on Youtube, a 5 part presentation (documentary) is being shown on the Lemba people. The Lemba Jews say they were never lost......they have only been scattered. Their trek, over 4,000 miles, from Assyria to “Yemen” down the coast of Africa through Zimbabwe is revealed and confirmed by archaeologist and now, the linkage by DNA lends proof to their knowledge.