Okay - well how come there are black looking whites? Just 35,000 years ago? So how did the facial features come to be different?
Instead we are descended from the San People, and all the 13 different kinds of black folk are ALSO descended from the San People.
The San developed from earlier humans in SOUTHERN African ~ in the Temperate zone.
They were probably well on their way to trimming up to having light skin down there and then, when they moved North, those who got to Eurasia the first just kept right on changing. Those that stayed in Africa, were moving North into more Tropical climate zones and more direct Sunlight. They turned black!
Modern San have obviously mixed considerably with other African tribes ~ however, Nils Van Der Post and other researchers have hypothesized that the San cannot necessarily create fertile offspring with all other blacks ~ just with some!
There's a situation that involves enough Northern Europeans and the Sa'ami that is of enough concern that it's been studied ~ to little avail.
It's called Indeterminant Infertility. That's where you and somebody else get together and have chilluns. Let's say you have 8 kids. 4 of them will be infertile for no discernible reason. At the same time there are CERTAIN Sa'ami males with what appears to be a workaround for the problem ~ super sperm! The females with indeterminant infertility can sometimes hit if visited by such a man.
No one has studied the situation enough to pin everything down and these days the Sa'ami are sober and monogamous, so that just ruins everybody's research.
Interestingly enough a "related population" still live in the Orkneys, and Charles Darwin, who had a fair number of ancestors from there, married a first-cousin ~ four of their 8 offspring were infertile!
I suspect the San/Bantu breeding problems, to the degree they exist, have something to do with this other system. It's probably far more widespread than we imagine. So, not everything is onesy-twosy, sometimes it onesy-whole buncha' women, and nothing at alsy!