We all have one black African Grandma.
200,000 years ago, all human beings on this planet were black and were residing only in Africa.
During the last glacial age, Most of Britain, all of Scandinavia were covered by ice several kilometers thick. New York, Beijing Tokyo all were under thick Ice and not habitable.
Only the Africa was green at that time and all humans lived there. It is also the time when the Green Africa started drying out. The Sahara deserts were newly forming.
As a result, roughly 70,000 years ago, our human population crashed to fewer than 2,000 individuals. We nearly went extinct. But before that, we moved out of Africa and spread to Middle East then Asia, Australia, America in that order.
How do we know that the whitest caucasian has a black ancestor ?
Because every human on this Earth- the purest German to the whitest Scandinavians all share one Mitochondrial DNA from their mother’s side.
You get your mtDNA from your mother, and your mother’s mother, all the way back to the very first woman.
We all share one ancestor, a single person — Mitochondrial Eve — in Africa, an African woman who gave rise to all the mitochondrial diversity in the world today.
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On the father side.
The Y chromosome, the piece of DNA that makes men men, traces a purely paternal line of descent.
If you look at the Y-chromosome side, the male side of the story, the Y-chromosome Adam only lived around 60,000 years ago. He is again an African man who gave rise to all the Y chromosome diversity around the world.
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Is it not ironic that for ages, these white people used to capture their ancestors from Africa and sell and purchase them as slaves ?
Dr Ramakanta's Ideas 
Ramakant, it’s an interesting fact.đź‘ŚBut how could you substantiate the change of color from black to white?
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