[INTPenis]

Thank you for the clear explanation.

I've heard that humans were at some point reduced to a very small number, like thousands of individuals.

So how did a few thousand individuals become such great genetic diversity? Does genetic diversity come from being isolated, instead of mingling with other migratory groups?

[neonnoodle]

Human genetic diversity on the whole is very, VERY low compared to other species. The superficial physical variation we associate with ethnic diversity (skin tone, nose shape, lip shape, hair color/texture, eye folds and angles) are genetically insignificant compared to their visual impact.