Every time one reads these threads about the origins of one group or another, what is generally overlooked, is the the successful group, killed all of the other group that they could get their hands on. Early humans do not appear to like strangers. So the first groups to North-South America appear to have “displaced” the earlier settlers. And it also appears to have been true in Europe-Asia. IMHO
We later ones ain't too keen on them either!
There is a part of our brain (the fusifrom gyrus of the temporal lobe--about the size of the end of your thumb--and parts of the frontal lobe) that are involved in facial recognition. To give that much precious room in our noggins to this function is evidence of how important it is.
For other races, evidence shows that it does not work as well in that it is more difficult for whites to tell blacks and Asians from each other (and vice versa).
And the answer as to why this is would be simple: we need to be able to tell strangers apart quickly (for safety reasons--friend or foe?) among people who look like us, so these neural circuits work optimally. A white tribesman or woman would immediately know that a black or Asian were of a different tribe so our brains do not need to work that hard.