I'm referring to things that affect ability (things like skin color are different but not unequal in this regard). Even if certain small communities had some va

I'm referring to things that affect ability (things like skin color are different but not unequal in this regard). Even if certain small communities had some variations they become meaningless once you reach the scale of "asian", "european", or even just "chinese" so once your are talking about a group of any significant size it averages out. I used the term "necessarily" because by statistics on that large of a sample they will be equal unless there is a reason to think the underlying distribution between those groups is different (which I don't think there is on a large scale).