I think I take issue with that whole line of logic. Red and yellow fade imperceptibly into one another via orange but they are still distinct colors. Whether th

I think I take issue with that whole line of logic. Red and yellow fade imperceptibly into one another via orange but they are still distinct colors. Whether there is a sharp dividing line or not this is still the case. It would not be logical to claim the distinctness of A and B depended on a third entity C existing. You shouldn't need to know anything about C to say whether A and B are or aren't distinct. Claiming that orange makes red and yellow one and the same is the continuum fallacy. It does not follow that an intermediate population must be evidence of substantial gene flow between populations, rather simply that contact exists. What does substantial mean anyway? Moreover most human ethnic groups probably do not have "substantial" gene flow between one another, else how did they arise in the first place? With no data to back the claim up I guess less than 5% of people are "racially mixed".