After a few generations there would be 15 shades, and within 3 shades, and so on.

Utterly impractical, certainly would have brought globalization along a bit earlier.

“We gotta keep fuckin’ each other until were all the same color”.

Warren Beatty in “Bulworth”

You’d have to see it I guess…

In Classical times, nation fought against nation, and within a nation (an ethnic culture, actually), there were tribal, class and family conflicts. But in my opinion, racial prejudice may very well be a relatively recent invention.

I believe it started in the Christian era. Christianity was the first major, widespread movement that preached all men were equal. Slavery violated its very philosophical foundations. Of course, what you say is not always what you do, and old habits, particularly those with economic consequences, die hard. But by the time of the European expansion, it became harder and harder to justify the fabulously lucrative slave trade in the Indies with Catholicism. Only by considering the Indian, and the Negro, as sub-human, as not really people, could they justify it to themselves.

Different races have always had some conflict, and consideed each other barbarians. But I believe that is because racial geography often coincided with political and cultural boundaries. Consider Moorish Spain in the late middle ages. The Moors were black, although the Arab civilization they were a part of was racially diverse, with many Caucasian and Semitic racial elements. Spanish Muslims had a highly advanced and tolerant civilization. Cities like Granada and Cordoba had universities, libraries, civil courts, trade with foreign lands. That’s where you went to study, or to get your teeth fixed. Christians and Jews were allowed to live there in peace, with guaranteed rights and legal protection. They considered their fair-skinned, Christian neighbors in Castile and France as little better than savages.

Uninterrupted progress for that long would probably mean we had solved most of our social problems. My fears are more for fundamentalist religion vs racial problems. I have seen great progress in racial matters in my lifetime, while religious fundamentalism is almost viral.

As far as skin color goes, I have seen predictions that color will be optional long before racial mixing gets anywhere.