That is, we can't "wish" to evolve. Closest that could be accomplished is a specific breeding program... And whatever possible biological merits might be found in such an idea are very easily swept away by a tide of ethical counter-arguments.
We're naturally tribal, as I just pointed out. Evidence would seem to say that mammals cannot be social WITHOUT being tribal - we're not alone in this boat. It seems to stem from a combination of resource management and genetic propagation.
With that in mind, we are also inherently prone to conflicts, simply because we're individual creatures as well. Humans disagree on a lot of things; just as we're arguing right now. One can imagine this goes back pretty far as well.
Combine these two facets, and you get results like we see here in this story. Huymans disagree about something, and align along tribal lines to settle it out between them.
Now, just because these things are inevitable does not mean that things like war or armed conflict or the like are also inevitable; you're conflating things wrongly there. As the followup downthread makes the case for, conflicts can be defused by communication, social pressures, deals, any number of things. This is what I mean - peace can be obtained within the existing human framework of tribalism and conflict.
Think of it like this, since you're using America's race issue as an example - white peopel and black peopel are totally capable - as has been demonstrated for a long time - of living together peacefully, despite the conflicts that arise at times, all without forcing either to stop being the kind of people that they are.