I don't think that particular behavior is any different than how people naturally select and maintain social groups, though. Some level of homogeneity is necess

I don't think that particular behavior is any different than how people naturally select and maintain social groups, though. Some level of homogeneity is necessary for discourse (common language), let alone civil discourse. I tend to think that people divide because they can't relate on a conceptual/experiential level; they begin with different perceptive assumptions. That's just a theory, though.