I enjoyed this discussion by Bryan Caplan (and the trailing comments) about the (slow) decline of "otherness" in America. Read them.
Many of us can see it in our own lifetimes. We can also compare the state of "otherness" here and abroad if we have spent enough time outside the U.S.
I have posted many times that I think of residual tribalism as a great evil. "Otherness" is one of its manifestations. Modern America may represent the world's most auspicious path out of this atavism. Americans may pick from Barack Obama and Herman Cain based on perceptions of each candidate's personality and platform. If so, perceived "otherness" will have become the preoccupation of the inevitable retrogrades.
These continue to exist on the "right" as well as the "left". What's the difference? Those on the right are properly scorned for what they are. But those on the left are celebrated on university campuses everywhere. "Multiculturalism" is the fancy label attached to the preservation of otherness and tribalism. To say that they are playing with fire is understatement. In my view, they are also missing the point.
ADDED
Yesterday's NY Times included "In Strangers' Glances, Family Tensions Linger". There is always good news and bad news on this front. Mixed marriages and cross-race adoptions are up. The treatment of the individuals involved is also mixed. The insults include those that are intentional and also the ones that are unintentional, reflecting the inevitable obtuseness of many people.
This film is based on surviving minutes of the Nazis' Wanssee Konferenz, where plans for the death camps were drafted. Watch it to see what stumped the participants. What to do with mixed marriage (Jewish and Aryan) couples and families? We now know the answer. But the conferees worried over the sons of mixed marriage couples, returning from duty at the front, and seeing the Jewish mother or father was being carted off to be murdered.