Who are we-- and should it matter in the 21st century?

"As borders vanish, more people travel, cultures mingle, and communications across continents become easier, aren't relations between people supposed to be getting less fraught? Why then are people retreating into the refuges of religion, nationality, race, and region? In France the Roma are deported en masse, in Italy Prime Minister Berlusconi has called undocumented workers an 'army of evil' and in Oklahoma, where Muslims are only 0.2 percent o...