[Houshalter]

The Robbers Cave Experiment is really interesting: http://lesswrong.com/lw/lt/the_robbers_cave_experiment/

I have found the whole concept of "in-group vs out-group" to be very useful in explaining a great deal of human behavior. Humans evolved as hunter-gather tribes and all of our social instincts are from that. We have empathy for our friends and family, but it has an off switch labelled "enemy" or even "stranger". More than that, we are actually compelled to hate the out-group, or follow the in-group, far more than we would otherwise do.

The reason politics sucks is that everyone is trying to identify with a tribe more than they are rationally debating policies. The reason racism, ethnic conflicts, and even wars happen is we consider the other side a rival tribe that is a threat to us.