Why is tolerance so difficult?

[Binkie The Clown]

5. Because when humans were evolving

in forager bands anyone not a part of the band was a danger to survival. Therefore a tendency to fear otherness became an ingrained part of our genetic makeup. Simply put, there was a time when fearing and hating anyone "different" improved your ability to survive. We simply haven't evolved much beyond that geologically very recent past. That's probably the main reason that multiculturalism doesn't work as well as we all wished it would.