[guylhem]

As shocking as it may sound, I noticed the same thing in the caribbean where population is very mixed. It's not about racism - it's more as if a shared group identity encouraged cooperative behaviour.

Even weirder - there seems to be a trigger effect : until the non visible minority reaches 5% the cooperative behaviour keeps working.

Funny thing - it seems to works even if you account your own ethnicity - i.e. when you are in the <5% you will get more cooperation by people with a different ethnicity than you !!

Cross the 5% mark and it won't work as well - apparently even with people of the same ethnicity as you. Weird.

Some may call that parochialism. I find that interesting.

I've been quite puzzled by this (it contradicts all the mainstream thoughts about diversity) and I would love to know more about such issues (scientific research - can anyone with a sociology background give more details about that?)