If you have a deep and abiding interest in this subject, then you should read the work of Harvard Professor Robert Putnum. Try to get ahold of the orginal academic studies if you can. The article below is a summary of some of his work. http://www.boston.com/news/globe/ideas/articles/2007/08/05/the_downside_of_diversity/
What? I've never known a pot smoker NOT to be racist. Any time you get a little bit of saliva on a joint, everyone will tell you not to "nigger lip" it. If you have ever smoked pot, you know you have heard that expression countless times.
The human race has always been in conflict and will always be in conflict. There is just no way around it. With the world population at 6 billion+ there is that much more conflict.