"A group that has experienced considerable deprivation and difficulty has more need for outgroup hostility" http://books.google.co.uk/books?id=qmGEiPU-O-cC&pg=PA74&dq=A+group+that+has+experienced+considerable+deprivation+and+difficulty+has+more+need+for+outgroup+hostility&hl=en&sa=X&ei=9O2zU4a-A8bmPPj9gJgM&ved=0CCEQ6AEwAA#v=onepage&q=A%20group%20that%20has%20experienced%20considerable%20deprivation%20and%20difficulty%20has%20more%20need%20for%20outgroup%20hostility&f=false …