There was an interesting article ("The Cooperation Instinct") in the December 2012 issue of Discover (I'm behind on a lot of things). It was about the evolution of altruism and cooperation. It turns out that genetic relation is not necessary for the development of cooperation, it's just a natural change in life strategy.

Running a computer simulation, Martin Nowak (German pronunciation) saw the dominant strategy go through cycles. At first, the dominant strategy was to always screw over the other guy, what they called Always Defect, after the action in the Prisoner's Dilemma, where defecting means ratting out your partner in crime. Then the top strategy was one called Tit for Tat, or what I've heard called the Silver Rule--do unto others as they have done unto you. The individuals that follow this strategy strictly would cooperate with a new "opponent" if their last opponent cooperated with them, and would not cooperate with a new opponent if the last opponent didn't cooperate with them. Eventually, this gave way to a strategy called Generous Tit for Tat, which involves often cooperating even when the last opponent didn't cooperate. It's not quite the Golden Rule, but Nowak called this the evolution of forgiveness.

But like I said, things went in cycles. Once Generous Tit for Tat was dominant, the Always Defectors could take advantage of the situation and eventually that becomes the dominant strategy. The cycle is probably inevitable.

What I get out of this, aside from insight into a long view of history, is that different places may be at different points in the cycle when they come into contact with each other, causing cultural strife. Some of the problems we're having in the United States alone may be due to some areas trying to Always Defect (Tea Party), while others are trying to move into Generous Tit for Tat (Progressives).