Nice Guys Finish First
Nice Guys Finish First is a 1986 documentary by Richard Dawkins which discusses selfishness and cooperation, arguing that evolution often favors co-operative behavior, and focusing especially on the tit for tat strategy of the prisoner’s dilemma game.
I find it very interesting to see examples of cooperation emerging spontaneously, very often for the sake of preserving some balance. There are many examples in our society, such as a football match in which opposing teams decided to cooperate and make it a draw rather than trying to best one another. A more extreme example are two opposing armies in a war; it happens in every war that opposing soldiers decide to cooperate, realizing that doing so actually helps them survive.