It turns out
there's another name for that Manhattan phenomenon commonly called "sidewalk rage."
While it sounds like an oxymoron, altruistic punishment is basically how social norms get enforced. So when you expel a huffy "Excuse me!" to the rude sidewalk clogger in front of you who has stopped midstride to check his BlackBerry, you're trying to discourage behavior that endangers other members of the society. It's called "altruistic" punishment, because your efforts to protect civility come at personal cost with little chance of personal benefit: you are far more likely to get an obscene gesture or even a punch in the mouth than a thank you.
Many evolutionary psychologists believe, however, that without altruistic punishment, cooperation could not have evolved. In simulations of "selfish" versus "cooperative" strategies for living, for instance, researchers have found that altruistic or cooperative creatures beat out selfish ones only in an environment in which the failure to cooperate is actively detected and punished. Sidewalk rage — anger over the selfish violation of a cooperative social norm that protects the group — is a nice example of that.
What's the altruistic punishment for the people who argue about their coupons at Walgreens?
It turns out there's another name for that Manhattan phenomenon commonly called "sidewalk rage." 
