"Experiments show that when some people punish others, the reward part of their brain lights up like a Christmas tree. It turns out we humans avidly engage in something anthropologists call “altruistic punishment.”
What is altruistic punishment? It is when a person punishes someone who has done nothing against them personally but has violated what they perceive to be the norms of society. Why “altruistic”? Because the punisher is doing something that benefits society at large, with no immediate personal gain. Altruistic punishment is normally a good thing. Our entire criminal justice system is based on it. In our evolutionary past, small groups of hunter-gatherers needed enforcers, individuals who took it upon themselves to punish slackers and transgressors to maintain group cohesion. We evolved this way. As a result, some people are born to be punishers. They are hard-wired for it.
What does all this have to do with Amanda Knox? Almost all the nasty comments about her follow a pattern. Even though she did nothing to them, they are all demanding her punishment. This is altruistic punishment gone haywire, in which the anti-Amanda bloggers have become a cybermob not unlike the witch-hunts of medieval Europe or lynch mobs in the American South. These mobs form all over the Internet, and not just in the Amanda case, assailing everyone from Anne Hathaway to Katie Roiphe. Everywhere you look on the Internet you find self-appointed punishers at work. Never in human history has a system developed like the Internet, which allows for the free rein of our punishing instincts, conducted with complete anonymity, with no checks or balances, no moderation, and no accountability. On the Internet, our darkest evolutionary biology runs riot.