First, a simpler topic. Research on rhesus monkeys (attached) shows that neurogenesis (adult brain development) stops and depression sets in when the monkey loses a dominance struggle. From this, we imagine it was in the monkey's best interest to get depressed. He's just proven that he can't defeat the competitor. If his confidence stayed high, he might fight again and get killed. This line of thinking says that his self-imposed penalty helps him survive.

In the case of social rejection however, how can we imagine a benefit to self-imposing a 25% loss in our own IQ? How can you recover (e.g. find another mate, find another tribe) if you make yourself dramatically dumber? Let's assume that it can't be a direct benefit to punish yourself so it must be something else.

We fear rejection, perhaps due to the terrifying mental damage it causes. But why wouldn't we just decline to punish ourselves? People that did this would tremendously out-perform those poor, neurotic self-punishers... so why not?

What if fear of rejection is what makes us attractive to others and makes us obsess about our social standing and relationships. If that were true, it would be the glue that holds human culture together. The difference between us and solitary creatures is that our feelings are hurt when others don't like us. Said more clearly, we hurt our own feelings (and apparently IQ) when we are rejected.

Perhaps this explains the existence of sociopaths. Perhaps they represent Nietzsche's Overman. They feel no pain from social rejection, in fact, they decline to do so. This makes them powerful and scary since they lack the limits that we believe keep us under control. Richard Kuklinski, the assassin, on the subject of how he felt about killing: "I don't ... I don't have a feeling one way or the other ... nothing haunts me."

Following this line of thought, if we didn't fear rejection, the world we know could never hold together.