What Is It That Makes Us Take It So Personally?

Behavioral economist David Frum: Why do we take it so personally when we screw up? We'd like to be able to say okay. Well, you know I failed but hey I one step closer to the next success. But why is it that every time we get negative feedback on almost any little happy little thing that happens during the day I feel higher or lower in my self-worth column? He says many of our decision biases have to do with this Incredible need to preserve our sense of self-worth and where does that come from?