Our Sense of Fairness is Biological
Scientists at the California Institute of Technology gave 20 pairs of men $30 each and awarded one of them a bonus of $50. Using fMRI, they looked at the lucky guy's brain while they asked him how he'd feel if another $50 went to him or to his partner in the experiment. When he considered it going to his partner, his brain's reward centers lit up; equality outweighed his own self-interest. In what can seem like a dog-eat-dog world, it's heartening to know we're all at least wired for goodness.