Why is it that we care about other people? Why do we have those feelings? Also, at a cognitive level, how is that implemented? Another way of asking this is, are we predisposed to be selfish? Do we only get ourselves to be cooperative and work for the greater good by exerting self-control and rational deliberation, overriding those selfish impulses? Or are we predisposed towards cooperating? So in these situations where it doesn't actually pay, if we stop and think about it, rationality and deliberation lead us to be selfish by overriding the impulse to be a good person and help other people. 

DAVID RAND is an associate professor of psychology, economics, and management at Yale University, and the director of Yale University’s Human Cooperation Laboratory. David Rand's Edge Bio Page [2]