Social punishment created powerful selection pressures. Self-control becomes the lowest-cost strategy for avoiding social penalties. Shame and guilt likely evolved as mechanisms for internalizing the logic of team rules—a social contract written into our biology. We intuitively recognize what is considered punishable. And often punish ourselves. Cultures configure shame and guilt system triggers differently. But rules balancing short term individual selfish gain with longer-term or team interests are more evolutionarily productive. Thinking of our evolved urges as irresistible is a deep error, since self-control, especially relative to social rules, has long been needed for survival - http://blogs.scientificamerican.com/guest-blog/2013/05/29/justice-is-in-our-nature/