Kristophe Green and Dacher Keltner wrote this article for Greater Good. Kristophe is a senior Psychology major at UC Berkeley. He is fascinated with the study of positive emotions and how they inform pro-social behavior such as empathy, altruism and compassion. Dacher is the founding director of the Greater Good Science Center and a professor of psychology at the University of California, Berkeley. He is the author of The Power Paradox: How We Gain and Lose Influence and Born to Be Good, and a co-editor of The Compassionate Instinct.