I began by analyzing lists of virtues from around the world. Virtues are social constructions. The virtues taught to children in a warrior culture are different from those taught in a farming culture or a modern industrialized culture. There’s always some overlap among lists, but even then there are different shades of meaning. Buddha, Christ, and Muhammad all talked about compassion, but in rather different ways. Nonetheless, when you see that some version of kindness, fairness, and loyalty is valued in most cultures, you start wondering if there might be some low-level pan-human social receptors (analogous to taste receptors) that make it particularly easy for people to notice some kinds of social events rather than others.