This week, we are presenting an encore of a 2017 conversation with Dr. Robert Sapolsky. Sapolsky is a primatologist and neurologist with a unique gift for storytelling. Oliver Sacks called him “one of the best scientist-writers of our time”. Sapolsky has spent decades studying primate behavior. One of his most consuming fascinations is how humans are both the most violent species on earth – as well as the most altruistic, cooperative, and empathetic. That paradox, and the factors behind it, are the subject of his most recent book “Behave: The Biology of Humans at Our Best and Worst”. On May 22, 2017, Robert Sapolsky talked with psychology professor Dacher Keltner at the Nourse Theater in San Francisco.