Sam Harris speaks with Robert Sapolsky about the brain and human behavior. They discuss the relationship between reason and emotion, the role of the frontal cortex, the illusion of free will, punishment and retributive justice, neurological disorders and abnormal behavior, the relationship between science and religion, and other topics. Robert Sapolsky is a professor of biology and neurology at Stanford University and the recipient of a MacArthur Foundation genius grant. He is the author of A Primate’s Memoir, The Trouble with Testosterone, Why Zebras Don’t Get Ulcers, and Behave: The Biology of Humans at Our Best and Worst.   Episodes that have been re-released as part of the Best of Making Sense series may have been edited for relevance since their original airing.