How can people be so caring and sometimes cruel? What are the evolutionary, genetic, epigenetic, developmental, familial, tribal, community and cultural determinants that allow human beings to be heroic and give their own life for others or be killers and unbelievably cruel. Stanford biology professor Robert Sapolsky‘s book, Behave: The Biology of Humans at Our Best and Worst, explores what drives human behavior. It is a remarkable tour de force to explore and explain why we do as we do. Watch his February 6, 2018 lecture at the Jewish Community Center of San Francisco.