Reverend Graham points out that the Samaritans and the Jews were enemies at that time. But that did not stop the "Good Samaritan" from helping the injured man.

This idea of helping anyone who needs help is common among cultures and religions.

AARON GRAHAM: "This is a familiar story even beyond the Christian community. One of the things that unites many faiths is this call to love our neighbor. "

FAITH LAPIDUS: Helping others may be a religious duty. But some current research suggests that humans may also have a biological urge, an impulse, to help each other.

Robert Sussman and Robert Cloninger are professors at the University of Washington in St. Louis, Missouri. They worked together on a new book about working together. The book is called "Origins of Altruism and Cooperation." It brings together work by researchers who study crime, brains, genes, history and other subjects.

Bob Sussman is an anthropologist. Robert Cloninger is a professor of psychiatry in the School of Medicine. Dr. Cloninger says social animals, including humans, need to cooperate to survive.

ROBERT CLONINGER: "The need to be a social animal was probably a response to people not being safe just living -- functioning in a solitary way. If they're out in the open field in the bright sunlight they're easily spotted, but in groups they're safer."

ROBERT SUSSMAN: "We think cooperation is the core of social living animals, whereas most people who talk about cooperation think it’s a by-product of competition."