First up, we the streets. Join us in Times Square as we poll dozens of people waiting in line to buy discount Broadway tickets. Share in the outrage and mental grunt-work as these thrifty theater-goers try to answer tough moral quandaries. The questions -- which force you to decide between homicidal scenarios -- are the same ones being asked by Dr. Joshua Greene. He'll tell us about using modern brain scanning techniques to take snapshots of the brain as it struggles to resolve these moral conflicts. And he'll describe what he sees in these images: quite literally, a battle taking place in the brain between an "inner chimp" and a calculator-wielding rationale.

Then, we move from inner chimp to outer. Dr. Frans de Waals lets us watch a chimp fight at the Yerkes National Primate Research Center in Atlanta. And we turn our navel-gazing toward the furrier navels of the chimps to learn a little more about this thing called morality: where it comes from, its evolutionary benefit, and why you can't guilt-trip an ape.

Read more:

Joshua Greene: Moral Tribes: Emotion, Reason, and the Gap Between Us and Them

Frans de Waal: The Bonobo and the Atheist: In Search of Humanism Among the Primates