In the Middle Ages, people married, had children, went off to war and took on all the traditional trappings of adulthood by their early teens. But today many people put off those trappings until well into their thirties. Some have even suggested that we need a new vocabulary to describe the variety of life stages experienced by 21st century humans. John and Ken explore the new adulthood with Ethan Watters, author of Urban Tribes: A Generation Redefines Friendship, Family, and Commitment, in a program recorded in front a live audience at the Marsh Theater in Berkeley, California.