Novelist Siri Hustvedt knows how the creative process feels. Neuroscientist Heather Berlin knows what it looks like in the brain. Together with Steve, they explore the emerging science of creativity.

Thousands of sandhill cranes gather each fall on the banks of the Wisconsin River before they head south for the winter. Anne and Steve visited the Aldo Leopold Foundation in Baraboo, Wisconsin to witness this migration firsthand, along with their guide: wildlife ecologist Stan Temple.

The fact that so many animals migrate — sometimes thousands of miles — has puzzled people over the ages. Why do they take such risky journeys? Conservation biologist David Wilcove studies migration, and he says the scale of migration is staggering.