Terry Gross

Scientists think an asteroid killed the dinosaurs. In today's extinction, humans are the culprit.

In his new book, Dr. Kevin Fong explores how humans survive extremes of heat, cold, outer space and deep sea. "We're still exploring the human body and what medicine can do in the same way that the great explorers of the 20th century and every age before them explored the world," he says.

Kayla Williams and Brian McGough met in Iraq in 2003. Williams' new memoir, Plenty of Time When We Get Home, describes their homecoming after McGough suffered physical and cognitive injuries in an IED explosion.