On this edition of Conversations, David Quammen talks with host Dan Skinner about his latest book, “The Heartbeat of the Wild: Dispatches from Landscapes of Wonder, Peril, and Hope,” published by National Geographic. Quammen is one of the world’s top nature and science writers. He is the author of 17 books and a regular contributor to “National Geographic,” “The New Yorker,” and the “New York Times.”