Only on the "CBS This Morning" podcast, CBS News' Elaine Quijano talks with Susan Goldberg, the Editor in Chief of National Geographic magazine, about the August issue on human migration. Goldberg addresses the stories written about refugees displaced from their homes by warfare, poverty and climate change. She also discusses other causes behind the estimated 1 billion people on the move in the world today. Plus, she shares the strategies that made National Geographic the most followed brand on Instagram (and helped them amass more followers than Justin Bieber).