(Note: This interview originally aired earlier this year.) Our guest is Frans de Waal, a professor in Emory University's Psychology Department as well as the director of the Living Links Center at the Yerkes National Primate Research Center. He joins us to discuss his book, "Mama's Last Hug: Animal Emotions and What They Tell Us about Ourselves." Per The New York Times Book Review, the book is "game-changing.... For too long, emotion has been cognitive researchers' third rail.... But nothing could be more essential to understanding how people and animals behave. By examining emotions in both, this book puts these most vivid of mental experiences in evolutionary context, revealing how their richness, power, and utility stretch across species and back into deep time.... The book succeeds most brilliantly in the stories de Waal relates."