"Every surface, every bit of air, every bit of water in your home is alive," says scientist Rob Dunn. His new book, 'Never Home Alone,' examines the bacteria, fungi, viruses, parasites and insects we live with — from armpit bacteria to black mold in our walls. Also, linguist Geoff Nunberg chooses 'nationalist' as his word of 2018.In 'Burning,' Steven Yeun plays a mysterious South Korean playboy who may or may not be murdering his girlfriends. "To this day, I'm the only one who knows who Ben really is," he says of the character. He spoke with 'Fresh Air' producer Sam Briger.