How smart are animals? Humans may not be smart enough to know. That’s conclusion of primatologist Frans de Waal. He says humans tend to observe animal behavior with their own exceptionalism in mind. He bridges the dividing line between humans and animals in his new book "Are We Smart Enough to Know How Smart Animals Are?" We revisit our interview with de Waal about his research into the breadth of animal intelligence. Then, the rhythmic songs of birds and frogs have inspired modern music