Think again if you’ve been assuming curiosity is constant, like gravity. We talk to astrophysicist Mario Livio about his book, "Why: What Makes us Curious". Not only are some people more curious than others, and curious about different questions, but homo sapiens’ capacity for curiosity grew as its brain evolved. For all its variations, Livio deems curiosity an unstoppable drive. Original air date: July 11, 2017.