We eat a lot of chicken. But we didn't used to. What changed? In part, what changed was the discovery that antibiotics could build a bigger, better chicken. Now, the big chicken may be suffering the results of too much medicine. This week, we hear from science journalist Maryn McKenna about her new book "Big Chicken: The Incredible Story of How Antibiotics Created Modern Agriculture and Changed the Way the World Eats." We'll also hear from zoonotic disease specialist Tara Smith about the challenges scientists face trying to get out of the lab and into the pigpen. This episode is...