Dave Davies

ProPublica investigative reporter Peter Maass says that cellphone companies monitor where we are, who we call, what we buy -- and often provide it to law enforcement when requested. "They are collecting a heck of a lot more information than we expect them to be collecting about us," he tells Fresh Air.

Thor Hanson's new book looks at the evolutionary significance of feathers in birds. Hanson tells Fresh Air that he's amazed by birds' magnitude of feathers, how feathers grow and how they're the "most efficient insulation known."

In The Long Road to Antietam, historian Richard Slotkin traces how both Northern and Southern strategies changed in the summer of 1862, when both sides committed to an all-out total war, and Lincoln squared off against Gen. George McClellan.