This week we go deep and we go long, considering the tide of human history. How science, reason, and rational inquiry contribute to human progress.

Dr. Michael Shermer is our guest. He's the Founding Publisher of Skeptic magazine, a monthly columnist for Scientific American and a regular contributor to Time.com.

In his latest book, The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom, he claims that we are living in the most moral period of our history.