Listener Mail: Human Expansion, Tipping in America, and Shoutouts

Disco Funk inspires a strange series of thought experiments. Amdroid writes in on the controversy surrounding tipping. An author gives the gang a special shoutout in their upcoming book. All this and more in this week's listener mail segment.
They don't want you to read our book.: https://static.macmillan.com/static/fib/stuff-you-should-read/
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