I just finished the strangest, most disconcerting little book. It's called Why Do People Sing?: Music in Human Evolution by Joseph Jordania. If the title hasn't already piqued your interest, its thesis surely will. The thesis is wild, bold, and original, but makes an eerie amount of sense. If true, it would be a revolution — and I don't use the term lightly — in how we understand the evolution of music, cooperation, warfare, and even religion.