Support WBURWe Went From Hunter-Gatherers To Space Explorers, But Are We Happier?Play05:45Download AudioNPR StaffFebruary 07, 2015 ShareUntil about 30,000 years ago — around the same time these animals were drawn on the walls of France's Chauvet Cave — there were at least five other species of humans on the planet. (AFP/Getty Images)
