The summer olympics are in full swing. Humans are racing against other humans from all across the globe. But you know the one race they don’t have? The one where a human competes against a horse. Radiolab for Kids is back with one of our favorite Radiolab animal episodes of all time where we head to that race in the desert of Arizona. Turns out it has everything to do with what gives us humans… our humanity. Also our butts.

In this episode, Reporter Heather Radke and Producer Matt Kielty talk to researchers who followed the butt from our ancient beginnings through millions of years of evolution, all the way to today, out to a valley in Arizona, where our butts are put to the ultimate test.

Check out Heather's book Butts - A Backstory
Special thanks to Michelle Legro.

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Support for Terrestrials is provided by the Simons Foundation, the Arthur Vining Davis Foundations, the Kalliopeia Foundation and the John Templeton Foundation.