Did you know that some of the bacteria living inside us are essential for our health? Gastroenterologist Ari Grinspan delves into the complex world of the microbiome in the human digestive system. He explains how transplanting bacteria from healthy people to patients with a debilitating, sometimes lethal, disease has had astonishing success—despite a method of transfer that might be a little surprising. This SciCafe took place at the American Museum of Natural History on January 4, 2018. Subscribe to the Science@AMNH Podcast on iTunes, Soundcloud, or wherever you get your podcasts. The Scicafe Series is proudly sponsored by Judy and Josh Weston. SciCafe: The Power of Poop and related activities are generously supported by the Science Education Partnership Award (SEPA) program of the National Institute of Health (NIH).