Zoologist Bill Schutt argues that teeth were pivotal to the success of vertebrate animals, they're power tools for survival. His latest book is "Bite: An Incisive History of Teeth, from Hagfish to Humans." On this podcast extra, Schutt explains why teeth are key to understanding evolution; the controversy over fluoride in water; and why people once thought decay was caused by tooth worms. Learn more about sponsor message choices: podcastchoices.com/adchoices NPR Privacy Policy