Why Do We Smile

Many species show off their teeth as a threat, so where did humans get our friendly smiles Hosted by: Hank Green SciShow has a spinoff podcast It s called SciShow Tangents. Check it out at Support SciShow by becoming a patron on Patreon: Huge thanks go to the following Patreon supporters for helping us keep SciShow free for everyone forever: Kevin Carpentier, Eric Jensen, Matt Curls, Sam Buck, Christopher R Boucher, Avi Yashchin, Adam Brainard, Greg, Alex Hackman, Sam Lutfi, D. A. Noe, Piya Shedden, KatieMarie Magnone, Scott Satovsky Jr, Charles Southerland, Patrick D. Ashmore, charles george, Kevin Bealer, Chris Peters Looking for SciShow elsewhere on the internet Facebook: Twitter: Tumblr: Instagram: Sources: