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What makes us yawn?

May 7, 2014•5 min

Yawning is a universal human behavior, yet scientists still don't know exactly why we do it or what purpose it serves. Marshall Brain explores some of the theories behind yawning in this episode.Learn more about advertising on the HowStuffWorks podcasts at www.howstuffworks.com/advertisers.htmAnd to learn about your ad choices when listening to podcasts, visit https://www.howstuffworks.com/privacy.htm#ad-choices