Why Do We Laugh?

Knock knock! Who’s there? It’s Jessi and Squeaks exploring the science of why we laugh!
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SOURCES:

http://www.bbc.com/future/story/20140...
https://science.howstuffworks.com/lif...
https://www.scienceabc.com/humans/sci...
http://www.slate.com/articles/arts/cu...
http://www.nbcnews.com/id/3077386/ns/...
https://www.sciencealert.com/watch-he...
https://www.webmd.com/men/features/wh...