The Fake Laugh
Marlene Breverman stashed this in neurology
How laughter went from a primal signal of safety (the opposite of a menacing growl) to an odd assortment of vocalizations that smooth as much as confuse social interactions is poorly understood. But researchers who study laughter say reflecting on when and why you titter, snicker or guffaw is a worthy exercise, given that laughter can harm as much as help you.
“It’s a hall of mirrors of inferences and intentions every time you encounter laughter,” said Sophie Scott, a neuroscientist at University College London who studies how the brain produces and processes laughter. “You think it’s so simple. It’s just jokes and ha-ha but laughter is really sophisticated and complicated.”
I didn't realize laughter can harm us.