Ever walk with a friend and find yourself automatically matching their stride? The Chameleon effect compels us to ape the movements and behaviors of the people around us. So when the uptight Victorians in this video break out in a grin, our subconscious mind automatically has us joining the party.

You probably feel just a wee bit more spry after that little smiling spree. Crooners from Frank Sinatra to Katy Perry have long told us that smiling makes us more chipper, but is it really true? What does the brain science tell us?

Australian researchers asked participants to hold a pen in their teeth. This forced their facial muscles to replicate the movements of a smile.

The research found that this forced smiling stimulated the amygdala, the emotional center of the brain. This released neurotransmitters which encouraged a positive emotional state.