How many faces do you show the world? Happy, sad, surprised, scared, mad, excited? Yes, all those and more. Facial expressions are the way our brains move the muscles in our faces to  express the way we feel. We raise our eyebrows in surprise, we lower our eyelids in shyness, and we smile with happiness. That last facial expression is the one we most like to experience ourselves as well as to see in others.

We know what a happy smile looks like on the faces of our friends and families, but do our animals smile? And if they do, does the control of the facial muscles that create that smile come from some kind of emotion?