One of my favorite things to do when I’m out and about is smile at people. The responses to this are varied. Sometimes, I get no response because they never notice me smiling at them. But sometimes, I ...

“When you’re smiling, when you’re smiling, the whole world smiles with you.” Yes, the old song is right; smiles are contagious! But that’s just one of the superpowers of a smile. Various researchers ...