Remember the Christmas your grammy gave you that "unique" zebra sweatshirt with the puffy paint and rhinestone embellishments?... We humans exchange contrived smiles quite often in order to be sociable. But humans aren't the only ones who share fake (um, I mean "polite") smiles. I recently stumbled across this excellent blog: Field Notes from an Evolutionary Psychologist, and there's a wonderful posting about chimp smiles. The picture above shows a genuine chimp smile (adorable!), while the photo below displays a fake smile (very jazzhandsy!) If you love chimps, visit her site for loads more interesting, thoughtful, (and really cute!) primate stuff.