We always thought so, but now we know for sure. Smiles are contagious. Research explains that our brains actually make us mimic all facial expressions when we see them in order to understand what others are feeling. Then we’re able to respond to each other appropriately. It’s an instinctive form of communication. So even if we’re not particularly happy, seeing a smile will make us smile. And smiling makes us feel happy. Kinda cool, huh?