Why we smile? As many simple questions, the answer may be all but simple. As a first assumption, we could answer: 'Sometimes we smile because we see the smile of others'. Then why we yawn? Apparently, not only for similar reasons, but also using muscles in a similar way. The same logic applies to pain, but in the upper part of our face. Mirrored smiles, yawns and painful expressions will be the main topic of this analysis, because the ability to recognize an emotion exclusively on the visual information of somebody else's face is an essential feature for communication and social interaction in a society structured not only on materials and wealth.