Expressly Human: Decoding The Language of Emotion

Over billions of years of evolution, animals have become increasingly sophisticated and increasingly sentient. In the process, they evolved emotions, which helped improve their odds of survival in complex situations. These emotions were, at first, purely internal. But at some point, social animals began expressing their emotions, in increasingly dramatic ways. These emotional expressions could accurately reflect internal emotions (smiling to express happiness)-or they could be quite differe...