Book excerpt: Humans are unique in shedding tears of sorrow. We do not just cry over our own problems: we seek out sad stories, go to film and the theatre to see Tragedies, and weep in response to music. What led humans to develop such a powerful social signal as tears, and to cultivate great forms of art which have the capacity to arouse us emotionally? Friedrich Nietzsche argued that Dionysian drives and music were essential to the development of Tragedy. Here, the neuropsychiatrist Michael Trimble, using insights from modern neuroscience and evolutionary biology, attempts to understand this fascinating and unique aspect of human nature--Book jacket.