"Why What makes us curious," by Mario Livio (Simon and Schuster, 2017). A fascinating, informative, and except for a couple of chapters that are a bit technical (which Livio warns the reader about), very clearly written discussion of curiosity. What is it Where did it come from What effect does it have on humanity, on evolution He describes four different kinds, charted by the Canadian psychiatrist Daniel Berlyne, along two axes: between Perceptual and epistemic, and Specific and diversive curiosity. Perceptual curiosity is about novelty, ambiguity, puzzling stimuli; it generally diminishes with continued exposure. Epistemic is the general desire for knowledge, curiosity about everything and anything. Specific curiosity is the desire for a particular piece of information, to solve a problem. Diversive curiosity is the restless desire to explore and to see novel stimulation to avoid boredom. With variations and deeper investigation, these seem to cover the territory. He looks at Leonardo da Vinci and Richard Feynman, two indisputable geniuses. Their hallmark was a constant curiosity about everything around them. Leonardo explored any natural phenomenon that struck his fancy. Feynman was the same way. Also, Leonardo would go on for a while until either he found a solution or decided the problem was too frustrating or impossible to resolve. Livio delves into the chemical, DNA and biological elements that seem to create curiosity in people (this is the part that slowed me down). Basically, he says, it may be that curiosity is the thing that made us finally human (he looks at how the brain evolved, growing in size). One thing I missed is that he did not deal with curiosity among animals: predators tend to be more curious than herbivores: anything could be a source of food. Ultimately he makes a plea for continued curiosity in our culture: support of science and openness. He talks about how only open societies enable continued curiosity. Systems where the authorities think they have the answers do not want questions; they don't want discoveries that might upset their system. Think of Galileo and the Church (or any of those early astronomers): if the earth was not the center of the universe; if it was not unique; then the entire cosmology and belief structure was threatened with collapse. Also consider Darwin and faith. Good book. Fun, too.