A landmark experiment that was designed to provide some answers to this question was conducted by Stanley Miller and Harold Urey, working at the University of Chicago (see Fig. 1-1). Electrical discharges, which simulated lightning,were delivered in a glass vessel that contained water and the gases methane (CH4), ammonia (NH3), and hydrogen (H2),in the same relative proportions that were likely on prebiotic Earth. The discharging went on for a week, and then the contents of the vessel were analyzed chromatographically. The “soup” that was produced contained almost all the key building blocks of life as we know it today: Miller observed that as much as 10–15% of the carbon was in the form of organic compounds. Two percent of the carbon had formed some of the amino acids that are used to make proteins. How the individual molecules might have interacted to form a primitive cell is still a mystery, but at least the building blocks are known to arise under very plausible and readily reproduced physical and chemical conditions