Where do we come from? It's one of the most difficult questions humanity has ever asked. From the beginning, religion has proposed more or less fanciful solutions to this enigma. But since we invented the scientific method—the best tool we have for approaching reality—we have begun to better understand the true origin of life as we know it. We are far from a definitive answer, but we have now discovered several of the long and complicated processes that have led to the emergence of intelligent beings on this planet.