In the early 1800s, most people, scientists included, accepted as fact that every species was specially created by God in a form that never changed. The epic voyages and revolutionary insights of two brave young British naturalists, Charles Darwin and Alfred Russel Wallace, overturned this long-held idea. Prodigious collectors of animals and plants, each man developed a keen appreciation for the variation within species, the relatedness of species, and the patterns of geographic distribution—evidence that was hard to reconcile with special creation. This hard-earned knowledge led each to ask why and how creatures came to live in a given place.