Charles Darwin was a British naturalist most famous as the developer of the theory of natural selection as the mechanism behind the origin of species. In a well-known book, "On the Origin of Species" published in 1859, Darwin outlined his theory that animals passed along adaptations to their offspring that became magnified and diverged in succeeding generations until they were so different that a new species existed. He based his theory on his observations collecting specimens in the Galapagos Islands. While his observations on the wide variety of finches on the islands is widely thought to be the origin of Darwin's realization, Quammen gives credence to authors who dispute that the finches played such an important role in Darwin's thinking.