For many centuries, scientists and scholars did not question the origin of life on earth. The description of the creation of all life by God found in the book of Genesis was accepted as the only way in which life could be formed. This belief, known as creationism, was supported by the observations made by scientist about the everyday world. Organisms seemed well adapted to their environments and ways of life, as if created specifically to fill those roles. Moreover, most organisms did not seem to change in any observable manner.

However, about 200 years ago, evidence began accumulating that cast doubt upon creationism. As people began to explore the natural world in greater detail, they discovered seemingly bizarre forms of life in remote habitats. Fossils were discovered showing animals that were no longer seen alive. These discoveries led scientists to develop new theories as to the creation of species. Early pioneers in this area included Count George-Louis Leclerc de Buffon, who proposed that species today were not in the same form as when they were created and Jean Baptiste Lamarck, who proposed the mechanisms of use and disuse and inheritance of acquired traits to explain how species might change over time. These theories, though in many ways incorrect and incomplete, paved the way for Charles Darwin, the father of evolution.