The English naturalist Charles Robert Darwin (1809-1882) discovered that natural selection was the agent for the transmutation of organisms during evolution, as did Alfred Russel Wallace independently. Darwin presented his theory in Origin of Species.

The concept of evolution by descent dates at least from classical Greek philosophers. In the eighteenth century Carl Linnaeus postulated limited mutability of species by descent. But most naturalists were concerned with identifying species, the stability of which was considered essential for their work. Natural theology regarded the perfection of adaptation between structure and mode of life in organisms as evidence for a predetermined divine plan.

Charles Lyell wrote his Principles of Geology (1830-1833), which Darwin on his Beagle circumnavigation found extremely useful. Fossils in South America and apparent anomalies of animal distribution triggered the task for Darwin of assembling a vast range of material. Reading Thomas Malthus's Essay on the Principle of...