Darwin's theory of evolution is based on what process?

Darwin's theory of evolution is based on natural selection, the process by which heritable differences affect which organisms survive and reproduce. Over generations, advantageous traits tend to become more common in a population when they improve reproductive success in a particular environment.

Darwin published his detailed explanation in On the Origin of Species in 1859. He argued that organisms produce more offspring than can survive, individuals vary, and some of those variations are inherited. This creates competition and differences in reproductive success—the basic ingredients of natural selection.

Darwin and Alfred Russel Wallace jointly presented the principle to scientific audiences in 1858. Darwin had developed his ideas partly from observations made during the second voyage of HMS Beagle and partly from Thomas Malthus's writing about population growth and limited resources.

Natural selection is often confused with mutation or artificial selection. Mutation can create new genetic variation, while artificial selection is directed by human breeders. Natural selection is not purposeful or guided toward perfection; it is the cumulative result of environmental conditions and unequal survival and reproduction. Sexual selection is a related but narrower process involving differences in mating success.