Charles Robert Darwin
- was a naturalist who wrote the book: "On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life"
1809 - 1882
(2/12/1809 - 4/19/1882)
In his book on the origin of species Darwin expanded on, and further promoted, an idea published and sent to him a year earlier by his friend and colleague: Alfred Wallace
. The idea was that all the known species in existence today had their origin through a process whereby they evolved from other, existing, species (descended). Evolution was made possible by a process of adaptation through selection of the most fit descendants.
Adaptation via generational selection is often conflated with evolution, which is sometimes even referred to as "the theory of natural selection". The process of selection, however, —both natural and human-directed— was well understood for many centuries before Wallace and Darwin employed it as an explanation for origins of new species.
It has also been posited that natural selection and adaptation, which would be capable of leading to evolution of truly new species, requires small random (possibly merely complex) variations over multiple descendants. Many of the mechanisms by which this could occur have since been filled in by physics at the atomic and sub-atomic levels.