Charles Robert Darwin FRS (12 February 1809 – 19 April 1882), an English naturalist. He established that all species of life have descended over time from common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection, this theory thouroughly explored in his book On the Origin of Species. In modified form, Darwin's scientific discovery is the unifying theory of the life sciences, explaining the diversity of life. Apart from the study of evolution of the species, Darwin also published his observations on human evolution and sexual selection as well as other significant research of the natural world.