Charles Darwin 
The Expression of the Emotions in Man and Animals 

Charles Robert Darwin (12 February 1809 – 19 April 1882) was an English naturalist who established that all species of life have descended over time from a common ancestry, and proposed the scientific theory that this branching pattern of evolution resulted from a process that he called natural selection.He published his theory with compelling evidence for evolution in his 1859 book
On the Origin of Species
, overcoming scientific rejection of earlier concepts of transmutation of species.