In 1831 Darwin sailed around the world aboard the HMS Beagle. He made numerous observations of the geologic and natural processes that helped inform his theory of natural selection. After returning to England, Darwin published on these topics but only decided to publish his theory of natural selection after he received a letter containing a similar idea from Alfred Russel Wallace. In 1859 Darwin published the first edition of On the Origin of Species, a work that drew both praise and criticism. He remained largely out of the public view until his death in 1882. Darwin's work and ideas remain extremely influential today.
Alfred Russel Wallace
Wallace independently conceived of the idea of natural selection. He prompted Darwin to publish On the Origin of Species.
Lyell conceptualized the principle of uniformitarianism and argued against the prevailing theory at the time of catastrophism. His work, Principles of Geology, influenced Darwin's conceptualization of the theory of natural selection.
Huxley was one of Darwin's greatest supporters. Known as "Darwin's bulldog," Huxley often publicly defended Darwin's ideas, and in 1863 published his own book discussing human evolution.
Lamarck believed characteristics acquired during the lifetime of an animal are inherited by their offspring. This is known as Lamarckian evolution, which preceded Darwin's theory of natural selection.