Jean-Baptiste LemarckLemarck gave his first solid lecture on his theory of evolution. It outlined that enviromental changes made to a living organism could be passed down from generation to generation.
Alfred WallaceAlfred Wallace had developed the same ideas as Charles Darwin independently, they had even been working together. When Darwin discovered that Wallace had developed the same ideas as him, he went against his own wishes, and published a book called 'On The Origin Of Species'.
Charles DarwinSailing with the HMS Beagle, Darwin's notebooks and pressing pads exploded with ideas and specimens. His ideas were constantly supported by the evidence of evolution he was finding. He put forth the idea that species evolve when the fittest of the race bred and created more fit beings, while the weaker died off. This is called 'Natural Selection'.
Julian HuxleyIn 1938, Huxley published three reports on evolutionary topics.Two were on sexual selection, an idea of Darwin's whose standing has been revived in recent times. He was among a team of scientists who incorporated genetics into evolution, to come up with out current theory of evolution. Evolution... is the most powerful and the most comprehensive idea that has ever arisen on Earth.
— Sir Julian Huxley
'Education and Humanism', in Essays of a Humanist (1964),