Charles Darwin:
Charles Darwin was an English biologist, naturalist and others. He contributed to science in many different way, but he's most regarded for his evolution theory which can be found in his famous book, On the Origin of Species.
Evolution, Darwinism:
When he first published his book many people thought he was crazy and that his theory was a total blasphemy, and they even created what we would now call a meme, as we can see in the first image. Turns out, the book was published in 1859, which meant he had enough evidence to prove his theory due to the fact that in 1831 he did his famous voyage in the HMS Beagle to the Galapagos, where he studied different species of finches.
But, going deeper in to the theory, he suggested that animals developed in tiny steps as natural selection went causing modifications to their genes so that they could be more competitive in their environment. That was also part of his proposal to how new species originated - at one point, so many changes would have occurred that the product of natural selection would be a total new species.
A visual way of representing his theory would be with the famous "monkey-scale" where we can see how our upright and non-hairy appearance originated, as we can see in the second image.
Hope it helped,
BiologiaMagister