Charles Darwin proposed natural selection in On the Origin of Species, published in 1859.
Darwin’s book, first published in London on November 24, 1859, argued that species change over generations and that natural selection can drive adaptation. Individuals vary, some variations are heritable, and organisms with advantageous traits are more likely to survive and reproduce in particular environments.
Darwin developed his ideas through observations made during the voyage of HMS Beagle, especially in South America and the Galápagos Islands. He also studied domesticated plants and animals, using selective breeding as a comparison for change in nature.
Alfred Russel Wallace independently developed a theory of natural selection, and a joint presentation of their ideas took place in 1858. Darwin’s book provided the fuller argument and extensive evidence. It did not explain genetics, which was later clarified through the rediscovery and development of Gregor Mendel’s work and modern evolutionary biology.