When Was the Theory of Evolution Published?

On 24 November 1859, Charles Darwin published "On the Origin of Species by Means of Natural Selection." The entire first print run of 1,250 copies sold out on the first day. Darwin had developed his theory over 20 years, drawing on observations from his five-year voyage on HMS Beagle (1831-1836), particularly in the Galápagos Islands. The book argued that species change over time through natural selection: individuals with traits better suited to their environment are more likely to survive and reproduce, passing those traits to offspring. Alfred Russel Wallace independently conceived a similar theory, prompting Darwin to finally publish.