Charles Darwin named natural selection after studying variation in organisms during and after the HMS Beagle voyage.
Darwin sailed on HMS Beagle from 1831 to 1836 as the ship’s naturalist. His observations in South America and the Galápagos Islands helped him recognize that related organisms could differ from island to island. Finches, tortoises, and mockingbirds were especially important examples.
Darwin initially used the phrase “descent with modification” more often than “evolution.” He developed natural selection as an explanation for how inherited differences could accumulate when some individuals survived and reproduced more successfully than others.
Alfred Russel Wallace independently reached a similar conclusion, but Darwin had already spent years developing and documenting his theory. Darwin and Wallace jointly presented their ideas in 1858, before Darwin published On the Origin of Species in 1859.