Charles Darwin

Charles Darwin was an English naturalist whose theory of evolution by natural selection reorganised biology around a single mechanism. He spent five years aboard the Beagle collecting the observations that prompted it, then two decades assembling evidence before publishing On the Origin of Species in 1859. He was a careful writer as well as a careful scientist, and his later books on human descent, emotion and earthworms show the same habit of following an ordinary question a very long way.