When the young naturalist Darwin set sail on a round-the-world expedition at the end of 1831, it was only with a vague notion that the relationships between all life forms, both present and extinct, were more complex than the Christian version of the world s creation purported them to be. During his five-year voyage of discovery on board HMS Beagle and more than two decades subsequently devoted to research, he painstakingly collected a mass of evidence from across the planet from Paraguay and the Galápagos Islands to Staffordshire and Scotland building a compelling case for the theory of natural selection, which would change the way we look at the world for ever. The founding text of evolutionary biology which prompted a revolution in the fields of science and religion similar in magnitude to the discoveries of Copernicus and Newton Darwin s On the Origin of Species was an instant best-seller when it was published in 1859 and has become a cultural milestone that has influenced a wide range of disciplines of human knowledge.