Machines, competition, empire and progress fascinated the Victorians. One of the most famous scientific theories of the era, Charles Darwin's theory of natural selection, tells of machine-like organisms that compete, colonise and improve. To notice resemblances such as these, between the context of Darwin's theory and its content, is nothing new. In 1862, Karl Marx, in a letter to his collaborator Friedrich Engels, wrote: 'It is remarkable how Darwin recognises among beasts and plants his English society with its division of labour, competition, opening up of new markets, “inventions”, and the Malthusian “struggle for existence”. It is Hobbes' “bellum omnium contra omnes” [“the war of all against all”].' In our own day, debates over the cultural conditioning of scientific knowledge have made this old insight newly problematic. This chapter attempts to clarify these new problems. Drawing on recent thinking about culture and science, it looks at how Darwin's social, material and intellectual culture conditioned the form and content of his theory of natural selection. One view may be dispensed with at the start: that Darwin developed the theory of natural selection because he was a genius, and, since geniuses do not belong to mundane history like most people, it is pointless to ask about the cultural conditioning of his theory.