The publication of The Origin of Species in 1859 was the culmination of more than twenty years of work by Charles Darwin and the ideas he presented in it would lead to a fundamental change in the way we think about life on earth. Evolution, as it came to be known, described how the extraordinary variety of life could develop and adapt by natural means rather than being entirely the creation of a supreme being. It was controversial at the time and now, as the bicentenary of Darwin's birth approaches in 2009, it remains the subject of bitter argument, with the opposing sides of the debate, the supporters of Darwinian evolution like Richard Dawkins and the proponents of intelligent design, as polarised as they have ever been. Bill Price looks at the origins of Darwin's theory and the arguments that have surrounded it ever since.