Charles Darwin’s 200th birthday is Feb. 12, and he is still controversial. A new book, "Darwin’s Sacred Cause," just published by two British science historians, argues that the "source of the moral fire" of Darwin’s quest to understand human origins was rooted in his hatred of slavery, and his wish to show that all human beings had similar roots. The authors are James Moore of Britain’s Open University and Adrian Desmond of University College London. They have profiled Darwin before, and now say they’ve found new documents and letters from his family. "We are not trying to explain away all of Darwin’s work as being due to his passion for emancipation, but our argument is that his passion for racial unity is what drove him to touch this untouchable and treacherous subject," says Moore in London’s Telegraph. "Darwin was finally goaded into starting his work on the origins of man in 1865 by a rising tide of scientific belief that the races were separate species."