The Origin of Darwin

Kottke points to an article saying the theory of evolution had been around for centuries, and that Darwin hadn't invented it. He just formalized it and provided some evidence. I also read a biography of FA Hayek once (I think it was this one anyway) that said Darwin stole the idea of evolution from Adam Smith, since the idea of spontaneous order and natural selection is essentially Smith's idea of the invisible hand (which also probably didn't originate with him, either).