Darwin's Watch: The Science of Discworld III;

When Charles Darwin writes the wrong book and reverses the progress of science, Unseen University’s wizards must once again save Roundworld (Earth, that is) from an apocalyptic end.
 
Ever since a wizardly experiment inadvertently brought about the creation of Roundworld, the wizard scholars of Unseen University have done their best to put things on the right course. In Darwin's Watch they may face their greatest challenge yet: A man called Darwin has written a bestselling book called The Theology of the Species, and his theory of scientific design has been witlessly embraced by Victorian society. As a result, scientific progress has slowed to a crawl, and the wizards must find a way to change history back to the way it should have been.
 
DARWIN'S WATCH EXPLORES THE REVERBERATIONS of major scientific advances on our planet and our culture, the dangers of obscurantism, and the theory of evolution as you have never seen it before. This brilliant addition to Pratchett's beloved Discworld series illustrates with great wit and wisdom how the laws of our universe truly are stranger than fiction.