Charles Darwin’s publication of On the Origin of Species in 1859 was an extraordinary milestone for science, but it also had profound effects on theology, philosophy, literature, and society in general. Nowhere is this more true than in the United States, where the teaching of evolution has been contentious since the early part of the 20th century. Why have Darwin’s ideas been so valuable– and yet so controversial? The answers lie not in science, but in history and culture.