"Piltdown Man" might be the most famous scientific hoax of all time. This skull, which was originally "found" by collector Charles Dawson, fooled most of the world's paleontologists into believing it represented a key missing link on the ape-human evolutionary chain. The hoax survived for 40 years before finally being revealed as a fraud in 1953. In fact, the skull turned out to be nothing more than a modern human cranium attached to the jawbone of an orangutan.