After the theory of evolution is called into question by a group of radicals led by Dr. Banjo on Earth, Professor Farnsworth drags the crew with him to a lifeless planet to live.  While on the planet, the Professor unleashes some nanobots to clean the water and the robots soon evolve through various stages of life including dinosaurs and up to talking humanoids.  When the Professor claims to have invented them, they put him on trial, by eventually evolve into beings that no longer care and the Professor and crew head back to Earth to prove that evolution exists.  Dr. Banjo is willing to admit that they proved evolution... but that it was still created by a higher being, thus proving that creationism still exists.  Sure, we'll buy it.