In "The Greatest Show on Earth" Dawkins takes on creationists, including followers of 'Intelligent Design' and all those who question the fact of evolution through natural selection. He sifts through fascinating layers of scientific facts and disciplines to build a cast-iron case: from the living examples of natural selection in birds and insects; the 'time clocks' of trees and radioactive dating that calibrate a timescale for evolution; the fossil record and the traces of our earliest ancestors; to confirmation from molecular biology and genetics.