Caricature of Anaximander (c. 611-546 BC), ancient Greek philosopher. With Thales and Anaximines, Anaximander was one of the three great thinkers from Miletus. He believed that everything in the physical world is derived from materials formed out of an infinite mass not subject to age and decay which he called the apeirion. As well as describing the cosmological relationship between the Earth and the other heavenly bodies, he speculated that life first emerged from slime and that humans developed from another species, essentially anticipating the theory of evolution.