Empedocles was a philosopher in Acragas, a city-state in Sicily. He lived during the fifth century BCE. He is responsible for the idea that the universe is made up of the four elements fire, water, earth, and air, which are combined by love and torn apart by strife. He had a theory of natural selection where at some point in the history of the world there were all sorts of creatures with combinations of different attributes, like dogs with human heads and humans with six legs (these are just examples, Empedocles did not list these to my knowledge) and so on. It was each organism's ability to cope in its environment that determined whether or not its kind died out or not, and what we have today are the organisms that were best suited for survival in their environment.