Animal evolution: historical perspective.

Evolution is the theory that biological species undergo sufficient change with time to give rise to new species. The concept of evolution has ancient roots. Anaximander suggested in the sixth century BCE that life had originated in the seas and that humans had evolved from fish. Empedocles (fifth century BCE) and Lucretius (first century BCE), in a sense, grasped the concepts of adaptation and natural selection. They taught that bodies had originally formed from the random combination of parts, but that only harmoniously functioning combinations could survive and reproduce. Lucretius even said that the mythical centaur, half horse and half human, could never have existed because the human teeth and stomach would be incapable of chewing and digesting the grassy food needed to nourish the horse’s body.