The history of the evolution of life on Earth is divided into four eons: Hadean, Archean, Proterozoic, and Phanerozoic. Phanerozoic includes three eras: Paleozoic, Mesozoic, and Cenozoic. Over 4 billion years of evolution, many simple organisms, complex plants and animals have appeared. The evolution of the genus Homo lasted 2 million years. During this time many species of people appeared and disappeared. The ancestor of the first species of the human genus could be Australopithecus afarensis.