At the beginning of formation, collisions of rocks caused Earth to melt repeatedly. Heavy metals sank to the core and lighter elements formed the crust. Volcanic activity and condensation of water vapor formed oceans, seas, and atmosphere. Simple prokaryotic life evolved in these early oceans.
The Cryptozoic Eon (4.6–570 million years ago) covers the early formation of Earth and the first unicellular life.
The Palaeozoic Era (570–240 million years ago) saw the evolution of multicellular animals, plants, and amphibians.
The Mesozoic Era (240–65 million years ago) is the age of dinosaurs and reptiles.
The Cenozoic Era includes the evolution of mammals, flowering plants, and modern ecosystems.
Modern humans evolved about 56,000 years ago with social, cultural, and technological development.