Chapter 24 Early Life and the Diversification of Prokaryotes Overview: The First cells Chemical and physical processes on early Earth may have produced very simple cells through a sequence of stages: 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into macromolecules 3. Packaging of molecules into protocells 4. Origin of self-replicating molecules Synthesis of Organic Compounds on Early Earth ? Earth formed about 4.6 billion years ago, along with the rest of the solar system ? Bombardment of Earth by rocks and ice likely vaporized water and prevented seas from forming before 4.2 to 3.9 billion years ago ? Earth?s early atmosphere likely contained water vapor and chemicals released by volcanic eruptions