Assures short term survival of organism as a chemical system. As discussed above, it took some time for these conditions to evolve on Earth. Fossil Evidence - for the origin and evolution of early life is limited. But data suggest that life is at least as old as the oldest rocks now known. Graphite Concentrations - graphite is a mineral consisting of pure carbon that occurs in the oldest known sedimentary rocks.
Archean graphite has the same carbon isotope ratios as found in biological systems today.
Mats trap carbonate mud. Cyanobacteria grow up through the mud to form new mat layer. Amino acids are the building blocks of proteins. These can metabolize. Self Replication - not clear how this developed.