Tuesday, 23 May 2017

epoch and era

Via Kottke, we learn of Professor Olivia P Judson’s proposal to parse the history of life on Earth into ages not typified by geology or the complexity of biology per se but rather into energetic revolutions.
Evolution of life from its earliest forms, which populated the planet not long after inception, up to the present day can be framed within the context of five energy expansions, beginning with the geochemical processes that break down nutrients into usable forms (exobiologists expect to find alien life on distant, cold worlds that similarly exploit background processes like radiation or environmental—rather than internal—chemistry as a food source). Solar power comes next followed by the great Oxidation Event once the terraforming archaea of earlier stages had crossed a threshold that allowed respirating life to emerge. Each stage exhibits a higher level energy-efficiency with flesh (carnivorous behaviour) being developed before finally harnessing fire.