The initial formation of primitive living structures (protocells) is thought to require a specific supporting chemical environment
- Early Earth had a chemically-reducing atmosphere, which when exposed to energy in various forms (heat, electrical discharge, etc.) produced a variety of simple organic compounds (monomers)
- These compounds accumulated in a molecular ‘soup’, allowing for the formation of more complex compounds (polymers)
There are a number of locations posited as providing suitable conditions for the formation of a concentrated chemical soup, including volcanoes, hydrothermal vents, shorelines and outer space
1. Volcanoes
- The gas composition of volcanic eruptions contain high levels of fixed nitrogen and other raw materials which could be used for primitive metabolism
- Intensive volcanic activity could also generate sufficient thermal energy to catalyse the formation of organic molecules
2. Hydrothermal Vents
- Hydrothermal vents are regions of the ocean floor where superheated water is released from the Earth’s crust
- These vents also release hydrogen-rich fluids to create a chemical gradient and pH viable for organic synthesis
3. Shorelines
- Organic life may have evolved at a sea shore or other region where there is an alternation of wet and dry conditions
- The drying of clay particles could have precipitated catalysing reactions needed for the formation of organic molecules
4. Extraterrestrial Origins
- The necessary conditions required for the formation of life may have initially been derived on other planets (e.g. Mars)
- Comets contain a variety of organic material (~20% of a comet’s tail is comprised of organic matter)
- Heavy meteorite bombardment approximately 4 billion years ago may have delivered organic material to the Earth
- The theory that life on Earth was initially seeded in space or on another planet is called panspermia
Possible Origins for Life on Earth
