The origin of the first form of life has been an intriguing concept for many years. Different theories and experimental proofs were forwarded by different scientists during the time interval. Some of these theories were rejected as they failed to provide shreds of evidence while some others were accepted. However, there is no theory that could provide a wholesome view of the origin of life. The following theories have been suggested over the years:
1. Theory of special creation- This theory suggests that all the living forms were created as it is by God. Different religions have different narratives as fas as this theory is concerned. There is no scientific ground for this theory.
2. Theory of Spontaneous generation- This theory suggested for the origin of living forms from the non-living or inanimate objects. Aristotle, Epicurus, Vel Holmont are some of the supporters. They believed that a slice of rotten meat gave birth to the maggots. This was disapproved.
3. Theory of Panspermia- This theory suggested by Richter in 1865 and proposed that life reached the earth from other cosmic bodies.
4. Theory of biochemical evolution or Materialistic Theory- This theory was suggested by Oparin in 1923 and Haldane in 1928. It suggested that primitive earth was reducing in nature due to the absence of oxygen and several chemicals condensed together in oceans, warmed by hot temperature, formed a 'primordial' soup' in which the first living cell took its form. Several amino acids, nucleic acids, sugars and other organic and inorganic molecules together formed coacervated that were capable of absorbing water and nutrients and perform budding. These kept on uniting with more and more molecules and formed the first living cell.
The theory of biochemical origin had been experimentally supported by Urey and Miller, where they developed primitive Earth-like conditions by providing lightning, water vapors, and inorganic molecules and obtained the
Hence, it can be concluded that a little insight exists about the origin of life but there are still more possibilities to explore. With the advancement in scientific technologies, there are chances of gathering more pieces of evidence in this regard.