Modern theory was proposed by Haeckel and evidenced by the brilliant works of Oparin (1928), Haldane (1928) as well Miller and Urey (1953). The modern theories state that the life arose on the early earth by a series of progressive biochemical reactions.
The entire process presumably involves the following sequence of events:
Chemical Origin of Life:
A.I. Oparin (1922), a Russian bio-chemist opined that complex organic compounds like carbohydrates, fatty acids, glycerol, aminoacids and proteins resulted from the simple compounds under the influence of ultraviolet rays, ionizing radiations, electric charges and heat. This stage of the sea water has been termed by Haldane (1928) as the hot dilute soup. Coacervates are the large organic molecules which were synthesized abiotically on primitive earth. Due to intermolecular attraction they formed large colloidal aggregates. They were capable of growth and division. Sydney fox (1964) called them microsphere and Oparin named coacervates. There was then gradual origin of macromolecules (Polymers) including nucleic acid, followed by origin of Genetic Code and finally the giant molecules of nucleoproteins. These giant molecules could be compared to the present day viruses and were termed as Protovirus (The first living form).
Miller and Urey:
The theory of chemical evolution of life has been evidenced by the experiments of Miller and Urey (1953), who provide the formation of carbohydrates and aminoacids from a mixture of CH4, NH3 and H2O (vapour) under the influence of electric discharges experiments for about one week.
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