Answer:
First scientific theory on origin of life came from Russian biochemist Alexander Oparin which stated that first life on earth appeared through chemical evolution .
Step-by-step explanation:
Chemical evolution theory supports evolution of life through abiogenesis. Oparin's idea received immediate support from Haldane who also thought that life evolved through abiogenesis in primitive ocean which was described as hot prinordial soup by Haldane himself.
Scientific proof in favour of chemical evolution theory came much later through innovative simulation experiments , conceptualised and pioneered by Harold Urey and Stanley Miller in 1950s. Such experiments were conducted in flasks containing gaseous mixtures, closely mimicking primitive atmosphere of earth.
Such simulation experiments showed that biologically important organic molecules like amino acids could have been generated in a reducing primitive atmosphere. Those molecules also generated polymers like proteins. Aggregated protein molecules formed coacervates in the primitive sea; eventually lipid bilayer appeared around coacervates.
Chemical evolution gave rise to nucleotides and first nucleic acid was definitely RNA , which in the beginning of life on earth acted both as a genetic material and as an enzyme inside the first generation of cells.
Answer