This theory was given by Oparin and Haldane and stated that life originate...
The theory of chemical evolution or Oparin-Haldane theory:
This theory was given by Oparin and Haldane and stated that life originate from pre-existing non-living organic molecules. i.e., RNA, protein etc... And this also states formation of diverse organic molecules from inorganic constituent. The condition on the earth favouring chemical evolution were high temperature, volcanic storms, reducing atmosphere containing CH4, NH3 etc...
Experimental evidence of chemical evolution or Stanley Miller's experiment
S L Miller and H C Urey performed an experiment in 1953 for chemical evolution.
He created electric discharge in a closed flask containing CH4, H2, NH3 and water vapours at 800 oC.
After few weeks he observed formation of amino acids and complex molecules like sugars, nitrogen bases, pigments and fats in the flask.
Conclusion:
It provides the experimental evidence for the theory of chemical origin.
It showed that the first non-cellular form of life was created about 3 billion years ago.
It showed that non-cellular biomolecules exist in the form of DNA, RNA, polysaccharides and proteins. Formation of first cell first non-cellular.