What evidence do we have for the origin

solution:
B.S. Haldane suggested that life must have developed from the simple inorganic molecules which were present on earth soon after it was formed. He speculated that the conditions on earth at that time could have given rise to more complex organic molecules that were necessary for life. The first primitive organisms would arise from further chemical synthesis.

Later on, Stanley L. Miller and Harold C. Urey conducted experiment to find out about the origin of organic molecules. They assembled an atmosphere similar to that thought to exist on early earth (this had molecules like ammonia, methane and hydrogen sulphide, but no oxygen) over water.

This was maintained at a temperature just below $100^{\circ} \mathrm{C}$ and sparks were passed through the mixture of gases to simulate lightning. At the end of a week, $15 \%$ of the carbon (from methane) had been converted to simple compounds of carbon including amino acids which make up protein molecules. This is how, life originated on earth from inanimate matter.