Formation of Organic Compounds 

 on the Primitive Earth 



STANLEY L. MILLER 



Department of Biochemistry, College of Physicians and Surgeons, 

 Columbia University, U.S.A. 



One of the most fundamental problems of biology is posed by the question, 

 'How did Ufe arise on the Earth'. The Theory of Evolution offers an explanation 

 for the development of complex multi-celled living organisms from single-celled 

 organisms, but this theory does not explain the development of the first organism. 

 To assume that hfe arose from inorganic matter presents overwhelming difficulties. 

 Not only would a self-duplicating organism have to be made from the inorganic 

 matter, but the organism would have to contain the complex apparatus to syn- 

 thesize all its components and energy requirements from carbon dioxide, water 

 and light. 



Oparin [i] in his book The Origin of Life proposed that spontaneous genera- 

 tion of life would be less difficult if the ocean contained a large amount of 

 complex organic compounds similar to those present in living organisms. These 

 compounds would serve both as structural components and as the energy source 

 for the first organisms. Oparin also proposed that the Earth had a reducing 

 atmosphere of methane, ammonia, water and hydrogen in its early stages, and 

 that organic compounds might be formed under these conditions. Bernai [2] 

 has given a similar discussion. 



Urey [3, 4] based his arguments for the reducing atmosphere on the 

 thermodynamic properties of the gases in a cosmic dust cloud from which the 

 solar system was formed. The equiUbrium constants at 25 °C. for the 

 reactions of the gaseous species are given in Table i. 



Table i 



These equilibria show that in the "presence of hydrogen the carbon will be 

 as methane, the nitrogen as ammonia and the oxygen as water. Urey proposed 



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