CHAP. 32] THE ORIGIN OF LIFE • 857 



gravitational energy released during the condensation of the dust to form the 

 Earth and the energy released from the decay of the radioactive elements. It is 

 not known whether the Earth was molten at any period during its formation, 

 but it is clear that the crust of the Earth would not remain molten for any 

 length of time. 



Studies on the concentration of some elements in the crust of the Earth 

 indicate that the temperature was less than 150°C during this lengthy fractiona- 

 tion, and that it was probably near ordinary terrestrial temperatures (Urey, 

 1953). 



Hydrogen cyanide, acetylene and other compounds are synthesized by heating 

 methane and ammonia or nitrogen to temperatures of 400 to 1000°C for short 

 periods of time. The short contact times of the atmospheric gases with lava 

 flows might be useful in synthesizing some of these compounds, although the 

 efficiency would probably be low. Long contact times with the lava would give 

 an equilibrium mixture of C, CO, CO2, CH4, H2 and H2O. 



Eox et al. (1956) have maintained that organic compounds were synthesized 

 on the Earth by heat. When heated to 150°, malic acid and urea were converted 

 to aspartic acid and ureidosuccinic acid, and the aspartic acid decarboxylated 

 to a- and /S-alanine. The difficulty with these experiments is the source of the 

 malic acid and urea, a question not discussed by Fox. He has also synthesized 

 some peptides by the well known reaction (Katchalski, 1951) of heating amino 

 acids to 150-180°C. The reaction will proceed at lower temperatures using 

 poljqihosphoric acid (Vegotsky and Fox, 1959) as a catalyst and dehydrating 

 agent, but it is not likely that polyphosphoric acid would have been present 

 on the primitive Earth. Salts of polyphosphoric acid are possible but the reaction 

 has not been shown to work with these salts. These polymerizations were 

 carried out with pure amino acids. It is questionable whether this polymeriza- 

 tion would work in the presence of large quantities of salts and other impurities. 



There is a difficulty connected with heating amino acids and other organic 

 compounds to high temperatures. Abelson (1957) has shown that alanine, one 

 of the more stable amino acids, decarboxylates to methylamine and carbon 

 dioxide. The mean life of alanine is lO^ years at 25°C but only 30 years at 

 150°C. Therefore, any extensive heating of amino acids will result in their 

 destruction, and the same is true for most organic compounds. In the light of 

 this and since the surface of the primitive Earth was probably cool, it is difficult 

 to see how the processes advocated by Fox could have been important in the 

 synthesis of organic compounds. 



E. Organic Phosphates, Porjihyrins 



Gulick (1955) has pointed out that the synthesis of organic phosphates is a 

 difficult problem because phosphate precipitates as calcium and other phos- 

 phates under present Earth conditions in the oceans. He proposes that the 

 presence of hypophosphites, which are more soluble, would account for higher 

 concentrations of phosphorus compounds in early times when the atmosphere 



