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The Origin of 

 Organic Molecules 



Harold C Urey 



School of Science and Engineering 



University of California, San Diego 



La Jolla, California 



Darwin and Wallace proposed the theory of evolution almost simul- 

 taneously and quite independently. They and their numerous fol- 

 lowers of the past century have demonstrated that, given an organism 

 of the most primitive type, all the species of today and of past geo- 

 logical periods could and did evolve from such cells. We are beginning 

 to understand the processes by which inherited characteristics are 

 carried from generation to generation by means of deoxyribonucleic 

 acids, and also we understand how variations in species of animals and 

 plants occur. Many details remain, but the broad outline has become 

 clearer during recent years and decades. Also, we find marked bio- 

 chemical similarities between all living things, indicating tbat they 

 are all part of a single evolutionary process. These fundamental bio- 

 chemical processes were established in the distant past before the time 

 of the oldest fossils, namely, some 500 million or more years ago. 



At least after the development of sexual reproduction, evolution 

 must have occurred by mutation in one individual, it is true, but tbc 



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