CHEMICAL DIVERSITY OV EARLY LIFE 



57 



CHEMICAL DIVERSITY OF EARLY *LIFE': THE PIRIE DRAWING 



Many other dements must have taken part in these early processes 

 of inorganic photosynthesis. In contrast to the present life, with its 

 extremely varied morphological expression based on a narrowly limit- 

 ed number of biochemical reactions, these early processes of inorganic 

 photosynthesis, this proto-life, probably showed very large chemical 

 variety, but was probably not yet coupled to any definite morphology. 

 Pirie stressed this difference in his famous drawing, which is re- 

 produced here as Fig. 14. In an extremely simplified form, the evolu- 



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O 



CM 



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 o 



CM 



Fig. 14. Simplified presentation of the origin and the development of 

 life on earth, according to Pirie (1959). The lower cone shows the 

 early inorganic chemical processes and the early life, chemically diversi- 

 fied but without much morphological expression. The upper cone re- 

 presents the development of our present mode of life, characterized by 

 morphological diversification upon a narrowly restricted group of 

 biochemical reactions. 



