SEVEN ASSUMPTIONS 127 



That is, approximately, to the last half-billion years, from the 

 Cambrian system onwards. As stated above, this period is not only 

 much shorter, but also much later than that in which the origin of 

 life and its early beginnings took place. Nevertheless, the two are 

 often treated together, the findings of later evolution are extrapolated 

 backwards in an unpermissable way, and the distinction between the 

 two is often ignored in the literature. 



SEVEN ASSUMPTIONS 



As a case in point let me cite the very recent and authoritative book 

 by Kerkut (1960), who, in a thoughtful essay, takes a delightfully 

 critical attitude towards evolution. Kerkut maintains that the theory 

 of evolution is based on seven assumptions, which together form the 

 'General Theory of Evolution'. These assumptions are (Kerkut, 1960, 

 p. 6): 



1. Non-living things gave rise to living material, i.e. spontaneous 

 generation occurred *. 



2. Spontaneous generation occurred only once. 



(The other assumptions, according to Kerkut, all follow from 

 the second one.) . 



3. Viruses, bacteria, plants and animals are all interrelated. 



4. Protozoa gave rise to Metazoa. 



5. The various invertebrate phyla are interrelated. 



6. The invertebrates gave rise to the vertebrates. 



7. Within the vertebrates, the fish gave rise to the amphibia, the 

 amphibia to the reptiles, and the reptiles to the birds and mam- 

 mals. 



As stated before, I do not think the usage of the phrase spontaneous 

 generation' to be a happy one in this context. On p. 7 of his work 

 Kerkut uses the word biogenesis', an expression coined, I believe, by 

 Bernal, as a synonym. Biogenesis will be used here also to denote 

 transition from non-living to living. 



