340 The Organization of Matter and Life 



had the property of inexorable increase and the necessities of hfe 

 were limited, all organisms could not go on reproducing forever. 

 The habitable world had a finite carrying capacity. The occurrence 

 of mutations resulted in inequality between different individuals, 

 based on physiological differences and hence expressed as differ- 

 ences in ecological fitness. The automatic expression of natural 

 selection has continuously tended to eliminate mutations less 

 suited to the environment, resulting in the survival or "selection" 

 of the better adapted types and eventual elimination of the others. 

 This sifting type of ordering is the only one operating in clonal 

 organisms. 



Simultaneously, natural selection effected a second type of or- 

 dering. Because of the selective advantages resulting from a com- 

 bination of different beneficial mutant types in the same individual, 

 natural selection favored any device in which this combining came 

 about. The evolution of sex resulted. The sexual mechanism es- 

 tablished a rigid order by uniting the individuals of a species into 

 an interbreeding system, the phylogenetic line. Within this organi- 

 zation the criterion of genetic compatibility became a new factor, 

 screening, and thus ordering, genetic mutation. 



The dynamic nature of phylogenetic lines in conjunction with 

 the factor of genetic incompatibility formed the foundation for 

 the next kind of randomness. Various circumstances, especially the 

 geotectonic factor, led to an increase in the number of species, a 

 new randomizing effect. This process has been going on since sex 

 became established and has resulted in the formation of many 

 million different species. The production of more species tended 

 to reduce the order of species themselves by increasing the hy- 

 bridization between them. Hybridization between species occurs 

 in varying degrees thus introducing a randomizing element com- 

 posed of an increase in the genetic variability within each species. 

 Again by the action of natural selection, however, a number of 

 processes have evolved which tend to reduce hybridization and 

 thus promote a more rigid ordering of individuals into discrete 

 species progressing through time. 



The geotectonic factor, however, congregates species in addi- 

 tion to splitting them, and this congregation of species set in mo- 

 tion evolutionary developments resulting in a new kind of order, 

 that of multi-species systems or biotic communities. In these com- 

 munities the evolution of certain of the inter-species relationships 

 such as food chains, commensalism, and symbiosis has resulted in 

 an obligatory coexistence, which is a rigid kind of organizational 



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