CHAPTER XXVII 



GUIDING FACTORS. INTRODUCTION 



Preliminary discussion. — All of the factors hitherto discussed ap- 

 pear to operate on a random basis, obedient to the laws of pure chance. 

 Of themselves, then, they might be conceived of as producing a high 

 degree of diversity and innumerable novelties, but that would be all. 

 If there is something of orderliness, something of direction, something 

 adaptive, something progressive, or even something purposive about 

 evolution, there should be guiding factors responsible for each and all 

 of them. 



The extent to which guiding factors are a necessary part of the 

 evolutionary mechanism depends upon the extent to which there ac- 

 tually exist in nature conditions that cannot be accounted for on a 

 purely random basis. Guiding or directing factors imply goals, ob- 

 jectives, definite trends, improvements of one sort or another. What 

 is there about nature that seems to require a guiding hand? 



Adaptations. — One of the marvels of life is that the organism and 

 the environment seem so well adapted to each other, that the particular 

 organs of an individual seem so well designed to perform their many 

 and varied functions, that the various species are so nicely adjusted to 

 one another in any given natural community that each seems to be a 

 strand in an intricate and delicately adjusted "web of life." One of 

 the most important goals or objectives of evolution, then, must be 

 adaptation. We are using these terms "goals" and "objectives" with- 

 out implying any teleological considerations, though why there may 

 not be purpose in nature I do not know. At least it is better for the 

 scientist to shy away from any taint of teleology. So let us assume 

 that adaptation is one of the main objectives of evolution, using the 

 term "objective" only to imply that evolutionary processes somehow, 

 by devious paths, seem to arrive at various degrees of fitness. The 

 mechanism bringing about this fitness may be blind and may vision no 

 goal, but it gets there just the same. 



Since adaptation is so intimately associated with evolution — in 

 fact, one of its principal attributes — it will be necessary to take a short 

 excursion into natural history in order that we may come to realize at 

 least some of the facts of adaptation that confront the evolutionist 



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