Chap. IV. 



Natural Selection. 



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undoubtedly occurred, that other variations useful in some way to 

 each being in the great and complex battle of life, should occur in 

 the course of many successive generations ? If such do occur, can we 

 doubt (remembering that many more individuals are born than can 

 possibly survive) that individuals having any advantage, however 

 slight, over others, would have the best chance of surviving and of 

 procreating their kind ? On the other hand, we may feel sure that 

 any variation in the least degree injurious would be rigidly de- 

 stroyed. This preservation of favourable individual differences and 

 variations, and the destruction of those which are injurious, I have 

 called Natural Selection, or the Survival of the Fittest. Variations 

 neither useful nor injurious would not be affected by natural selec- 

 tion, and would be left either a fluctuating element, as perhaps we 

 see in certain polymorphic species, or would ultimately become 

 fixed, owing to the nature of the organism and the nature of the 

 conditions. 



Several writers have misapprehended or objected to the term 

 Natural Selection. Some have even imagined that natural selection 

 induces variability, whereas it implies only the preservation of such. 

 variations as arise and are beneficial to the being under its con- 

 ditions of life. No one objects to agriculturists speaking of the 

 potent effects of man's selection ; and in this case the individual 

 differences given by nature, which man for some object selects, 

 must of necessity first occur. Others have objected that the term 

 selection implies conscious choice in the animals which become 

 modified; and it has even been urged that, as plants have no voli- 

 tion, natural selection is not applicable to them! In the literal 

 sense of the word, no doubt, natural selection is a false term ; but 

 who ever objected to chemists speaking of the elective affinities of 

 the various elements ? — and yet an acid cannot strictly be said to 

 elect the base with which it in preference combines. It has been 

 said that I speak of natural selection as an active power or Deity ; 

 but who objects to an author speaking of the attraction of gravity 

 as ruling the movements of the planets ? Every one knows what 

 is meant and is implied by such metaphorical expressions; and 

 they are almost necessary for brevity. So again it is difficult to 

 avoid personifying the word Nature ; but I mean by Nature, only 

 the aggregate action and product of many natural laws, and by laws 

 the sequence of events as ascertained by us. With a little familiarity 

 such superficial objections will be forgotten. 



We shall best understand the probable course of natural selection 

 by taking the case of a country undergoing some slight physical 

 change, for instance, of climate. The proportional numbers of its 



