LECTURE XIV. 



DIRECTIVE FACTORS IN EVOLUTION: 

 SELECTION. 



1. Selection the Central Idea in Darwinism. 2. Logical Objec- 

 tions to Darwinism. 3. Sentimental Recoil from Darwinism. 

 4. Changes in Selection Theory since Darwin's Day. 5. 

 Scientific Critique of Selection Theory. 6. Subtlety of 

 Selection Theory. 7. Sexual Selection. 8. Selection and 

 Progressiveness. 9. Selectionist Interpretations and the 

 Argument from Design. 



1. Selection the Central Idea in Darwinism. 



THE central idea in Darwinism is the natural selection 

 of the relatively fitter variants in the struggle for existence. 

 Our understanding of Darwinism must therefore depend 

 on our appreciation of what is implied in variation, in the 

 struggle for existence, and in selection. A rough and ready 

 understanding of it is easy, but when we are dealing with 

 living creatures that is apt to mean misunderstanding, and 

 so it has been. By the hasty-minded, and by those more 

 anxious to score points than to get at the truth, Darwinism 

 has been persistently misunderstood. This has been largely 

 due to trusting to second-hand impressions instead of going 

 to Darwin's own works. Natural Selection may be described 

 as the process by which, in the struggle for existence, certain 

 variants of a species, marked from their fellows by the pres- 

 ence or absence of some innate character, are on that very 

 account favoured with longer life or with more successful 

 families than their neighbours, who are on that account 



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