EXCURSIONS OF AN EVOLUTIONIST 



ancestors, and he can do almost nothing to vary 

 it. The life of such creatures is conservatism 

 cut and dried, and there is nothing progressive 

 about them. 



In what I just said I left an " almost." There 

 is a great deal of saving virtue in that little ad- 

 verb. Doubtless even animals low in the scale 

 possess some faint traces of educability ; but 

 they are so very slight that it takes geologic ages 

 to produce an appreciable result. In all the in- 

 numerable wanderings, fights, upturnings and 

 cataclysms of the earth's stupendous career, each 

 creature has been summoned under penalty of 

 death to use what little wit he may have had, 

 and the slightest trace of mental flexibility is of 

 such priceless value in the struggle for existence 

 that natural selection must always have seized 

 upon it, and sedulously hoarded and transmitted 

 it for coming generations to strengthen and in- 

 crease. With the lapse of geologic time the up- 

 per grades of animal intelligence have doubtless 

 been raised higher and higher through natural 

 selection. The warm-blooded mammals and 

 birds of to-day no doubt surpass the cold- 

 blooded dinosaurs of the Jurassic age in mental 

 qualities as they surpass them in physical struc- 

 ture. From the codfish and turtle of ancient 

 family to the modern lion, dog, and monkey, it 

 is a very long step upward. The mental life of 

 a warm-blooded animal is a very different affair 

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