206 ORIGIN OF SPECIES 



innovation. Why, on the theory of Creation, should there 

 be so much variety and so little real novelty? Why should 

 all the parts and organs of many independent beings, each 

 supposed to have been separately created for its proper place 

 in nature, be so commonly linked together by graduated 

 steps? Why should not Nature take a sudden leap from 

 structure to structure? On the theory of natural selection, 

 we can clearly understand why she should not; for natural 

 selection acts only by taking advantage of slight successive 

 variations; she can never take a great and sudden leap, but 

 must advance by short and sure, though slow steps. 



ORGANS OF LITTLE APPARENT IMPORTANCE, AS AFFECTED 

 BY NATURAL SELECTION 



As natural selection acts by life and death, — ^by the sur- 

 vival of the fittest, and by the destruction of the less well- 

 fitted individuals, — I have sometimes felt great difficulty in 

 understanding the origin or formation of parts of little im- 

 portance; almost as great, though of a very different kind, 

 as in the case of the most perfect and complex organs. 



In the first place, we are much too ignorant in regard to 

 the whole economy of any one organic being, to say what 

 slight modifications would be of importance or not. In a 

 former chapter I have given instances of very trifling char- 

 acters, such as the down on fruit and the colour of its flesh, 

 the colour of the skin and hair of quadrupeds, which, from 

 being correlated with constitutional differences or from de- 

 termining the attacks of insects, might assuredly be acted on 

 by natural selection. The tail of the giraffe looks like an 

 artificially constructed fly-flapper; and it seems at first in- 

 credible that this could have been adapted for its present 

 purpose by successive slight modifications, each better and 

 better fitted, for so trifling an object as to drive away flies; 

 yet we should pause before being too positive even in this 

 case, for we know that the distribution and existence of 

 cattle and other animals in South America absolutely depend 

 on their power of resisting the attacks of insects : so that 

 individuals which could by any means defend themselves 

 from these small enemies, would be able to range into new 



