XVIII THE PROBLEM OF UTILITY 387 



because the whole problem is included in that of species ; 

 it is in them that the process and laws of development 

 can be best studied free from many of those complexities 

 of modification and survival of disused and partially 

 aborted parts and organs which often constitute generic 

 or family characters. If every one of the new characters 

 or new combinations of characters which arise when a 

 new species becomes differentiated from its parent-form, — 

 if every one of these is adaptive and utilitarian, then no 

 higher groups can possess characters other than those 

 which were once adaptive, since genera and families can 

 never acquire new characters except through every one 

 of their component species acquiring those characters. 

 The problem as exhibited in species includes therefore 

 the problem in all higher groups. 



Characters fixed hy Natural Selection must he Useful. 



I have already set forth in some detail the argument 

 for utility founded on the fact of the continuous progress 

 of the discovery of utilities with the continuous growth 

 of our knowledge of the life-histories and inter-relations 

 of plants and animals.^ I will therefore now devote more 

 special attention to the fundamental argument, that 

 whereas every modification of a species which arises 

 under the influence of natural selection must, from the 

 very nature of its origin, be useful to the new form, no 

 other agency has been shown to exist capable of pro- 

 ducing non-utilitarian characters in every individual con- 

 stituting a species, neither more nor less. Noav the general 

 cause which is adduced as being able to do this is stated 

 by Darwin in the following passages, which are quoted by 

 Mr. Romanes as expressing his own views : — 



"There must be some efficient cause for each slight 

 individual difference, as well as for more strongly marked 

 variations which occasionally arise ; and if the unknown 

 cause were to act persistently, it is almost certain that all 

 the individuals of the species would be similarly modified " 

 {Origin of Species, p. 171). 



^ Darwinism, pp. 131-142. 



c c 2 



