190 THE LESSON OF EVOLUTION 



If we examine any large order of animals that is 

 one containing many species we shall find that the 

 ordinal characters, and those of the families into 

 which it is divided, are of utilitarian value. But 

 when we come to the smaller groups the case will 

 be different. A large proportion of the genera and 

 almost all the species will be distinguished by charac- 

 ters which, so far as we can see, are non-utilitarian, 

 and could not therefore have been developed by 

 natural selection. So it appears after all, that 

 natural selection is not so much a theory of the 

 origin of species from varieties as one of the origin 

 of genera and the higher groups from species. 

 Natural selection picks, as it were, here and there 

 one species out of many and makes it the founder of 

 a family. The rest the vast majority " have 

 their day and cease to be." They vanish altogether 

 from the board, without leaving any descendants 

 behind them, although some linger longer than 

 others. 



It is then to natural selection that we owe pro- 

 gress, and it is chiefly to isolation that we owe 

 variety. Without isolation all organic beings would 

 have been nearly uniform, and all would have be- 

 longed to a single type, which would be the one 

 best fitted for getting food and for propagating its 

 race : a half-animal, half-vegetable, and a ruthless 

 cannibal. This unhappy result was prevented by 

 the first organisms being sexless, so that there was 

 no inter-crossing, but each could develop indepen- 

 dently. It is useful to contemplate what might 

 "have been, for we can then realise what the principle 



