X.] IN ANIMALS AND MAN. Q^^ 



by the song — and this may be accepted as proved,— we can 

 understand the development of an at first imperfect musical 

 apparatus out of the primitive veins of the wing, and its 

 gradual improvement up to its present condition. The females 

 must, at all times, have preferred the males that sang the best : 

 this being the case, according to the law of heredity, the best 

 developed apparatus was, in each generation, transmitted to 

 the males of the next, so that a gradual improvement in the 

 power of performance must have taken place. The continued 

 preference for the best singers necessarily led to improvement 

 in song and in the sound-producing organ, until the latter 

 became incapable of further improvement. 



Let us now briefly consider the song of birds. Here, too, 

 the power of song is possessed by the males alone, and its 

 origin cannot be explained by natural selection, inasmuch as it 

 does not help in the preservation of the species, but is rather 

 disadvantageous, for it betrays the presence of the little 

 creatures to their enemies at a distance. But it can be well 

 explained by sexual selection. The males that sang the best 

 being always preferred by the females, we can understand 

 how out of the primitive chirp a kind of song arose in the 

 course of generations, and how, in certain species, it became 

 more and more complex, until at length it developed into songs 

 which delight even man by their beauty, such as those of the 

 linnet, the blackbird, and the nightingale. Hence sexual 

 selection affords a sufficient explanation of the origin of song 

 in birds and insects. 



But how can man have acquired the power of making and 

 understanding music, and how can we conceive of the agents 

 by which such a faculty has been developed ? 



Can these agents be found in the processes of natural and of 

 sexual selection ? Undoubtedly man is as completely subser- 

 vient to the influence of natural selection as any other animal or 

 plant. Man, like every other organism, is variable, is bound 

 by the laws of heredity, and wages a constant struggle for 

 existence. Therefore, with him as with them the qualities 

 which aid m that struggle will be retained and improved, 

 while those which are disadvantageous will be lost. And this 

 is natural selection. 



It is impossible to doubt that the intelligence of the human 



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