530 Allen, Evolution of Bird-song. [o" t k 



tion, whatever they may be, or through the special process of sexual 

 selection. The evidence, however, seems to favor the belief that 

 most songs are transmitted from generation to generation by imi- 

 tation, each individual imitating, consciously or unconsciously, the 

 songs of other individuals, whether the songs of his parents heard 

 while he was in the nest or those of other birds. The songs would 

 naturally be modified and improved by enterprising and gifted 

 singers, but would, of course, always be subject to the conservative 

 action of the herd instinct, which would repress and suppress any 

 too great departure from the normal. (This last observation I offer 

 as a substitute for Mr. Hawkins's theory of the opposing influences 

 of the male and female germs.) ■ In this way the characteristic songs 

 of the species are preserved, just as primitive human language 

 passes from individual to individual within the tribe, and as the 

 folk-songs of the various races of men have been handed down from 

 generation to generation. 



This growth and development by invention and imitation must, 

 it seems to me, account in great measure for the forms and general 

 characters of bird -songs as we know them, but surely some other 

 process was necessary to produce the beauties of tone and melody 

 and rhythm that characterize so large a percentage of the songs. 

 Superabundant vitality produces noise in human beings and doubt- 

 less also in birds, but it cannot account for beauty, any more than 

 it can account for the more or less intricate patterns of the vocal 

 utterances that we call songs. Weismann remarks that " it is not 

 easy to see why a more active metabolism should be necessary for 

 the production of strikingly bright colours than for that of a dark 

 or protective colour," ] and it would be fully as difficult, I think, 

 to show how it could produce music out of noise. Equally impo- 

 tent in this direction must be such an agency as natural selection, 

 for obviously birds can pick up a living, escape their enemies, and 

 propagate their kind without the help of music; many species do so. 

 Imitation could not of itself produce musical qualities, and in the 

 absence of any standards of taste it would be as likely to perpetuate 

 harsh and unpleasing notes as beautiful ones. 



All these agencies failing, unless we postulate some supernatural 



1 The Evolution Theory, English translation by J. Arthur Thomson and Margaret R. 

 Thomson 1904, (original published in 1902), vol. i, p. 212. 



