DARWIN AND HUMBOLDT, 



[327] 23 



have been able to strike, as it were, 

 straight down upon some of the most 

 important truths which have ever 

 been brought to light in the region 

 of mental science. These we shall 

 now proceed to consider. 



The chapter in the Origin of 

 Species to which we have referred, is 

 occupied chiefly with an application 

 of the theory of natural selection to 

 the phenomena of instinct, and in our 

 opinion it has done more than all other 

 psychological writings put together 

 to explain what instinct is, why it is 

 and how it came to be. Before this 

 chapter was published, the only scien- 

 tific theory concerning the origin of 

 instincts that had been formed was 

 the theory wh'ch regarded them as 

 hereditary habits. Because we know 

 that in the individual intelligent ad- 

 justments become, by frequent rep- 

 etition, automatic, it was inferred 

 that the same might be true of the 

 species, and therefore that all instincts 

 were to be regarded as what Lewes 

 has aptly termed "lapsed intelli- 

 gence." In this view there is, with- 

 out any question, much truth, and the 

 first thing we have to notice about 

 Mr. Darwin's writings with reference 

 to instinct is that they not only rec- 

 ognized this truth, but, by elucida- 

 ting the whole subject of heredity, 

 placed it in a much clearer light than 

 it ever stood before. Mr. Darwin, 

 however, carried the philosophy of 

 the subject very much further when 

 he agued that, in conjunction with the 

 cause formulated as "lapsing intelli- 

 gence," there was another at least as 

 potent in the formation of instincts — 

 namely, natural selection. His own 

 statement of the case is so terse that 

 we cannot do better than quote it. 



" If Mozart, instead of playing the 

 pianoforte at three years with won 

 derfully little practice, had played a 

 tune with no practice at all, he might 

 truly be said to have done so instinct 

 ively. But it would be a serious error 

 to suppose that the greater number 

 of instincts have been acquired by 

 habit in one generation, and then 

 transmitted by inheritance to succeed- 



ing generations. It can be clearly 

 shown that the most wonderful in- 

 stincts with which we are acquainted, 

 namely, those of the hive-bee and of 

 many ants, could not possibly have 

 been acquired by habit.* 



"It will be universally admitted ) 

 that instincts are as important as cor- 

 poreal structures for the welfare of 

 each species, under its present con- 

 ditions of life. Under changed con- 

 ditions of life, it is at least possible 

 that slight modifications of instinct 

 might be profitable to a species ; and 

 if it can be shown that instincts do 

 vary ever so little, then I can see no 

 difficulty in natural selection preserv- 

 ing and continually accumulating 

 variations of instinct to any extent 

 that was profitable. It is thus, I be- 

 lieve, that all the most complex and 

 wonderful instincts have originated." 



Briefly, then, in Mr. Darwin's 

 view, instincts may arise by lapsing 

 intelligence, by natural selection of 

 accidental and possibly non-intelligent 

 variations of habit, or by both prin- 

 ciples combined — seeing that "a little 

 dose of judgment "is often commin- 

 gled with even the most fixed (or 

 most strongly inherited) instincts. 

 One good test of the truth of the view 

 as a whole is that which Mr. Darwin 

 has himself supplied — namely, search- 

 ing through the whole range of in- 

 stincts to see whether any occur 

 which are either injurious to the 

 animals exhibiting them, or benefical 

 only to other animals. Now there 

 is really no authentic case of the 

 former, and the latter are so few in 

 number that they may reasonably be 

 regarded, either as rudiments of in- 

 stincts once useful (so analogous to 

 the human tail), or as still useful in 

 some unobservable manner (so anal- 

 ogous to the tail of the rattlesnake). 

 The case of aphides secreting honey- 



* Because the individuals which exhibit 

 them, being neuters, can never have progeny. 

 It is indeed surprising, as Mr. Darwin 

 further on observes, that no one previously 

 " advanced this demonstrative case of neuter 

 insects against the well-known doctrine of 

 inherited habit as advanced by Lamarck." 



