RELATION OF TONE AND GESTURE TO WORDS. 1 55 



been developed in virtue of the sic^n-making faculty as this is 

 exempHfied in gesture. I maintain that we can see very good 

 reason why (even if we suppose all the other conditions 

 parallel) the branch of the Primates which presented the 

 power — or the potentiality — of articulation should have been 

 able to rise in the psychological scale, as we evolutionists 

 believe that it has risen ; while all the companion branches, 

 being restricted in their language to gesture, should have 

 remained in their original condition. 



To this it may be answered that the talking birds might 

 be looked to as the possible — or even probable — rivals of 

 articulating mammals in respect of potential intelligence ; 

 and, therefore, that according to the views which I am 

 advocating, it might have been expected that there should 

 now be existing upon the earth some race of bird-like creatures 

 ready to dispute the supremacy of man. 



This, however, would be a very shallow criticism. The 

 veriest tyro in natural science is aware that, if there is any 

 truth at all in the general theory of descent, we are every- 

 where compelled to see that the conditions which determine 

 the development of a species in any direction are always of a 

 complex character. Why one species should remain constant 

 through inconceivably enormous lapses of geological time, 

 while others pass through a rich and varied history of upward 

 change — why this should be so in any case we cannot say. 

 We can only say, in general terms, that the conditions which 

 in any case determine upward growth or stationary type are 

 too numerous and complex to admit of our unravelling them 

 in detail. Now, if this is the case even as between the 

 structures of allied types — where there may be nothing to 

 indicate the difference of the conditions which have led to the 

 difference of results, — much more must it be the case between 

 animals so unlike as a parrot and an ape. I think he would 

 be a bold man who would affirm that even if the oransf- 

 outang had been able to articulate, this ape would necessarily, 

 or probably, have become the progenitor of another human 

 race. Absurd, then, it is to argue that, if the human race 



