THE DESCENT OR ORIGIN OF MAN 97 



shown that no such inverse ratio really exists. Those in- 

 sects which possess the most wonderful instincts are cer- 

 tainly the most intelligent. In the vertebrate series, the 

 least intelligent members, namely fishes and amphibians, 

 do not possess complex instincts; and among mammals the 

 animal most remarkable for its instincts, namely, the beaver, 

 is highly intelligent, as will be admitted by every one who 

 has read Mr. Morgan's excellent work.' 



Although the first dawnings of intelligence, according 

 to Mr. Herbert Spencer,* have been developed through the 

 miiltiplication and co-ordination of reflex actions, and al- 

 though many of the simpler instincts graduate into reflex 

 actions, and can hardly be distinguished from them, as in 

 the case of young animals sucking, yet the more complex 

 instincts seem to have originated independently of intelli- 

 gence. I am, however, very far from wishing to deny that 

 instinctive actions may lose their fixed and untaught charac- 

 ter, and be replaced by others performed by the aid of the 

 free will. On the other hand, some intelligent actions, after 

 being performed during several generations, become con- 

 verted into instincts and are inherited, as when birds on 

 oceanic islands learn to avoid man. These actions may then 

 be said to be degraded in character, for they are no longer\ 

 performed through reason or from experience. But the 

 greater number of the more complex instincts appear to 

 have been gained in a wholly different manner, through 

 the natural selection of variations of simpler instinctive 

 actions. Such variations appear to arise from the same 

 unknown causes acting on the cerebral organization which 

 induce slight variations or individual differences in other 

 parts of the body; and these variations, owing to our igno- 

 rance, are often said to arise spontaneously. "We can, I 

 think, come to no other conclusion with respect to ihe ori- 

 gin of the more complex instincts, when we reflect on the 

 marvellous instincts of sterile worker- ants and bees, which 



5 "The American Beaver and Mg Works," 1868. 

 ■" "Tne Principlea of Psychology," 2d edit., 1870, pp. 418-443. 

 Descent — Vol. I. — 5 



