474 



SCIENCE 



[N. S. Vol. XXXIII. No. 848 



ciations, or associative memory, and we 

 shall follow the usage of these writers. It 

 is obvious that the possession of this faculty 

 marks an important step in advance upon 

 the creatures whose actions are fatally de- 

 termined by their instinctive make-up. 

 From its beginning in forms in which the 

 simplest associations are established only 

 after a large number of experiences, intelli- 

 gence has assumed a role of ever-increasing 

 importance in the evolution of animal life, 

 until in man, who is notoriously a weakling 

 compared with the large beasts with which 

 he has had to contend it became the main 

 factor to which the human species owes its 

 supremacy in the struggle for existence. 



In considering the origin of intelligence 

 one is naturally led to the subject of the 

 relation of intelligence to instinct. For- 

 merly it was the custom to contrast these 

 two faculties as if they represented dia- 

 metrically opposed types of activity. In- 

 stinct was regarded as something unalter- 

 ably fixed, machine-like and practically 

 perfect in its adaptation to the needs of 

 the animal; intelligence was recognized as 

 the anthithesis of all these qualities — vari- 

 able, plastic and eminently fallible. With 

 the establishment of the theory of evolu- 

 tion writers became more disposed to dis- 

 cover the kinship and filiation of instinct 

 and intelligence and they have given us a 

 variety of views as to the relation of these 

 faculties. 



Basing his theory on Lamarck's doctrine 

 that instinct is inherited habit, G. H. 

 Lewes attempted to explain instinct ,as 

 " lapsed intelligence." Performances 

 which are learned with difiiculty come, 

 after sufficient repetition, to be carried out 

 automatically and without any intelligent 

 guidance. If the acquired facility of per- 

 forming these acts is inherited and the acts 

 are repeated generation after generation, 

 it is probable that they might finally be 



performed by an individual without any 

 previous instruction at all; that is, they 

 would become instinctive. An animal's in- 

 stincts, according to this view, represent 

 the stereotyped and mechanized behavior 

 which its ancestors found to be profitable; 

 their adaptiveness rests upon the wisdom 

 acquired by ancestral experience. More 

 recently this view has been upheld bjy 

 Eimer, and in a less extreme form by 

 Romanes, Wundt and many others. 



One difficulty with the theory of lapsed 

 intelligence is that it involves the accept- 

 ance of the doctrine of the transmission of 

 acquired characters, which has come to be 

 a very questionable biological theory. But 

 another and more fundamental difficulty is 

 revealed by recent work on the behavior of 

 lower organisms. If instinct were derived 

 from intelligence by a sort of mechanizing 

 process we should expect, as Whitman has 

 urged in his criticism of Lewes 's theory, to 

 find intelligence dominant in lower forms 

 of life, and that acts which are instinctive 

 in the higher animals would be intelli- 

 gently performed by the lower ones. The 

 work that has been done on the behavior of 

 lower organisms enables us to state with 

 confidence that such is not the case. In 

 several large phyla of the lower inverte- 

 brates there has not, as yet, been demon- 

 strated the least glimmer of intelligence^ 

 and, as we pass up the scale of life, in- 

 telligence gradually supersedes instinct, 

 not the reverse. We can say with some de- 

 gree of assurance that, however the transi- 

 tion may have been effected, intelligence 

 has grown out of purely instinctive 

 behavior. 



It is not possible, however, to fix, except 

 with the rudest approximation, the stage 

 of evolution at which intelligence makes its 

 first appearance. The transition from 

 instinct to intelligence has been made, in 

 all probability, not once, merely, but several 



