Maech 20, 1896.] 



SCIENCE. 



Ul 



variation in the same lines of function as those 

 which their acquisition by the individual called 

 into play. But there is no need in either case 

 to assume the Lamarckian factor. 



The intelligence holds a remarkable place in 

 each of these categories. It is itself, as we have 

 seen, a congenital variation : but it is also the 

 great agent of the individual's personal adapta- 

 tion both to the physical and to the social en- 

 vironment. 



The emphasis, however, of the first of these 

 two lines of hereditary influence gives promi- 

 nence to instinct in animal species, and that of 

 the other to the intelligent and social coopera- 

 tion which goes on to be human. The former 

 represents a tendency to brain variation in the 

 direction of fixed connections between certain 

 sense centers and certain groups of coordinated 

 muscles. This tendency is embodied in the 

 white matter and the lower brain centers. The 

 other represents a tendency to variation in the 

 direction of alternative possibilities of connec- 

 tion of the brain centers with the same or simi- 

 lar coordinated muscular groups. This tendency 

 is embodied in the cortex of the hemispheres. 

 I have cited ' thumb-grasping ' because we can 

 see in the child the anticipation, by intelligence 

 and imitation, of the use of the thumb for the 

 adaptation which the simian probably gets en- 

 tirely by instinct, and which I think an isolated 

 and weak-minded child, say, would also come 

 to do by instinct. 



IV. Finally there are two general bearings 

 of the position taken above regarding the de- 

 velopmental function of intelligence and imita- 

 tion which may be briefly noted : 



1. We reach a point of view which gives to 

 organic evolution a sort of intelligent direction 

 after all; for of all the variations tending in the 

 direction of an instinct, but inadequate to its 

 complete performance, only those will be supple- 

 mented and kept alive which the intelligence ratifies 

 and uses for the animal's personal adaptations. 

 The principle of selective value applies to 

 the others or to some of them. So natural 

 selection kills off" the others ; and the future 

 development of instinct must at each stage of a 

 species' development be in the directions thus rati- 

 fied by intelligence. So also with imitation. 

 Only those imitative actions of a creature 



which are useful to him will survive in the 

 species; for in so far as he imitates actions 

 which are injurious he will aid natural selec- 

 tion in killing himself off". So intelligence, and 

 the imitation which copies it, will set the di- 

 rection of the development of the complex in- 

 stincts even on the Neo-Darwinian theory ; and 

 in this sense we may say that consciousness is 

 a ' factor ' without resorting to the vague postu- 

 lates of ' self-adaptation,' 'growth-force,' ' will- 

 efibrt,' &c., which have become so common of 

 late. 



2. The same consideration may give the 

 reason in part that instincts are so often coter- 

 minous with the limits of species. Similar 

 structures find the similar uses for their intelli- 

 gence, and they also find the same imitative 

 actions to be to their advantage. So the inter- 

 action of these conscious factors with natural 

 selection brings it about that the structural 

 definition which represents species, and the 

 functional definition which represents instinct, 

 largely keep to the same lines.* 



J. Mark Baldwin. 



Princeton University, February 5, 1896. 



INSTINCT. 



Editor of science: Some remarks appended 

 to my letter published in Science No 62, on the 

 subject of Prof. Morgan's views on instinct by 

 ' The Writer of the Note,' in view of the im- 

 portance of the subject are worthy of further 

 consideration. 



Before drawing conclusions from observations 

 on domestic animals, it is well to consider simi- 

 lar facts in connection with their wild con- 

 geners, especially if such conclusions are of a 

 far-reaching character, and it cannot be too well 

 borne in mind that our experiments are very 

 clumsy imitations of nature in a large propor- 

 tion of cases. 



* In conversation with Prof. Lloyd Morgan I was 

 glad to find that he was inclined to interpret the 

 facts which I have quoted from him (and others) in 

 somewhat the same way — that is, as pointing to gen- 

 eral conclusions similar to those reached above. 

 While I have reached my conclusions quite inde- 

 pendently and from a psychological point of view, 

 any confirmation which they get from so expert and 

 eminent a biologist gives them much greater weight. 



