154 ANIMAL BEHAVIOUR 



the activities of other human beings and of many non-human 

 animals show all this quite clearly. We are very familiar with 

 *' aimless," '' purposeless," '' desultory " behaviour in other 

 people and sometimes oppressed with our own disinclination to 

 sustained effort. We are often annoyed by the inability of a 

 dog to do what we want it to do. Something is common to 

 all these kinds of behaviour — the randomness of the chains of 

 reflexes that occur and the absence of definite choice of neurone- 

 patterns. 



54^. Intelligence and Instinct. The methods of behaviour 

 by trial and error, with the acquired basis of historical action 

 constitute intelligence. In man this rises to the plane of rational 

 activity, when we have to deal with the conception of '' excess- 

 value " (see the following sections). When we come to consider 

 instinct the analyses of motives, purposes, establishment of motor 

 habits, memory and " subconscious " memory all follow along 

 the lines already indicated. So far as the limitations of space 

 permit we have discussed intelligence and little need be said 

 about instinct. 



An instinctive activity is one that is purposeful, has not to 

 be " learned," or acquired by the individual animal that performs 

 it, and which is efficiently carried out the first time that it is 

 attempted. It is innate in the organization of the individual. 

 The swimming of a dog, the building of a nest by a stickleback, 

 the choice of an empty gastropod shell by a hermit-crab larva, 

 the suckling actions of the human infant, the gripping move- 

 ments of the hands, etc., are all instinctive activities. The 

 problem that we encounter in dealing with such kinds of behaviour 

 is not their origins, for these may be explained just as we have 

 indicated in the cases of intelligent activities. What is really 

 troublesome is the question of the transmission of action so 

 that things that are learned, or acquired by the individual, can 

 be done also, without being re-acquired in the same ways, by 

 the offspring of that individual. That is, some kinds of behaviour 

 may originate and be " transmitted " by heredity. Instincts, in 

 short, are " mutations " of behaviour, just as there are mutations 

 of structure and functioning, and the discussions that follow in 

 sections with regard to the latter phenomena appear to apply 

 also to the transmissibility of instincts. That is all that need 

 be said about the problem in the present place. 



