Chapter XI 



INTELLECTUAL EVOLUTION 



I DO not intend to attempt to trace the course of evolution from 

 the dim consciousness of the one-celled organism to the crowning 

 triumph of Shakespeare's intellect. But I wish to give some 

 evidence that the highest brain-power may have been evolved 

 no less than bones or thews and sinews ; we have not before 

 us a problem which need stagger an evolutionist. I propose 

 also to discuss the question whether civilised people are still 

 advancing in intellectual power. 



At the lowest rung of the ladder, in the simplest proto- Conscious- 

 zoon, there is, we have reason to believe, consciousness, how- ness 

 ever dim. We may feel sure that the human brain is akin to 

 brains of lower organisation and that all its faculties, however 

 exalted, owe their grandeur to the ennobling of originally 

 humble powers that are found in the lower animals no less than 

 in man. In the case of memory we can see how this has come Memory 

 about. Memory is due to the association of ideas. The brain 

 is a very complicated organ with a number of different centres 

 communicating by means of connecting fibres. Thus ideas 

 become connected, and any particular idea may be re-awakened 

 by the awakening of another which at some time has become 

 linked with it in the mind. To take an instance, cowbells may 

 become associated in a man's thoughts with Swiss mountains and 

 a whole host of holiday pleasures. The notes of such a bell 

 will call up visions of snow mountains with all the experiences 

 connected with them. We remember the mountains when 

 we hear or see the bell. The stimulus is reinstated, the idea 

 is rung up a term I adopt from Professor Mark Baldwin by 

 an associated idea. In the case of a protozoon no less, a stimulus 

 may be reinstated so that the creature will repeat its behaviour 



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