42 BRAINS OF RATS AND MEN 



the old saw, "I'd rather have fingers than toes." For 

 there is no great development of complex cerebral 

 centers of higher adjustment of behavior in the 

 absence of a sufficiently complex motor apparatus to 

 make efficient use of such enlarged powers of analysis 

 and synthesis of the sensory data. Many authors 

 have pointed out that the primate hand is the 

 precursor of the primate cerebral cortex. 



Wood Jones (191 6) has developed this idea with 

 a wealth of illustration. He emphasizes also the con- 

 verse aspect of this matter. The fullest use of a well- 

 developed motor equipment is impossible unless the 

 brain also has attained a grade of organization which 

 is adequate for the realization of the educational 

 possibilities of a complex mode of life. 



Physical perfections of adaptation are useless, unless ad- 

 vantage can be taken of them by a specialized type of brain; but 

 specialization of the cerebral architecture cannot proceed in the 

 absence of, yet cannot create, physical specializations in evolu- 

 tion Neopallial perfections did not, for instance, create 



the hand, but cerebral advances made possible the full utiliza- 

 tion of this very primitive yet very plastic member [p. 198]. 



A similar argument is graphically presented by Elliot 



Smith (1924, pp. 33, 36, 145): 



Man has evolved as the result of the continuous exploita- 

 tion throughout the Tertiary period of the vast possibilities which 

 the reliance upon vision as the guiding sense created for a mam- 

 mal that had not lost the plasticity of its hands by too early 

 specialization. 



The development of the behavior patterns and of 

 the correlated nervous mechanisms of young sala- 



