EVOLUTION OF MAN 425 



so that we can hardly say that the use of tools or weapons is an 

 exclusively human attribute ; but the hand of man is undoubtedly 

 one of his most characteristic features, and by its aid man has 

 been able to make for himself an unlimited number of what are 

 really additional organs, derived not from his own body but from 

 his environment. 



To the experience gained by the exercise of the hands in so 

 many different ways must also be attributed in large measure 

 the extraordinary mental and moral development which, more than 

 anything else, separates mankind from the apes. The constant 

 exploitation of the environment stimulated and exercised the brain, 

 which in turn suggested methods of employing the hands and 

 the tools which they had constructed to ever greater advantage ; 

 and thus both hand and brain progressed until they attained their 

 present wonderful state of efficiency. 



The development of the brain has, however, long since taken 

 the lead in human evolution and, considering the immense 

 difference in intellectual capacity, it is surprising that there 

 should be so little structural difference between the brain of 

 man and that of the higher apes. As Huxley has pointed 

 out: 



" It is only in minor characters, such as the greater excavation 

 of the anterior lobes, the constant presence of fissures usually 

 absent in man, and the different disposition and proportions of 

 some convolutions, that the Chimpanzee's or the Orang's brain 

 can be structurally distinguished from Man's." l 



Intellectual capacity appears, however, to depend mainly upon 

 the size of the cerebral hemispheres, which is doubtless correlated 

 with the number of nerve cells present, and in this respect the 

 human brain is far in advance of that of any ape. 



One of the most important characters which differentiate man- 

 kind from the apes is the faculty of articulate speech, but even this 

 undoubtedly had its beginnings in the inarticulate sounds made 

 by ape-like ancestors, either as spontaneous expressions of their 

 emotions or as a means of communicating more or less definite 

 ideas to one another. The development of speech provided a 

 new means for the transmission of experiences from one genera- 

 tion to the next, and as a consequence knowledge began to 

 accumulate in the minds of the human race. When oral tradition 



1 Huxley, " Man's Place in Nature," p. 140 (Collected Essays, Vol. VII). 



