EVOLUTION OF MAN— SMITH. 571 



cortex. When the ape-man attained a sufficient degree of intel- 

 ligence to wish to communicate with his fellows other than by mere 

 instinctive emotional cries and grimaces, such as all social groups 

 of animals employ, the more cunning right hand would naturally 

 play an important part in such gestures and signs; and, although 

 the muscles on lioth sides of the face would bo called into action in 

 such movements of the features as were intended to convey informa- 

 tion to another (and not merely to express the personal feelings of 

 the individual), such bilateral movements would certaiidy be con- 

 trolled by the left side of the brain, because it was already more 

 highly educated. 



THE ORIGIN OF SPEECH. 



[This argument was elaborated to explain the origin of speech. 

 The increasing ability to perform actions demanding skill and deli- 

 cacy received a great impetus when the hands were liberated for the 

 exclusive cultivation of such skill; this perfection of cerebral con- 

 trol over muscular actions made it possible for the ape-man to learn 

 to imitate the sounds around him, for the act of learning is a training 

 not only of the motor centers and the muscles concerned, but also 

 of the attention, and the benefits that accrued from educating the 

 hands added to the power of controlling other muscles, such as those 

 concerned with articulate speech. 



The usefulness of such power of imitating sounds could be fully 

 realized in primitive man, not only because he had developed the 

 parts of the brain which made the acquisition of such skill possible, 

 but also because he had acquired, in virtue of the development of 

 other cortical areas, the ability to realize the significance and learn 

 the meaning of the sounds heard.] 



I do not propose to discuss the tremendous impetus that the 

 invention of speech must have given to human progress and intellec- 

 tual development, in enabling the knowledge acquired by each 

 individual to become the property of the community and be handed 

 on to future generations, as well as by supplying in words the very 

 symbols and the indispensal)le elements of the higher mental process. 



We are apt to forget the immensity of the heritage that has 

 come down to us from former generations of man, until we begin 

 dimly to realize that for the vast majority of mankind almost the 

 sum total of their mental activities consists of imitation or acquiring 

 and using the common stock of behefs. For this accumulation of 

 knowledge and its transmission to our generation we are almost 

 wholly indebted to the use of speech. In our forgetfulness of these 

 facts we marvel at the apparent dullness of early man in being 

 content to use the most roughly chipped flints for many tliousands 

 of years before he learned to polish them, and eventually to employ 



