218 DOCTRINE OF EVOLUTION 



Written history furnishes a wealth of material for 

 interpreting the mental conditions of ancient peoples, 

 but beside documentary evidence the anthropologist 

 learns to use inscriptions of prehistoric times, the primi- 

 tive graphic representations on tombs and monuments, 

 and even the characteristics of crude implements like 

 axes and arrow-heads. The layman finds it difficult 

 at first to regard such relics as indications of the mental 

 stature of the people who made and possessed them ; 

 but a little thought will show that a man who used a 

 rough stone ax in the time of the ancient Celts could 

 not possibly have had a mind which included the con- 

 ception of a finished iron tool or modern mechanism. 

 So in all departments of human culture, the evolution 

 of material objects may be justly employed in inter- 

 preting and estimating the mental abilities of ancient 

 peoples. 



Language is undoubtedly the most important single 

 intellectual possession of mankind, for it constitutes, 

 as it were, the very framework of social organization. 

 Without a ready means of communication the myriad 

 human units who perform the varied tasks necessary 

 for the economic well-being of a body-politic would 

 be unable to coordinate their manifold activities with 

 success, and the structure of civilized societies at least 

 would collapse. It needs no legend of a Tower of Babel 

 to make this plain. So fundamental is this truth that 

 although we may not have recognized it explicitly, we 

 unconsciously form the belief that speech and language 

 are exclusive properties of the human species, and even 



