THE ANIMAL, MAN (ANTHROPOLOGY) 



551 



Gaining Ideas and Passing Them On 



Once the brain of man had evolved far enough to incubate ideas, 

 speech came to the rescue and made possible the transfer of ideas 

 from one individual to another. Thus, the intellectual accumula- 

 tions of experience and tradition were preserved and utilized, and 

 the emancipating process of learning made possible. Language, 

 it goes without saying, has been one of the most important factors 

 in human evolution. 



There are various ways in which animals can communicate with 

 each other. Ants pass the time of day by touching antennae together, 

 and dogs comply with the social conventions of the dog world largely 

 through the sense of smell, but humankind has spoken and written 

 language as the primary means of communication. 



There are certain skeletal differences in the lower jaws of apes and 

 humans which help to explain why one speaks and the other does 

 not. In man the lower jaw spreads, like a letter V, while in the apes 

 it is more U-shaped, due in part to the projecting canine teeth that 

 make a "corner" between 

 the incisors in front and the 

 premolars and molars that 

 are arranged behind along 

 the side of the jaw. There 

 is thus more room for the 

 tongue within the arch of 

 the human lower jaw than in 

 that of the ape, which is of 

 prime importance in speech. 

 Moreover, the ape does not 

 have a projecting chin to pro- 

 vide more room for play of 

 the tongue, as in the case 

 of man, although the whole 

 face projects more. This is 

 an important difference, for 

 the two halves of the lower 



jaw are anchored together by a bony formation on the inside, 

 the so-called "simian shelf," a horizontal junction which reduces 

 decidedly the available space for the tongue and its muscular attach- 

 ment. In man, the simian shelf disappears with the outside de- 

 H. w. H. — 36 



Lower jaw of man (above) and ape ([)elow! 



