THE ALIMENTARY CANAL AND ITS APPENDAGES 157 



Mammals generally, but little specialised. The molars in parti- 

 cular are comparatively simple cuspidate teeth, such as are found 

 among the oldest Mammals. Judged from the form of their 

 teeth, the Primates would appear to have branched off very 

 early from the common Mammalian stem. If we can draw 

 conclusions from the fossils as yet found, the Apes were not very 

 widely distributed in earlier periods. They probably lived, as 

 they now do, as climbing animals in tropical climates. In con- 

 sequence partly of their frugivorous manner of life, and partly of 

 the higher development of their intelligence, their teeth, of no 

 great service for warfare in the struggle for existence, appear to 

 have remained comparatively simple. 



The dentition of Man agrees with that of the Old Worjd 

 Apes in number and shape of the teeth. The dental formula is : 



2. 1. 2. 3 

 *-9~c.r- p.m. m. 32. The New World Apes, on the other 



hand, have one more premolar in each set, their formula being 



2. 1. 3. 3 



i o o = 36. If the teeth of Man are compared with those of 



a. 1. O. O 



the nearly related Anthropoids, it is found that their respective 

 milk teeth agree in form and size more nearly than do their 

 permanent or successional dentitions. In the Anthropoids [with 

 the exception of the Gibbon (Hylobates)] the teeth of the second 

 series are larger and stronger than in Man, the contrast being 

 most marked in the size of the canines. The latter serve, in the 

 Ape, as powerful weapons in the struggle for existence, 1 and the 

 prernolars of the Apes are also, in consequence of the greater 

 development of their outer cusps, more caniniform than in Man. 

 The molars, on the contrary, are remarkably similar throughout, 

 although they are larger in Anthropoids than in Man ; and in 

 Hylobates, both in form and size, they can hardly be distinguished 

 from those of the human subject. 



[Since, among Mammals generally], the milk teeth, i.e. those 



1 We have abundant evidence that teeth were once used by Man or by his 

 ancestors as weapons of defence ; traces of such a use have not altogether disappeared 

 in human beings of the present day, and I cannot refrain from quoting in this connec- 

 tion a comment of Darwin which occurs in Ids book on the Origin of Man. 



"He who rejects with scorn the belief that the shape of his own canines, and 

 their occasional great development in other men, are due to our early forefathers 

 having been provided with these formidable weapons, will probably reveal by sneer- 

 ing the line of his descent. For though he no longer intends, nor has the power, to 

 use these teeth as weapons, he will unconsciously retract his ' snarling muscles ' (thus 

 named by Sir C. Bell) so as to expose them ready for action, like a dog prepared 

 to fight." 



