416 



KNOWLEDGE. 



November, 1913. 



chin per se as a sexual orna- 

 ment was a failure. Women, 

 it is true, have not adopted 

 this form of hirsute decoration ; 

 but I doubt if this goes far 

 in helping the aesthetic 

 argument, since, according to the 

 ideals generally current, a big 

 jaw and formidable chin are 

 nowhere considered an excellent 

 thing in woman. I think we 

 shall find that before aesthetics 

 came greatly into play, more 

 prosaic evolutionary forces had 

 already exerted pressure upon 

 the lower jawbone, and had 

 begun to mould it into the 

 general shape in which we find 

 it now. 



A glance at the drawing of 

 the mandible of a chimpanzee 

 (see Figure 485) with the roots 

 of the teeth exposed shows the 

 real status of the chin in the 

 anthropoids. It is mainly 

 formed by two thick bony 

 buttresses supportingthe sockets 

 of the lower canine teeth. 

 This apparently was the real 

 physical beginning of the bony 

 chin, or rather was, as it were, 

 the gross concrete foundation 

 upon which evolutionary forces 

 of another kind have based the 

 modern structure. 



It is a most remarkable and 

 suggestive fact that after man 

 (or the infra-man) had lost his 

 huge lower canines, this abun- 

 dance of bony tissue in the 

 lower edge of the mandible did 

 not disappear, but became more 

 marked as an anatomical feature 

 (see Figure 487). From analogy 

 with the elephant, such a 

 degeneration should have taken 

 place at once. That this did 

 not happen is a proof that the 

 part more than justified its 

 continued existence by perform- 

 ing some function of vital 

 importance to the species. 



Sir E. Ray Lankester, in one 

 of his delightful scientific 

 causeries, has pointed out that 

 man's chin consistsof something 

 more than a bony prominence 

 on the jaw. There is a distinct 

 fleshy pad upon its outer 

 surface, which materially influ- 

 ences its outline and which 

 consists of fatty tissue bound 



Figure 504. Modern man. 



up in little cushion-like com- 

 partments almost exactly com- 

 parable to the pads on our 

 fingers and toes. Although 

 the aesthetic and sex influences 

 may be apparent here rather 

 more than in the bony 

 mandible itself — for who can 

 gainsay the charm of a softly 

 rounded chin ? — the probable 

 origin of this cushion - like 

 covering is to be found in the 

 fact that the protruding chin 

 needed a pad for exactly the 

 same reason as do a cricketer's 

 shins. It was into a world 

 full of brutal tumult and hard 

 knocks that the nascent chin 

 first made its appearance ! In 

 the prize-ring to-day it is a 

 well-known fact that a blow 

 on the chin is the most rapid 

 way of putting your opponent 

 hors de combat ; and, more- 

 over, it has become apparent 

 that the nearer the exponent 

 of " the noble art " is in 

 structure to a chimpanzee or 

 gorilla the better chance will 

 he have of wearing the glorious 

 " Champion Belt of all the 

 World." If we look at the 

 bony structure of the chin in 

 some of the prehistoric jaws, we 

 find it of astonishing strength, 

 being stout and buttressed as 

 if to stand terrific violence. 

 This is remarkably shown in 

 Emil Selenka's admirable 

 monograph on primitive jaws, 

 published by Kreidel, of Wies- 

 baden, in 1903. From the 

 above facts it seems reasonable 

 to infer that man acquired such 

 advantages as a chin can give 

 at his peril ; and here, again, 

 it is suggested that some 

 evolutionary need, of excep- 

 tional potency, moulded man's 

 jawbone into its modern shape. 

 It is when we turn a human 

 mandible round and look at it 

 from the inside, and observe 

 the surface beneath the central 

 incisor teeth, that we begin to 

 get hints as to the actual func- 

 tions of the chin and the causes 

 which have led to our deviation 

 from ancestral type. About 

 half-way between the rim of 

 the central tooth-sockets 

 and the lower edge there 



