266 



KNOWLEDGE 



[December 1, 1899. 



ON THE TREATMENT AND UTILIZATION OF 

 ANTHROPOLOGICAL DATA. 



By Arthur Thomson, ma., m.b. 

 VI.— FACIAL FOEM. 



THE skeleton of the face, as one might reasonably 

 expect from a knowledge of the living, displays 

 many characteristic varieties of form. As was 

 pointed out in a previous article, the shape of 

 the skull is to some extent dependent on the size 

 of the jaws, and the development of the muscles which 

 control the movements of the mandible. It will be obvious 

 that the size of the jaws will be largely determined by the size 

 of the teeth, and as in savage races the teeth are, as a rule, 

 larger than in the more highly civilised peoples, it naturally 

 follows that the architecture of the face will be modified 

 by the massiveness of the jaws and their associated 

 structures. The late Professor Sir William Flower was 

 amongst the first to recognise this fact, and by comparing 

 the length occupied by the upper molars and premolar 

 teeth with the length of the cranio-facial axis (basi-uasal 

 length) he determined the dental index by the following 

 formula : — 



Length of 5 molars x 100 ^ , , . -, 

 D • , , .L Dental index. 



Basi-uasal length 



In this way he was able to group the races of man 



according to the size of their teeth into three varieties : — 



h 

 Fio. 1. 



o i f 



Fia. 2. 



Figs. 1 and 2 represent Skulls witU large, mediani, and small Toetli. 



a, Mari'odont -. h. mesodoiit ; c. micvodont. 



I. — The Microdont, with an index below 42, including 

 mixed Europeans, ancient Kgyptians, low-caste natives of 

 India, and Polynesians. 



II. — Mesodont, with an index ranging between 42 and 

 44, comprising Chinese, American Indians, Malays, etc. 



III. — Megadont; having an index over 44. This group 



* KifowLEDaE, October, 1899. 



embraces Melanesians, Andamanese, and the Australian 

 and Tasmanian races. 



The reduction in the size of the teeth in the higher 

 races is probably explained by a reference to the 

 more common methods of preparing the food by 

 cooking, etc., which renders unnecessary a powerful 

 masticator}- apparatus. On the other hand, the size 

 of the teeth in the lower races is oftentimes much 

 larger than might be at first assumed from a casual in- 

 spection of a large number of skulls. This fact was borne 

 out during the discussion which took place on the remark- 

 able fossil remains brought from -Tava by Dr. Dubois. 

 These included a skull, a thigh bone, and two molar teeth, 

 presumably all belonging to the same individual. We are 

 not at present concerned with the skull or thigh bone, 

 which the discoverer claimed, with much show of truth, 

 belonged to an intermediate form between man and the 

 higher apes, which he distinguished under the name of 

 Pithecanthro-piis erect]is, but rather to draw attention to the 

 aspects of the case as determined by the teeth. These 

 were of large size, and, among other points, it was urged 

 that they were too big to be human. This assertion at 

 once put all the anatomists who had large collections 

 under their charge on the " qui vive," and many hundreds 

 of specimens were examined with the object of determining 

 this point. It soon became apparent that this argument 

 against the Trinil teeth being human would have to be 

 abandoned, as a number of instances were forthcoming in 

 which undoubtedly human teeth equalled, if they did not 

 excel, the fossil specimens in size. It would therefore 

 appear extremely hazardous to express any opinion as to 

 the limits of size within which we should regard teeth as 

 human. 



The teeth, which are embedded in the alveolar border 

 of the jaw (we are speaking now only of the upper 

 jaw) must, when large, occupy more room, and, necessarily, 

 lead to the expansion of that part of the jaw which 

 supports them ; this need not necessarily produce an 

 equal development of the entire bone, though doubt- 

 less, involving modifications of form, but will of course 

 cause an expansion or projection of its lower part, com- 

 parable to the muzzle seen in many animals. The reader 

 wUl at once appreciate the form of face dependent on 

 this projection of the jaws if he studies the appearance 

 presented by a typical negro, in whom, however, it is 

 as well to bear in mind that the appearance is much 

 exaggerated by the thickened and everted lips. To this 

 projection of the muzzle attention was directed by a 

 Dutch anatomist named Camper, who was the first to 

 attempt to estimate it by a scientific method. He 

 found that the angle formed by the intersection of two 

 lines, of which one passed across the face, cutting the 

 orifice of the ear posteriorly, and lying on the level with 

 the lower edge of the septum of the nose in front, whilst 

 the other was applied to the profile of the face, resting on 

 the most prominent part of the forehead above and the 

 anterior surface of the upper incisor teeth below, varied 

 considerably, ranging from 62° to 85°, corresponding, in 

 the first instance, with a projecting muzzle and a sloping 

 face, in the latter with a profile more nearly approaching 

 the vertical. On the living. Camper's method of determining 

 the facial angle is still employed by the use of appropriate 

 instruments, but in this country the method suggested by 

 Flower is that more commonly made use of to determine 

 the amount of projection of the upper jaw in the macerated 

 skull. This method depends on the proportions which two 

 measurements bear to one another — the basi-nasal length 

 (i.e., the distance from the anterior edge of the foramen 

 magnum to the fronto-nasal suture) as compared with the 



