Eskimo Osteology c51 



There was a marked reduction in the height of the lowermost rectangle in crania 

 D-3 and F-31, and these vitiated the results to a considerable degree in the male 

 and female series respectively. Otherwise the average for this rectangle would 

 have been nearer 100. In a previous paper the author has pointed out that the 

 middle and lowermost rectangles are approximately squares in the Eurasiatic 

 type of cranium; that is to say, their indices are in the vicinity of 100. It will 

 be noted from the table that the averages for these two rectangles in the present 

 series of Eskimo skulls support this assertion. 



THE EVOLUTION OF THE ESKIMO TYPE OF SKULL 



It is evident from the foregoing description that if the Eskimo is really 

 Mongoloid in origin, which would bring him into relation with the Mongols of 

 Asia, the Polynesians of the Pacific Ocean and the aboriginal Indians of the 

 Western Hemisphere, then his skull exhibits at the present day some profound 

 alterations from the generalised Mongolian type. Take first of all his contracted 

 nasal aperture, which is perhaps his most important cranial specialisation, since it 

 places the Eskimo skull in a category by itself. It will probably be granted by most 

 observers that this modification can be explained by his climatic environ- 

 ment. The inhaling for prolonged periods of cold air, frequently registering 

 many degrees below zero, would most assuredly compel nature to design and 

 provide as narrow an aperture as possible, so as to reduce the chilling effect of 

 this intensely low temperature to a minimum. 



Now, in reference to the dolichocephalic Eskimo skull, I do not personally 

 consider that this has much significance when contrasted with the brachycephaly 

 of the Mongol, for it is a well recognized fact that the cephalic index has quite 

 an extensive range of variation, even in members of the same race. For example 

 the average type of Scottish skull approximates to the dolichocephalic type, 

 and yet Sir Wm. Turner found that 35 out of a series of 174 skulls collected 

 from various parts of Scotland exhibited well-marked brachycephaly (,"). 



The post-orbital constriction in these Eskimo skulls is so marked that it 

 deserves some comment. It has been already remarked that the tempora 

 muscles must have been powerfully developed, judging from the extreme^ 

 depth of the lower parts of the temporal fossse of these skulls. It seems to the 

 writer that these strongly acting muscles might possibly have had a constricting 

 effect upon this portion of the cranium, and thus diminished its post-orbital 

 diameter. This conclusion is strengthened by a comparative study of the crania 

 of some lower mammalia. In the gorilla, for example, the temporal muscles 

 are huge, and meet in a sagittal crest on the cranial vertex. Their constricting 

 effect is shown by the marked reduction of the post-orbital diameter, and of 

 course by a pronounced lowering of the fronto-parietal index. This post-orbital 

 constriction is, moreover, a striking feature of the crania of carnivora, the 

 fronto-parietal index for the lion skull in the Nova Scotia Provincial Museum 

 being found by the writer to be as low as 53, which meant that the post-orbital 

 constriction was reduced to nearly one half of the maximum parietal breadth. 

 On studying the conditions in modern Hominidse the author finds that the 

 fronto-parietal index is usually above 80 in the Anglo-Saxon type of cranium, 

 due of course to the fact that the skull has been compelled to adapt itself to the 

 lateral expansion of the frontal lobes of the brain in these higher races. On the 

 other hand he found this index as low as 72-6 in a Melanesian skull(^); while 

 Duckworth(i'') gives the average index for the aboriginal Australian cranium 

 as 77. There can be no doubt that these lowly evolved types of modern man 

 indulge in a very vigorous and unconventional type of mastication; thus en- 

 couraging their powerful temporal muscles to exert this constricting effect upon 

 their skulls, and therefore lower their fronto-parietal indices. Note further, that 



50844—41 



