310 ANTHROPOLOGICAL SURVEY IN ALASKA [ETH. ANN. 46 



Our rather extensive present data on children show that these 

 formations are absent in infancy. They begin to develop in older 

 childhood, in adolescence, or even during the earlier adult life; they 

 stop developing at different stages in different individuals, and they 

 never lead to any deformity of the body of the mandible. 



These overgrowths are further seen to be more common and to more 

 frequently reach a pronounced development in the males than in the 

 females. 



What is the effect of these hyperostoses? They strengthen the 

 dental arch. With them the arch is stronger; without them it would 

 be weaker. The view is therefore justified that they augment the 

 effectiveness of the dental arch; which is just what is needed or 

 would be useful in such people as the Eskimo where the demands on 

 the jaws exceed in general those in any other people. 



All these appear to be facts of incontrovertible nature; but if so 

 then we are led to practically the same conclusion that I have reached 

 in the study of the central and Smith Sound Eskimo, which is that 

 the lingual mandibular hyperostoses are physiological formations, 

 developed in answer to the needs of the alveolar portions of the 

 lower jaw. They could be termed synergetic hyperostoses. 



The process of the development of these strengthening deposits of 

 bone is probably still largely individual; yet the tendency toward 

 such developments appears to be already hereditary in the Eskimo, 

 as indicated by their beginning here and there in childhood. But 

 their absence in nearly one-third of the Eskimo mandibles, their 

 marked differences of occurrence and development in the two sexes, 

 and their occasional presence in the jaws of various other peoples, 

 including even the whites, speak against the notion of these hyper- 

 ostoses being as yet true racial features. 



Taking everything into consideration, the writer is more than ever 

 convinced that the lingual hyperostoses of the normal lower (as well 

 as the upper) jaw, in the Eskimo as elsewhere, are physiological, 

 ontogenic developments, whose object and function is the strength- 

 ening of the lower alveolar process in its lateral portions. Only 

 when excessively developed, which is very rare, they may, mechani- 

 cally, perhaps cause discomfort and thereby approach a pathological 

 condition. 



Main References 



Danielli, 20 1884 : " Saw the condition in lower jaws of 1 Swede, 

 1 Italian, 1 Terra di Lavoro jaw, 1 Slovene, 1 Hungarian, 1 Kirghis, 

 1 ancient Peruvian." 



Found hyperostoses in 9 out of 14 Ostiak lower jaws. 



"Danielli, Jacopo, Iperostosi in niandibole umano speclalmente di Ostiacchi, ed anclie 

 in mascellari superiore. Archivio per l'antropologia e I'etuologia, 1884, xiv, 333-346. 



