Part 40

The Eskimo lower jaw differs substantially in many respects from that in other races, particularly from that of the whites. It is characterized by a high and stout body; by broad but low rami; and by excessive breadth at the angles. The body-ramus angle is moderate. To which may be added that the chin is generally of but moderate prominence, and that the bone at the angles in males is occasionally markedly everted.

MANDIBULAR HYPEROSTOSES

These hypertrophies or hyperostoses are rarely met with also in the jaws of the Indian and other people. They are symmetric and characteristic, though often more or less irregular. They generally extend from the vicinity of the lateral incisors or the canines backward, forming when more developed a marked bulge on each side opposite the bicuspids, which gives the inner contour of the jaw when looked at from above a peculiar elephantine appearance. They may occur in the form of smooth, oblong, somewhat fusiform swellings, or as a continuous more or less uneven ridge, or may be represented by from one to four or five more or less rounded or flattened hard "buttons" or tumorlike elevations. In development they range from slight to very marked.

These hyperostoses have been reported by various observers (Danielli, Søren Hansen, Rudolf Virchow, Welcker, Duckworth & Pain, Oetteking, Hrdlička, Hawkes). They received due attention by Fürst and Hansen in their "Crania Groenlandica" (p. 178). They have been given the convenient, though both etiologically and morphologically inaccurate, name of "mandibular torus"; I think mandibular hyperostoses or simply welts would be better. Fürst and Hansen found them, taking all grades of development, in 182, or 85 per cent, of 215 lower jaws of Greenland Eskimo; in 28 jaws, or 13 per cent, they were pronounced, the remainder being slight to medium. A special examination of 62 lower jaws of children and 710 lower jaws of adult western Eskimo (with a small number from Greenland) gives the following record:

LINGUAL MANDIBULAR HYPEROSTOSES IN THE WESTERN ESKIMO

CHILDREN

[62 mandibles, completion of milk dentition to eruption of second permanent molar]

+-----------------+-------------+-------------+------------ |None or | Slight to | | |indistinguishable| moderate | Medium | Pronounced ----------+-----------------+-------------+-------------+------------ Specimens | 47 | [169]10 | [170]5 | Per cent | _75.8_ | _16.1_ | _8.1_ | ----------+-----------------+-------------+-------------+------------

ADULTS

[Both sexes. 710 mandibles]

+-----------------+-------------+-------------+------------ Specimens | 215 | 356 | 114 | 25 Per cent | _30.3_ | _50.1_ | _16.1_ | _3.5_ ----------+-----------------+-------------+-------------+------------

ADULTS

[Sexes separately. M. 350; F. 360 mandibles]

Column Headings A: B: ----------+-----------------+--------------+--------------+-------------- |None or | Slight to | | |indistinguishable| moderate | Medium | Pronounced ----------+--------+--------+------+-------+------+-------+------+------- | Males |Females | Males|Females| Males|Females| Males|Females ----------+--------+--------+------+-------+------+-------+------+------- Specimens | 71 | 144 |193 | 163 | 67 | 47 | 19 | 6 Per cent | 20.3 | 40.0 | 55.1 | 45.3 | 19.1 | 13.1 | 5.4 | 1.7 ----------+--------+--------+------+-------+------+-------+------+-------

The significance of these hyperostoses is not yet quite clear. Danielli, who in 1884 reported them[171] in the Ostiaks, Lapps, a Kirghiz, a Peruvian Indian, and four white skulls, offered no explanation. For Søren Hansen,[172] who first suggested the resemblance of these formations to the torus palatinus, "the significance of this feature, which also occurs in other Arctic races not directly related to the Eskimos, is not clear." R. Virchow,[173] who reports "wulstigen und knolligen Hyperostosen" on both the upper and lower jaws of a Vancouver Island Indian, restricts himself to a brief mention of the condition with a suggestion as to its causation (see later). Welcker[174] found them in the skulls of a German (Schiller?), Lett, and a Chinese, but has nothing to say as to their meaning. Duckworth and Pain[175] report the "thickening" in 10 out of 32 Eskimo jaws, but do not discuss the causation; and the same applies to Oetteking,[176] who reported on a series of Eskimo from Labrador. In 1909 Gorjanovič-Kramberger[177] somewhat indirectly notes the condition, without a true appreciation of its meaning.

In 1910 I had the opportunity to report on the mandibular hyperostoses in a rare collection of crania and lower jaws of the central and Smith Sound Eskimo.[178] Of 25 lower jaws of adults and 5 of children, 18, or 72 per cent, of the former and 2 of the latter showed distinct to marked lingual hyperostoses, while in the remaining cases the feature was either doubtful (absorption of the alveolar process) or absent. Two of the five children showed the peculiarity in a well-marked degree. A critical consideration of the condition leads me to the conclusion that it is not pathological, and my remarks were worded (p. 211) as follows: "A marked and general feature is a pronounced bony reinforcement of the alveolar arch extending above the mylohyoid line from the canines or first bicuspids to or near the last molars. This physiological hyperostosis presents more or less irregular surface and is undoubtedly of functional origin, the result of extraordinary pressure along the line of teeth most concerned in chewing; yet its occurrence in infant skulls indicates that at least to some extent the feature is already hereditary in these Eskimo."

In 1912, Kajava[179] reported lingual hyperostotic thickenings on the lower jaws of 68 adult Lapps, and found the condition in frequent association with pronounced wear of the teeth. In 1915, finally, Fürst and C.C. Hansen, in their great volume on "Crania Groenlandica," approach this question much more thoroughly. They, as also Kajava, did not know of the writer's report of 1910. They found the "torus" (p. 181), "also in the mandibles of some various Siberian races in a not insignificant percentage * * * and also not infrequently among European races, especially in the Laplanders (30 to 35 per cent)." They also report the presence of the condition "in a Chinaman," and saw indications of a good development of it in 17 per cent of 164 middle ages to prehistoric, and in 12 per cent of later Scandinavian lower jaws. Their interesting comments on its possible causation, though at one point seemingly not harmonizing, are as follows (p. 180): "The possibility is not precluded that we have here a formation which, even though it has at first arisen and been acquired through mechanical causes, has in the end become a racial character, albeit a variable one." And page 181: "There seems to be no doubt whatever that it is a formation connected with Arctic races or Arctic conditions of life; and, accordingly, it can not safely be assumed to be a racial character, however difficult it is to regard it as a formation only acquired individually."

With both the previously published and the present data, I believe the subject of these bony formations may now be approached with some hope of definite conclusions.

These hyperostoses give no indication of being pathological. They are formed largely, if not entirely, by compact bone tissues of evidently normal construction. They never show a trace of attending inflammation or of ulceration or of breaking down. They resemble occasionally the osteomae of the vault of the skull, and more distantly the osteomae of the auditory meatus, but in those cases where the bony swelling is uniform and in many others they show to be of quite a different category. (Pl. 61.)

As a rule these bony protuberances in the Eskimo are not connected with evidence of pyorrhoea, root abscesses, or any other pathological condition of the teeth, for those conditions are practically absent in the older Eskimo skulls; therefore they can not be ascribed to any irritation due to such conditions, and the Eskimo have no habits that could possibly be imagined as favoring, through mechanical irritation, the development of these bony swellings. Wear of the teeth, which has been thought to stand possibly in a causative relation to these developments, is common in many races and even in animals (primates, etc.), without being accompanied by any such formations.

The development of such overgrowths is not wholly limited, as already indicated from the cases reported by Danielli (1884) and Virchow (1889), to the lower jaw, but somewhat similar growths may also be observed, though much more rarely, both lingually and on the outer border of the alveolar process of the upper jaw in the molar region. When present in the latter position they interfere with the measurement of the external breadth of the dental arch.

But, if neither pathological themselves nor due to any pathological or mechanical irritation, then these hyperostoses can only be, it would seem, of a physiological, ontogenic nature; and if so, then they must be brought about through a definite need and for a definite purpose or function.

These views are supported by their marked symmetry, which is very apparent even where they are irregular; by the fact that in general they are not found in the weakest jaws (weak individuals), or again in the largest and stoutest mandibles (jaws that are strong enough, as it is); and by the history of their development.

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 hyperostoses 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 strengthening of the lower alveolar process in its lateral portions. Only when excessively developed, which is very rare, they may, mechanically, perhaps cause discomfort and thereby approach a pathological condition.

FOOTNOTES:

[169] None in the younger children.

[170] All in older children or adolescents.

[171] Danielli, J., Arch. p. l'antrop. e l'etnol., 1884, XIV.

[172] Meddel. om. Grønl., 1887, No. 17.

[173] Beitr. Kraniol. d. Insul. w. Küste Amer., 1889, 398.

[174] Arch. Anthrop., 1902, XXVII, 70.

[175] J. Anthr. Inst., 1900, XXX, 134.

[176] Abh. und Ber. Zool. und Anthr. Mus., Dresden, 1908, XII.

[177] Sitzber. preuss. Ak. Wiss., LI-LIII.

[178] Anthrop. Pap's. Am. Mus. Nat. Hist., V, pt. II.

[179] Verh. Ges. Finn. Zahnärzte, 1912, IX.

MAIN REFERENCES

Danielli,[180] 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.

Material: Young 2, adult 6, old 6.

Hyperostoses in young 1, adult 3, old 5.

Mantegazza, at his request, examined some Ostiak and Eskimo skulls in Berlin and found the hyperostoses in 2 Ostiak lower jaws (slight) and in 1 Eskimo skull from Greenland (marked).

Found also smaller hyperostoses in the upper jaw ventrally to the molars ("situate quasi sempre dalla parte interna in corrispondenza dei molari"):

Skulls: 2 Italians, 1 Hungarian, 7 Norwegians, 2 Lapps, 5 Ostiaks.

Plate shows 8 lower jaws, 1 with slight, 7 with marked hyperostoses (1 symphyseal swellings, 3 tumorlike).

Refrains from interpretation (could not reach conclusion).

Virchow,[181] 1889, page 392: In upper jaws of three Santa Barbara skulls: "An den Alveolarrändern der weiblichen Schädel Nr. 3-6 von S. Barbara besteht eine höchst eigenthümliche und seltene, knollige Hyperostosis s. Osteosclerosis alveolaris, wie ich sie in gleicher Stärke früher nur bei Eskimos gesehen hatte. Ein leichter Ansatz dazu zeigt sich auch bei dem männlichen Schädel Nr. 4 von S. Cruz. Es dürfte dieser Zustand, der mit tiefer Abnutzung der Zähne zusammenfält, durch besonders reizende Nahrung bedingt sein."

Vancouver Island skulls: "dagegen sehen wir dieselbe alveolare Hyperostose, die wir bei den Leuten von S. Barbara und weiterhin bei Eskimos kennen gelernt haben."

Virchow,[182] 1892: "Der Alveolarrand gleichfalls mit hyperostotischen Wülsten besetzt, jedoch mehr an der inneren Seite, besonders stark in der Gegend per Prümolares und Canini, weniger stark in der Gegend der Incisici."

Welcker,[183] 1902: "Exostosen der Alveolarränder. Von erheblicher Beweiskraft können Eigenthümlichkeiten und Abnormitäten des Knochengewebes under der Knochenoberfläche werden, wenn dieselben, bei an sich grosser Seltenheit ihres Vorkommens, an einem Oberschädel und Unterkiefer zugleich vorkommen.

"So fand ich am Unterkiefer der Gypsabgüsse des sogenannten Schillerschädels sehr merkwürdige, bis dahin nirgends erwähnte, erbsenförmige Exostosen an den Alveolen der Eck- und Schneidezähne. Ganz ähnliche, wenn auch etwas flächere Exostosen zeigen die Alveolen eben derselben Zähne des Oberschädels, und es beweist dieses seltene Vorkommen bei dem Zutreffen aller übrigen Zeichen das Zusammengehören beider Stücke mit hoher Sicherheit.

"In einer etwas anderen Form, in der dieselben einen geschlossenen, exostotischen Saum bilden, fand ich Alveolarexostosen bei einem Lettenschädel (G. Gandras, 47 J., Halle Nr. 52). Hier sind die Alveolarränder der Schneide-und Eckzähne mit flachen, am Oberkiefer streifenförmigen (senkrecht gestellten), am Unterkiefer mehr rundlichen Exostosen besetzt, so dass der sonst papierdünne Zahnflächenrand beider Kiefer in einen, die Zahnhälse begrenzenden wulst-förmigen Saum umgewandelt ist. Der gleiche Charakter dieser nicht häufigen Abnormität an beiden Kiefern giebt die vollste Ueberzeungung der Zusammengehörigkeit.

"In schwächerem Grade zeigt diesen Zustand ein Chinesenschädel der Halle'schen Sammlung (Lie Assie)."

Fürst,[184] 1908: "Wir haben hier auf diese interessante anatomische Bildung aufmerksam machen wollen, die, wenn nicht konstant, doch in sehr hohem Prozentsatze und in bestimmter charakteristischer Form bei den Eskimos auftritt und in verschiedenen Variationen auf dem Unterkiefer anderer Rassen, speziell nordischer oder arktischer, vorkommt.--Wir wollen später eine ausführlichere Beschreibung über den Torus mandibularis mitteilen."

Gorjanovič-Kramberger,[185] 1909: "Durch die Ausbiegung der seitlichen Kieferflächen würde ferner die Druckrichtung der M und P eine gegen die innere Kieferwandung gerichtete. Als direkte Folge dieses Druckes hat man die starke Ausladung der entsprechenden lingualen Kieferseiten im Bereiche der P und M anzusehen, die da eine auffallende Einengung des inneren Unterkieferraumes bewerkstelligte."

Hrdlička (A.), 1910. See text.

Hansen,[186] 1914: "The lower jaws attached to the skulls are powerfully formed, high, and, above all, very thick, their inner surface being markedly protruding, rounded, and without any special prominence of linea mylohyoidea. This peculiarity, which is common enough, among the Eskimo and certain Siberian tribes, but is otherwise exceedingly rare, must be regarded as a hyperostosis of the same nature as the so-called torus palatinus. It is a partly pathological formation due to a peculiar mode of life rather than a true morphological mark of race."

Fürst, C. M., and Hansen, C. C., 1915. See text.

Cameron,[187] 1923: "In some instances the bony thickening was excessive. For example, in mandible XIV H-8 the inward bulging of the bone was so marked that the transverse distance between the inner surfaces of the body opposite the first molars was reduced to 21.5 millimeters. This jaw had therefore an extraordinary appearance when viewed from below. (See fig. 5.) The writer would regard these bulgings as bone buttresses built up by nature to resist the excessive strain thrown upon the alveoli of the molar teeth. He exhibited the mandibles to Prof. H. E. Friesell, dean of the dental faculty, University of Pittsburgh, and this authority concurred in the opinion expressed above." A disagreement with this view is expressed by S. G. Ritchie, pages 64c-65c, same publication.

FOOTNOTES:

[180] Danielli, Jacopo, Iperostosi in mandibole umano specialmente di Ostiacchi, ed anche in mascellari superiore. Archivio per l'antropologia e l'etnologia, 1884, XIV, 333-346.

[181] Virchow, E., in Beiträge zur Craniologie der Insulaner von der Westküste Nordamerikas. Zeitschr. f. Ethnol. Verhandl., 1889, XXI, 395, 401.

[182] Virchow, R., Crania Ethnica Americana. Berlin, 1892, Tafel XXIII. A "long-head" male adult of Koskimo, Vancouver Island.

[183] Welcker, H., Die Zugehörigkeit eines Unterkiefers zu einem bestimmten Schädel, nebst Untersuchungen über sehr auffällige, durch Auftrocknung und Wiederanfeuchtung bedingte Gröben und Formveränderungen des Knochens. Arch. f. Anthropol., 1902, XXVII, 70.

[184] Fürst, Carl M., Demonstration des Torus mandibularis bei den Askimos und anderen Rassen. Verhandlungen der Anatomischen Gesellschaft in Berlin, 1908, Ergänzhft z. Anatom. Anz., 1908, XXXII, 295-296.

[185] Gorjanovič-Kramberger, K., Der Unterkiefer der Eskimos (Grönländer) als Träger primitiver Merkmale. Sitzungsberichte der königlich preussischen Akademie der Wissenschaften, 1909, LI.

[186] Hansen, Søren, Contributions to the anthropology of the East Greenlanders. Meddelelser om Grønland, Copenhagen, 1914, XXXIX, 169.

[187] Cameron, John, The Copper Eskimos. Report of the Canadian Arctic Expedition, 1913-1918. Ottawa, 1923, XII, c. 55.

SKELETAL PARTS OTHER THAN THE SKULL

The skeletal parts of the western Eskimo, outside of the skull, are but little known. The only records are those on two skeletons (one male, one female) from Point Barrow by Hawkes,[188] and those on a few bones from Port Clarence by Cameron.[189] The data on the skeletal parts of the northern and eastern Eskimo are only slightly richer, being for the most part fragmentary and scattered.[190] Nor has the time arrived yet for a comprehensive study of such material, for notwithstanding the relative abundance in crania and the more resistant individual skeletal parts, the securing of anywhere near complete skeletons is very difficult. Nevertheless there is now a good number of the long bones of the western Eskimo in the possession of the National Museum and the main data on these, all secured personally by the writer, will be given. They must for the present remain essentially as so many figures without adequate discussion and comparisons. Nevertheless a few facts appear so plainly that they may well be pointed out before concluding this section.

FOOTNOTES:

[188] Amer. Anthrop., 1916, LVIII, 240-243.

[189] Rep. Canad. Arct. Exp., 1913-1918, Pt. C, 1923, 56-57.

[190] Mainly by Turner (London, 1886); Duckworth (Cambridge, 1904); Hrdlička (New York, 1910); Cameron (Ottawa, 1913-1918); also a series of incidental references and comparisons.

WESTERN ESKIMO: THE LONG BONES