A comparison of considerable interest is also that of the cranial module or mean diameter, to the capacity of the same skulls. This comparison reveals an important sex factor.[148] Relatively to the module, the capacity is very appreciably smaller in the female than it is in the male. This is a universal condition to which, so far as known, there are occasional individual but no group exceptions. It appears very clearly in the Eskimo. In 283 western male Eskimo skulls in which we have so far measured the capacity,[149] the module averages 15.38 centimeters, the capacity 1,490 cubic centimeters; while in 382 female skulls thus far gauged the former averages 14.82 centimeters, the latter 1,337 cubic centimeters. The percentage relation of the capacity to the module, the numbers taken as a whole, is 96.8 in the males but only 90.2 in the females. This means that relatively to the external size of the skull the female Eskimo brain is 6.66 per cent smaller. Similar sex disproportion exists in other American groups as well as elsewhere. Some day when suitable data accumulate it will be of much interest to study this condition on a wider scale.
FOOTNOTES:
[148] See writer's "Relation of the Size of the Head and Skull to Capacity in the Two Sexes," Am. J. Phys. Anthrop., 1925, VIII, No. 3.
[149] All measured de novo by my aide, T. D. Stewart; for procedure see my "Anthropometry."
ADDITIONAL REMARKS ON CRANIAL MODULE
Before we leave this subject, it may be well to point out two noteworthy facts apparent from the data on the northwestern and northeastern groups. The first is that the figures on both sexes from Barrow and Point Barrow are very nearly the same, suggesting strongly the identity of the people of the two settlements; and the Point Hope group is in close relation. The second fact is the curious identity of the old Igloo group, 8 miles southwest of Barrow, with the Greenlanders. The import of this will be seen later.
SKULL SHAPE
Utilizing the materials of the Otis and Barnard Davis Catalogues and with measurements taken for him on additional specimens in several of our museums, Boas, in 1895 (Verh. Berl. anthrop. Ges., 398), as already mentioned, reported the cranial index of 37 "western Eskimo" skulls of both sexes (without giving localities or details) as 77. He also reports in the same place (p. 391) the cephalic index of 61 probably male living "Alaska Eskimo," again without locality, as 79.2. These rather high indices and the relatively elevated stature (61 subjects, 165.8 centimeters) lead him to believe (p. 376) that both are probably due to an admixture with the Alaskan Indian, though the report contains no measurements of the latter.
The data that it is now possible to present may perhaps throw a new light on the matter. As was already seen in part from the data on the living, the head resp. the skull tends to relative shortness and broadness throughout the southwestern, midwestern, and Bering Sea region (excepting parts of the Seward Peninsula). Important groups in this region, particularly those on some of the islands, had little or no contact with the Indian. The cranial index in most of the groups of the southwestern and midwestern Eskimo equals or even exceeds that of the Indian. And Eskimo groups with a relatively elevated cranial index are met with even in the far north, as at Point Hope, Hudson Bay, and Smith Sound.[150] Finally, the shorter and broader head connects with that of the Asiatic Eskimo and that of the Chukchee, as well as other northeastern Asiatics.[151]
The records now available show the highest cranial indices to occur on the coast between Bristol Bay and the Yukon and on lower Yukon itself, while the lowest indices of the midwest area, though still mesocranic, occur in the aggregate of Nunivak Island and the mouths of the Yukon. Another geographical as well as somatological aggregate is that of the people of the St. Lawrence and Diomede Islands and of Indian Point, Siberia, the cranial index in these three localities being identical.