| Research Abstract |
The superior view of the Japanese skull has changed from the anteroposteriorly long shape in the medieval times to the short one at the present. This phenomenon is called brachycephalization. The causes for this brachycephalization, however, have not been determined yet. Since 1992, the present author has examined correlations between cranial and postcranial measurements as a step toward clarifying the causes for brachycephalization and found that, while cranial breadth has no consistent association with any measurements of the vertebrae, ribs, and shoulder girdle, cranial length is strongly associated with the sagittal and transverse diameters of the vertebral bodies, and with sacral breadths. In the present study, the correlations between neurocranial measurements and those of the upper and lower limb bones were further examined for the same purpose.
In result, the present analyses and previous findings suggest that the chronological changes of three variables, i.e., the shape of the pelvis, body size, and the amount of skeletal muscles, can cause brachycephalization through their influence on the changes in maximum cranial length. Further, it is possible to consider that the causes for the changes in such physical variables, especially in body size and the amount of skeletal muscles, are chronological changes in nutrition intake and the amount of labor. Of course, the correspondency of these possible causes with the morphological changes in the skull should further be investigated in the future.
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