Cranial thickness of modern and neolithic populations in Japan.

Cranial vault thicknesses were measured directly with a spreading caliper at six anatomical reference points in the modern Japanese and Neolithic Jomon series. Because no statistically significant correlation was found between age and cranial thickness in our study, the age-related change in thickness was not indicated in the modern Japanese. The cranial thicknesses at the frontal and parietal eminences were significantly greater in the female than in the male in modern Japanese. In the male series the cranial thickness of the Neolithic Jomon was significantly greater than that of modern Japanese. It is suggested that the temporal change that has occurred in Japan during the last 2000 years is consistent with the trend toward decreasing cranial thickness during the last 10,000 years in many parts of the world.