Demographic structure of skeletal populations in historic Japan: a new estimation of adult age-at-death distributions based on the auricular surface of the ilium

The reconstruction of past demographic structures from skeletal remains is one of the most important themes in the field of biological anthropology and bioarchaeology. However, the paleodemographic reconstruction is far from satisfactory in terms of providing reliable demographic structures of past populations. The purposes of this study are to examine demographic profiles from historic Japan, focusing on archaeological skeletal populations; to reconstruct adult age-at-death distributions using a new method for auricular surface aging [Buckberry, J.L., Chamberlain, A.T., 2002. Age estimation from the auricular surface of the ilium: a revised method. Am. J. Phys. Anthropol. 119, 231–239] and compare them with those of the traditional method [Lovejoy, C.O., Meindl, R.S., Pryzbeck, T.R., Mensforth, R.P., 1985. Chronological metamorphosis of the auricular surface of the illium: a new method of determining adult age at death. Am. J. Phys. Anthropol. 68, 15–28]; and to discuss whether paleodemographic data from skeletal remains provide important information concerning adult mortality patterns. This study analyzes well-preserved auricular surfaces of 114 individuals from the Chusei Shudan Bochi site and 99 individuals from the Hitotsubashi site, which are individuals of 15 years of age and above. The comparison of the results of the traditional and revised methods shows that the revised method has older age distributions with a majority of individuals being over 65 years and improves the age estimation for elderly individuals. A comparison between skeletal remains and historical census records strengthens the conclusion that the revised age estimation for elderly adults is more appropriate than the traditional method. The new method employed here brings technical innovations to allow us to reconstruct appropriate mortality profiles of past populations.