Estimation of mortality profiles from non-adult human skeletons in Edo-period Japan

Abstract

Reconstruction of the mortality profiles of non-adult human skeletons from an archeological site should greatly assist the interpretation of the sanitation, health, disease, and behavior of past human populations. The purposes of this study are to examine non-adult skeletons from the Sakai-kango-toshi 871 (SKT 871) site in Edo-period (17–19th centuries AD) Japan, to estimate their age-at-death distribution, and to discuss whether paleodemographic estimates can yield appropriate mortality patterns of this sample. The use of the Bayesian method for fetal age estimation, assuming uniform priors, yielded a peak of deaths at 10 months of gestation. The age-at-death distribution obtained from the whole population further indicated the peak of deaths being at the fetal stage and the number of deaths decreasing with age. The concentration on full-term of gestation implied deaths related to birth, which is consistent with natural mortality. Another important finding of this study is that individuals aged less than 7 years accounted for about 98% of the deaths and there was no burial for adults. An explanation for the lack of adults is preferential mortuary practices, in which the very young are buried separately from adults. It is concluded that this paleodemographic study of non-adults provides us with important information on mortality profiles and mortuary practices in Edo-period Japan.