Don't throw the baby teeth out with the bathwater: Estimating subadult age using tooth wear in commingled archaeological assemblages

Abstract

Abstract Commingled assemblages of fragmentary human skeletal remains are a common feature of many archaeological sites and pose significant analytical problems for bioarchaeologists. Such deposits often contain a high volume of the teeth of subadults for which it is challenging to estimate age, including developing permanent teeth with damaged roots, articulated teeth with roots obscured by alveolar bone, and deciduous teeth with completed root apices. Here, we present a new method for more precisely estimating age for the developmentally ambiguous teeth of subadults from archaeological contexts. We used a sample of articulated subadult dentition from the Copper Age site of Marroquíes in Jaén, Spain, to build linear models of the relationship between dental age and tooth wear for deciduous and permanent molars. We tested three different strategies for identifying and removing outliers to build a linear model with the strongest relationship between age and wear. The Adjusted Residual strategy, which used diagnostic plots of linear regression residuals in the statistical package R to identify and remove outliers, was found to produce the strongest linear model. The linear model developed using the Adjusted Residual strategy was then used to provide estimated midpoint ages and upper and lower age bounds based on the wear scores from the sample of developmentally ambiguous teeth. This study demonstrates that it is possible to estimate the age of developmentally ambiguous deciduous and permanent molars with reference to an adequate sample of subadult dentition with estimated ages from the same population. This new method is valuable as it extracts information from developmentally ambiguous teeth that would otherwise be inaccessible, allows for rapid data collection, employs standard macroscopic dental scoring methods, and can be used for sites from other regions and periods. We conclude by discussing the applications of this new method within bioarchaeology and identify directions for future research on subadult dental wear.