Evaluating three methods to estimate the number of individuals from a commingled context

An estimate of how many individuals are represented in a commingled assemblage is important to interpret the wider context (archaeologically or forensically), for further analyses, and for palaeodemographic studies. The aim of this study was to establish whether the Minimum Number of Individuals (MNI) and Minimum Number of Elements (MNE) estimates produced by three different methods (traditional MNI (White, 1953); zonation method (Knüsel and Outram, 2004); the landmark method (Mack et al., 2015)) are the same or, if different, to evaluate these differences. The methods were applied to an assemblage recovered from a Spanish medieval cemetery from Navarra and used to estimate the Number of Identified Specimens (NISP), the MNI and the MNE according to each method. Fragmentation analysis was also performed. The results indicate different values of MNE and MNI when applying different methods. White's MNI equaled 84; the MNI by zones 68; and the MNI by landmarks 61. All methods showed differences but the disparity between the traditional MNI and the MNI by landmarks was highest. Furthermore, the results indicate that different methods had a minimal impact on estimates of smaller bones. Individuals may be double counted by White's MNI count and the zonation method, when refitting exercises cannot be applied to all fragments from the same context or site, or if the 50% presence rule is not applied to the method. Finally, these findings have important implications for future analysis of commingled remains, because MNE and MNI estimates, as well as levels of fragmentation can impact on decisions made to further analyse the collection. Further research on a known collection is needed to identify the most reliable method to use.