A method to assess wear rate in pig teeth from archaeological sites

The recording of age at death is an important aspect of zooarchaeological analysis as it provides evidence about a variety of research questions, spanning from the origins of domestication to husbandry strategies. Age estimation based on tooth eruption and wear is a commonly used method to establish the age at death of archaeological populations. However, this approach has its limitations. It relies on the principle that tooth wear rate is relatively constant in different populations but, since no method has ever been developed to quantify the rate of wear, such an assumption has never been fully verified. As a consequence, the extent to which variable speeds of wear in different populations may affect age estimations is still unknown. To clarify this bias and offer transparency into the issue, the development of a method to assess wear rate in archaeological teeth is of paramount importance. In this paper, we propose a simple system that allows such an assessment to be undertaken. The system has been developed for pig mandibular/lower teeth but can also be extended to other species. The methodology is then tested on several English Late Medieval and Early Modern pig assemblages which represent ideal case studies as they cover a historical period when extensive changes in pig dietary regimes occurred. The evidence reassuringly suggests that differences in wear rates between these periods were not substantial, which bodes well for the comparability of kill-off patterns. However, comparisons with several outgroups indicate that the potential range of wear rates is much greater than attested in our core case study. Wild boars and prehistoric pigs, in particular, appear to wear their molars more slowly. Caution is therefore needed and it is suggested that tooth wear rates (TWR) and average wear rates (AWR) should routinely be calculated when tooth-based age profiles are analysed.