A comparison of minimally-invasive sampling techniques for ZooMS analysis of bone artifacts

Abstract

Bone and antler are important raw materials for tool manufacture in many cultures, past and present. The modification of osseous features which take place during artifact manufacture frequently make it difficult to identify either the bone element or the host animal, which can limit our understanding of the cultural, economic, and/or symbolic factors which influence raw material acquisition and use. While biomolecular approaches can provide taxonomic identifications of bone or antler artifacts, these methods are frequently destructive, raising concerns about invasive sampling of culturally-important artifacts or belongings. Collagen peptide mass fingerprinting (Zooarchaeology by Mass Spectrometry or ZooMS) can provide robust taxonomic identifications of bone and antler artifacts. While the ZooMS method commonly involves destructive subsampling, multiple minimally-invasive sampling techniques also exist. In this paper, we compare three previously proposed minimally-invasive sampling methods (forced bag, eraser, and polishing film) on an assemblage of 15 bone artifacts from the pre-contact site EjTa-4, a large midden complex located on Calvert Island, British Columbia, Canada. We compare the results of the minimally-invasive methods to 10 fragmentary remains sampled using the conventional destructive ZooMS method. We assess the reliability and effectiveness of these methods by comparing MALDI-TOF spectral quality, the number of diagnostic and high molecular weight peaks as well as the taxonomic resolution reached after identification. We find that coarse fiber-optic polishing films are the most effective of the minimally-invasive techniques compared in this study, and that the spectral quality produced by this minimally-invasive method was not significantly different from the conventional destructive method. Our results suggest that this minimally-invasive sampling technique for ZooMS can be successfully applied to culturally significant artifacts, providing comparable taxonomic identifications to the conventional, destructive ZooMS method.