Examining collagen preservation through glutamine deamidation at Denisova Cave

Abstract The use of glutamine deamidation has been controversially proposed as a means of measuring relative decay in archeological bones using peptide mass fingerprinting data. If reliable, it could be used to identify intrusive fossils in stratigraphic layers and relatively date unprovenanced remains. However, growing empirical evidence suggests that there is no reliable link between glutamine deamidation and chronological age. To explore this and understand what contribution, if any, glutamine deamidation can make to our understanding of the archeological record we analyze 2459 fossils using MALDI-TOF MS from the East Chamber of Denisova Cave where robust chronological studies have been carried out and burial conditions are well understood. We then compare these results with additional data from 15 fossils measured using LC-MS/MS and the recently published deamiDATE tool. Our results reveal that intra and inter layer variability is too high to be able to detect a pattern of deamidation at Denisova Cave, suggesting caution should be applied when attempting to link deamidation with relative decay or chronological age.