Impact of storage conditions on the preservation of taphonomically altered human skeletal remains: Insights from ATR-FTIR spectroscopy and DNA analysis

Abstract

The preservation of skeletonised human remains is crucial for successful archaeological and forensic analyses, yet it is influenced by various intrinsic and extrinsic factors. While numerous studies have addressed preservation states and their implications, the effects of storage conditions on taphonomically altered remains have been largely overlooked. This study examines the impact of storage conditions—freezer and room temperature—on bone samples from 21 femur shafts excavated from a World War II mass grave over a period of 1, 2, and 3 years. Changes were analysed using ATR-FTIR spectroscopy and DNA analysis to explore correlations between molecular alterations and DNA preservation.

Results demonstrate that storage conditions significantly affect bone preservation. Freezer storage showed minimal degradation, primarily characterised by changes in mineral crystallinity due to the loss of loosely bound ions, while collagen quality improved initially, likely due to molecular reordering. In contrast, room-temperature storage accelerated both mineral and collagen deterioration, with pronounced effects on collagen quantity and quality correlating with increased crystallinity and apatite domain proportions. DNA quality and quantity exhibited similar trends under both conditions, though correlations with mineral and collagen changes varied by storage environment.

Over three years, freezer storage mitigated degradation by limiting mineral and collagen loss, whereas room-temperature storage accelerated changes, especially in collagen. These findings highlight the importance of controlled storage conditions, as significant molecular and structural alterations were observed within a relatively short period. This has important implications for the long-term preservation of forensic and archaeological samples, emphasising the need for appropriate storage strategies to ensure sample integrity for future analyses.