Unveiling intra-skeletal variability in mature and immature human skeletal remains via ATR-FTIR spectroscopy

Molecular characteristics of skeletal remains were studied utilizing ATR-FTIR spectroscopy, focusing on comparisons between mature adult and immature non-adult skeletal elements. To cover the intra-skeletal variability, different types of bones were analysed. The objective was to identify significant differences between various skeletal elements of adults and non-adults. Additionally, the correlation between observed differences and DNA preservation was investigated. Despite exposure to taphonomic factors, findings indicate minimal diagenetic changes or a well-balanced alteration in mineral and collagen within bones. The identified differences primarily reflect functional and structural differences among various skeletal elements. Significant differences between adults and non-adults, or lack of it, is attributed to different paths of bone maturation from childhood to adulthood. High DNA preservation in non-adult petrous bones was attributed to the interplay between DNA and carbonates, both occupying hydroxyl sites in the lattice. Conversely, lower DNA content in other bones, especially non-adult bones, was correlated with high relative concentrations of collagen, in which DNA is less stable and more prone to degradation. This study highlights the importance of skeletal variation (inter, intra, developmental stage) when assessing the preservation state of the remains and choosing samples for further analyses such as DNA. For the first time, differences between mature adult and immature non-adult bones are included.