Postmortem chemical transformation of bone bioapatite can take place during early diagenesis resulting in a more thermodynamically stable mineral phase. This paper examines the impact of a 1-year postmortem interval on unburnt and burnt bone’s structural and chemical alterations. This question is of importance for the reconstruction of funerary practices involving cremation in the archaeological record, as well as forensic anthropological investigations. Fleshed pig (Sus scrofa) tibiae were left exposed in a field, then collected at 14, 34, 91, 180, 365-day intervals prior to being burnt in an outdoor fire (≤750 °C bone temperature). Fresh (fleshed) tibiae acted as unburnt and burnt controls. Also included in the study were two cremated human bone fragments from Middle/Late Neolithic (ca. 3300–2500 cal BC) Ireland. Samples were analysed for major and trace elements by wavelength dispersive electron microprobe analyser (EMP-WDS) and molecular structures by Fourier Transform Infrared Spectroscopy (FTIR). Linear regression, PCA, LDA, and MANOVA were performed for statistical analysis. Results indicate that the concentrations of elements associated with extracellular fluid (K, Na, Cl) change with the postmortem interval (PMI) and survive burning. K values under 0.07 ± 0.01 wt% in inner and mid-cortical zones of burnt bones suggest that bones were not burnt immediately after death. Using this criterion, results from the archaeological samples would indicate a PMI of at least weeks to months prior to cremation. Ca, P, Fe, Al, Si, and Sr are not significantly altered with burning, and Fe, Al, Si, Sr are also unaffected by the PMI. In unburnt bones increased crystallinity and carbonate loss are detectable in <1 year, but both are obscured by burning. Structurally, the carbonate to phosphate ratio (C/P), the phosphate high temperature (PHT), and cyanamide to phosphate (CN/P) are the most useful ratios for discriminating between unburnt and burnt bones.

The information that can be derived from the rate of preservation of cremated human remains is highly valuable for forensic anthropologists and bioarchaeologists. Especially when taphonomic agents, such as fire, are intentionally introduced to obscure lesions on the skeleton. When sharp force trauma is present on bones, one of the main questions that arise is whether it is possible to tell what instrument was used for trauma infliction. This study used quantitative methods to examine kerfs on bones treated with heat as a taphonomic agent. The experiment used three sharp-bladed weapons to inflict trauma on porcine long bones: a single bladed non-serrated kitchen knife, a hacksaw and a wood saw. The bones were de-fleshed and traumatized prior to maceration to produce trauma similar to that which occurs in the peri-mortem period. The traumatized bones along with control bones were burnt in controlled laboratory conditions at temperatures ranging from 300°C to 1000°C. Quantitative analysis was undertaken on both the macroscopic and microscopic (scanning electron microscopy) images. The cut-marks were clearly identifiable and distinguishable from heat related fractures at all temperatures. Shrinkage of the kerf dimensions were recorded only at 1000°C; all cut-marks' lengths shrank at this temperature, and all widths shrank as well, excepting marks from the wood saw, which instead showed an increase in maximum width. Individualization of the saws was not possible using only the metric traits. However, the class of the weapons (knife versus saw) could always be identified. It has been concluded that burning may cause fluctuation in kerf widths.