Burned bones tell their own stories: A review of methodological approaches to assess heat-induced diagenesis

Abstract

One of the biggest struggles of biological anthropology is to estimate the biological profile from burned human skeletal remains. Bioanthropological methods are seriously compromised due to bone heat-induced alterations in shape and size. Therefore, it is urgent to improve our ability to estimate sex, age at death, stature and ancestrality, to recognize peri mortem traumas and differentiate them from fractures due to fire, and to determine what was the intensity of burning, namely maximum temperature and heat exposure length. This review focuses on different methodologies to assess heat prompted changes in bone submicrostructure. Some of these are extensively used in burned bones research, namely infrared and Raman spectroscopy and X-ray diffraction, while others such as neutron spectroscopy and diffraction are rarely applied to bone samples although their contribution may be crucial for establishing new bioanthropological methods for a reliable examination of burned victims.

Biomaterials from human bone – probing organic fraction removal by chemical and enzymatic methods

“…from HAp to defatted/deproteinated and intact bone), no signicant shis were observed in the transition energy from that of the reference HAp (630 cm À1 ) to bone samples subject to either hydrazine or enzymatic treatment (637 and 636 cm À1 , respectively). The splitting of the n 4 (PO 4 ) infrared signals (at 565 and 603 cm À1 ) is also a reliable measure of the crystal microstructure of hydroxyapatite, 4,8,16,51,52 and is commonly quantied by the crystallinity index (CI) calculated as the sum of the heights of the two n 4 (PO 4 ) absorption bands divided by the height of the minimum between them. 8 The CI values presently obtained for HAp, intact bone, hydrazine-and enzyme-exposed samples, respectively 7.56, 2.89, 3.49 and 3.04 clearly reect a decrease of the degree of crystallinity from the reference hydroxyapatite to the processed bone samples, the intact bone being the most amorphous material, as anticipated.…”

“…3 The examination of human remains is routinely carried out by bioanthropologists and chemists to retrieve varied information, such as radiocarbon dating or post-mortem changes. [4][5][6][7][8][9][10][11][12][13][14][15][16] The skeleton oen constitutes the only preserved remains found in archaeological and forensic settings and their importance for the study of past populations or for victim identication is unquestionable. However, retrieving information on the physical and chemical properties of the bone matrix (e.g.…”

“…intact, subject to burning events or to specic chemical handling, or even archaeological artefacts. 3,8,15,16,24,[30][31][32][33][34][35][36][37][38][39] FTIR, mainly in attenuated total reectance (ATR) mode, is a low-cost, non-destructive and rapid method for this type of analysis, that requires very small amounts of sample and yields very reliable data providing information on the chemical and structural characteristics of the bone, namely its organic components (protein and lipids), possible mineral contaminants (e.g. including uorapatite (francolite), chloroapatite, cinnabar or gypsum) or pathology-induced changes.…”

“…INS, in turn, is an extremely powerful technique for probing hydrogenous materials and has been shown to be particularly useful for the analysis of bone, revealing even minor variations in composition. 8,33,35,37,38 The INS intensity of each vibrational transition is normally expressed in terms of the so-called dynamic structure factor S * i ðQ; n k Þ; which has the simplied expression, for a given atom…”

Crystal clear: Vibrational spectroscopy reveals intrabone, intraskeleton, and interskeleton variation in human bones

“…The amount of A‐type and B‐type carbonates relative to phosphate are represented by the API and BPI indices, respectively (Sponheimer & Lee‐Thorp, ; Snoeck et al, ). Although this classification is common throughout the literature it should be emphasized that the calculation of the API is based on the vibrational band at 1540 cm −1 , which has a very large contribution from the amide II mode (at 1540–1550 cm ‐1 ) (Mamede, Gonçalves, Marques, & Batista de Carvalho, ) (Figure ). At higher temperatures (>600/700°C), the organic matter is destroyed and A‐type carbonates are reflected by that band.…”