Chemosteometric regression models of heat exposed human bones to determine their pre-burnt metric dimensions.

OBJECTIVES: Heat exposure can lead to apparently random osteometric changes that hinder the application of metric methods used for biological profiling. The impracticality of using objective and burn-specific osteometric methods reduces the chances of establishing the biological profiles of unknown individuals based on their skeletal remains. We investigated the potential of chemometry analysis based on infrared spectroscopy to predict the amount of heat-induced osteometric changes and how this reflected into sex estimation. MATERIAL AND METHODS: Bones from 41 identified adult skeletons (24 females and 17 males with ages between 62 and 90 years old) were experimentally burnt to maximum temperatures ranging from 450°C to 1,100°C (attained after 65 to 240 min). Measurements were taken both before and after each experiment and powder samples were analyzed through FTIR-ATR. Correlations among heat-induced metric changes and chemometric indices (crystallinity index; B-type carbonates; carbonate [A + B] to carbonate B ratio; hydroxyl to phosphate ratio; 630 cm-1 , 1450 cm-1 , 3572 cm-1 , and 3642 cm-1 ) were tested. Significant variables were used to build regression models to predict heat-induced metric change which were then tested on an independent set of samples. Agreement in sex estimation between the pre- and post-burnt samples was also evaluated. RESULTS: All indices were significantly correlated to heat-induced metric changes (α = .01) and the highest correlations were obtained for the 630 cm-1 , 3572 cm-1 , and crystallinity index. We confirmed that regression models based on chemometrics obtained from infrared spectra through FTIR-ATR are better at estimating heat-induced metric changes affecting bone and at sexing remains than other osteometric methods such as those based on correction factors or on metric references specific to calcined bones. DISCUSSION: Regression models avoid the subjectivity associated with the application of other methods. While the latter can be applied only to calcined bones, which is difficult to assess sometimes, regression models can be applied to all bones regardless of their condition. Also, regression models have the advantage of allowing to infer about heat-induced metric change on a case-by-case basis.

Potential of Bioapatite Hydroxyls for Research on Archeological Burned Bone.

The estimation of the maximum temperature affecting skeletal remains was previously attempted via infrared techniques. However, fossilization may cause changes in the composition of bones that replicate those from burned bones. We presently investigated the potential of three OH/P indices (intensity ratios of characteristic infrared bands for OH and phosphate groups, respectively) to identify bones burned at high temperatures (>800 °C) and to discriminate between fossil and burned archeological bones, using vibrational spectroscopy: combined inelastic neutron scattering (INS) and FTIR-ATR. The INS analyses were performed on two unburned samples and 14 burned samples of human femur and humerus. FTIR-ATR focused on three different samples: (i) modern bones comprising 638 unburned and 623 experimentally burned (400-1000 °C) samples; (ii) archeological cremated human skeletal remains from the Bronze and Iron Ages comprising 25 samples; and (iii) fossil remains of the Reptilia class from the Middle Triassic to the Eocene. The OH/P indices investigated were 630 cm-1/603 cm-1, 3572 cm-1/603 cm-1, and 3572 cm-1/1035 cm-1. The OH signals became visible in the spectra of recent and archeological bones burned between 600 and 700 °C. Although they have episodically been reported in previous works, no such peaks were observed in our fossil samples thus suggesting that this may be a somewhat rare event. While high crystallinity index values should always correspond to clearly visible hydroxyl signals in burned bone samples, this is not always the case in fossils which may be used as a criterion to exclude burning as the agent responsible for high crystallinity ratios.

A case of enchondroma from Carolingian necropolis of St. Pere De Terrassa (Spain): An insight into the archaeological record.

Enchondromas occur with an estimated modern incidence rate of 27.7% of benign bone tumors (Hauben and Hogendoorn, 2010), but few are represented in the paleopathological record. The medieval site of St. Pere in Spain has produced a convincing case. The diagnosis was confirmed by X-Ray, CT-scan and µ-CT scan. Therefore UF 755 from St. Pere - a male of more than 60 years old - can be confirmed as a femoral case of enchondroma, supported by evidence, in the paleopathological record.

Hip Dislocation and Dystocia in Early Medieval Times: Possible Evidence of Labor Maneuver.

BACKGROUND: In ancient times, maternal mortality would occur frequently, particularly during labor. Evidence of dystocia resulting in the death of a pregnant woman is very infrequent in paleopathologic literature, with only a few cases being demonstrated. CASE: In the early medieval site of Casserres, the skeleton of a young woman with a fetus in the pelvic region was found. Some abnormal findings of the maternal skeleton were evaluated, including a sacral anomaly, femoral head wound, the rare position of the lower left limb with the femoral head dislodged anteriorly and cephalad from the socket, and a fibular fracture. CONCLUSION: Examining the anomalies all together, a case of anterior hip dislocation related to a McRoberts-like maneuver performed during labor is a plausible explanation of the findings.

Cremation practices coexisting at the S'Illot des Porros Necropolis during the Second Iron Age in the Balearic Islands (Spain).

The necropolis of S'Illot des Porros, one of the most important prehistoric funerary sites of the Balearic Islands (Spain), was in use from the VIth and Vth century BCE until the Ist century CE. Located in a funerary area which contains two cementeries and one sanctuary, this site is constituted by three funerary chambers named A, B and C, respectively. Investigations on all the human burnt bone remains of the chambers, carried out mainly by the X-ray diffraction and supplemented in some cases by Fourier Transform Infrared spectroscopy pointed to the simultaneous use of inhumation and cremation funerary rites, probably due to existing social differences. In particular, it was argued that the chambers were differentiated, i.e., B was dedicated to inhumations and A to cremations, the cremations found in chamber B very likely being a result of a cleaning-purification of the burial area. Moreover, chamber C, which is the most ancient (IVth century BCE) and with the largest number of inhumed remains, contains the smallest number of remains that were exposed to fire and just in one case it seems possible to attribute a genuine high-temperature cremation.

The potential of X-ray diffraction in the analysis of burned remains from forensic contexts.

In view of the difficulties in extracting quantitative information from burned bone, we suggest a new and accurate method of determining the temperature and duration of burning of human remains in forensic contexts. Application of the powder X-ray diffraction approach to a sample of human bone and teeth allowed their microstructural behavior, as a function of temperature (200-1000 degrees C) and duration of burning (0, 18, 36, and 60 min), to be predicted. The experimental results from the 57 human bone sections and 12 molar teeth determined that the growth of hydroxylapatite crystallites is a direct and predictable function of the applied temperature, which follows a nonlinear logistic relationship. This will allow the forensic investigator to acquire useful information about the equilibrium temperature brought about by the burning process and to suggest a reasonable duration of fire exposure.