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Accurate and precise age estimation is of paramount importance in forensic analysis of human remains. Despite several research efforts most commonly applied techniques provide poor age estimates. The low predictive power of macroscopic skeletal age estimation methods can be attributed to several factors such as the inappropriate statistical modelling, poorly sampled reference material, and an over reliance on an indicator-specific approach. The objective of this pilot study is to illustrate a general approach to age-at-death estimation from skeletal degeneration of major articulations of the appendicular skeleton, cervical and lumbar spine. A sample of 256 adult male individuals with known age-at-death was constructed from the identified skeletal collections held at the University of Coimbra. Articular degeneration of the appendicular skeleton was mapped by analysing marginal lipping, bone formation, porosity and eburnation of bone surfaces. Vertebral degeneration was analysed by scoring marginal lipping and porosity of body surfaces. To tackle the complexity of age-related skeletal degeneration, a machine learning approach is proposed around decision trees forests. Decision trees offer a flexible tool for age-at-death estimation as they can map regression functions without assuming a structural form for the predictive surface. Individual tree ensembles were created for each articulation and spinal segment, forming what is called here skeletal aging woods. To solve the issue of combining age prediction obtained from different aging woods, a final and larger forest is trained on the cross-validation predictions of the woods. From individual aging woods, older individuals tend to be accurately identified but age predictions for young individuals tend to be very broad and imprecise. However, prediction error from the final forest can be as low as 7.59 years, with the major errors more broadly concentrated on middle-aged individuals. Tools for visualizing age-related subspaces spanned by the proximity matrix of tree ensembles are also presented.

In a forensic case, ancestry is one of the four parameters of the individual's biological profile to be estimated. The cranium is the most informative part of the skeleton for this analysis, although sometimes it is absent or damaged. To overcome this limitation, some researchers conducted ancestry estimation studies in the postcranial skeleton. In 1965, Bunning and Barnet analyzed different population groups: British, Indian, Sri Lankan and Nigerian, and classified the calcanei in three types according to the number of talar articular facets present. Type A: three articular facets, type B: two articular facets and type C: one articular facet. The study found a high frequency of type A calcanei associated to the Europeans, and of type B to Africans and Indians. Type C was rarely observed. Subsequent investigations corroborated these results. The aim of this research is to test the Bunning and Barnett (1965) method in the 21st Century Identified Collection housed at the Laboratory of Forensic Anthropology, University of Coimbra. For this, the calcanei of 268 Portuguese individuals of European ancestry of both sexes were analyzed. The bones presenting signs of pathology or affected by post mortem fragmentation were excluded. From an intra- and inter-rater reliability analysis, it can be concluded that Bunning and Barnett (1965) morphotype classification is highly reproducible. The probability of agreement between observations was 0.959. Using Bunning and Barnett (1965) method, only 50.7 % of the individuals were classified with type A (European associated morphotype), 42.9 % classified as type B (African and Native American associated morphotype), and 6.4 % were assigned no classification due to asymmetric calcanei. The obtained results show that the calcanei morphology is of little value in ancestry estimation of contemporaneous Portuguese and its analysis should be used with caution in forensic settings.

Accurate and effective data collection from human remains in a forensic examination is often hindered by unpredictable factors such as taphonomy, pathology and recovery. The main purpose of this preliminary work is to illustrate the value of statistical reconstruction of missing cranial landmark three-dimensional coordinates in the context of ancestry estimation through 3D-ID software. Twenty-eight to thirty-one Cartesian coordinates were collected from 60 individuals from the 21st c. Identified Skeletal Collection housed at the University of Coimbra (Portugal) using the arm digitizer MicroScribe® G2X and missing Cartesian coordinates were calculated using R functions. When assessing ancestry using 3D-ID, the obtained results before and after missing points estimation showed differences in 25 individuals (41.7 %) from the total sample. Albeit more studies will be required, this method is becoming valuable for forensic anthropologists evaluating population affinities of skeletonized individuals.

Burned skeletal remains often undermine the anthropological methodology's reliability due to heat-induced changes (HIC). Research based on controlled experimental burnings has tried to address this problem, but may not replicate real scenarios as it employs homogeneous heating provided by electrical furnace. In contrast, real fire situations are often more heterogeneous with intermittent heating caused by the constant on and off action of the flames. The objective of this research was to assess ihe value of spectroscopic analyses on dry skeletal remains depends on the type of burning event: i) electric furnace (homogeneous) and ii) open-air ignited trailer (heterogeneous). The association between organic phase pyrolysis and temperature and between the inorganic phase and individual chemometric indices was investigated in order to examine for differences. A sample of 70 right antimere belonging to the 21st Century Identified Skeletal Collection (CEI/XXI) and of a sample of 30 antimeres from the Non-Identified Skeletal Collection (NISC) from the Santarem Cemetery housed at the Laboratory of Forensic Science in the University of Coimbra, Portugal were used in this study. Both skeletal collections were burned with temperatures ranging from 500 °C to 1050 °C. The methods used to analyze the samples are vibrational spectroscopy and inelastic neutron scattering spectroscopy. It was possible to observe through spectroscopic analyses that in the organic phase, a relation between the concentration of the chemical elements and maximum temperature was present in both samples. The same was observed for the inorganic phase and the chemometric indices. Results of this small experiment suggest that maximum temperature estimation and the individualization of commingled burned skeletal remains based on heat-induced recrystalization and diagenesis are possible in varied burning conditions. Therefore, the assessment of the parameters in real-fire settings appears to be quite promising.