Human or non-human? A histological and proteomic approach for the identification of burnt and fragmented bone remains

Étant la première étape de la démarche anthropologique, l’identification de l’origine humaine ou non-humaine est fondamentale autant pour les cas médico-légaux que pour l’interprétation des pratiques funéraires en archéologie. Dans un premier temps, ce travail vise à explorer en détail les changements histomorphométriques des systèmes haversiens exposés à différentes températures. À l’aide de 736 coupes histologiques réalisées en miroir sur un corpus humain et non-humain, un rétrécissement significatif de l’ostéon à 700°C a été noté, entrainant sa déformation et celle du canal haversien. Ces modifications structurelles sont en adéquation avec les grands changements physico-chimiques. Des différences significatives qualitatives et quantitatives entre le tissu haversien humain et non-humain ont été constatées sur l’ensemble des températures. Ces différences ont mené à l’élaboration d’une méthode d’identification basée sur un algorithme de forêt aléatoire permettant une fiabilité à plus de 98%. Cette méthode permet de répondre à la variabilité histomorphométrique intra-osseuse et convient mieux à l’identification des fragments. Une approche protéomique a été explorée dans le quatrième volet. Par la caractérisation des protéines osseuses, il a été possible d’identifier le taxon des échantillons non-brûlés et ceux chauffés à 200°C pendant 30 et 60 min. Cette approche est prometteuse pour une utilisation sur des os peu chauffés. Dans le dernier chapitre, l’identification de fragments osseux provenant d’un incendie a permis de confronter ces deux approches. Ce travail enrichie et contribue au progrès des recherches axées sur l’identification des restes osseux en anthropologie.As the first step of the anthropological process, the identification of the human or non-human origin is fundamental for forensic cases and the interpretation of funerary practices in archaeology as well. This work aims to explore in detail the histomorphometric changes of Haversian systems exposed to different temperatures. Using 736 histological cross-sections taken in mirrors of each other on human and non-human samples, it was possible to demonstrate a significant shrinkage of the osteon at 700°C, leading to the deformation of its structure and the Haversian canal. These structural modifications are in line with the major physicochemical changes observed at high temperatures. Significant differences between human and non-human Haversian tissue from a qualitative and quantitative point of view were observed over the whole temperature range. These differences led to the development of an identification method based on a random forest algorithm that provides precision over 98%. This method address the intra-bone variability and to be more suitable for fragment identification. A proteomic approach was also explored in the fourth part of this work. By characterizing the proteins contained in bones, it was possible to identify with certainty the taxon of unburned samples and those heated at 200°C for 30 and 60 minutes. This approach is extremely promising for use on bones heated at low temperatures. In the last chapter of this work, the identification of bone fragments from a domestic fire in a residence allowed us to compare these two approaches. This work enriches and contributes to the progress of research focused on the identification of bone remains in anthropology

Distinction os humain/os animal : état des lieux et perspectives de recherche

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L’homme ou la bête ? Le règne de l’ostéon

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Testing the accuracy of a new histomorphometric method for age-at-death estimation

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Using histomorphometry for human and nonhuman distinction: A test of four methods on fresh and archaeological fragmented bones

International audiencePositive identification of human remains is the very first step in anthropological analysis, and the task may be particularly difficult in the case of fragmented bones. Histomorphometry methods have been developed to discriminate human from nonhuman bones, based on differences in the size and shape of Haversian systems between the two groups. Those methods all focus on a very specific type of bone, section, and zone. Therefore, the objective of this study was to test the efficiency of four histomorphometric methods on a sample of fragmented bones. The sample is composed of 37 archaeological and fresh specimens, 25 nonhumans (Bos taurus, Equus caballus, Sus scrofa, Capreolus, Canis familiaris, Cervus elaphus, Ovis, and Capra) and 12 humans (Homo sapiens). Eight histomorphometric criteria were collected from all intact osteons visible on each fragment and then inserted into the corresponding discriminate function of each method. The results were compared with the real origin to establish rates of correct classification for each method. The methods of Martiniaková et al. (2006) and Crescimanno and Stout (2012) obtained very low percentages of good classification (32% and 67%). Those of Cattaneo et al. (1999) obtained 94% correct classification, but only after a correction of the units of measurement for Haversian canal area in their formula. The methods of Dominguez and Crowder (2012) obtained an 86% rate for well-classified specimens. Some of the methods tested here contain errors in the original publication that make them unusable in their current state. Plus, it seems that histomorphometric methods developed from specific areas are more difficult to apply to fragments. A reduced number of intact osteons analyzed may partially affect the reliability of the method by being unrepresentative of the entire microstructure. Therefore, this study demonstrates that one should be cautious with the use of histomorphometric methods to distinguish human and nonhuman fragmented bone until further research can refine these methods to achieve greater reliability

Testing the accuracy of a new histomorphometric method for age-at-death estimation

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Aspects méthodologiques de l’estimation de l'âge chez l'adulte en fonction du système haversien

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