Regular ArticleMeasurements and Relationships of Diagenetic Alteration of Bone from Three Archaeological Sites
Abstract
Four diagenetic parameters have been chosen to represent the state of diagenesis of bone buried on archaeological sites. They are: histological preservation, protein content, crystallinity, and porosity. How these parameters are measured is described and results from populations of bones from three different sites are presented. The results show the extent and variation in the degree of change, both within a site and between sites. In particular the correlations between diagenetic parameters are examined, which give clues about the processes which cause alteration. The value of porosity determinations (both at the intercrystalline level, and at coarser levels) in revealing the degree of diagenetic change in bone, and in underlying the dynamics of the interaction between buried bone and the surrounding water is stressed. The data also indicate (but are too restricted to prove) the following:
Microbiological attack is generally complete within less than 500 years;
Substantial levels of protein may remain in bone after maximal micromorphological alteration;
Loss of protein appears to be independent of other diagenetic change;
The correlated lose of microporosity with increase of crystallinity suggests these changes may arise from the dissolution, perhaps with subsequent recrystallization, of the smallest hydroxyapatite crystallites.
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Comment on “assessing the extent of bone bioerosion in short timescales – A novel approach for quantifying microstructural loss [Quat. Int., in press https://doi.org/10.1016/j.quaint.2023.01.011]”
2024, Quaternary InternationalWe outline issues with a recent publication by Mein and Williams (2023), which is primarily based on the morphology and quantification of osteocyte lacunae, microscopic cavities that house cells (osteocytes) which sustain bone tissue in living vertebrates. Using 26 rats (Rattus rattus) of unreported age and sex, the authors propose a method whereby post-mortem bone degradation on a short timescale can be quantified by analysing subtle shape changes of osteocyte lacunae. However, a lack of consideration is given to the natural variation and other biological factors influencing osteocyte lacunar morphology; the proposed diagenetic composition of lacunae is not determined; and the methods employed, including the animal model used, are unfit for the purpose of the study. Given these issues, we believe the conclusions presented by the authors should be treated cautiously and not extended to forensic investigations of post-mortem interval, particularly in humans.
Histotaphonomy of a Pleistocene megamammal assemblage from Argentine Pampas
2023, Journal of South American Earth SciencesThis work involves a multy-proxy approach of taphonomic features of the extinct giant ground sloth Lestodon armatus (Xenarthra, Mylodontidae). The study is based on paleohistological, mineralogical, and geochemical analyses from the Late Pleistocene Playa del Barco site (Buenos Aires Province, Argentina). Transverse thin sections of ribs and vertebrae were studied under light microscope, polarizing petrographic microscope, and scanning electron microscope (SEM), combined with chemical analysis using energy dispersive spectroscopy (EDS) and micro-X-ray diffraction (μXRD). The internal crystalline structure and mineral composition remains almost unaltered. The bone microstructure is well preserved in all the samples, although it was affected by different types of microfractures and infillings. Numerous radial microcracks were identified in the secondary osteons of all specimens evidencing wet depositional environment. The mineralogical and geochemical composition of the infillings and encrustations indicates that the enrichment with new elements was due to direct exchange with the sediments in which they were buried. Mineralogical evidence from the infillings allows to identify different diagenetic pathways; most of the skeletal elements were quickly buried in the vadose zone, while others were buried in the phreatic zone, directly or after some time immersed in a continental aquatic context. The fossildiagenetic information obtained from the Lestodon armatus fossils provides novel information to interpret and reconstruct the whole taphonomic history and the environmental and climatic conditions that favored the preservation of the Playa del Barco fossil assemblage during the end of the Last Glacial Maximum.
Multifactorial approach to describe early diagenesis of bones: The case study of the Merovingian cemetery of Saint-Linaire (France)
2023, Quaternary InternationalThe excavation of the Merovingian cemetery of Saint-Linaire (France) was an opportunity to describe the completeness of the tombs preserved from soil erosion. An anthropobiological study was carried out on the osteological material and the different categories of graves. On the basis of a complete archaeo-anthropological corpus we have undertaken an analysis of the differential preservation of the bones according to the different archaeobiological parameters such as the type of bone, the individual age but also the type of grave such as earthen graves, coffin, or sarcophagus.
In order to establish whether and how funerary practices had impacted the early diagenesis of the bones, FTIR was used to investigate the carbonate and fluoride content of the bones, and the infra-red splitting factor (SF), while XRD analysis was performed to estimate the crystallinity index (CI). In addition, the micro, macro and total porosity of the bones were measured by water adsorption, and bone carbon and nitrogen amounts were obtained by EA-IRMS. These diagenetic variables were analysed with regards to environmental (grave filling: humus, calcareous, clay), cultural (type of grave) and biological (mature versus immature individuals) factors. While there is a tendency of a better preservation of the skeletons in humus, and of juvenile bones to show less post-mortem alteration than the adult skeletons, the most important factor which determines the fate of the skeleton is the type of bone, with a preferential preservation of the ribs at Saint-Linaire.
Assessing the extent of bone bioerosion in short timescales – A novel approach for quantifying microstructural loss
2023, Quaternary InternationalThe evaluation of bone diagenetic phenomena in archaeological timescales is well established, but little is known about the extent of bone diagenesis in short forensic timescales. In particular, the use of the Oxford Histological Index (OHI) has become synonymous with assessing bioerosion in archaeological bone samples, but it may not be ideal for use on samples with shorter, forensic post-depositional timescales. Here, we present a novel method of quantifying the extent of bioerosion occurring on samples with short post-depositional periods by counting the number of normal and diagenetic osteocyte lacunae observed within the microstructure of the bone, which enables calculation of the percentage of destroyed bone within the sample. Due to the potential for condition of the remains, or depositional environment to affect bone diagenesis, this study investigated multiple conditions; whole rat carcasses, defleshed rat long bones, and excised fleshed rat limbs that were either placed in soil in plastic boxes or exposed on a clean plastic surface, and left to decompose from four to 28 weeks, to allow bone bioerosion to occur. Statistically significant differences in the number of average diagenetic lacunae observed were found between the three conditions, while a statistically significant difference was observed between OHI scores of samples in the two deposition environments. The number of diagenetic osteocyte lacunae increased in all conditions, showing statistically significant increase in the percentage of destroyed bone over time. Diagenetic changes were seen as early as 4-weeks post-deposition. Comparisons between the OHI scores and the lacunae counts showed that, while the use of OHI could not distinguish between samples with discrete microstructural deterioration, counting the normal and diagenetic lacunae could distinguish such diagenetic changes.
Marine sponge bioerosion in the forensic taphonomy of terrestrial bone
2023, Quaternary InternationalBone and teeth, specialised bio-mineralized connective tissues, are left after the typical decomposition process of any vertebrate organism. Their analysis can reveal insights into an organism's life and retrace the history of the remains after death (also known as taphonomy), which ultimately evolves to destruction or fossilization. Studies on the taphonomy of terrestrial mammalian bio-mineralized tissues have mostly focussed on terrestrial depositional environments. Here, samples submerged in the marine environment are investigated.
Five archaeological bones of terrestrial mammalian species (pig and oxen) with historically known post-mortem submersion interval (PMSI) (69–316 years) and recovery sites, were analysed macroscopically, microscopically and by microCT. The aim was to characterize for the first time the alterations produced by marine bioeroding sponges, and to discuss their potential interdisciplinary application, with special focus on forensic investigations.
The pig samples showed microanatomical preservation (Oxford Histological Index = 3–5), increased total porosity, the presence of old tissue flakes with sponge spicules and traces of bioerosion, such as papillary holes, canals and chambers with microsculptured walls. The presence of such tissue flakes suggested that, at the time of recovery, they may have been free of sediment and inhabited by live sponges. The shape of one internal chamber was identified as the ichnospecies Entobia convoluta as typically produced by shallow, warm-water Cliothosa spp. Surface analyses for further biological evidence remained inconclusive.
The taphonomy of skeletal remains has always been relevant in anthropological, natural and forensic studies. In forensics, the role of taphonomy is to contribute to personal identification, cause of death and post-mortem interval (PMI). This study detected the past colonization of terrestrial mammalian bone by marine bioeroding sponges, and aimed to link the taphonomic findings to natural processes and environments. Bioeroding sponges are for the first time confirmed to colonize terrestrial mammalian bone submerged in marine environments, and to promote diagenesis through bioerosion.
Human femur morphology and histology variation with ancestry and behaviour in an ancient sample from Vietnam
2023, Annals of AnatomyThere is a genetic component to the minimum effective strain (MES)—a threshold which determines when bone will adapt to function—which suggests ancestry should play a role in bone (re)modelling. Further elucidating this is difficult in living human populations because of the high global genetic admixture. We examined femora from an anthropological skeletal assemblage (Mán Bạc, Vietnam) representing distinct ancestral groups. We tested whether femur morphological and histological markers of modelling and remodelling differed between ancestries despite their similar lifestyles.
Static histomorphometry data collected from subperiosteal cortical bone of the femoral midshaft, and gross morphometric measures of femur robusticity, were studied in 17 individuals from the Mán Bạc collection dated to 1906–1523 cal. BC. This assemblage represents agricultural migrants with affinity to East Asian groups, who integrated with the local hunter-gatherers with affinity to Australo-Papuan groups during the mid-Holocene. Femur robusticity and histology data were compared between groups of ‘Migrant’ (n = 8), ‘Admixed’ (n = 4), and ‘Local’ (n = 5).
Local individuals had more robust femoral diaphyses with greater secondary osteon densities, and relatively large secondary osteon and Haversian canal parameters than the migrants. The Migrant group showed gracile femoral shafts with the least dense bone made up of small secondary osteons and Haversian canals. The Admixed individuals fell between the Migrant and Local categories in terms of their femoral data. However, we also found that measures of how densely bone is remodelled per unit area were in a tight range across all three ancestries.
Bone modelling and remodelling markers varied with ancestral histories in our sample. This suggests that there is an ancestry related predisposition to bone optimising its metabolic expenditure likely in relation to the MES. Our results stress the need to incorporate population genetic history into hierarchical bone analyses. Understanding ancestry effects on bone morphology has implications for interpreting biomechanical loading history in past and modern human populations.