High temporal resolution insights into early life histories: integrating histomorphometric, trace element and isotopic analyses of dental hard tissues in archaeological populations from Italy

Teeth, with their high mineralisation, incremental growth, and lack of remodelling, serve as biological archives that document an individual's development. This project aims to utilise the potential of teeth in bioarchaeological studies to achieve three primary objectives: 1) to investigate the application of histological and histochemical methods in reconstructing developmental bio-chronologies and early life histories; 2) to refine the temporal precision of isotopic analysis of dentine collagen by developing a novel protocol that integrates micro-sampling techniques with high-resolution histomorphometrics; and 3) to synthesise data from enamel and dentine for a comprehensive understanding of early life development and dietary transitions. This study adopts an integrated multidisciplinary bioarchaeological approach, conducting histomorphometric analysis on enamel and dentine across deciduous and permanent dentitions. It applies high-temporal resolution trace element analysis to enamel using LA-ICPMS and δ13C and δ15N isotope analyses through sequential micro-sampling to dentine of permanent teeth. Samples were selected from diverse archaeological contexts across the Italian peninsula, covering the Upper Palaeolithic, Copper Age, and Early Medieval periods, providing insight into diachronic variations in infant development and life history. Findings highlight the efficacy of histological and histochemical techniques in accurately determining growth rates, physiological stress, dietary shifts (particularly timing of weaning), and age at death in infant remains. The consistency and comparison between enamel and dentine underscores the enhanced insight obtained from integrating information from both tissues. Importantly, the newly proposed protocol significantly improves the temporal accuracy of dentine collagen analysis, facilitating precise chronological placement of the results over broad developmental associations. This study reaffirms the significance of teeth as valuable bioarchaeological instruments. By introducing and testing multidisciplinary methods, it provides deeper insights into early life history and cultural practices across diverse chronological contexts, highlighting the importance of advanced methodologies in extracting detailed, accurate, and nuanced information from past populations.

Dove il DNA antico tace: studio della 'life history' individuale nelle popolazioni umane del passato tramite analisi istologica e biogeochimica ad alta risoluzione di tessuti dentali mineralizzati da contesti archeologici e paleontologici umani

Questa tesi mira a presentare una panoramica, anche sperimentale con dati editi ed inediti, della ricostruzione delle life histories umane mediante metodi istologici e biogeochimici applicati allo smalto dentale delle dentizioni decidue. La tesi si concentra sulle metodologie biogeochimiche ad alta risoluzione spaziale che consentono di ottenere livelli temporali di dettaglio senza precedenti (da stagionali fino a sub-settimanali), quando combinate con l'analisi istomorfometrica dei tessuti dentali mineralizzati. La presente ricerca si concentra sulla creazione di modelli consistenti di variazione delle concentrazioni di elementi in traccia (con particolare riferimento a stronzio e bario) lungo la giunzione smalto dentinale, ottenuti tramite LA-ICPMS (Laser Ablation Inductively Coupled Mass Spectrometry), in funzione dei cambiamenti nella dieta (allattamento, svezzamento) nel primo anno di età di individui a storia nutrizionale nota (utilizzando denti decidui naturalmente esfoliati). In una prospettiva bioarcheologica, i risultati delle indagini sulla dieta altamente risolte nel tempo e interpretate con modelli come quelli proposti si correlano direttamente alle life histories individuali e consentono una analisi più sfumata e completa del comportamento umano nel passato, fornendo informazioni essenziali per la comprensione degli adattamenti bioculturali e aprendo finestre conoscitive su aspetti quali il rapporto madre-progenie, la gravidanza, l’allattamento, lo stress infantile, la dieta sia della progenie che della madre, la mobilità ad alta risoluzione e molti altri aspetti della vita delle popolazioni del passato che lo studio del DNA antico e della morfologia scheletrica non possono fornire. Dove il DNA antico tace, lo studio avanzato delle life histories parla.

Molecular mechanisms controlling physiological plasticity in marine mussels under the influence of natural and anthropogenic stress factors

Marine mussels are exceptionally well-adapted to live in transitional habitats where they are exposed to fluctuating environmental parameters and elevated levels of natural and anthropogenic stressors throughout their lifecycle. However, there is a dearth of information about the molecular mechanisms that assist in dealing with environmental changes. This project aims to investigate the molecular mechanisms governing acclimatory and stress responses of the Mediterranean mussel (Mytilus galloprovincialis) by addressing relevant life stages and environmental stressors of emerging concern. The experimental approach consisted of two phases to explore (i) the physiological processes at early life history and the consequences of plastic pollution and (ii) the adult physiology processes under natural habitats. As the first phase, I employed a plastic leachate (styrene monomer), and polystyrene microplastics to understand the modulation of cytoprotective mechanisms during the early embryo stages. Results revealed the onset of transcriptional impairments of genes involved in MXR-related transporters and other physiological processes induced by styrene and PS-MPs. In the second phase, as a preliminary analysis, microbiota profile of adult mussels at the tissue scale and its surrounding water was explored to understand microbiota structures that may reflect peculiar adaptations to the respective tissue functions. The broader experiment has been implemented to understand the variability of transcriptional profiles in the mussel digestive glands in the natural setting. All the genes employed in this study have shown possibilities to use as molecular biomarker responses throughout the year for monitoring the physiology of mussels living in a particular environment and, in turn, more properly detecting changes in the environment. As a whole, my studies provide insights into the interactions between environmental parameters, and intrinsic characters, and physiology of marine bivalves, and it could help to interpretation of responses correctly under stress conditions and climate change scenarios.