DEGRADATION OF ORGANIC AND MINERAL PHASES IN BURIED HUMAN REMAINS: THE EARTH SCIENCES ANALYTICAL CHARACTERIZATION
Tesi di Dottorato
Data di Pubblicazione:
2017
Citazione:
DEGRADATION OF ORGANIC AND MINERAL PHASES IN BURIED HUMAN REMAINS: THE EARTH SCIENCES ANALYTICAL CHARACTERIZATION / V. Caruso ; tutor: L. Trombino ; co-tutor: C.Cattaneo ; coordinator: E. Erba. DIPARTIMENTO DI SCIENZE DELLA TERRA "ARDITO DESIO", 2017 Feb 24. 29. ciclo, Anno Accademico 2016. [10.13130/caruso-valentina_phd2017-02-24].
Abstract:
The thesis focuses on the characterization of the alteration of the mineral and organic phases, investigated with different approaches, of human bone tissue from different burial contexts, with ages spanning from the Late Roman period to our time. This topic is very important in paleontological, archaeo-anthropological and forensic contexts in order to understand the taphonomic agents and then to provide biological data as possibly to discern human behavior in ancient funerary as well as in recent forensic contexts. It is well-known that peri and post mortem events may leave marks that have to be interpreted in the light of the state of the conservation or degradation of the skeletal remains.
In fact, physical anthropologists are frequently required to date human bone remains, in order to recognize if osteological samples have an archaeological, historic or forensic interest. The determination of post mortem interval (PMI), the time elapsed between the death and the discovery of the corpse or skeletal remains, is extremely difficult to evaluate in absence of direct chronometric dating (e.g. C14), since bones might undergo several alterations, both structural and chemical, depending on the environment in which they deposited in. Because of bone tissue is an intimate association of mineral (carbonate-hydroxyapatite) and organic components (collagen) arranged in an ordinary structure, different levels of degradation are possible. Over time post mortem degradation is dominated by loss of structural collagen by collagenolytic enzymes, which caused a rapid swelling and hydrolysis of the protein fibers. Collagen dissolution is generally accompanied by the alteration of mineral crystals, which are vulnerable to diagenetic changes due to their small size. During diagenesis, the protein can be totally or partially removed and can replaced by inorganic precipitates, the most common beign hydroxyapatite, which in the process is subjected to recrystallization, ion exchange and substitution. As consequence, when depositional conditions are favorable for bone preservation, the mineral crystallinity increase, the porosity and chemical composition change.
The quality and the assessement of organic and inorganic phase, can act positively or negatively both on bone mechanical properties in live, both on decomposition process after death, reducing or accelerating it.
Several studies were performed to better understand the taphonomy of bone material during burial time. It appears that bone degradation depends on a wide range of environmental interactions, including biological, chemical and physical factors. These include: average temperature and humidity, microbilological composition and activity, soil chemistry (mineralogy and pH) and permeability, mechanical pressure and other numerous factors.
Different type of bone degradation are observable at different scale of observation; particularly, in this study, bone preservation was investigated at macroscopic, biomolecular, microscopic, ultramicroscopic and chemical scale.
The aim of this research is thus to further describe the impact of environmental conditions on bone preservation, and the effect of time, by applying and comparing the results from different analitical techniques.
For this study 40 human skeletons of adult individuals from four different dated burial location in the Milan area were analyzed. The first one is a necropolis dated to the Late Roman age (3th-4th century AD), the second one is a 17th century AD mass grave, the third one is an ossuary contanining bones dated between 15th and 18th century AD, and the last one is a modern cemetery.
The macroscopic analysis evaluated the general appearance of the remains and their state of preservation, through the o
Tipologia IRIS:
Tesi di dottorato
Keywords:
bone diagenesis; 3D micro-computed tomography; macroscopy; histology; Luminol test; FT-IR spectroscopy; taphonomy; buried human remains; synchrotron light source; birefringence; organic and mineral phases; hydroxyapatite; collagen preservation; decalcification protocol; decalcified thin bone sections; bone conservation; SEM-EDS; chemical analysis; morphological analysis; cortical human bone; bone porosity; PMI; necropolis of Travo; skeletal record; Amide I quantity; CO3 content; IRSF; grave soil analysis; bone fractures; burial environment; Milan osteological collection; decalcified histological index; bone analytical characterization;
Elenco autori:
V. Caruso
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