Stable isotope analyses of oxygen are used in anthropology for such purposes as determination of origin of individuals, tracking migration routes or dynamics of human community relocation. The methodology related to oxygen isotope analysis has been founded on the relationship between its isotopic composition within phosphate groups of bone tissue (δ18Op) in individuals being analysed and the water consumed by such individuals (δ18Ow). Such a relationship has been observed in many species of mammals, including humans. However, the influence of culinary practices on the isotopic delta values of apatite phosphates of individuals has not yet been researched. The present study, which was conducted using laboratory rats, is an investigation of the influence of the thermal processing of water drank by such rats on the isotopic composition (δ18Op) of bone apatite. Increasing the value of the isotopic composition of water by about 6.1 ‰ during boiling resulted in an increase in the oxygen isotopic value δ18Op of rats drinking the water by about 4 ‰ (29%). It can be expected that regular consumption of heavily isotopic drinks and foods by humans may cause the δ18Op of individuals to exceed the range of isotopic environmental variability, even by a few per mille.
The oxygen isotope ratio (δ18O) in tissues is the outcome of both climatic and geographical factors in a given individual’s place of abode, as well as the physiology and metabolism of his organism. During an individual’s life, various rates and intensities of physiological and metabolic processes are observable in the organism, also within the bone tissue.
The aim of this study is to verify whether involutional changes occurring as a result of the organism’s ageing have a significant impact on δ18O determined in the bone tissue.
The material used for analysis was fragments of the long bones taken from 65 people, (11 children and 54 adults), whose remains had been uncovered at the early mediaeval (X–XI century) cemetery located at the Main Market Square in Kraków (Poland).
The correlation analysis between δ18O of bone tissue and an individual’s age shows that up to 40 years of age, such a relationship does not exist in both, males and females. However, the conducted correlation analysis prompted the observation that after 40 years of life, δ18O in bone tissue significantly drops as females increase in age.
Results suggest that the δ18O in bone tissue among older people may be the outcome not only of environmental factors but also involutional changes in bone linked to an organism’s ageing. Therefore, the interpretation of δ18O results relating to the description of the origin and migrations of older individuals should be treated with caution.
Diagenetic signals from ancient human remains - bioarchaeological applications
This preliminary study examines the potential effects of diagenetic processes on the oxygen-isotope ratios of bone and tooth phosphate (δ18O) from skeletal material of individuals representing the Corded Ware Culture (2500-2400 BC) discovered in Malżyce (Southern Poland). Intra-individual variability of Ca/P, CI, C/P, collagen content (%) and oxygen isotopes was observed through analysis of enamel, dentin and postcranial bones. Using a variety of analytical techniques, it was found that, despite the lack of differences in soil acidity, not all the parts of a skeleton on a given site had been equally exposed to diagenetic post mortem changes. In a few cases, qualitative changes in the FTIR spectrum of analysed bones were observed. The data suggest that apart from quantitative analyses, i.e., the calculation of Ca/P, CI, C/P and collagen content, qualitative analyses such as examination of the absorbance line are recommended. The degree to which a sample is, contaminated on the basis of any additional, non-biogenic peaks, deemed to be contaminated should also be specified.