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The human bone oxygen isotope ratio changes with aging

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.