Chemometrics and thermal analytical investigation of ancient human bones through the estimation of activation energy values of main degradation processes

Background: The investigation of human bones unearthed from necropolises is a useful tool to enhance our knowledge about ancient cultures. In the present study, the possibility of using the activation energy (EA) values of thermogravimetric degradation processes coupled with exploratory analysis methods in order to investigate human remains, has been tested. Methods: Several human bones from four distinct necropolises have been analyzed by thermogravimetry and then thirteen different approaches have been used to estimate their activation energy of the degradation processes of carbonate and collagen. The entire set of data has been analyzed by Principal Component Analysis (PCA) in order to draw some preliminary considerations over the remains. Results: PCA analysis highlighted the possibility of recognizing grouping tendencies related to the funeral ritual bodies underwent and/or their age. Additionally, in the second part of the work, where the focus is on the activation energies of collagen and carbonates degradation processes estimated by the method which was considered the most reliable (i.e., the Arrhenius formula with the third order decay), some tentative considerations about a trend in cremation temperatures are drawn. Conclusion: The estimation of values from thermogravimetric signals combined with chemometrics is a useful tool for the investigation of bone samples, which allow obtaining additional info about trends and/or grouping tendencies in complex systems as human remains.