Synchrotron Radiation Fourier Transform Infrared (SR-FTIR) spectroscopy in exploring ancient human hair from Roman period Juliopolis: Preservation status and alterations of organic compounds

Abstract

We explore the preservation status and alterations of organic compounds in Roman period human hairstrandsfrom a specific individual (M196) excavated at Juliopolis (JP). How do these organic compounds present in this c. 2000-year-old human hair compare to those present in modern hair? Alterations to organic compounds in archaeological human hair are caused by biological degradative processes dependent on multifactorial processes acting on the hair since the deposition of a body in a mortuary context. We investigate the type of organic compounds present using Synchrotron Radiation Fourier Transform Infrared (SR-FTIR). Juliopolis (Iuliopolis) is an ancient multiperiod city, located in the Çayırhan district of Nallıhan, northwest of Ankara. The Juliopolis necropolis from which M196 was recovered was in use throughout the Hellenistic, Roman, and Byzantine periods, and yielded over 700 tombs with numerous human remains. One tomb (M196) contained human remains of exceptional preservation status, including substantial amounts of hair. Human hair from archaeological contexts is not only extremely rare, but importantly, has high analytical value, with potential for analysis of diet, geographical origins, ancient DNA, metal exposure, and other aspects of life in a time-resolved manner. These data make significant contributions to the life history of the individual (osteobiography), as well as contribute towards key archaeological questions. As these analyses are in their majority destructive, prior evaluation of the preservation of sufficient amounts of the organic compounds on which many such analyses rely upon is crucial, to avoid unnecessary loss of precious ancient samples. The results of our SR-FTIR analyses at SESAME synchrotron show that keratin in the JP M196 is more degraded in comparison to the modern reference sample. However, the results also point to clear potential for further analyses with techniques relying on organic compound preservation, such as C and N isotopic analyses for diet, and aDNA.

Keywords: Ancient Anatolia; Ancient hair; Fourier transform infrared spectroscopy (FTIR); Hair degradation, preservation and alteration; Juliopolis; Roman archaeology.