Presenting the Compendium Isotoporum Medii Aevi, a Multi-Isotope Database for Medieval Europe

The Middle Ages (c. 500 to 1500 CE) is a formative period of European history. It was marked by major transformations in political and economic systems, vast population movements, violent armed conflicts, climate change, development of religious movements, and technological innovations, albeit with regional variations1,2,3,4,5,6,7,8,9. The study of such historical phenomena has been predominantly based on written sources although these may vary in quality and representativity10. In particular, the lifestyles of lower socioeconomic classes are often mis- or under-represented given their illiteracy. Knowledge gaps can be reduced by isotopic analyses of human remains from which it becomes possible to build iso-biographies describing the diets and spatial mobility of single individuals from across socioeconomic, religious, and cultural spectra11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29. Isotopic analyses of animal and plant remains have also been employed in medieval contexts to reconstruct past climatic and environmental conditions plus to investigate economic and agricultural activities30,31,32,33,34,35,36,37,38,39,40,41,42,43. In the late 1970’s, stable carbon isotope analysis of human remains was first employed for paleo-diet reconstruction44,45. Since then, the use of isotopic methods in archaeological research has expanded following several developments in isotope ratio mass spectrometry methods and lab pretreatment protocols that increased the number of measurable isotopic ratios across a wide variety of materials46,47,48. Such developments have allowed for a larger number of applications in archaeological research and for more accurate and precise assessments of past phenomena. The reconstruction of past human subsistence, nutrition and spatial mobility, the study of past animal and crop management practices, or the reconstruction of paleo-environments and -climates are just some examples that illustrate the importance of isotopic methods in archaeological research49,50,51,52,53,54,55,56,57. This is also evident from the exponential growth in recent decades in the number of archaeological publications reporting isotopic results58. Once collected and curated, amassed isotopic data can be subject to meta-analyses from which it is possible to investigate past human and natural phenomena at varying spatial and temporal scales59,60,61. Recent databases have partially compiled isotopic data for the European medieval world62,63. Here we present the open-access CIMA (Compendium Isotoporum Medii Aevi) database, the first isotopic database to comprise the full extent of the medieval period across the entirety of Europe and its margins. This database also includes for the first time all types of bioarchaeological remains (plants, animals, and humans) and isotopic measurements (δ13C, δ15N, δ34S, δ18O, and 87Sr/86Sr) on bulk organic remains and on tooth increments. To address various historical questions, CIMA includes metadata that characterizes the political, religious, and social context of listed samples. Here we describe CIMA and briefly illustrate its research potential.