A tale of two isotopes: exploring human movement through strontium isotope analysis in two medieval Danish cemetery populations

Abstract

During the Medieval period of Denmark, economic and trade relations grew inter-regionally, with culture, ideas, and products being transferred on a more regular basis through the 11th to 13th centuries. Beginning around 1050 AD and lasting until AD 1536, the country faced drastic climatic changes, shifting economic and agricultural practices, and disease outbreaks (most notably the bubonic plague). The current study seeks to investigate mobility during this period from two medieval cemeteries around Horsens, Denmark: the rural site of Sejet and the urban site of Ole Wormsgade, both used throughout the 12th to 16th centuries. A previous isotopic analysis using oxygen indicated that some movement was seen at these sites, with three individuals identified as potential migrants from other Scandinavian regions. This study compares the existing oxygen isotopic data with variations in 87Sr/86Sr ratios from these samples. Such ratios represent local bedrock baselines of strontium, which are slightly different between eastern and western Denmark. ICP-MS was used to measure 87Sr/86Sr ratios, and results are interpreted in the context of climatic changes and shifting socioeconomic practices. The results suggest that longer-distance movements into Denmark were seen during the Early Medieval Period. The potential migrant identified in this research points to movement towards the rural population at Sejet, and could possibly connect this migration with marriage rules influencing immigration at the time. This research demonstrates that movement during the medieval period of Denmark was a complex, dynamic, and multilinear process during a time of increasing urbanization.