Diachronic forager mobility: untangling the Stone Age movement patterns at the sites Norje Sunnansund, Skateholm and Västerbjers through strontium isotope ratio analysis by laser ablation

Abstract

Strontium isotope ratios in human teeth from the three Swedish prehistoric Stone Age hunter-fisher-gathering societies Norje Sunnansund (Maglemose), Skateholm (Ertebølle) and Västerbjers (Pitted Ware Culture) were analysed with laser ablation to produce data on both individual movement patterns and societal mobility trends. The analyses of teeth from both Skateholm and Västerbjers displayed homogeneous ratios and corresponding mobility patterns, while the data from Norje Sunnansund showed larger variances with heterogenous strontium ratios and varied inter-individual mobility patterns. Correlation with the bioavailable baseline suggests that the size of the geographical areas, where human strontium ratios could have originated, was roughly comparable for all three sites. The teeth measurements were reflected within a 50-km radius of the surrounding landscape and the 25–75% data quartile matched with distances between 3 and 30 km from the sites, suggesting limited mobility ranges among aquatically dependent foragers from southernmost Sweden. By applying ethnographic analogies and site-specific contextual inferences, the results suggest that mobility ranges at Norje Sunnansund were likely not delimited by neighbouring group territories. This changed over time and an increasing territorialisation of the landscape may have influenced movement patterns and caused restrictions to the foraging activities at both Skateholm and Västerbjers.