Sedimentary ancient DNA metagenomic analysis provides new insights into farming in central Norway from the Bronze Age to late Medieval period

Abstract

Sedimentary ancient DNA (sedaDNA) has been proposed as a key methodology for reconstructing paleoclimates and biodiversity over time. To a lesser extent, it has been explored as a complementary tool for reconstructing human-driven local environmental changes over time, such as those explored in open air archaeological sites. Our study employs a sedaDNA metagenomic approach to investigate land use and environmental change at the archaeological site of Torg[a]rdsletta in central Norway, spanning from the Bronze Age through the Medieval period. Stratigraphic sediment samples reveal temporal shifts in plant, animal and microbial communities, reflecting evolving human practices and climatic conditions. Progression through the layers indicate signs or land clearance, cultivation and animal husbandry in the region. Notably, a significant reduction in microbial and plant diversity during periods of climatic upheaval--such as the AD 536-540 volcanic event--correlates with landscape and societal adjustments. The findings demonstrate that sedaDNA complements traditional proxies, providing high-resolution insights into past land use, environmental interactions, and societal organization. The successful extraction of ancient genetic material underscores sedaDNAs potential to reconstruct dynamic prehistoric landscapes and anthropogenic impacts, offering further potential for understanding long-term human-environment relationships in Scandinavia.