Sedimentary ancient DNA analysis from the Iron Age courtyard and cooking pit site of Rodskjaer in Troms, Northern Norway

In an innovative study conducted at the Rodskjaer site in northern Norway, researchers employed a novel framework for sedimentary ancient DNA (sedaDNA) metabarcoding sampling to shed light on Iron Age courtyard and cooking pit sites. These structures, exclusive to Norway, have long been linked to cooking pit fields, which may indicate feasting practices, yet the primary purpose of these sites remains largely unknown.

The investigation involved analyzing 63 sediment samples sourced from cooking pits, fire pits, a hearth, a fireplace, the natural shell-sand, and topsoil. Remarkably, 52 of these samples yielded successful detection of both plant and animal sedaDNA. The plant diversity was notably high, ranging from 41 to 100 taxa. Crucially, sedaDNA analysis revealed archaeologically significant taxa that were previously undetected by conventional methods, such as Avena (oats), Quercus (oak), Equus (horse), and Salmo salar (salmon).

Furthermore, the study underscored the value of comparing inter-sample data and considering worm sedaDNA, which helped identify archaeological contexts affected by partial bioturbation and root penetration. These factors can complicate the interpretation of spatial or temporal differences in the use of these features. This pioneering research emphasizes the importance of collecting multiple samples from both modern and natural sediments, alongside the application of multi-proxy analysis when conducting sedaDNA metabarcoding studies at open-air archaeological sites.

By accounting for these variables, sedaDNA from cooking pits can prove to be a valuable tool for investigating the uses and significance of courtyard and cooking pit field sites.