Leveraging sedimentary ancient DNA from Bluefish Cave III to provide paleoenvironmental context for human activity in eastern Beringia

Beringia was a dynamic landscape during the Pleistocene-Holocene transition, facilitating the migration of numerous plants and animals across eastern and western hemispheres. Detailed and accurate paleoenvironmental understanding of Beringia during this period is crucial to interpreting past human activity, including initial peopling events. Sedimentary ancient DNA ( sed aDNA) analysis augments traditional methods of paleoenvironmental reconstruction by identifying taxa for which there are no visible fossil remains, revealing novel environmental insights. However, the application of sed aDNA analysis to terrestrial settings, including rockshelters, remains limited. Here, we demonstrate the feasibility of extracting sed aDNA from non-frozen loess deposits at the rockshelter site Bluefish Cave III in Yukon, Canada to reconstruct the local paleoenvironment of eastern Beringia. Metagenomic sed aDNA generated via shotgun sequencing of loess deposits from Bluefish Cave III reveals distinct floral and faunal community composition, which align with previous pollen and zooarchaeological interpretations, that eastern Beringia was a mosaic of environments rather than an enduring grassland at the end of the Pleistocene. Though complex site formation processes limits fine-grained temporal paleoenvironmental interpretation of Bluefish Cave III, sed aDNA still reveals paleoenvironmental insights on a hyperlocal scale, including nonanthropogenic animal site use. These findings expand the application of sed aDNA analysis to include non-frozen loess deposits from scientifically significant rockshelters and demonstrates how sed aDNA can augment paleoenvironmental reconstruction in archaeological contexts.