Coastal socio-environmental trajectories in north-Brittany (NW France) since the Neolithic: palynological and ancient DNA marker records

International audienceNeolithic human societies that settled in Brittany are known to have erected numerous megalithic monuments. In North-Brittany (France) the Bay of Goulven appears to be a key area to understand coastal socio-environmental trajectories thanks to an important concentration of gallery graves, erected during the Recent and Late Neolithic, testifying to a high population density. To shed new light on environmental and anthropogenic dynamics, a multidisciplinary approach mobilizing sedimentological, palynological and ancient DNA analyses was implemented on twin sedimentary cores, covering the last 7 kyrs BP and retrieved in the coastal wetland closed to Plouescat.Preliminary results of XRF and palynological analyses display a progressive sedimentary infilling of the former maritime marsh up to a continental area totally disconnected from the marine influence at 5.4 ka BP. Superimposed to this environmental context, the first obvious, but tenuous anthropogenic markers occur from 6.8 to 5 ka BP, before disappearing up to 4.7 ka BP. This 300-years period corresponds to a potential abandonment of this coastal area before a new anthropogenic influence detected at 4.7 ka BP, and that subsequently increases reaching its maximum at 2.4 ka BP (i.e., Second Iron Age).There are still open questions about the identification of anthropic activities in coastal environments. The low taphonomic resolution of Anthropogenic Pollen Indicators (API; i.e., ruderal, adventitious or cultivated taxa) together with the poor dispersion capacities of crops far from production areas limit the expression of anthropogenic activities in the pollen signal. The next step of this study is to combine the extracellular DNA preserved in sediments, detecting DNA markers of domestic mammals and anthropogenic plant groups, with palynological approaches to accurately reconstruct the past history of local agro-pastoral practices in northern Brittany