Neolithic societies and landscape transformations in northwestern France: A high-resolution multi-proxy study including sedimentary DNA

To understand the impact of human practices on Mid-Holocene vegetation in northwestern France, more pollen records and multi-proxy studies with accurate chronologies located near excavated archaeological sites are needed. In northwestern Normandy, the Caen Plain is particularly suitable for gaining further insight into the impact of early human activity on the landscape, due to the high density of recognized and excavated archaeological sites dating back to Neolithic times. Therefore, in this area, we developed a high temporal resolution approach using multiple palaeobiological proxies (pollen, non-pollen palynomorphs (NPPs), charcoal analysis, and sedimentary ancient DNA (sedaDNA)), along with sedimentological proxies to analyze a new sequence from the Vey valley, located close to the excavated Neolithic site of Cairon, and which could be compared to the archaeobotanical and archaeozoological data from archaeological excavations. Our specific objective was to propose a reconstruction of the landscape changes under human influence at a local scale, in order to gain a precise understanding of the processes of anthropization in the Caen Plain at the end of the Mesolithic and during the Neolithic. The impact of human activity during the Mesolithic and Early Neolithic appears to have been limited. Nevertheless, the end of the Late Mesolithic (5900–5200 BCE; 7850–7150 cal. BP) showed the first increase in local fire frequency. These fires were responsible for temporary clearings of the forest along the wetland, and sedaDNA indicated that wild boar were present in the wetland. Most notably, the Cairon site offered the first opportunity to precisely determine the impact of changing land use in an area that had been inhabited since the Middle Neolithic (4400–3475 BCE; 6350–5425 cal. BP). The combined use of sedaDNA, NPPs, and charcoal analysis demonstrated the importance of pastoral practices and fires in opening up environments and transforming alluvial wetlands during this period.