To Sum it Up studies the reconstruction of population dynamics in the western Scheldt basin (Belgium and Northern France) between the Mesolithic period (ca. 9500 BCE) and
the High Medieval period (ca. 1200 CE). A multiproxy approach consisting of summed probability distributions of radiocarbon dates, site counts, non-metric multidimensional scaling of pollen records and soil phosphorus analyses revealed the dynamic nature of the region. Large datasets consisting of nearly 5000 radiocarbon dates, more than 10.000 site phases, seven sites with high-resolution pollen records and six sites with high-resolution phosphorus data were constructed. By comparing the different proxies, and correcting for numerous biases related to soil taphonomy, differences in research methodology and intensity, investigation bias and shifting building traditions, and modelling chronometric uncertainty, could a reconstruction of the regional dynamics be assembled. This study revealed the variable nature of human populations, activity and impact throughout time. During the Mesolithic, dispersed hunter-gatherer communities did not have a discernible impact on their environment in the proxies that were used, yet exhibited high intra-basin mobility. The Early Neolithic witnessed the onset of farming, localised to a small region in Hainaut, and subsequent large shifts in activity. By the end of the Final Neolithic, anthropogenic indicators in pollen records became clearly evident and the landscape was opening up. More sites and indicators of human activity are present. From this period onwards, the landscape opened up progressively more and human activity grew exponentially throughout the Bronze and Iron Age. By the Roman period, the landscape became semi-open and the region was densely occupied. Only during the Late Roman Period and the start of the Early Medieval period did a decline in activity and impact occur for a short period, reforestation took place and sites were abandoned. After only two centuries, new settlements emerged and forests were cut down once more opening up the landscape. By the end of the High Medieval period, closed forests were absent once more and populations became more urbanised and dense. This rapidly expanded towards the present day. The study provides valuable insights into long-term population dynamics, land use patterns, and human-environment interactions in the western Scheldt basin.