When the present writer published his Mesolithic Settlement of Northern Europe in 1936, much had already been established about the pre-neolithic occupation of the West Baltic area. Paradoxically it is for this very reason that recent advances in this field are of more than regional interest, for it is only by intensifying fundamental research in the most favourable territories, in conjunction with more extensive surveys, that we can gain the evidence needed for a real insight into the processes of prehistory. One reason for the pre-eminence of the area in mesolithic research is the scope it provides for co-operation between archaeologists and natural scientists. Team-work in quaternary research has made it possible to study the earliest cultures in their correct chronological and ecological setting, and it has also guided prehistorians to the sites most likely to yield the maximum range of cultural evidence.