Research in the centre and east of Cantabria has studied the adaptations of Mesolithic populations to the environmental changes that took place in the early and middle Holocene owing to the rise in temperatures after the Last Glacial Maximum. Deglaciation not only resulted in changes to the coast line, but also freed mountain areas of snow and ice, opening up new territories to be occupied and compensating for the loss of land on the coast.

256 shell-middens have been documented in the region between the Ria de Suances in the west, the limit with area of the Asturian Mesolithic, and the Ria de Ontón in the east, on the boundary with the Basque Country, and from the coast to the Cantabria Mountains in the south. In a chronological framework between the ninth and sixth millennia cal BC, 49 dates have been obtained for 31 sites.

The documentation of these sites and the information provided by archaeological excavations in 18 deposits has shown how the economic model adapted to the diversity of the new landscapes and the exploitation of marine and woodland resources. Variability is seen in the consumption of marine molluscs depending on the distance of the site from the coast and their replacement by terrestrial gastropods in inland and mountain areas.

Changes are also seen in the technology and settlement pattern; the latter connected with the use of different seasonal resources derived from the environmental changes and probably the population density, which led to certain sedentarisation. The distribution of the population was influenced by the cold climate events between 9.9 and 9.5 ka BP, related with the GS1, and in 8.2 ka (8.4-8-0 ka BP) (GRIP), which is identified by the abandonment of occupation sites.