Temporal and spatial variability of prehistoric aquatic resource procurement: a case study from Mesolithic Northern...

Prehistoric shell middens hold valuable evidence of past human-environment interactions. In this study, we used carbon (δ¹³C) and oxygen (δ¹⁸O) stable isotopes of Mytilus galloprovincialis shells excavated from El Perro, La Fragua and La Chora, three Mesolithic middens in Cantabria, Northern Spain, to examine hunter-gatherer subsistence strategies in terms of seasonality and collection areas. Furthermore, we used shell δ¹⁸O to reconstruct water temperature during the early Holocene. Stable isotopes reveal a shellfish harvesting diversification trend represented by the gradual establishment of the upper estuaries as new procurement areas and an increase of harvesting mobility in both coastal and in-land sites. These innovations in subsistence strategies during the Mesolithic coincided with major changes in the surrounding environment as attested by the water temperature reconstructions based on δ¹⁸O and backed by several global and regional records. Overall, our results show that shell δ¹³C and δ¹⁸O stable isotopes have an underexplored potential as provenance proxies which stimulates their application to the archaeological record to further understand prehistoric human resource procurement and diet.