Seasonal exploitation of intertidal resources at El Mazo (N Iberia) reveals optimized human subsistence strategies during the Mesolithic in Atlantic Europe

Over the last few decades, research has significantly enhanced our understanding of the role played by shellfish in human subsistence during the Mesolithic period along the Atlantic coast of Europe. Instrumental to this advance has been the analysis of stable oxygen isotope measurements (δ¹⁸O) from mollusc shells, which offers valuable insights into the seasonality of shellfish exploitation. The δ¹⁸O values serve as reliable indicators of past seasonal seawater temperature variations experienced by the molluscs, enabling us to accurately determine the time of year when past humans collected them. Recent studies using this approach have successfully identified seasonal exploitation patterns of the topshell Phorcus lineatus (da Costa, 1778) in Atlantic Europe. However, uncertainties remain regarding the exploitation schedule of Patella depressa Pennant 1777, one of the most abundantly collected species in Mesolithic sites. Here we used shell δ¹⁸O values of P. depressa from the Mesolithic sites of El Mazo (Northern Iberia) to determine its seasonality of exploitation. Our study reveals that P. depressa was prevalently exploited during colder months. Modern specimens of the same limpet species were also collected during two annual cycles to assess potential seasonal changes in meat yield return. Results obtained has profound implications for better understanding how last coastal foragers managed available littoral resources throughout the year.