Shellfish resilience to prehistoric human consumption in the southern Red Sea: Variability in Conomurex fasciatus across time and space
Intertidal environments have been the main source for mollusc gathering and consumption for at least the last 164,000 years. However, our knowledge of long-term trends is compromised by the fact that the majority of Pleistocene and early Holocene shorelines, and in turn their archaeological sites, are either currently submerged under water or have long been destroyed by sea-level change. Ecological information on the resilience of intertidal resources is crucial in assessing how attractive they were to past humans as a long-term source of food. Of particular interest is the southern Red Sea and its function as the southern gateway out of Africa into Arabia during a period of aridity. The role that marine food sources likely played in this dispersal is underplayed and largely ignored when interpreting periods of terrestrial aridity. Here we analyse the resilience of Conomurex fasciatus and report size measurements of over 15,000 specimens from the Holocene shell middens on the Farasan Islands, Saudi Arabia, as an ecological baseline for prehistoric shellfish exploitation to determine the long-term sustainability of shellfish harvesting in an arid environment. Changes in shell-size and relative abundance can indicate whether a species was subjected to changes in the intensity of human harvests and we use this dataset to reconstruct how the species was affected by a known intense exploitation period between 7360 and 4780 cal BP. Our results indicate no signs of resource depletion throughout the occupation period and add to the growing body of evidence that marine resources along arid shorelines are an important part of a mixed diet. Further, by measuring size changes occurring during early life stages of C. fasciatus we were able to reveal changes in size that were unaffected by human harvesting pressure and instead suggest patch-selection as the main control. These results have implications for the interpretation of shellfish harvesting during periods of terrestrial aridity and specifically the potential of shellfish as a reliable food source during Palaeolithic migrations out of Africa.