Stuck to the shore? : investigating prehistoric hunter-gatherer subsistence, mobility and territoriality in a Mediterranean coastal landscape through isotope analyses on marine mollusc shell carbonates and human bone collagen

Subsistence and mobility strategies of hunter-gatherers in the Mediterranean Basin during the transition from the late Pleistocene to the early Holocene have been the object of few studies, even though its karst coastal regions have high densities of prehistoric sites. One such area is the territory of the Conca d’Oro in NW Sicily, which has numerous sites with faunal remains testifying to economies mainly based on hunting of terrestrial ungulates and on the regular consumption of molluscs. This paper presents results from the study of faunal remains from cave sites occupied by hunter-gatherers in the late Pleistocene and early Holocene, and of isotope analyses on shells of marine molluscs collected for food and on collagen from the bones of the hunter-gatherers buried in these caves. The mollusc assemblages are dominated by inter-tidal rocky shore species of the genera Patella and Osilinus, which from 16 to 9 kyrs cal BP were the principal marine resources exploited by the hunter-gatherers of the Conca d’Oro. Oxygen isotope analyses on shells of Osilinus turbinatus show that in the late Pleistocene the exploitation of marine molluscs at the Addaura caves, relatively close to the shoreline, was restricted to late autumn and winter, while at Grotta Niscemi, which is further inland, these resources were exploited less intensively but for longer in the year, from autumn to the early spring. The data from the shells (both isotope and biometrical) suggest that late Pleistocene hunter-gatherers spent the coldest months of the year close to the coast, moving inland in late spring and for the summer. In the early Holocene, by contrast, marine molluscs were exploited longer during the year, attesting to a change in mobility strategies and, probably, frequent moves within more restricted territories. Carbon and nitrogen isotopes in human bone collagen from Grotta Addaura Caprara and Grotta della Molara show that marine foods were marginal in the diets of both late Pleistocene and early Holocene hunter-gatherers. Overall, the data indicate that the territory of the Conca d’Oro hunter-gatherers probably extended from the coastal plain to the upland areas during the late Pleistocene, but became more restricted in the early Holocene. This model might have broader application to hunter-gatherer settlement systems in other karst coastal areas of the Mediterranean