Harvesting molluscs in the Eneolithic: a study of freshwater bivalve accumulations from the tell settlements of Borduşani-Popină and Hârşova (Romania, 5th millennium BC)

Freshwater bivalve shells are frequently identified in faunal assemblages from Neo-Eneolithic tell settlements along the Danube River valley in South-East Romania (5th millennium BC). Up until now, significant accumulations of freshwater bivalve shells have been identified only in household refuse areas of the settlements, where they form consistent shell layers. The origin and formation of such shell accumulations and, more generally, the role of bivalves in the animal economy of the prehistoric populations that inhabited the settlements, are poorly understood. Two freshwater bivalve shell accumulations were studied in household refuse areas of Eneolithic tell settlements, one at Borduşani-Popină and the other at Hârşova tell. The occurrence of similar accumulations in the two settlements indicates generalized practices between the two communities. This first study of such accumulations addresses the relationship between bivalves and other animal species used in alimentation by the two Eneolithic communities, as well as the relationships between these communities, their environment, and the evolution of the settlements. Bivalves were harvested in the close vicinity of the settlements and large quantities were obtained only towards the end of the summer season. During this season there is an inverse relationship between high water levels in the river and the availability of bivalves for harvesting. Bivalves played an important role in the alimentation of the prehistoric populations – at Hârşova tell their contribution to alimentation in terms of energetic yield surpasses that of fish, at least for the short period of time represented by the stratigraphic sequence analysed. Bivalve shells were used, along with other types of household refuse, in construction techniques aimed at limiting soil humidity in the settlements and inside the dwellings.