First evidence of Pleistocene ochre production from bacteriogenic iron oxides. A case study of the Upper Palaeolithic site at the San Teodoro Cave (Sicily, Italy)

The use of iron pigments is well documented in the archaeological horizons of the different parts of the world since the Middle Pleistocene. The mineralogical and chemical composition of the pigments allowed defining, in most cases, their inorganic origin, which were then used after a limited transformation and manipulation. The use of a biogenic ochraceous pigment and its manipulation has recently been described in a late Holocene archaeological horizon of the American continent. Here we describe the earliest case of archaeological use of ferrous pigment produced by iron-oxidising bacteria (FeOB), the first identified in a European Epigravettian (late Upper Palaeolithic) layer, at the San Teodoro site in Sicily, Italy. Samples of the ochraceous archaeological deposit, overlying a large burial site, were analysed according to current methods of physical analysis and SEM highlighting a matrix of bacterial structures and a chemical composition coherent with biogenic productions. The physical-chemical analysis of the archaeological material from the Palaeolithic site, and of the modern bacteriogenic iron sediments from two close springs gave consistent results even after heat treatment. In absence of Terra Rossa or other easily available inorganic ferrous materials in the hinterland of their site, the hunter-gatherers identified several possible water sources rich of pigment used for covering a multiple burial. The implications of these results influence interpretations of the ecology of the late-glacial and Epigravettian sites in Europe, especially in relation to problems such as the increasing complexity of behaviours, the need to establish rituals and the search for materials.