Livestock enclosures dating back over 6,000 years to the Ancient Neolithic have previously been documented at other sites on Spain's Sierra de Cantabria, about 300 kilometres north-northeast of Madrid, and around 100 kilometres south of the Bay of Biscay. A new study by the same team looks at ancient activities inside these shelters during the Copper Age, about 5,000 years ago.
     Ana Polo-Diaz, a researcher at the University of the Basque Country explains: "This is a piece of pioneering work in the studies on agro-pastoral communities on the Iberian Peninsula. We have evidence that the human groups that occupied San Cristobal during the Chacolithic used the shelter as a pen for goats and/or sheep and that this use, although repetitive throughout hundreds of years, was not ongoing but of a temporary nature linked to a seasonal exploitation of the rich natural resources available on the Sierra de Cantabria. We also know thanks to the microscopic study of the sediments that every now and again they used to burn the debris that had built up, probably to clean up the space that had been occupied and that this combustion process was carried out in line with some specific habits: they used to pile up the debris and on top of them pile up woody remains, perhaps to help to get the fire going before going on to burn the debris."
     Analyses of micro-sediments and mineral remains of the skeleton of plants makes it possible to determine the grazing available around the shelter. Pollen reveals that a forest grew in the immediate surroundings of San Cristobal during the period, in which hazelnut trees predominated along with deciduous oaks, and grazing areas and farmland fairly close to the shelter.
     Charcoal remains indicate a clear change in the selection of woody materials: during the oldest phase a predominance of pine followed by yew, in the latter phase increased use of species such as oak, holm oak, the rose family, and box.
     Correlating data with that from neighbouring sites and the immediate area reveals that San Cristobal was part of a network of shelters and enclosures, and the people were very likely the same ones using the dolmens of the Rioja Alavesa region.

Edited from Popular Archaeology (9 June 2016)