Extended methodology for “Investigating the coprolites of Moynagh Lough using biomolecular approaches”

During excavations at Moynagh Lough, 200 coprolites (preserved faeces) were recovered. These were preserved via partial mineralisation in the waterlogged sediments surrounding the crannog. Here, a subset of eleven coprolites was subjected to multiproxy bioarchaeological testing – ancient DNA, metaproteomic and amino acid analysis of the coprolite matrix, and a zooarchaeological assessment, ZooMS and radiocarbon dating of embedded bone fragments. Ancient DNA analysis identified male and female dogs as the depositors of 6 of the 11 coprolites; dogs were also the most likely depositors of 4 of the remaining 5, along with one possible coprolite deposited by a female pig. Evidence for the presence of preserved proteins within the coprolite matrix, which could potentially confirm depositor identifications and provide information on diet and gastrointestinal health, was obtained by detection of high hydrolysable amino acid to free amino acid ratios. The techniques applied did not yield informative proteomic information, however, indicating that further method development is needed to obtain meaningful palaeo-proteomic data from coprolites. Nevertheless, inspection of bone inclusions, and ZooMS analysis, provided evidence of butchery and suggested that the dogs were consuming a range of domesticated animals, including cattle, pig and horse/donkey. Furthermore, radiocarbon dating of bulk bone from five coprolites suggested that occupation of the site could be as early as the late sixth century. Taken together these data suggest that, even within the very confined footprint of the crannog, dogs (and maybe pigs) lived alongside their human counterparts and, despite the prohibition on human consumption of horse meat, it was eaten by dogs in early medieval Ireland. Thus, this integrated bioarchaeological study of the Moynagh Lough coprolites has revealed new information about human activities, the presence of animals, and their diets, providing new insights into life on the crannog.