Did military orders influence the general population diet? Stable isotopes analysis from Medieval Tomar, Portugal

This study integrates bone collagen stable isotope data (carbon, nitrogen and sulphur) from 33 human adult tibiae (15 females; 18 males) and 13 faunal remains from Tomar, while it was under the Military Orders domain (eleventh–seventeenth centuries). Historical literature indicates that the amount of meat consumption amongst Templars was lower than in individuals with similar social status. In Medieval times, these Military Orders had total control of towns and angling and fishing rights, but their influence on the general population diet remains unknown. While no statistically significant differences (p > 0.05) were found between sexes, social status, or for bone collagen δ13C and δ34Sbetween age groups, δ15N did differ significantly with age, which may be related to tooth loss in old individuals. Additionally, the human samples have higher stable isotope differences, in comparison with faunal samples, than would be expected within the food web, particularly for δ13C. This human bone collagen δ13C enrichment may reflect a diet rich in aquatic protein intake, which is also supported by δ34S archived in human and faunal samples, and the presence of oysters and cockles shells at the excavation. The religious diet restrictions might have led to a higher intake of aquatic protein when meat consumption was not allowed.