The monks of San Millán: Investigating the transition between pre-monastic and monastic diet using carbon and nitrogen isotope ratios in incremental dentine

Abstract

From the early Medieval period, Christian monasteries were wealthy and powerful, and played a central role in both religious and political life. Those who entered the monasteries did so at the age of 7–8 years and were drawn from a wide range of social strata. From that point, they were subject to the dietary rules imposed by the rules of each monastic order. In order to assess the origins and diet of 10 monks who lived in the monastery of San Millán de la Cogolla Yuso (La Rioja, Spain) during the 17th – 18th century, collagen from small sections of human dentine (representing the childhood diet) and from ribs (an average of the last 5–10 years of adult diet) was measured to establish lifetime variations in the isotope ratios of carbon (δ13C) and nitrogen (δ15N). Bulk collagen δ13C (overall mean = -18.2‰ +/-0.4) and δ15N (overall mean = 12.6‰ +/-0.8) values from the ribs suggest 2 adult cohorts: one with a diet based on C3 plants and a high intake of protein from meat or dairy products and some marine resources and a second cohort with some C4 plant consumption alongside meat and dairy. Data from the dentine sections revealed different dietary patterns during the period of tooth formation among the monks, suggesting that 4 of them entered the monastery after consuming lower status diets during childhood.