The Islamic cemetery at 33 Bartomeu Vicent Ramon, Ibiza: investigating diet and mobility through light stable isotopes in bone collagen and tooth enamel

Abstract

The Balearic Islands occupy a central space in the western Mediterranean, at the maritime crossroads between North Africa, the Iberian Peninsula and the rest of southwestern Europe. As such, it is well placed to investigate changes in subsistence practices associated with the major cultural transitions following the arrival of Islamic rule. Stable carbon and nitrogen isotope analysis was carried out on bone collagen from the Islamic cemetery (ca. AD 950-1150) population excavated at 33 Bartomeu Vicent Ramon, Ibiza, including human (n = 42) and faunal remains (n = 3). Stable oxygen and carbon isotope analysis was also undertaken on human tooth enamel carbonate (n = 6), and six humans were directly radiocarbon dated, confirming the presence of two distinct burial phases. The collagen results emphasise a C 3 -based diet, with variable but generally minor contributions from marine and/or C 4 foods. However, the enamel carbonate results indicate a far greater importance of C 4 crops than suggested by the collagen results, contributing up to 40% of energy intake. In keeping with previous studies of the region and period, the dietary contribution of marine protein is probably limited. A small number of outliers in both collagen and carbonate isotope results are identified, suggesting the presence of individuals originating elsewhere. The results are compared with those from previous investigations on the Balearics and the Spanish mainland, highlighting the complexity of factors-both cultural and methodological-affecting inter-regional dietary investigation.

The effect of diet and sociopolitical change on physiological stress and behavior in late Roman‐Early Byzantine (300–700 AD) and Islamic (902–1,235 AD) populations from Ibiza, Spain

“…Islamic migration is associated with greater consumption of C 4 crops such as millet, sorghum, and sugarcane (Adamson, 2004; Butzer, Mateu, Butzer, & Kraus, 1985; Glick, 2005; Peña‐Chocarro et al, 2019). Isotopic studies confirm greater consumption of C 4 crops in Islamic Ibizan populations (Alaica et al, 2019; Dury et al, 2018; Fuller et al, 2010; Nehlich et al, 2012; Peña‐Chocarro et al, 2019; Pickard et al, 2017). However, the greater isotopic diversity of Islamic individuals may also reflect migration, because isotopic signatures of certain individuals may reflect migration from locations where cultivation of C 4 crops was more extensive (Alexander et al, 2019; Dury et al, 2018; Fuller et al, 2010; Pickard et al, 2017).…”

“…This study focuses on the relationship between diet, stress, and behavior. Previous isotopic studies of diet have demonstrated diachronic change and inter‐individual variability in diet throughout the Late Roman‐Early Byzantine (LREB) and the Medieval Islamic period (Alaica et al, 2019; Alexander, Gutiérrez, Millard, Richards, & Gerrard, 2019; Dury et al, 2018; Fuller, Márquez‐Grant, & Richards, 2010; Márquez‐Grant, Fuller, & Richards, 2003; Nehlich, Fuller, Márquez‐Grant, & Richards, 2012; Pickard et al, 2017). Other lines of evidence also suggest political, economic, and cultural change across these periods (Costa, 2019c; Ferrer Abárzuza, 2019a; Gurrea & Martín, 2000; Ramon, 1986).…”

“…Thus, it remains unclear whether higher δ 13 C values of Islamic populations reflect increased cultivation of C 4 crops, an increase in the number of migrants, or both. Differences in rural and urban diet have not been systematically studied, but it has been previously noted that rural Islamic groups have lower δ 15 N signatures than urban groups, a pattern suggesting increased consumption of plant foods (Dury et al, 2018; Pickard et al, 2017).…”

“…Recently, a new study has raised the possibility that the calorie contribution of C 4 crops to the Ibizan/ Spanish diet has been overlooked. Dury et al (2018) examined isotopic signatures of enamel apatite as well as bone collagen from a single Islamic period urban cemetery. Apatite's chemical composition reflects the combined isotopic values of carbohydrates, protein, and lipids (Dury et al, 2018; Jim et al, 2004; Katzenberg, 2008).…”

“…Dury et al (2018) examined isotopic signatures of enamel apatite as well as bone collagen from a single Islamic period urban cemetery. Apatite's chemical composition reflects the combined isotopic values of carbohydrates, protein, and lipids (Dury et al, 2018; Jim et al, 2004; Katzenberg, 2008). While collagen samples indicated primarily C 3 protein sources, the apatite δ 13 C was consistent with C 4 crops comprising 25–40% of whole diet.…”