Isotopic evidence for dietary diversity at the mediaeval Islamic necropolis of Can Fonoll (10th to 13th centuries CE), Ibiza, Spain

Abstract

The diet of the population interred at the Islamic necropolis of Can Fonoll, Ibiza, Spain, which was in use between the 10th and 13th centuries AD, is reconstructed from the carbon (δ13C) and nitrogen (δ15N) stable isotope ratios of bone collagen from 112 individuals. The mean ± sd (1σ) δ13C (− 19.0 ± 1.3‰) and δ15N (10.3 ± 0.8‰) values of the Can Fonoll population indicate a diet based largely on terrestrial C3 resources. However, the wide range of both δ13C (− 20.6‰ to − 8.6‰) and δ15N (7.0‰ to 12.1‰) values attested at Can Fonoll indicate significant variation in individual diet. The elevated δ13C values of a small proportion of the individuals buried at Can Fonoll are consistent with the consumption of a large proportion of, or dependence on, C4 resources, such as millet. Comparison of the δ13C and δ15N values of the Can Fonoll population with those of other mediaeval populations from the Balearic Islands and mainland Spain highlights a wide range of stable isotope values, which reflects not only significant differences in diet but also points to widespread mobility within the Mediterranean Basin

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

“…In addition, the islands' port towns in particular might be expected to have had higher numbers of immigrants at any given time, some of whom would have died and been buried on the islands. Our study builds on previous work on both themes, which has increased substantially in recent years, allowing these wider comparisons to be made (Alexander et al 2015;Fuller et al 2010;Nehlich et al 2012;Pickard et al 2017;Salazar-García 2011;Salazar-García et al 2014;van Strydonck et al 2002van Strydonck et al , 2005Ziriax 2017). …”

“…The implication is one of very small-scale local differences in diets between contemporaneous populations. This is perhaps easiest to understand when comparing the rural site of Can Fonoll with the two Eivissa sites, with the latter having greater access to marine foods and to imported foodstuffs (Pickard et al 2017), though it was not until the twelfth century that the Balearic Islands became more thoroughly enmeshed in international Mediterranean trade (Doxey 1994). The explanation for this subtle, small-scale patterning may instead relate to the strong, clan-based territorial divisions on Ibiza set out during its resettlement in 902 (Kirchner 2002(Kirchner , 2006(Kirchner , 2009Kirchner and Retamero 2015: Fig.…”

“…An issue when investigating the role of marine foods, as discussed above and as also noted by Pickard et al (2017;cf. Craig et al 2009), is that their contribution to δ 13 C in bone collagen can be masked in diets dominated by C 3 carbohydrates (wheat, barley, rice) and lipids (e.g.…”

“…The site means at Can Fonoll of − 19.0 ± 1.3 and 10.3 ± 0.8‰ for δ 13 C and δ 15 N (n = 112), respectively, indicate predominantly C 3 diets. Five individuals are identified as outliers in δ 13 C, with values above − 18‰ (but no corresponding increase in δ 15 N), the highest being − 8.6‰, suggesting a diet almost entirely comprised of C 4 foods and so undoubtedly a recent migrant to Ibiza (Pickard et al 2017). Removing these outliers, together with an N values to terrestrial fauna, and so cannot be easily distinguished in isotopic studies, is, in the case of the former, based on an inappropriate comparison of modern fish flesh values to archaeological fish bone.…”

“…Significantly higher δ In contrast to the mainland, some sites on the Balearic Islands show low but statistically significant positive correlations between δ 13 C and δ 15 N (Table 5), consistent with some contribution of marine foods in island diets. The two exceptions are the Late Antiquity/Byzantine cemetery at S′Hort des Llimoners and the large Islamic cemetery of Can Fonoll, both on Ibiza (Fuller et al 2010;Pickard et al 2017). The site means at Can Fonoll of − 19.0 ± 1.3 and 10.3 ± 0.8‰ for δ 13 C and δ 15 N (n = 112), respectively, indicate predominantly C 3 diets.…”