Investigation of diachronic dietary patterns on the islands of Ibiza and formentera, Spain: Evidence from carbon and nitrogen stable isotope ratio analysis.

To examine how dietary patterns may have changed in the western Mediterranean through time, stable carbon and nitrogen isotope ratios were measured on extracted bone collagen from fauna (n = 75) and humans (n = 135) spanning four distinct chronological periods: Chalcolithic (c.2100-1600 BC), Punic (6th-2nd/1st century BC), Late Antiquity-Early Byzantine (4th-7th century AD), and Islamic (c.10th-13th century AD) on the islands of Ibiza and Formentera, Spain. The Chalcolithic, Punic, and Late Antiquity-Byzantine societies all showed evidence of a predominately C(3) terrestrial-based diet with a possible input of a small amount of marine and/or C(4) dietary resources. In contrast, the Islamic population on Ibiza had a subsistence strategy that was reliant on a significant amount of C(4) plants and/or animals fed a C(4) diet, likely millet. These results indicate a fairly constant C(3) terrestrial-based diet on the islands of Ibiza and Formentera through time, with a shift to C(4) dietary resources during the Islamic Period. Further research is needed from other Islamic populations in and around the Mediterranean to better understand this unique dietary adaptation. Am J Phys Anthropol 143:512-522, 2010.