Investigation of diachronic dietary patterns on the islands of Ibiza and Formentera, Spain: Evidence from sulfur stable isotope ratio analysis

We present sulfur isotope ratio measurements of bone collagen from animals (n = 75) and humans (n = 120) from five sites dating to four chronological periods (Chalcolithic, Punic, Late Antiquity‐Early Byzantine, and Islamic) from the Balearic Islands of Ibiza and Formentera, Spain. This study is a follow up to previously published δ¹³C and δ¹⁵N values by Fuller et al.: Am J Phys Anthropol 143 (2010) 512–522] and focuses on using δ³⁴S values to better understand the dietary patterns of these populations through time and to possibly identify immigrants to these islands. The range of δ³⁴S values (10.5–17.8‰) observed for the animals was relatively broad, which suggests that a significant sea spray effect has added marine sulfates to the soils of Formentera and Ibiza. The mean δ³⁴S values of the different human populations were found to be: Chalcolithic (16.5 ± 1.4‰), Punic rural (13.6 ± 1.7‰), Punic urban (12.9 ± 1.8‰), Late Antiquity‐Early Byzantine (12.3 ± 2.1‰), and Islamic (9.1 ± 2.7‰). These human δ³⁴S results are similar to the animal data, a finding that supports the notion that there was little marine protein consumption by these societies and that the diet was mainly based on terrestrial resources. During the Punic and Late Antiquity‐Early Byzantine periods the δ³⁴S values were used to identify individuals in the population who likely were not born or raised on the islands. In addition, 18 of the 20 individuals analyzed from the Islamic period have δ³⁴S values that indicate that they were immigrants to Ibiza who died before acquiring the new local sulfur isotopic signature. Am J Phys Anthropol 2012. © 2012 Wiley Periodicals, Inc.