Temporal Trends in Mobility and Subsistence Economy among the Tomb Builders of Umm an-Nar Island

With the earliest recorded Umm an-Nar (2700–2000 BC) tombs, Umm an-Nar Island (UAE) offers insight into early strategies of human social organization in southeastern Arabia. The author used strontium, oxygen, and carbon isotope ratios from the enamel of those interred within three tombs to test the hypothesis that, over time, these populations became increasingly sedentary and more reliant on coastal resources. Variable strontium isotope ratios allude to either a more mobile lifestyle or a more diverse diet. Corresponding oxygen and carbon isotope values suggest that residents did not become more mobile in the latter period; instead, dietary variability became more pronounced. This shift in subsistence economy may be explained by differential resource access, which is possibly a result of either dissimilar regional geographic origins or growing social hierarchies and disparate access to power.