Aridity and adaptation among Arabian Bronze Age communities

Rapid aridification in southeastern Arabia at the end of the Umm an-Nar period (2700–2000 BCE) coincided with major changes in material culture and social organization demarcating the subsequent Wadi Suq period (2000–1600 BCE). Aridification should be observable in the oxygen isotope values of human dental enamel of people whose interments span the third to the second millennium BCE. Radiogenic strontium and stable carbon isotope ratios can also provide contextual information regarding shifts in mobility and diet. Stable isotopes analysis was conducted on skeletal material from a monumental tomb at the Shimal Necropolis (Emirate of Ras al-Khaimah, United Arab Emirates). An average oxygen isotope value difference of 0.9‰ between the Umm an-Nar and Wadi Suq periods is likely indicative of an increasingly arid climate and a time of transition when human populations worked to adapt to their changing surroundings. Strontium-oxygen ratios are best explained by the consumption of water from an isotopically similar source throughout the late third and early second millennia BCE that nevertheless underwent ¹⁸O-enrichment in response to regional aridification. Intra-individual variations in strontium and carbon isotope values exhibit uniformity over time, suggesting continuity in lifestyle that is suggestive of a community that sought to maintain their way of life in both patterns of mobility and diet, despite undergoing other social changes visible in changing mortuary practices, trade, and settlement patterns. Such resiliency speaks to the active maintenance by local agents of some aspects of structural and social identity while adapting in other ways in the face of environmental change.