Ancient mobility in northern Jordan during the Roman and Byzantine periods using stable strontium isotope analysis of human dental enamel

The 700-year stretch from the 1st century BCE until the 6th century CE marks the period of greatest population density in northern Jordan. This agriculturally fertile region contains a number of small villages likely interconnected with each other and with the larger Roman and Byzantine population centers of Jerash (Gerasa), Umm Qais (Gadara), Quailbeh (Abila), and Tabaqat Fahl (Pella). The human mobility within these villages was explored using ⁸⁷Sr/⁸⁶Sr values in human dental enamel, which mirrors the origin of ingested food during childhood and thus the geological region where individuals spent their early years. Thirty-four human dental enamel samples from the archaeological sites of Natfieh, Sa’ad, Ya’amun, and Yasieleh were analyzed isotopically to identify immigration into the region as a potential source of increased population density. The results indicate that the individuals within each site received varied inputs from different geological regions during childhood, either through spending their early years in a separate location, or temporal or inter-individual shifts in the location of dietary resource acquisition. The results seem to demonstrate exceptional regional continuity and resilience even through the climate crisis of the Late Byzantine period, likely due to flexibility concerning dietary resources and economic exchange. However, the lack of clear patterns of ⁸⁷Sr/⁸⁶Sr variation in the region may limit larger interpretations of these data.