Mid-Holocene environmental change and human occupation at Sai Island, Northern Sudan

Holocene environmental change in the northern and central Nile Valley was controlled primarily by shifts in the Intertropical Convergence Zone over time, leading to changes in aridity and water availability for early occupants of the region. Although local environmental changes may help to motivate societal changes such as those in settlement patterns or technological productions, evidence from pedogenic carbonates at Sai Island, in northern Sudan, indicate that the most significant environmental changes predated a key shift in local food production from foraging to pastoralism. Changes in local environmental conditions from a wetter and more diverse vegetative context to a more arid and C-4-dominant landscape occurred during the occupation of Khartoum Variant foragers, whereas later Abkan pastoralists arrived without any notable differences in the region compared to the environments inhabited by the most recent foragers. The lack of an external environmental driver for food production changes at Sai suggests that other, potentially cultural factors were more important in these economic decisions in the mid-Holocene.