Multiscalar perspectives on Holocene climatic and environmental changes in the Sahara and Nile Corridor, with special consideration of archaeological sites on Sai Island, Sudan

This multiscalar study explores Holocene environmental changes across the Sahara, within the eastern Sahara, and along the Nile in northern Sudan. The Early Holocene saw increased moisture across most parts of northern Africa after c. 10,000 BC, with peak humid conditions 7800–7000 BC. A short but significant dry interval after c. 7000 BC was followed by wetter conditions around 6000 BC, and then a gradual aridification from 5000 BC. The latter dry phase has continued until present times. The exceptional environments near the Nile are known to have seen impressive variations as climate oscillations and flora left traces in the palaeobotanical record. Multidisciplinary archaeological studies in this area—including analysis of plant macroremains—have focused on the transitions from hunting-fishing-gathering (Khartoum Variant) to pastoralism (Abkan) and later to agro-pastoralism (Pre-Kerma). The palynological data from four Sai Island sites (8-B-10C, 8-B-76, 8-B-81, and 8-B-10A) and the nearby mainland site of Amara West (2-R-66) provide new perspectives on local environmental shifts during this time of profound economic and social change. Despite poor pollen preservation, the high number of samples enables comparisons that show both diachronic changes and synchronic variation. Since the earliest phases, pollen spectra reflect mixed flora from various habitats and some seasonal variability. During the Early Holocene and the initial part of the Middle Holocene, dramatic floods on Sai’s east side and seasonal desiccation on Sai’s west side together created an ecological mosaic that exposed people to several different habitat types within a short distance. These included swamps and marshes, wooded savannas, grasslands and desert savanna, providing access to plants used for food, medicine, and other purposes. Documenting localized patterns of vegetation variation and change can lay important groundwork for explaining changes in subsistence and social organization.