Stable isotope evidence for (mostly) stable local environments during the South African Middle Stone Age from Sibudu, KwaZulu-Natal

Site-specific environmental and climatic records are crucial to our understanding of human behavior and cognition during the African Middle Stone Age. This is particularly true of the South African Middle Stone Age record with its enigmatic and relatively short lived Still Bay and Howieson’s Poort industries. Existing environmental models for the South African Middle Stone Age are primarily contingent on global climatic data which are temporally, spatially, and/or stratigraphically separated from archaeological sites. The well-dated and extensive Middle Stone Age sequence of Sibudu provides a rare opportunity to gather the high-resolution on-site data which are sorely needed to evaluate behavior-environment links ‘on the ground.’ Stable carbon and oxygen isotope data were collected from faunal tooth enamel samples spanning the entire Sibudu sequence excavated by Wadley from >77 to ∼38 thousand years ago (ka). Two periods of habitat change are identified at Sibudu. The pre-Still Bay (>73 ka) is characterized by more closed, likely forested, and mesic conditions than the rest of the sequence. Late and final Middle Stone Age industries (∼48–38 ka) at Sibudu are associated with more open and likely drier conditions than earlier. No major environmental or habitat changes based on stable isotope data, however, are identified in the Sibudu record concordant with the Still Bay, Howieson’s Poort, or post-Howieson’s Poort techno-complexes. These results suggest that social and demographic changes were presumably as significant as environmental conditions, if not more so, in behavioral transitions at Sibudu.