Late Quaternary environmental change in the Southern Cape, South Africa, from stable carbon and oxygen isotopes in faunal tooth enamel from Boomplaas Cave

Pleistocene palaeoclimates and palaeoenvironments of southernmost Africa are important for understanding southern hemisphere climate dynamics and for reconstructing human evolution and early human settlement in this region. Measurements of δ¹³C in tooth enamel of 136 faunal specimens from the archaeological site of Boomplaas Cave, South Africa, show significant shifts in proportions of C₃ and C₄ vegetation from the earliest deposits, probably dating to Marine Isotope Stage (MIS) 5, to the late Holocene. Vegetation communities during the Last Glacial Maximum were strongly C₃-dominated, indicating an eastward expansion of the winter rainfall zone at this time. This is consistent with climate models postulating northwards shift and/or intensification of the circumpolar westerly frontal systems during glacials. Winter rainfall and lower temperatures, both of which favour C₃ grasses, were clearly more important than lower pCO₂ (which favours C₄ grasses) in determining the nature of the vegetation. The intervals 40–36 and 17–14k cal a BP supported substantial quantities of C₄ grasses, indicating a greater proportion of summer rainfall at these times. These two intervals correspond with warmer climates as reflected in Antarctic ice cores. δ¹³C of an as yet unnamed caprine indicate that these animals were primarily C₃ grazers.