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In this chapter, we focus our attention on the potential links between hominin evolution and environmental change in Africa as revealed by stable light isotope evidence. We begin with an exploration of some of the gaps to which isotope approaches may be applied to good effect and follow with an overview of the principles and the materials typically available for analysis. The results for carbon isotope ratios of pedogenic carbonates and faunal enamel have now pushed back the emergence of C₄ grasses, and thus more open environments, to ca. 9 Ma. These data also show that in spite of a trend toward more open grassy environments observed from the Pleistocene and Pliocene records, consideration of the Late Miocene and Early Pliocene sequences as well suggests that proportions of grassy and forest habitats fluctuated on very broad timescales. New high-resolution biomarker records from Olduvai, and a single speleothem record from South Africa, show that, within the broader framework, shifts also occurred on shorter, orbitally controlled timescales. Faunal data indicate that herbivore families adapted to emerging C₄ resources at very different rates, with hominins showing signs of engaging with C₄ biomass only after 4 Ma. Aridity indicators reflect generally dry and warm conditions in East Africa, but the relationship between humidity and aridity on the one hand, and forest or open grassy cover on the other, varies for different environments. All lines of isotopic evidence from East and South Africa suggest a significant change to more open, grassy ecosystems ca. 1.8 Ma, broadly concordant with the emergence of Homo ergaster.

DOI: 10.1007/978-3-642-39979-4_9

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