Dietary versatility of Early Pleistocene hominins

Abstract

New geochemical data from the Malawi Rift (Chiwondo Beds, Karonga Basin) fill a major spatial gap in our knowledge of hominin adaptations on a continental scale. Oxygen (δ¹⁸O), carbon (δ¹³C), and clumped (Δ₄₇) isotope data on paleosols, hominins, and selected fauna elucidate an unexpected diversity in the Pleistocene hominin diet in the various habitats of the East African Rift System (EARS). Food sources of early <i>Homo</i> and <i>Paranthropus</i> thriving in relatively cool and wet wooded savanna ecosystems along the western shore of paleolake Malawi contained a large fraction of C₃ plant material. Complementary water consumption reconstructions suggest that <i>ca.</i> 2.4 Ma, early <i>Homo</i> (<i>Homo rudolfensis</i>) and <i>Paranthropus</i> (<i>Paranthropus boisei</i>) remained rather stationary near freshwater sources along the lake margins. Time-equivalent <i>Paranthropus aethiopicus</i> from the Eastern Rift further north in the EARS consumed a higher fraction of C₄ resources, an adaptation that grew more pronounced with increasing openness of the savanna setting after 2 Ma, while <i>Homo</i> maintained a high versatility. However, southern African <i>Paranthropus robustus</i> had, similar to the Malawi Rift individuals, C₃-dominated feeding strategies throughout the Early Pleistocene. Collectively, the stable isotope and faunal data presented here document that early <i>Homo</i> and <i>Paranthropus</i> were dietary opportunists and able to cope with a wide range of paleohabitats, which clearly demonstrates their high behavioral flexibility in the African Early Pleistocene.