Hominins, sedges, and termites: new carbon isotope data from the Sterkfontein valley and Kruger National Park

Stable carbon isotope analyses have shown that South African australopiths did not have exclusively frugivorous diets, but also consumed significant quantities of C-4 foods such as grasses, sedges, or animals that ate these foods. Yet, these studies have had significant limitations. For example, hominin sample sizes were relatively small, leading some to question the veracity of the claim for australopith C-4 consumption. In addition, it has been difficult to determine which C-4 resources were actually utilized, which is at least partially due to a lack of stable isotope data on some purported australopith foods. Here we begin to address these lacunae by presenting carbon isotope data for 14 new hominin specimens, as well as for two potential C-4 foods (termites and sedges). The new data confirm that non-C-3 foods were heavily utilized by australopiths, making up about 40% and 35% of Australopithecus and Paranthropus diets respectively. Most termites in the savanna-woodland biome of the Kruger National Park, South Africa, have intermediate carbon isotope compositions indicating mixed C-3/C-4 diets. Only 28% of the sedges in Kruger were C-4, and few if any had well-developed rhizomes and tubers that make some sedges attractive foods. We conclude that although termites and sedges might have contributed to the C-4 signal in South African australopiths, other C-4 foods were also important. Lastly, we suggest that the consumption of C-4 foods is a fundamental hominin trait that, along with bipedalism, allowed australopiths to pioneer increasingly open and seasonal environments. (c) 2004 Elsevier Ltd. All rights reserved.