Diet of Australopithecus robustus at Swartkrans from stable carbon isotopic analysis

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

“…This disparity cannot be ascribed to diagenesis, as there is no evidence that browser or grazer d 13 C has been irrevocably altered, and diagenesis should affect hominins and non-hominins alike. It appears, however, that we previously underestimated the importance of non-C 3 foods to australopiths (Lee-Thorp et al, 1994;Sponheimer and LeeThorp, 1999a). We previously estimated that about 25% of australopith diets came from non-C 3 sources.…”

“…This high degree of variability is very unusual among both modern and fossil faunas in South Africa (Lee-Thorp et al, 1994Sponheimer et al, 1999Codron, , and might be ascribed to environmental heterogeneity. There is considerable evidence that South African australopith habitats became more open between w3.0 Ma and 1.8 Ma (Vrba, 1980(Vrba, , 1985Reed, 1997;Luyt and Lee-Thorp, 2003), and in fact the d 18 O data for the hominins in this study are consistent with increasing aridity in the Sterkfontein valley as 1.8 Ma Paranthropus (x Z ÿ0.6&, s.d.…”

“…In the provenience column, site abbreviations (SK Z Swartkrans, MAK Z Makapansgat, ST Z Sterkfontein) are followed by the appropriate Member number. The 1994 publication is Lee-Thorp et al, 1994; the 1999 publication is Sponheimer and Lee-Thorp, 1999a summer rainfall zones utilize C 4 photosynthesis, 72% of the specimens we analyzed were C 3 plants (which reflects the local abundance). This unexpected result has been affirmed by a recent herbarium survey of South African sedges which found that 65% use C 3 photosynthesis (Stock et al, 2004).…”

“…Consequently, it was expected that early hominins, like the modern frugivorous chimpanzee, would have a C 3 isotopic signature (Schoeninger et al, 1999;Carter, 2001). Unexpectedly, however, all of the carbon isotope studies to date have shown australopiths to be rather enriched in 13 C, suggesting that foods other than fruits were also important dietary components (Lee-Thorp et al, 1994;Sponheimer and Lee-Thorp, 1999a;.…”

“…Thus, C 4 grasses, C 4 sedges, and animals that ate these foods were all offered as possible australopith foods (Lee-Thorp et al, 1994;Sponheimer and Lee-Thorp, 1999a;Peters and Vogel, in press). Amongst the reasons for this inability to identify the C 4 dietary source was a lack of data available on the carbon isotope compositions of potential C 4 foods other than grasses and large vertebrates.…”