The first hominid meat eaters?

Based of dental morphologies, it has long been believed that Australopithecus africanus subsisted on a diet of fruits and leaves—not unlike that of a chimpanzee. However, stable carbon isotope analysis by Matt Sponheimer and Julia Lee-Thorp show a different dietary story for these early hominids.

Stable isotope analysis of molar tooth enamel from A. africanus specimen from Makapansgat, South Africa show that, despite being well adapted for tree foraging, a large part of their diet consisted of carbon 13-rich foods that are found in open grasslands. This would include grasses and sedges, or possibly the animals that consumed these foods these food-sources. It is commonly believed that stone-tool wielding; large brained Homo species were the first to consume meat. But, this stable carbon isotope analysis may generate a new idea in regards to who the first meat-eating member of the hominid line really was.

To get a better idea of the ecological context of the Makapansgat africanus, Sponheimer and Lee-Thorp also analyzed the enamel of other fossil fauna in the area. The stable isotope results from A. africanus differed from the grazers and browsers of the area, while they shared similarities the carnivore Hyaena makapani. The analysis showed that all but one specimen fell outside the range that corresponds to diets that relied heavily on the consumption of fruit and leaves.

These results could suggest that A. africanus may have utilized grasses and sedges to avoid competition. However, the tooth wear patterns of A. africanus are not consistent with grass eaters. It is also possible that they were consuming plant-eating insects of young grazing mammals. To further the argument, the stable isotope analysis from early Homo specimen did not show any more indication for meat consumption then africanus, They propose, “The primary dietary difference between A. africanus and Homo may not have been the quality of their food but their manner of procuring it.”

Extent chimpanzees could be a clue to the dietary patterns of A. africanus. They occasionally supplement their diet with meat, and are known for eating C-13 rich insects. It seems likely that the dentally similar A. africanus would do the same thing.

The evidence given by Sponheimer and Lee-Thorp is not completely conclusive. It is possible that A. africanus was subsisting in grasses or on animals that consumed those grasses. However, it is compelling evidence that suggests that Homo may not have been the first meat eater. Regardless of what exactly A. africanus was eating, it does give interesting insight into their subsistence strategies. Whether they were eating grasses and sedges, termites, hunting mammals, or scavenging, this evidence shows that early hominids were broadening their resource base.

Sponheimer Matt and Julia Lee-Thorp. 1999. "Isotopic Evidence for the Diet of an Early Hominid, Australopithecus Africanus." Science 283, no. 5400: 368-70.