The hominids that lived in South Africa 1.8 million years ago, known as Australopithecus robustus, were traditionally thought to be vegetarians, chomping coarse plant matter with their large, flat teeth and powerful jaw muscles. But now, a microscopic analysis of bone tools found in two South African caves suggests that termites were high on their menu. The conclusion fits with other recent evidence that suggests Australopithecus had a protein-rich diet.
Francesco d'Errico of the Institute of Quaternary Prehistory and Geology in Talence, France, and paleoanthropologist Lucinda Backwell of the University of Witwatersrand in Johannesburg, South Africa, looked at high-quality replicas of the world's oldest bone tools: 85 pieces from the caves of Swartkrans and Sterkfontein, found close to the remains of Australopithecus robustus. Using microscopes and image resolution software, they examined scratch marks on the bones.
The scratches on the bones belie scientists' earlier belief that they were used for tuber-digging, the team reports in the 16 January Proceedings of the National Academy of Sciences. Bone tools created by other researchers show angular marks when used to dig for tubers. The Australopithecus tools, in contrast, had striations running parallel to the bone's axis. This pattern closely matches the marks found on experimental bone tools used exclusively for opening up termite mounds. In addition, the marks reflect abrasion by fine-grained sediment--like the dirt that makes the hard outer crust of a termite mound. The authors say they also have circumstantial evidence that termites were available: The rock layers that contain the tools also include the fossils of several species of termite-eaters.
The study is consistent with carbon isotope evidence from Australopithecus bones, which suggest they enjoyed a varied diet including either grasses or meat and perhaps insects (Science, 15 January 1999, p. 368), says Stanford University anthropologist Richard Klein. "The only thing that bothered me," says Klein, "is that the termite nests I've seen might require a steel chisel."
Termites apparently are well worth all the trouble. d'Errico and Backwell say nothing beats them as a source for protein, fat, and essential amino acids--as well as calories. While a rump steak yields only 322 kilocalories per 100 grams, termites are good for 560 kilocalories.