Though not a popular item in Western cuisine, termites are prized in other cultures. And with good reason: they represent a valuable source of protein and fat. In fact, a 100-gram serving of these insects provides 75 percent more calories than an equivalent amount of rump steak. Chimpanzees, too, feed on termites, as Jane Goodall first noted 40 years ago in Tanzania, when she watched a nearby chimpanzee pluck a blade of grass, trim it with care and dip the modified stem into a termite mound to fish for the insects. Now it appears that ancient hominids also had a taste for termites. According to a report published today in the Proceedings of the National Academy of Sciences, modified bones dated to between 1.8 and 1.1 million years old that were thought to represent tools for digging up tubers were instead used to dig into termite mounds.

Francesco d'Errico of the University of Bordeaux and Lucinda Backwell of the University of the Witwatersrand analyzed more than 23,000 animal bone fragments from two South African hominid fossil localities known as Swartkrans and Sterkfontein. Earlier studies had identified 69 of these bones as putative tools, but the new work added 16 others to the list. Comparing these 85 specimens at the microscopic level with bones known to have been altered by natural agencies like animal gnawing, water, wind and so forth, the team confirmed that the markings on the purported tools did not match those of the naturally modified examples. Moreover, turning to modern examples, d'Errico and Backwell showed that the orientation of the marks on tools used for digging tubers differed significantly from that seen on tools used for breaking into termite mounds. The wear pattern on the fossil bone tools, they observed, closely resembles the modern termiting tool pattern.

Two kinds of hominid remains have been reported from these South African sites: a robust form of Australopithecus and an early member of our own genus, Homo. Homo is generally thought to have consumed more meat than Australopithecus robustus, whose large, flat teeth would appear to reflect a vegetarian diet. But recent chemical analyses of the A. robustus remains from Swartkrans have revealed a surprisingly high level of so-called C4 dietary carbon, which indicates an unusually sizeable protein intake for a vegetarian species. Termite consumption might explain this find. Indeed, Pennsylvania State University researcher Pat Shipman points out in a commentary accompanying the PNAS report that the termite-eating aardvark has a carbon-isotopic signal rather similar to that for A. robustus. For now the identity of the tool users remains unknown. Only further research will reveal whether one or both of these early hominids dined on termites.