Hungry human ancestors living in southern Africa at least a million years ago had a simple approach to putting more protein and fat in their diet: They used sharpened pieces of bone to tear apart termite mounds so that they could gulp down mouthfuls of the edible insects.
Both chimpanzees and modern human foragers enthusiastically eat termites and other bugs. For the first time, though, researchers have direct evidence for this behavior in our fossil ancestors. Ancient bone tools used for digging tubers out of the ground exhibit different marks than do those used to open termite mounds, according to a report that will appear in an upcoming Proceedings of the National Academy of Sciences.
"The first hominids [members of the human evolutionary family] from southern Africa may have used bone tools, and perhaps wooden tools as well, to dig up termites," says archaeologist Francesco d'Errico of the National Center for Scientific Research in Talence, France. He coauthored the new study with Lucinda R. Backwell of the University of the Witwatersrand in Johannesburg, South Africa.
In a study of 23,000 bones from the Swartkrans caves in South Africa, Backwell discovered 16 probable bone tools in addition to 69 others that had been identified by earlier investigators. She also detected a probable bone tool from the nearby Sterkfontein site.
Hominids lived at these two locations from 1.8 million to 1 million years ago. Both sites contain remains of early Homo and Australopithecus robustus, a small-brained, large-jawed hominid.
Backwell and d'Errico compared the microscopic pattern of incisions and wear on the ends of the 86 probable bone implements with 35 reference sets of fossil and modern bones. In each set, marks were from known sources, such as hyenas' chewing, river-gravel wear, and trampling by animals. The researchers also examined bones they had used experimentally to dig bulbs and tubers, to cut and scrape animal hides, and to break into termite mounds.
Patterns of incisions and wear on nearly all of the ancient bone tools closely matched only those on the bones Backwell and d'Errico used to penetrate termite mounds, the researchers say.
In a comment to be published with their report, anthropologist Pat Shipman of Pennsylvania State University in University Park calls the bone-tool evidence for termite collecting "a remarkable discovery." Chemical analyses of Swartkrans fossils indicate that A. robustus ate a surprisingly large amount of protein, which termites could have provided, Shipman says.
Lucinda R. Backwell
Department of Anatomical Sciences
University of Witwatersrand
Private Bag 3, Wits
Institut de Préhistoire et de Géologie du Quaternaire
Unité Mixte de Recherche 5808 du Centre National de la Recherche Scientifique
Avenue des Facultés
Department of Anthropology
Pennsylvania State University
University Park, PA 16802