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Tartar on the teeth of a young male Australopithecus sediba

To someone in the dentist’s chair, plaque is an unwelcome discovery, but to paleoanthropologists, it’s a gold mine of information. And the hardened plaque, called tartar or calculus, on the teeth of two Australopithecus sediba

individuals revealed that these early humans had a taste for trees

that included not only fruit, but also bark, wood, and leaves. Researchers recovered

the 2-million-year-old remains of two A. sediba, a species from which some scientists suspect modern humans descended

, from a site in South Africa. By analyzing the physical wear, chemical makeup, and tartar content of the teeth, paleoanthropologists could determine what this proto-human usually ate. For example, the ratio of different carbon isotopes in the teeth suggested that they preferred to consume forest food rather than the grassland pickings that other early humans enjoyed. The tartar, meanwhile, contained plant particles linked to bark and woody material. But bark may not have been the hominins’ first food choice: modern primates tend to eat it only when tastier food is unavailable. Perhaps, the researchers suggest, these early humans had to deal with drought or a similarly stressful environment. [via Scientific American

] Image courtesy of Amanda Henry / Nature