JOHANNESBURG, SOUTH AFRICA—According to a Newsweek report, scientists from the Max Planck Institute for Chemistry and the University of Witswatersrand analyzed nitrogen isotopes taken from the tooth enamel of seven Australopithecus individuals. These hominins, whose remains were discovered in southern Africa’s Sterkfontein Cave, lived some 3.5 million years ago. “Tooth enamel is the hardest tissue of the mammalian body and can preserve the isotopic fingerprint of an animal’s diet for millions of years,” said geochemist Tina Lüdecke of the Max Planck Institute for Chemistry. Plants are known to contain more 14N, a lighter form of nitrogen, which is excreted by animals through urine, feces, and sweat, while a heavier form of nitrogen, 15N, tends to stay in the mammalian body. Herbivores, who consume only plants, therefore have more 15N and less 14N, while carnivores, who consume only meat, have a lot of 15N and little 14N, the researchers explained. Lüdecke and her colleagues then compared the levels of 15N and 14N in the Australopithecus tooth enamel with that of animals such as monkeys, antelopes, and hyenas, and determined that Australopithecus ate a varied plant-based diet. Eggs and termites may have been consumed occasionally, they added. The team members plan to investigate the possibility that eventual hominin meat consumption may have been linked to an increase in brain size. To read about the skeleton of another australopithecine found at Sterkfontein, go to "Sticking Its Neck Out."
