DUNEDIN, NEW ZEALAND—According to a statement released by the University of Otago, biological anthropologist Ian Towle and dentist Carolina Loch examined more than 20,000 teeth from fossils and living primates and noted the position and size of any tooth fractures for clues to the diets of early humans. The researchers found that extreme tooth wear and high rates of tooth fractures were normal within the Homo genus, similar to the rate of tooth fracture found in living primates who eat a diet of hard foods. Paranthropus robustus, a human relative that lived about three million years ago, had been thought to eat a diet of seeds and nuts based upon its massive back teeth. But the researchers found a low rate of tooth fracture among the Paranthropus teeth studied, similar to modern primates that eat soft fruit or leaves. The tooth fractures observed in early humans may have also been caused by non-food items, the researchers explained, such as grit in the diet or stone tools. Teeth may have evolved to be smaller as other parts of the skull expanded, Towle added. To read about a two-million-year-old Paranthropus robustus skull, go to "Consider the Craniums."