A new study by a team of researchers led by Matthew Ravosa, professor of biological sciences and concurrent professor of aerospace and mechanical engineering and anthropology at the University of Notre Dame, offers surprising insights into dietary influences on the growing skull.
Ravosa notes that the robust jaws and large, thick-enameled molars of the first human ancestors from Africa, known as australopiths, have longbeen interpreted as adaptations for hard object feeding, especially in the genus Paranthropous robustus, and to a lesser extent, Australopithecus.
Recent studies of molar surface microware indicate that only Paranthropous robustus regularly ate hard items, suggesting that the oral anatomy of other australopiths reflected rare, seasonal exploitations of hard fallback foods. Fallback foods are typically more mechanically challenging than diets exploited on a more annual basis are critical to survive seasonal periods when easier to process preferred resources are scarce. The ecological and morphological importance of fallback foods have been implicated in a number of recent studies of living and fossil mammals.
"In contrast to this highly influential hypothesis about australopith feeding adaptations, our study demonstrated that hard object feeding cannot explain the extreme morphology of Paranthropous boisei," Ravosa said. "Rather, analysis of long-term dietary plasticity in an animal model, in this case rabbits, suggests year-round reliance on tough foods requiring prolonged post-canine processing in Paranthropous boisei. Increased consumption of such food items may have marked the transition from the earlier hominids Ardipithecus to Australopithecus, with routine hard object feeding in Paranthropous robustus representing a novel behavior."
The researchers used a sample which contained 30 five-week-old weanling male rabbits divided equally into three dieta
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University of Notre Dame