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Mon September 24, 2012
Dr. Darryl de Ruiter, Texas A&M University – Australopithecine Diet
In today’s Academic Minute, Dr. Darryl de Ruiter of Texas A&M University reveals what we can lean about the diet of Australopithecus through a chemical analysis of their fossilized teeth.
Darryl de Ruiter is an associate professor of anthropology at Texas A&M University where his research focuses on the ecology and evolution of African australopiths. His current project site, Malapa, is a recently discovered early Pleistocene locality in South Africa. His research has been widely published and he holds a Ph.D. from the University of Witwatersrand in Johannesburg, South Africa.
Dr. Darryl de Ruiter – Australopithecine Diet
Dietary adaptations are crucial for the survival of any species, including fossil australopiths, or, ancient human ancestors. We had previously established that the diets of australopiths consisted largely of forest based foods, but with a significant portion derived from the grasslands of Africa. This grassland-based component set australopiths apart from our chimpanzee cousins, since chimpanzees almost never eat grassland foods, things like tubers, sedges, or grasses. We hypothesized that the dietary variability we saw in the australopiths, this ability to consume a wide variety of resources that are not exploited by chimpanzees, might represent a fundamental evolutionary adaptation that allowed our ancestors to become so successful in ancient Africa.
Most recently, we examined the diet of a new species of australopith that we discovered in South Africa, Australopithecus sediba, to see how it compared with what we knew of other australopiths. We employed a variety of techniques, including studying microscopic scratches found on their teeth, as well as the chemical composition of those same teeth. We even recognized microscopic plant parts that were embedded in the calculus, or plaque, that built up on their teeth.
What we found was a diet rich in things like tree leaves, fruits, wood, and bark, alongside grasses and sedges that probably grew near streams or other permanent sources of water. Their diet was more similar to that of a savanna chimpanzee than anything we had seen before. On the one hand this is not surprising, since we share a common ancestry with chimpanzees, but on the other hand is quite surprising, since we have never before seen such a chimpanzee-like diet in an australopith.
This discovery has paradoxically demonstrated that the dietary adaptations of australopiths were even more diverse than we had previously established, and has further expanded our understanding of the early hominin dietary repertoire.