An Australopithecus sediba skull. (Photo : Wikimedia Commons)
One of our earliest ancestors seemed to dine on foods more similar to the diet of chimpanzees rather than other hominids. Researchers from Max Planck Institute of Evolutionary Anthropology and the University of Colorado Boulder looked at the teeth from some of our 2-million-year old, upright ancestors and have determined that they ate fruits, bark, and bushes in instead of grasses and sedges.
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Almost all other human ancestors tested from Africa showed a diet of the grasses and sedges that were abundant at the time. Instead, Australopithecus sediba chose to eat in the woods, much like chimps, and avoid the open grasslands. The diet could help shed light on more of our evolutionary history as a species.
"It is an important finding, because diet is one of the fundamental aspects of an animal, one that drives its behavior and ecological niche. As environments change over time because of shifting climates, animals are generally forced to either move or to adapt to their new surroundings," said Paul Sandberg, co-author of the study.
To find out what Australopithecus sediba ate, the scientists used a laser to test for certain types of carbon residue. C3 would indicate trees, shrubs, and bushes, while C4 would indicate grasses and sedges. The teeth from the Australopithecus sediba contained carbon isotopes that didn't match with any of the 81 previously tested hominids.
"The lack of any C4 evidence, and the evidence for the consumption of hard objects, are what make the inferred diet of these individuals compelling," said Sandberg.
Scientists are still unable to place Australopithecus sediba accurately on our evolutionary tree because they have such different characteristics than most early hominids. The first two fossils of the species were found in a hidden pit at the Malapa cave site where they had apparently fallen and died. Their upright posture, long thumbs, and complex brains made them intriguing to scientists.
"What fascinates me is that these individuals are oddballs," said Professor Matt Sponheimer, another co-author.
"I had pretty much convinced myself that after four million years ago most of our hominid kin had diets that were different from living apes, but now I am not so sure. And while our sample is too small to be conclusive, the rate at which Malapa is spewing hominid fossils makes me reasonably certain we won't have to wait another two million years to augment our data set. "