Friday, July 6, 2012
Next time you’re grumbling about a stale cookie or a steak that tastes “like cardboard,” count yourself lucky that you’re not Australopithecus sediba, the human ancestor who ate bark. At least, that’s what scientists say about A. sediba, a short, gangly South African species from two million years ago. Their study indicates the creature targeted trees, bushes and fruits for its diet, chomping on harder foods than other other known early hominids, or human ancestors. Virtually all others that have been tested from Africa—including Paranthropus boisei, dubbed “Nutcracker Man” thanks to its massive jaws and teeth—focused more on grasses and sedges, according to anthropology doctoral student Paul Sandberg of the University of Colorado Boulder, a co-author of the new study. The findings were published in the June 27 online edition of the research journal Nature. Scientists analyzed the A. sediba diet by zapping fossilized teeth with a laser, said Sandberg. The laser breaks off telltale carbon from the enamel of teeth, so researchers can pinpoint which types of plants the carbon comes from. The results show which of two groups of plants were consumed: so-called “C3” plants like trees, shrubs and bushes preferred by A. sediba, and “C4” plants like grasses and sedges consumed by many other early hominids. The teeth from both A. sediba individuals analyzed had levels of C3 outside the range of all 81 previously tested hominids, the researchers reported. “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. “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 Sandberg.