Ancient human ancestors snacked on bark: Study

Ancient human ancestors snacked on bark: Study

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Researchers examining the remains of the ancient hominid species Australopithecus sediba say that the creature seems to have preferred a diet that was unique among ancient African hominids, according to a release from the University of Colorado Boulder. Whereas the predominant diet of other groups appears to have centered around grasses and sedges, A. sediba appears to have dined on a tougher diet of trees, bushes, and fruits.

Paul Sandberg, a CU-Boulder doctoral student and co-author of the study, says, “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.”

The skeletons of the prehumans yielded direct evidence of their woody diet because of the way they met their demise. Scientists say that the ancient hominids fell into a sinkhole and were quickly buried, offering scientists a well-preserved set of teeth for future examination.

“We have a very unusual type of preservation,” said Peter Ungar of the University of Arkansas. “The state of the teeth was pristine.”

The research team notes that the prehumans were preserved in such a way that a pocket of air surrounded the teeth.

The researchers examined teeth from two A. sediba individuals by irradiating the teeth with a laser. The energy of the laser light released carbon from the enamel on the surface of the teeth, which was then analyzed. They found that the A. sediba teeth revealed a predominance of a type of carbon called C3, rather than an alternative type called C4. Plants may be broadly divided into groups which preferentially incorporate either the C3 or the C4 form of carbon. A predominance of one form in ancient remains indicates a preference for that group of plants in the diet of the organism. A. sediba’s inclusion of C3 indicates that the hominids of this group fed mainly on C3 plants, which include tougher plants like fruit-bearing trees and shrubs. Additionally, the researchers suggest that A. sediba likely included fibrous and tough foods such as bark in their diet, similar to modern chimpanzees. Sandberg added that this finding was supported by microscopic analysis of the teeth, which shows the pits and scratches consistent with a tougher diet.

Anthropologists agree that A. sediba dwelt in Africa around 2 million years ago, but are not in agreement about where the species fits on the hominid family tree. The species shows some interesting human-like characteristics, including a human-like angle and an upright posture.

The study was funded by the National Science Foundation, the Smithsonian Institution, the Max Planck Society, and the Institute for Human Evolution at the University of Witwatersrand. The paper, titled “The diet of Autralopithecus sediba,” was recently published in Nature.

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