Ancient human ancestor ate bark, according to a laser analysis of its...

Ancient human ancestor ate bark, according to a laser analysis of its teeth

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Researchers have discovered that a 2 million-year-old African hominid lived on a woody diet of bark, bushes and fruits. Our ancient human ancestor’s diet was vastly different than all other prehumans. A study led by the Max Planck Institute of Evolutionary Anthropology reveals details about the first direct evidence of a hominid’s diet.

According to the study, Australopithecus sediba ate woodier foods than other prehumans, selecting trees, bushes and fruits. By comparison, other prehumans ate grasses and sedges, according to University of Colorado-Boulder doctoral student Paul Sandberg, who co-authored the study.

Sandberg says that the research team used a laser to determine Australopithecus sediba’s diet  from its well-preserved teeth. Zapping the fossilized teeth with a laser allowed scientists to remove carbon from their enamel. After analyzing the carbon, scientists could accurately guess the types of plants that the prehuman ate.

Scientists tested the carbon data of two ancient human ancestors and found that the fossilized teeth had carbon isotope values that were vastly different than all other known prehumans.

“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. C4 is the carbon signal for plants like grasses and sedges.

“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,” he added.

The international research team found that our ancient human ancestors ate a woody diet on at least a seasonal basis. Researchers note that while this is the first time that direct evidence of a woody diet has been documented among prehumans, woody foods are a frequent dietary component for primates. Sandberg notes that the prehuman’s may be similar to that of African savanna chimpanzees.

Scientists were thrilled to analyze fossilized particles of planet tissue known as phytoliths (a hardened form of dental plaque), said corresponding study author Amanda Henry of the Max Planck Institute.

“The fact that these phytoliths are preserved in the teeth of 2 million-year-old hominids is remarkable and speaks to the amazing preservation at the site,” said Sandberg. “The phytolith data suggest the A. sediba individuals were avoiding the grasses growing in open grasslands that were abundant in the region at the time.”

Scientists made this discovery using the skeletons of two ancient human ancestors who fell into a sinkhole in the Malapa Cave and passed away. Researchers say that the position in which the prehumans died revealed both primitive and modern hominids.

The prehumans found in the Malapa Cave were approximately 2 million years old, according to researchers. Scientists also say that the environment that the prehumans lived in was perfect for their woody diet. The area around the Malapa Cave was full of both grassland and woody vegetation.

“What fascinates me is that these individuals are oddballs,” said CU-Boulder’s Sponheimer. “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. ”

A paper on the subject was recently published online by Nature.

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