Diet of Early Human Relative Consisted of Leaves, Fruits, Nuts and Barks

Posted on June 27, 2012

Australopithecus sediba, believed to be an early relative of modern-day humans, ate a diet of leaves, fruits, nuts and barks according to a new study published here in the journal Nature. Australopithecus sediba was an ape-like creature with human features living in a region about 50 miles northwest of today's Johannesburg. The creature consumed this diet even though its habitat was near grassy savanna with its rich variety of savory sedges, tasty tubers and even juicy animals.

Benjamin Passey, a Johns Hopkins University geochemist on the international team that conducted the study, says, "This astonished us. Most hominin species appear to have been pretty good at eating what was around them and available, but sediba seems to have been unusual in that, like present-day chimpanzees, it ignored available savanna foods."

Passey also says, "We know that if you are a hominin, in order to get to the rest of the world, at some point you must leave the forests, and our ancestors apparently did so. The fates of those that did not leave are well-known: They are extinct or, like the chimpanzee and gorilla today, are in enormous peril. So the closing chapter in the story of hominin evolution is the story of these 'dids' and 'did nots.'"

Passey used a laser to extract and vaporize tiny bits of fossilized tooth enamel from two Au. sediba individuals. He then used a mass spectrometer to detect, in the vapor, the ratio of two forms of carbon : carbon-12 and carbon-13. A reading heavy in carbon-12 indicates a diet comprising mostly forest foods, such as leaves and fruits, and a reading heavy in carbon-13 signals a diet that included larger amounts of savanna foods such as seeds, roots and grasses. Passey and the team concluded that Au. sediba consumed between 95% and 100% forest-based foods, despite other foods easily available to them.

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Texas A&M anthropologist Darryl de Ruiter says the new findings are in contrast to previously documented diets of other hominin species and suggests that Australopithecus sediba had a different living environment than other hominins in the region.

Darryl de Ruiter says, "This gives us a very clear picture of their diet, and it was surprising. It shows that they ate more fruits and leaves than any other hominin fossil ever examined, more like what a chimp might eat. There was no evidence of them eating native grasses of the area at that time, which is what we see in other australopiths in the region."