Evolution Icon Evolution

Au. sediba: Another Human &quotAncestor&quot Bites the Dust Bark

David Klinghoffer


In our home we’re currently trying to settle on a color of bark to lay down on a patch of sloping front yard that needs some sprucing up. For Australopithecus sediba, however, that same bark would make a tasty meal.
Just nine months ago in this space, Casey Luskin was predicting that a much-hyped human “ancestor,” Au. sediba, wouldn’t hold that title long and would instead soon enough be relegated to the side of the ledger that’s filled with ape-like non-ancestors.

The trail of fallen ancestors brings us to the present day, September 2011, when the media has started a new cycle of hype with Australopithecus sediba. If history is a guide, within months or a few years we should expect to see cooler heads prevail in their analyses of this fossil.

Sure enough, the cooling trend is now plainly in evidence, with Nature reporting that the creatures had a very notable characteristic in common with chimps, not humans, that had not previously been recognized: their diet, highlighted by tree bark and wood. This was found thanks to an analysis of tooth enamel and dental tartar and microwear. The NY Times lets its readers down softly:

The discovery, by Lee Berger of the University of Witwatersrand in Johannesburg, of two partial skeletons — one an adult female, the other a juvenile male — was the basis for the announcement two years ago of the new hominin species. These and at least one other adult specimen indicate that these hominins stood little more than four feet tall and had small brains and a mix of primitive and more modern anatomies. Dr. Berger was an author of the new journal report.
Few other paleoanthropologists agree with Dr. Berger’s contention that the new species is the most plausible known ancestor of archaic and modern humans. Dr. [Amanda G.] Henry’s group said that studies of additional fossils from the Malapa caves “will provide a better understanding of the dietary ecology of Au. sediba.”

So discoverer Lee Berger, previously hailed for uncovering our tree-eating “ancestor,” is now decidedly out on a limb. Science reporter John Noble Wilford still calls the australopithicene species “prehumans” — since I guess anything, even a sponge, that came before Homo sapiens is arguably “prehuman” — yet allows that, as common sense would suggest, “you are what you eat.”