Sediba update, reported in BBC News, ScienceDaily and New Scientist 8 September 2011.

In April 2010 we reported on the finding of fossils named Australopithecus sediba This creature was promoted as the best candidate for an ape that was in the process of evolving into a human. More details about the fossils have now been reported in Science vol. 333, pp1402-1423, 9 September 2011.

According to the new analysis of the fossils, the 1.3m tall Au. sediba had a brain size of 420 cubic centimetres, arms and legs of ape-like proportions, long curved fingers suitable for grasping branches, ape-like shinbones and an ape-like heel bone. But some of its features are different from previously found Australopithecines in that the thumb is longer, the pelvis wider and the ankle more human-like. A computer generated cast of the brain indicates the brain had a larger section of the frontal lobe compared with other Australopithecines.

BBC, New Scientist, ScienceDaily

Editorial Comment: When we reported on Australopithecus sediba in 2010 we reminded readers that Australopithecus means “southern ape” and Au sediba received this classification simply because:

  1. The overall size and ratio of arm to body length proportions of the new fossils are those of apes; and
  2. The brain size is similar to that of a chimpanzee and estimates for previously found Australopithecines.

One of the new specimens has an almost complete cranium but most Australopithecines do not, so estimates for their brain sizes have to be made from composites of a number of different fossils. The most famous fossil in this group is Lucy, and it only has a few fragments of skull bones. The brain itself has not been preserved, so even the high tech x-ray analysis that was used to estimate the brain size and shape of the new fossil cannot reveal the internal structure of the brain or show how it functioned.

After all the extra information about this creature now available we stand by our assessment – it is still a dead ape. The fact that these creatures are now extinct is no indication they evolved into people, any more than currently living apes are evolving into people. Neither do any of the unusual features of this new fossil provide any evidence it evolved into a human. It is just a bit different from other Australopithecines.

Evidence News 14 September 2011

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