Thursday, October 6, 2011

Australopithecus sediba – A Close Relative?

Newly discovered skeletons of a 2-million-year old member of the human family called Australopithecus sediba have piqued the interest of paleontologists. Some are suggesting that A. sediba may be a closer relative of modern humans than Australopithecus afarensis – the most famous skeleton of which is “Lucy”, who lived about 3.2 million years ago. Others are not so sure.

In five articles in the September 9 issue of Science, scientists describe some of the primitive and modern features of the brain, pelvis, hands, and feet of this transitional archaic human. The brain shows signs of reorganization, including an enlarged frontal lobe. The hand looks like that of a modern human’s, but it is attached to a long arm typical of species that still swing from trees. The pelvis has some, but not all, of the features of an upright-walker. And the lower leg, ankle, and foot are an odd mixture of primitive and modern features. A. sediba probably could walk upright, though it’s gait would have been significantly different from our own.

Regardless of where paleontologists ultimately choose to place A. sediba in the human ancestral tree, further analysis of the species will almost certainly add significantly to our understanding of the transition to modern humans.

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