Au. Sediba Hominid Could Not Swing Arms When Running
Posted on April 12, 2013
Researchers from Wits University in South Africa, including Peter Schmid from the University of Zurich, have reconstructed the skeleton of Australopithecus sediba, a two million year old human ancestor. The findings indicate the early hominin would have had trouble swinging its arms when it walked or ran. The hominid had a conical ribgcage as well as a raised shoulder joint. The researchers also say the lower extremities of Au. sediba would have caused it to walk with its feet turned sharply inwards.
Schmid says, "They probably couldn't run over longer distances, especially as they were unable to swing their arms, which saves energy."
Au. sediba's lack of ability to swing its arms would have caused it to expend too much energy to run or walk very far. However, it probably made up for this by moving easily through the trees. The researchers think Au. sediba would have been an excellent climber. It may have been able to move quickly from branch to branch above the ground. This is known as brachiation, a form of mobility the modern gibbon excels at.
This image shows a small-bodied modern H. sapiens female skeleton, the reconstruction of Au. Sediba and the skeleton of a modern chimpanzee.
The new research Australopithecus sediba was published as part of special feature available here on Science magazine.