Ancient Apes Did not Walk on Two Legs: Study Confirms

The ancient ape did not walk on two legs as was previously believed, a new study reported. Researchers confirm that the two leg walking ability (bipedalism) was exclusively associated with human ancestors.

The study challenges the idea that ancient ape, Oreopithecus that lived around 9 to 7 million years ago had the capability to walk on two legs. Oreopithecus is an extinct genus of apes whose fossils were discovered in East Africa and South Europe. The ape is best known for its unique features that combine structures found in Old world monkeys and man-like apes. Previous research has shown that Oreopithecus could walk on both legs; however, whether the ape habitually stood erect isn't clear.

"Our findings offer new insight into the Oreopithecus locomotor debate. While it's certainly possible that Oreopithecus walked on two legs to some extent, as apes are known to employ short bouts of this activity, an increasing amount of anatomical evidence clearly demonstrates that it didn't do so habitually," said Gabrielle A. Russo from University of Texas at Austin, one of the lead authors of the study.

The new study was based on the analysis of Oreopithecus fossils. The research team, led by the University of Texas at Austin anthropologists, particularly focused on the lower spine anatomy of the ape. They compared measurements of the lower back (lumbar vertebrae) and sacrum - a triangular bone located at the base of lumbar vertebrate of humans, ancient apes and other mammals such as sloths.

Russo said that the lower spine in humans has unique features that support the habitual bipedal walk and so can be used to test bipedal-walking ability in other apes.

 "The lower spine of humans is highly specialized for habitual bipedalism, and is therefore a key region for assessing whether this uniquely human form of locomotion was present in Oreopithecus. Previous debate on the locomotor behavior of Oreopithecus had focused on the anatomy of the limbs and pelvis, but no one had reassessed the controversial claim that its lower back was human-like," Liza Shapiro, also from University of Texas at Austin, according to a news release.

The study is published in the Journal of Human Evolution.