A 4.5-Million-Year-Old Fossilized Ankle Bone From A Hominin Ancestor Has Revealed Frequent Upright Movement

New research of the hominin Ardipithecus ramidus had demonstrated that while these human ancestors were not perfect walkers, they were much better at moving upright than previously thought.

A display of a series of skeltons showing the evolution of humans at the Peabody Museum, New Haven, Connecticut, circa 1935.
Hulton Archive / Getty Images

New research of the hominin Ardipithecus ramidus had demonstrated that while these human ancestors were not perfect walkers, they were much better at moving upright than previously thought.

After a thorough analysis of a 4.5-million-year-old fossilized ankle bone and toe discovered in Africa from a hominin ancient ancestor known as Ardipithecus ramidus, scientists have discovered that these ancestors of humans actually walked upright a good deal of the time, which is contrary to what was previously believed.

As The Daily Mail reports, the discovery of these fossilized bones is part of a very “pivotal” time in the history of our own evolution, as is demonstrated by the fact that these hominins now being studied were found to frequently walk upright, even 4.5 million years ago.

At this point in time, the Ardipithecus ramidus had already developed adaptions inside of their bones which enabled them to walk upright on two feet, although scientists have admitted that their gait would still not have been even close to that of a modern human today.

According to Scott W. Simpson, from Case Western Reserve University School of Medicine, new research has demonstrated that while this hominin may not have been a perfect walker, they were nevertheless much more skilled than thought.

“Our research shows that while Ardipithecus was a lousy biped, she was somewhat better than we thought before. The fact that Ardipithecus could both walk upright, albeit imperfectly, and scurry in trees marks it out as a pivotal transitional figure in our human lineage.”

The new study on these ancestors of humans has also illustrated how the points of this hominin’s hips, toes, and ankles worked together to push it more easily into bipedal motion. This was an important discovery as previous studies had suggested that Ardipithecus ramidus could walk upright. However, before now, scientists did not know to what extent this would have been possible.

As Simpson noted, while no cartilage was left on these fossils due to wear and tear over time, “This evidence for cartilage shows that the big toe was used in a more human-like manner to push off. It is a foot in transition, one that shows primitive, tree-climbing physical characteristics but one that also features a more human-like use of the foot for upright walking.”

And just like modern humans today, the Ardipithecus’ knees were located just up from their ankles, which is in marked contrast to chimpanzees, whose knees were found to “sit outside” the region of their ankles.

The new study which has determined that the hominin Ardipithecus ramidus was capable of walking upright for extended periods of time has been published in The Journal Of Human Evolution.