Ashley Wiseman has created a 3D model of the leg muscles and pelvis of the hominid Australopithecus afarensis using “Lucy” scans. This species is considered the direct ancestor of man. It lived in East Africa about 3-4 million years ago. “Lucy” is one of the most complete Australopithecus skeletons ever discovered.

How did Lucy walk?

In the model, 36 muscles were regenerated in each leg. It turns out that most of them in Lucy were much larger than modern humans. For example, it turned out that the main muscles of the calves and thighs are more than twice as large. In addition, we have a much higher fat to muscle ratio. Australopithecus muscle made up 74% of Lucy’s total thigh mass, compared to 50% in humans.

Australopithecus muscle reconstruction / Photo by Dr Ashleigh Wiseman

Paleoanthropologists agree that Lucy was an upright walker, but they differ on exactly how she walked: more droopy like a chimpanzee or straight like modern humans.

Wiseman’s work gives additional weight to the latter concept. Lucy’s knee extensors validate her ability to straighten the knee joints as much as a healthy person can do today.

“For example, muscle reconstructions have already been used to measure the running speed of Tyrannosaurus rex. By applying similar methods to our human ancestors, we want to reveal the diversity of physical movements that contributed to our evolution, including abilities we lost.”– said Wiseman.