From the article:

One of the most famous fossils in human evolutionary history is known as “Lucy,” who belonged to an extinct species called Australopithecus afarensis—an early relative of Homo sapiens who was among the first hominins to walk upright. But scientists have long debated the extent of her bipedalism. Now a 3D digital re-creation of Lucy’s muscular anatomy, combined with computer simulations, has reaffirmed that she was quite capable of walking fully erect. The results appeared in a new paper published in the journal Royal Society Open Science.

“Lucy’s ability to walk upright can only be known by reconstructing the path and space that a muscle occupies within the body,” said author Ashleigh Wiseman, an archaeologist at Cambridge University. “We are now the only animal that can stand upright with straight knees. Lucy’s muscles suggest that she was as proficient at bipedalism as we are, while possibly also being at home in the trees.”