Human Ancestor ‘Lucy’ Was Athletic and Walked Fully Upright, Finds New Study

In a groundbreaking discovery that rewrites our understanding of human evolution, a new study utilizing advanced 3D muscle reconstruction has revealed that Lucy, the 3.2-million-year-old fossil of an Australopithecus afarensis, walked fully upright and possessed a remarkable muscular structure. The findings challenge previous assumptions about early hominid movement and shed light on the development of bipedalism.

A press release by University of Cambridge explains how the research has drawn attention for its potential to reshape our understanding of the transition from ape-like ancestors to early humans. The study, which involved an interdisciplinary team of scientists, is published in the prestigious scientific journal Royal Society Open Science. It is providing crucial insights into the remarkable abilities and adaptations of our ancient ancestors, with visual representations to show the findings.

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Reconstructing the muscles of Australopithecus afarensis 

Dr Ashleigh Wiseman 3D-modelled the leg and pelvis muscles of the hominin  Australopithecus afarensis using scans of ‘Lucy’, the famous fossil specimen discovered in Ethiopia in the mid-1970s.

Australopithecus afarensis was an early human species that lived in East Africa over three million years ago. The hominid was considerably shorter than Homo sapiens, at around 1.1 meters (3 ft 6inches) with an ape-like face and smaller brain. It is known it was able to walk on two legs but was adapted to both tree and savannah dwelling, helping the species survive for almost a million years.

Reconstruction of a male (left) and female (right) A. afarensis at the Natural History Museum, Vienna. Right, Lucy skeleton, Cleveland Natural History Museum. (CC BY-SA 4.0/CC BY-SA 4.0/CC BY SA 2.0)

But contrary to earlier beliefs that Lucy had a more ape-like posture, the 3D muscle reconstruction revealed that she walked upright, with her head held high and a straight spine and legs, more like that of modern humans. This finding offers a significant milestone in human evolution, suggesting that Lucy was capable of prolonged bipedal movement.

According to the press release, the research recreated 36 muscles in each leg, most of which were much larger in Lucy and occupied greater space in the legs compared to modern humans.

“Lucy’s ability to walk upright can only be known by reconstructing the path and space that a muscle occupies within the body,” said Wiseman.

The leverage allowed by Lucy’s simulated knee extensor muscles confirmed an ability to straighten the knee joints as much as a healthy person can today.

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Moreover, the analysis unveiled Lucy's powerful upper body and robust muscles, particularly in her shoulders and arms. These features indicate that she possessed exceptional strength, potentially adapted for climbing and manipulating objects in her environment. This combination of bipedalism and upper body strength provides a fascinating glimpse into the physical capabilities of early hominids.

A digitization of the muscle attachment areas used to build the model of Lucy’s muscles, next to the completed 3D muscle model. (Dr Ashleigh Wiseman/Royal Society Open Science)

The study's methodology involved state-of-the-art imaging techniques to create intricate 3D models of Lucy's bones and surrounding soft tissues. By comparing these reconstructions with modern human anatomy, the researchers were able to make informed inferences about her muscular structure and functional abilities.

While this discovery has undoubtedly captivated the scientific community, it has also ignited debates among experts. Some scientists question the speculative nature of muscle reconstruction and emphasize the need for additional evidence to support the conclusions. As a result, future research in the field of paleoanthropology will likely involve further analysis of fossil remains and advancements in imaging and modeling techniques.

Why Do We Care How Lucy Walked?

Lucy's significance in the study of human evolution cannot be overstated. As an Australopithecus afarensis, she represents a crucial transitional species between our ape-like ancestors and the emergence of the Homo genus. This latest research underscores her pivotal role in the development of bipedalism and provides invaluable insights into the ancient history of our species.

As the field of paleoanthropology continues to advance, it is anticipated that further discoveries and technological advancements will enhance our understanding of human evolution. Lucy's robust musculature and upright walking abilities serve as a testament to the remarkable journey of our species, fueling the quest for knowledge about our ancient past.

Top image: 3D computer generated illustration of male Australopithecus afarensis. Source: SciePro/Adobe Stock

By Gary Manners