Lucy, the iconic early human who lived 3.2 million years ago, could stand as upright as us, according to new research.
Shorter with an ape-like face and a smaller brain, she was able to walk on two legs.
The cavewoman was adapted to both tree and savannah dwelling – helping her species survive for almost a million years.
Dr. Ashleigh Wiseman, an expert in evolutionary biomechanics, said: “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. Lucy likely walked and moved in a way that we do not see in any living species today.”
Lucy belonged to a group of hominins, or early humans, known scientifically as Australopithecus afarensis.
The findings are based on a digital reconstruction of missing soft tissue from famous fossil specimens discovered in Ethiopia in the mid-1970s.
Dr. Wiseman, of Cambridge University, said: “Australopithecus afarensis would have roamed areas of open wooded grassland as well as more dense forests in East Africa around three to four million years ago.
“These reconstructions of Lucy’s muscles suggest that she would have been able to exploit both habitats effectively.”
She 3D-modelled leg and pelvic muscles from scans of her remains.
Named after the Beatles classic “Lucy in the Sky with Diamonds,” she is one of the most complete skeletons of her kind – with 40 percent recovered.
The study recreated 36 muscles in each leg – most of which were much larger and occupied greater space compared to those of modern humans.
For example, major muscles in her calves and thighs were over twice the size – as we have a much higher fat-to-muscle ratio.
Muscles made up three-quarters of the total mass in Lucy’s thigh – compared to only half in humans today.
Paleoanthropologists agree she was bipedal – but debate how she walked. Some have argued she moved in a crouching waddle, similar to chimpanzees – our closest ancestor.
But the results in Royal Society Open Science back an alternative theory that her movement was closer to our own upright stance.
Research in the last 20 years have seen a consensus begin to emerge for fully erect walking. Dr. Wiseman’s work adds further weight to this.
Lucy’s knee extensor muscles, and the leverage they would allow, confirm an ability to straighten the knee joints as much as a healthy person can today.
Dr. Wiseman said: “Lucy’s ability to walk upright can only be known by reconstructing the path and space that a muscle occupies within the body.”
Lucy was a young adult, who stood at just over three feet three inches tall and probably weighed around four-and-a-half stone.
Her brain would have been roughly a third of the size of ours.
Dr. Wiseman’s analysis started with living humans. Using MRI and CT scans of the muscle and bone structures of a modern woman and man, she was able to map the ‘muscle paths’ and build a digital musculoskeletal model.
She then used existing virtual models of Lucy’s skeleton to “articulate” the joints – that is, put the skeleton back together.
This defined the axis from which each joint was able to move and rotate – replicating how they moved during life.
Finally, muscles were layered on top, based on pathways from modern human muscle maps, as well as what little ‘muscle scarring’ was discernible – the traces of muscle connection detectable on the fossilized bones.
Dr. Wiseman said: “Without open access science, this research would not have been possible.”
These reconstructions can now help scientists understand how this human ancestor walked.
Dr. Wiseman said: “Muscle reconstructions have already been used to gauge running speeds of a T. rex, for example.
“By applying similar techniques to ancestral humans, we want to reveal the spectrum of physical movement that propelled our evolution – including those capabilities we have lost.”
Produced in association with SWNS Talker
Edited by Asad Ali and Saba Fatima