Lucy, the common name accorded to the world-famous fossilised remains of an early human ancestor who lived 3.18 million years ago, was adept at walking on her two legs as well as climbing trees, researchers have determined.
Evidence preserved in the internal skeletal structure of Lucy, a member of the ancient human species known as Australopithecus afarensis, suggests that she climbed trees, the study said.
Since Lucy’s discovery in Ethiopia 42 years ago, paleontologists have debated whether she spent her life walking on the ground or combined walking with frequent tree climbing.
The new analysis, published in the journal PLOS ONE, showed that Lucy’s upper limbs were heavily built, similar to tree-climbing chimpanzees, supporting the idea that she often used her arms to pull herself up, most likely onto tree branches.
“It may seem unique from our perspective that early hominins like Lucy combined walking on the ground on two legs with a significant amount of tree climbing, but Lucy did not know she was unique,” said one of the researchers John Kappelman from The University of Texas at Austin in the US.
Researchers also suggested that because her foot was better adapted for bipedal locomotion — or upright walking — rather than grasping, Lucy had to rely on upper-body strength when climbing, which resulted in more heavily built upper-limb bones.
“We were able to undertake this study thanks to the relative completeness of Lucy’s skeleton,” study’s lead author Christopher Ruff, Professor at Johns Hopkins University School of Medicine, noted.
“Our analysis required well-preserved upper and lower limb bones from the same individual, something very rare in the fossil record,” Ruff said.
A recent study by Kappelman proposed that Lucy probably died after falling from a tall tree, where she may have been nesting to avoid predators.