– Lucy, social climber
The early hominin’s strong arms suggest a life lived aloft. APRIL REESE reports.
Lucy, the world’s most famous early hominin, may have walked on two legs but she preferred to climb among the trees, a recent study suggests.
In the decades since the 1974 discovery of the 3.18-million-year-old
Australopithecus afarensis fossil, scientists have debated whether Lucy lived primarily on the ground or in the trees.
Hoping to settle that debate, a team led by Christopher Ruff at Johns Hopkins University in the US scanned Lucy’s arm and leg bones to create detailed 3-D models of their structure. Then the researchers compared the models with bone scans of other early hominins, modern humans and modern chimpanzees.
Lucy’s arm bones, it turns out, were much stronger than her leg bones, and the weaker structure of the leg bones meant she probably had a somewhat awkward, inefficient gait compared to later hominins. It seems likely, then, that she lived a primarily arboreal life, relying more on her arms to get around than her legs, the researchers conclude.
“Although bipedal when on the ground, the limb bone structural proportions of [Lucy] provide evidence for substantially more arboreal, i.e. climbing behaviour than either modern humans or Homo erectus,” the researchers write in the study, published in PLOS One in November.
Staying off the ground would have helped keep Lucy safe from predators, but it also posed its own risks: an earlier study found that she died by falling from a tree.
Recent scans of Lucy’s skeleton showed the bones of her arms were stonger than those of her legs – she was therefore probably a tree- dweller.