The Latest on Lucy: Early Hominin Spent Serious Time in Trees

3.18 million years ago, the member of Australopithecus afarensis better known as Lucy walked around what's now Ethiopia. But researchers still debate how she walked — and how much time she spent on the ground. (Image credit: Associated Press) Hey Lucy, you got some more explainin' to do. A controversial study published in August proposing that a fall from a tree killed Lucy, the world's most famous fossil, was just the opening salvo in a renewed debate. Researchers announced an even bigger breakthrough today: Analysis of micro-CT scans reveal Lucy was at home on the ground and in the trees, a finding that puts the team at odds with some of the field's biggest names. Researchers from Johns Hopkins University and the University of Texas Austin looked at cross sections of micro-CT scans of Lucy's upper and lower limb bones. The team compared the virtual slices with those of other early hominins plus modern humans and modern chimpanzees. Over time, use of limbs in load-bearing activities — such as, say, swinging from one tree branch to the next — thickens the bones' outer layers. "You can see the skeleton responding dynamically," says UT paleoanthropologist John Kappelman, an author on both today's paper and the August study on Lucy's apparent cause of death. "That was really the point of this whole paper, and the point of scanning Lucy. We wanted to see how she lived. Because the skeleton is plastic in the way it dynamically responds to loads, looking at this question of loading we can get at how the body, how the skeleton experienced mechanical loading during life." It's the first time that anyone has turned to micro-CT scanning to determine an early hominin's locomotion. And Kappelman and colleagues believe their findings will lay to rest what's long been a contentious argument over how and where Lucy lived.