Early Human Ancestor Lucy ‘Died Falling Out of a Tree’

An anonymous reader quotes a report from BBC: New evidence suggests that the famous fossilized human ancestor dubbed “Lucy” by scientists died falling from a great height — probably out of a tree. CT scans have shown injuries to her bones similar to those suffered by modern humans in similar falls. The 3.2 million-year-old hominin was found on a treed flood plain, making a branch her most likely final perch. It bolsters the view that her species — Australopithecus afarensis — spent at least some of its life in the trees. Writing in the journal Nature, researchers from the U.S. and Ethiopia describe a “vertical deceleration event” which they argue caused Lucy’s death. In particular they point to a crushed shoulder joint, of the sort seen when we humans reach out our arms to break a fall, as well as fractures of the ankle, leg bones, pelvis, ribs, vertebrae, arm, jaw and skull. Discovered in Ethiopia’s Afar region in 1974, Lucy’s 40%-complete skeleton is one of the world’s best known fossils. She was around 1.1m (3ft 7in) tall and is thought to have been a young adult when she died. Her species, Australopithecus afarensis, shows signs of having walked upright on the ground and had lost her ancestors’ ape-like, grasping feet — but also had an upper body well-suited to climbing. The bones of this well-studied skeleton are in fact laced with fractures, like most fossils. By peering inside the bones in minute detail, the scanner showed that several of the fractures were “greenstick” breaks. The bone had bent and snapped like a twig: something that only happens to healthy, living bones. “The Ethiopian ministry has agreed to release 3D files of Lucy’s right shoulder and her left knee. So anyone with an interest in this can print Lucy out and evaluate these fractures, and our hypothesis, for themsleves.” You can find the files here.


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