Buff upper arms let Lucy climb trees | Science News



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Buff upper arms let Lucy climb trees

Arm, leg bone X-ray data provide clues to famous hominid’s mobility

2:00pm, November 30, 2016
lucy fossil

ARM STRONG  Relatively long, robustly built upper arms let Lucy, the famous 3.2-million-year-old hominid, spend a lot of time in trees, scientists say. Scans of Lucy’s fossils also suggest she walked less efficiently than people today do.

Lucy didn’t let an upright stance ground her. This 3.2-million-year-old Australopithecus afarensis, hominid evolution’s best-known fossil individual, strong-armed her way up trees, a new study finds.

Her lower body was built for walking. But exceptional upper-body strength, approaching that of chimpanzees, enabled Lucy to hoist herself into trees or onto tree branches, paleoanthropologist Christopher Ruff of Johns Hopkins University School of Medicine and his colleagues report November 30 in PLOS ONE.

Lucy, and presumably other members of her species, “combined walking on two legs with a significant amount of tree climbing,” says coauthor John Kappelman, a paleoanthropologist at the University of Texas at Austin. A Kappelman-led team concluded earlier this year that, based on numerous bone breaks, Lucy fell to her death from a tree, either while climbing or sleeping (

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