Lucy’s 3-Million-Year-Old Death Solved?

     AUSTIN, Texas (CN) — It’s not exactly hot news, but it’s big news: Scientists say that Lucy, a 3.18 million-year-old Australopithecus afarensis fossil, probably died from falling from a tree.
     University of Texas at Austin anthropology Professor John Kappelman was lead author of the article, which was published Monday in the journal “Nature.”
     Lucy was discovered in 1974 in the Afar region of Ethiopia by Arizona State University anthropologist Donald Johanson and graduate student Tom Gray.
     Kappelman and geological sciences Professor Richard Ketcham used High-Resolution X-ray Computed Tomography to scan Lucy’s skeleton, which is only 40 percent complete, and digitize more than 35,000 CT slices.
     “CT is nondestructive, so you can see what is inside, the internal details and arrangement of the internal bones,” Ketcham said.
     Kappelman saw an unusual fracture pattern in Lucy’s right humerus, the upper arm bone: a series of sharp, clean breaks along with bone fragments and slivers. Such fractures are known as greenstick fractures.
     “This compressive fracture results when the hand hits the ground during a fall, impacting the elements of the shoulder against one another to create a unique signature on the humerus,” Kappelman said.
     Kappelman consulted with Austin-based orthopedic surgeon Dr. Stephen Pearce, who agreed that Lucy’s humerus fracture was consistent with a fall from considerable height, in which she stretched out an arm to break the fall.
     Kappelman noticed similar but less severe fractures throughout Lucy’s skeleton that were consistent with fractures caused by a fall. He said that Lucy — about 3 feet 6 tall inches and 60 lbs. — probably fell from more than 40 feet and hit the ground at more than 35 miles per hour.
     He thinks Lucy and her species probably stayed in trees at night to be safe from predators.
     Kappelman thinks Lucy’s species may have been predisposed to falls due to a compromised ability to climb trees.
     Lucy has been part of an intense debate on the extent of arboreal locomotion in early human evolution. The study gives evidence of arborealism in her species.
     Some scientists disagreed with Kappelman’s article and the nature of Lucy’s death.
     Timothy White, a paleoanthropologist at the University of California at Berkeley, told National Geographic: “These authors make no effort to test the alternative hypothesis that these cracks and other breaks were made during the process of fossilization and erosion.”
     Lucy discoverer Dr. Donald Johanson contested Kappelman’s theory, in a long email to Courthouse News.
     “In my opinion, and that of my team who worked on the Hadar hominin fossils, the breakage and plastic distortion seen on Lucy’s bones, as well as many of the other hominin fossils at Hadar, is a result of geological forces acting on the bones during the fossilization process,” Johanson wrote.
     “Many of the bones from the First Family (all belonging to Lucy’s species) locality at Hadar, Ethiopia show evidence of similar bone modification, again a reflection of geological processes. The sort of damage seen in hominin and many other mammalian fossils at Hadar is mirrored in other paleontological collections throughout Africa and much of the world.
     “Australopithecus afarensis was essentially a terrestrial animal, as witnessed from a biomechanical analysis of the many postcranial bones known for Lucy’s species, as well as the 3.6 mya [million years ago] human footprints found in a volcanic ash layer at Laetoli, Tanzania. The a priori assumption that Lucy spent much time in the trees is not supported.
     “There’s a myriad of explanations for bone breakage. Lucy may be have been run over by a stampede of larger animals, elephants or large bovids or antelopes prior to her being washed into a water environment where fossilization began. It is very possible that skeleton lay out on the ground for a short time as it decomposed and the skeleton was held together by tendons, during which time trampling may have damaged the bone.
     “Unfortunately, the authors did not address post depositional events. We don’t know how long the fossilization process takes, but the weighty set of forces placed on bones during the buildup of sediments covering the bones is a significant factor in promoting damage and breakage.
     “Such alternative explanations are not explored in the ‘Nature’ article. In this regard, the suggestion that she fell out of a tree is largely a ‘Just-So Story’ that is neither verifiable or falsifiable, and therefore unprovable.”
     Lucy’s name allegedly comes from the night that Johanson and other scientists were celebrating her discovery in their camp in Africa while listening to the Beatles song “Lucy in the Sky with Diamonds.”
     Someone in the group said: “If you think the skeleton is a female, why don’t you call her ‘Lucy’?”

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