Convoluted human evolution: Lucy fell from a tree (Introduction)

by David Turell , Monday, August 29, 2016, 20:58 (3008 days ago) @ David Turell

A complex CT scanner has revealed that Lucy had multiple fractures consistent with fall from a high tree. New findings from old bones using new technologies:-https://www.sciencedaily.com/releases/2016/08/160829140417.htm-"Lucy, a 3.18-million-year-old specimen of Australopithecus afarensis -- or "southern ape of Afar" -- is among the oldest, most complete skeletons of any adult, erect-walking human ancestor. Since her discovery in the Afar region of Ethiopia in 1974 by Arizona State University anthropologist Donald Johanson and graduate student Tom Gray, Lucy -- a terrestrial biped -- has been at the center of a vigorous debate about whether this ancient species also spent time in the trees.-***-"Kappelman first studied Lucy during her U.S. museum tour in 2008, when the fossil detoured to the High-Resolution X-ray Computed Tomography Facility (UTCT) in the UT Jackson School of Geosciences -- a machine designed to scan through materials as solid as a rock and at a higher resolution than medical CT. For 10 days, Kappelman and geological sciences professor Richard Ketcham carefully scanned all of her 40-percent-complete skeleton to create a digital archive of more than 35,000 CT slices.-***-"Studying Lucy and her scans, Kappelman noticed something unusual: The end of the right humerus was fractured in a manner not normally seen in fossils, preserving a series of sharp, clean breaks with tiny bone fragments and slivers still in place.-"'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," said Kappelman, who consulted Dr. Stephen Pearce, an orthopedic surgeon at Austin Bone and Joint Clinic, using a modern human-scale, 3-D printed model of Lucy.-"Pearce confirmed: The injury was consistent with a four-part proximal humerus fracture, caused by a fall from considerable height when the conscious victim stretched out an arm in an attempt to break the fall.-"Kappelman observed similar but less severe fractures at the left shoulder and other compressive fractures throughout Lucy's skeleton including a pilon fracture of the right ankle, a fractured left knee and pelvis, and even more subtle evidence such as a fractured first rib -- "a hallmark of severe trauma" -- all consistent with fractures caused by a fall. Without any evidence of healing, Kappelman concluded the breaks occurred perimortem, or near the time of death.-***-"In comparing her with chimpanzees, Kappelman suggested Lucy probably fell from a height of more than 40 feet, hitting the ground at more than 35 miles per hour. Based on the pattern of breaks, Kappelman hypothesized that she landed feet-first before bracing herself with her arms when falling forward, and "death followed swiftly."-***-"Kappelman conjectured that because Lucy was both terrestrial and arboreal, features that permitted her to move efficiently on the ground may have compromised her ability to climb trees, predisposing her species to more frequent falls. Using fracture patterns when present, future research may tell a more complete story of how ancient species lived and died."-Comment: A reasonable theory. Half ape/ half human will not handle trees as well as a full ape.