Lucy climbed trees and fell out, according to reports in ScienceDaily and New Scientistst 30 November, and PLoS One, DOI: 10.1371/journal.pone.0166095, and ScienceDaily and Science (AAAS) 19 August 2016 News and Nature, 2016; DOI: 10.1038/nature19332.

Scientists at University of Texas (UT) Austin have scanned the bones of the original Australopithecus afarensis (“Lucy”) specimen using an X-ray CT scanner which enables scientists to examine the internal structure of the bones.

During life bones respond to the forces impinging on them from muscles and body movement, and increase their thickness where the strongest forces are applied. Therefore scientists can assess which parts of the body were most active and had the strongest muscles. A tree-climbing ape will show most strength in the arms and upper body, whilst humans, who walk on two legs, show most strength in the legs and pelvis.

Researchers compared the structure of Lucy’s arm and thigh bones with those of chimpanzees and humans and found that Lucy’s bone strength was more like chimpanzees than humans. According to Christopher Ruff, Johns Hopkins University School of Medicine in Baltimore, Maryland, who helped analyse the bone scans, the extra bone strength in the arms “would not be present unless Lucy mechanically loaded her upper limbs more than most modern humans”. He went on to comment: “Ours is the best evidence to date that A. afarensis actually spent a significant portion of their time engaged in arboreal behaviour”. (“Arboreal behaviour” means tree climbing.)

Lucy is generally claimed to have walked upright on the ground like humans, but the scans on the thigh bone indicate her walking style was different to human walking, in that she had to shift her upper body sideways over the supporting leg when lifting the other one off the ground in order to take a step. This is an inefficient style of walking that uses more energy and is not good for long distance walking.

The bone scans not only indicated Lucy spent most of her time moving about in trees, but also that she could have died from falling out of a tree. The bones showed multiple breaks, including a “four-part proximal humeral fracture” of the right humerus. This is a fracture of the upper arm bone near the shoulder caused by landing heavily onto an outstretched arm. There were also cracks in left shoulder, right ankle, knee, pelvis and first rib. According to John Kappelman, one of the University of Texas researchers, these are the “hallmark of severe trauma”. According to Science News, the UT team “calculated that the forces that fractured Lucy’s upper arm were equal to a fall from a height of about 13.7 meters — as high as a four-story building or the top of a tall tree, such as a mature acacia — at a velocity of about 59 kilometres per hour”. The breaks are sharp and show no sign of healing.

However, some fossil scientists, including Donald Johansen who was part of the team that found Lucy, are sceptical. Johansen commented: “Terrestrial animals like antelopes and gazelles, elephants and rhinos and giraffes — all these bones show very similar fracture and breakage patterns as Lucy. You can be sure they didn’t fall out of trees”. Paleoanthropologist Tim White of the University of California, Berkeley explained that most breaks in fossil bones are the result of geological processes, e.g. tectonic forces, soil movement, pressure from overlying sediments, and weathering.

New Scientist, Science, ScienceDaily 

Editorial Comment: Since these findings fit with previous studies of Australopithecine bones, which indicate their limb lengths, body proportions and brain size were all ape like, we are not surprised that Lucy had arm and thigh bones suitable for tree climbing rather than bipedal ground walking. It pays to remember the unpopular fact that the original Lucy skeleton does not have feet, in spite of all the claims that Lucy and other Australopithecines walked upright on human-like feet. Any human-like foot bones or footprints claimed to be Australopithecines, have never been found attached to an Australopithecine skeleton, but were classified as such only on the basis of the alleged age of the rock layers they were found in. See our report Lucy Gets a Bone Graft here.

The debate about the bone fractures is interesting. It may be a case of both sides are right. The humerus fracture is typical of what occurs from a hard landing on an outstretched arm. Some of the other fractures may have occurred at the same time, and it is possible that Lucy did die following this fall before any healing processes started. Fractures of the first rib are very rare, and are usually associated with severe trauma also involving the neck vertebrae. It is not possible to tell if this happened as the Lucy specimen has no neck vertebrae.

Furthermore, fossils do get cracks in them from various earth movements after they have been buried, so some of the breaks may have occurred later.

Whatever really happened to Lucy, these two studies of the bones confirm that Lucy was an extinct tree dwelling ape, who like living apes, may have spent some time on the ground, but was no human ancestor.

Evidence News vol. 16 No. 24
14 December 2016
Creation Research Australia

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