The Death of Lucy: Has a 3.2 Million-Year-Old Mystery Finally Been Solved?
Scientists analyzing the bones of the Australopithecus Afarensis skeleton known as ‘Lucy’ have suggested that she died from injuries sustained by falling from a tree. They say that fractures present on the bones of the skeleton are consistent with those that a human has when falling from a great height onto a hard surface.
“The consistency of the pattern of fractures with what we see in fall victims leads us to propose that it was a fall that was responsible for Lucy’s death,” John Kappelman, an anthropologist who led the study at the University of Texas in Austin told The Guardian. “I think the injuries were so severe that she probably died very rapidly after the fall.”
Reconstruction of Lucy’s fall. ( John Kappelman et al. )
According to the New York Times , Lucy’s skeleton underwent CT scanning and 3D models were made by “piecing together the virtual fragments to get a more accurate idea of their original shapes.” When Dr. Kappelman noticed a break in Lucy’s upper right arm, he found that it could have been caused by a compressive fracture (when a force pushes down on a bone and sometimes even forces it into another.)
Kappelman sought out advice from orthopedic surgeon Stephen Pearce, and a subsequent analysis of the skeleton suggested that there are cracks in more than a dozen of Lucy’s bones. Her skull, spine, ankles, shins, knees, and pelvis all showed signs of what the duo describe as compressive fractures from a fall.
Moreover, the scientists believe that an injury in the right shoulder is consistent with the type of fracture evident in people who instinctively put their arms out to try to save themselves during a fall. Kappelman said that the discovery is ““a unique signature” for a fall and evidence that the individual was conscious at the time.”
However, the combination of broken bones and probable organ damage from a fall of a considerable height suggested to Kappelman and his team that “death followed swiftly.” As Lucy only weighed less than 30kg (66.14 lbs.), the scientists believe that it would have taken a fall of about 15 meters (49ft.) for her to sustain the injuries.
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If Lucy did fall from a tree and die from her injuries, it adds an interesting perspective to the question of how much time Australopithecus Afarensis still spent in the trees versus their time on the ground. Some researchers believe that the flat feet of the species were better suited to terrestrial activities, while others see their hook-like hands and flexible shoulders as evidence of a large amount of time still spent in the trees. The findings of Homo Naledi remains have also been useful in the search for when bipedalism began to take hold in evolution.
A reconstruction of a female A. afarensis. ( Public Domain )
If A. afarensis climbed trees to nest or search for food, they could have spent hours at considerable heights every day. “We know that chimps fall out of trees and often it’s because they step on a branch that turns out to be rotten, and boom, down they come,” Kappelman told The Guardian. The fall from a tree is the best reason for the breaks, and a good explanation for how Lucy died, according to Dr. Kappelman :
“Based on clinical literature these are severe trauma events. We have not been able to come up with a reasonable way that these could be fractured postmortem with the bones lying on the surface or even if the dead body was being trampled on. If somebody is trampled on the bone breaks in a different way. It doesn’t break compressively.”
Perimortem fractures in Lucy’s postcranial skeleton as described by the recent research. ( John Kappelman et al .)
The article, which was published in the journal Nature, has been met with criticism by researchers who say that there are many postmortem causes that could explain the bone fractures. For example, Donald Johanson at Arizona State University, who discovered Lucy more than 40 years ago in the Afar region of Ethiopia, told The Guardian that “We don’t know how long the fossilisation process takes, but the enormous set of forces placed on the bones during the build up of sediments covering the bones is a significant factor in promoting damage and breakage.”
Tim White, a paleoanthropologist at the University of California in Berkeley, also said :
“Such defects created by natural geological forces of sediment pressure and mineral growth are very common in fossil assemblages. They often confuse clinicians and amateurs who imagine them to have happened around the time of death. Every single element of the Lucy fossil has cracks. The authors cherry pick the ones that they imagine to be evidence of a fall from a tree, leaving the others unexplained and unexamined.”
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Dr. Kappelman admits that although the hypothesis is one worth looking into, it is not undebatable: “None of us were there. We didn’t see Lucy die. Thinking about testing this idea, it’s hard to get someone to fall out of a tree, but we have tests going on every single day in every emergency room on planet Earth when people walk in with fractures from falls.”
On a final note, Kappelman and his team have been given permission by the Ethiopian government to make the bone data available online for scientists and schoolchildren to learn more about their research and Lucy. It also opens the door further for analysis and debate on Lucy’s life and death.
Cast of the remains of "Lucy". ( CC BY-SA 3.0 )
The website eLucy.org provides 3D renderings of the skeleton’s bones and allows interested individuals to download or print out casts of Lucy’s bones. Of the project, Dr. Kappelman has said “I’m happy that the 3-D files are out there. People can much more fully evaluate our hypothesis by looking at them, and it will be fun to see where it goes.”
Top Image: The Hidden Treasures of Ethiopa’ exhibit at Houston Museum of Natural Science featuring a model of “Lucy.” Source: Jason Kuffer/CC BY NC ND 2.0