Aug 30, 2016 | By Alec

It’s probably the coldest case in the history of our species. 3.18 million years ago, an adult female specimen of Australopithecus afarensis – which could be one of the ancestors of modern man – died in what is now Ethiopia. Fortunately, a considerable portion of her skeleton was preserved for all time and holds important clues about the evolution of mankind. Known throughout the world as Lucy, she also generated considerable controversy as no one could agree about how she actually died. But according to anthropologists from the University of Texas, who 3D scanned and 3D printed parts of her skeleton, she died after falling from a tall tree. And you can test their hypothesis yourself by 3D printing their STL files of Lucy – which have just been shared with the public.

Lucy is one of the most valuable fossils in the world. The adult Australopithecus afarensis was found back in 1974 during a dig in northeastern Ethiopia – during which The Beatles’ Lucy in the Sky with Diamonds was heavily played. It is among the oldest and is certainly the most complete skeletons of any adult, erect-walking human ancestor ever found (40 percent complete). While the jury is still out about whether or not she is a direct ancestor of mankind (or part of another branch of hominid evolution), she certainly holds vital clues about the evolutionary process during which the ape left the trees and moved to the savannahs.

But she would certainly stand out like a sore thumb today. Just 3 feet and 6 inches tall (weighing about 60 pounds), she would have looked and behaved more like a chimpanzee than a human. Like chimpanzees, she likely foraged for food on the ground and sought nightly refuge in the trees – putting her in a very important point of the process in which our ancestors lost their arboreal nature. It would have allowed her species to start walking upright, but likely reduced their climbing ability. As John Kappelman, anthropology and geological sciences professor at the University of Texas and lead researcher on this project, put it, it is therefore also quite ironic that she probably died from injuries suffered while falling from a tree.

Until recently, that statement would have been controversial. But the team led by Kappelman argue that new 3D CT scans of Lucy’s fossils show fatal injuries sustained during a fall from a high point, and they have already published their findings in the journal Nature. The 3D scans were absolutely crucial in reaching this conclusion, as it revealed a fracture (a series of fine bone fragments in her right humerus) that had gone unnoticed before. “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 argued.

Sources: Univesity of Texas and Nature.

In fact, the fracture and other cumulative injuries suggest that she fell from a height of more than 40 feet, hitting the ground with a speed of at least 35 miles per hour. The nature of the injuries further suggest that Lucy landed feet-first, before bracing herself with her arms upon falling forward. Among others, Lucy broke her ankle, a knee, the pelvis and at least one rib – suggesting severe internal organ damage as well. Death probably followed soon after, and it is quite miraculous that such a large portion of her body remained in place for more than 3 million years.

These crucial 3D scans were made back in 2008 over a ten-day period in Austin. Lucy's remains were going on a museum tour at the time, but made an extra stop at the High-Resolution X-ray Computed Tomography Facility(UTCT) in the UT Jackson School of Geosciences. Their hardware can scan through any solid object and at a resolution higher than that of a medical CT, and Kappelman and geological sciences professor Richard Ketcham spent the ten days creating more than 35,000 CT slices of the skeleton. “This is the first time 3D files have been released for any Ethiopian fossil hominin, and the Ethiopian officials are to be commended,” Kappelman said. “Lucy is leading the charge for the open sharing of digital data.”

Aside from getting a clear view of the evidence, Kappelman and his team were also able to 3D print and examine the bones by hand. “It’s one thing for me to describe it in detail in paper, but it’s another thing to hold these things, to be able to print them out, look at them and put them together,” Kappelman told nature. Ketcham agreed, arguing that Lucy’s fossil too precious to study by hand. “There’s only one Lucy, and you want to study her as much as possible. CT is nondestructive. So you can see what is inside, the internal details and arrangement of the internal bones,” he said.

But as Kappelman said, this does more than move the research further – it also humanizes Lucy even more. “For me, understanding her death brought her to life for me for the first time,” Kappelman said. “When I better understood the potential cause of her death, I could picture her broken body lying there at the foot of the tree. I could empathize with her.”

Bottom: an original and reconstructed bone (top).

However ,the debate surrounding Lucy is probably not settled – some specialists have already disagreed with these conclusions. But the debate is certainly moving forward, as the 3D scans have also been released for free as 3D printable files – allowing everyone to study the models for themselves. Even students and enthusiasts can now hold these priceless fossils in their hands and see what could be ‘the Mother of Mankind’, as Lucy is sometimes called. This open source move has been approved by the National Museum of Ethiopia, and the 3D printable files can be found alongside relevant scholastic materials on eLucy.org.

 

 

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marc verhaegen wrote at 8/31/2016 12:13:21 AM:

We know Lucy regularly climbed trees: her curved hand-bones indicate vertical climbing. But was she our ancestor? And did she walk upright? She lay in a small slow-moving stream, said Johanson & Taieb (1976): "Fossil preservation at this locality is excellent, remains of delicate items such as crocodile and turtle eggs and crab claws being found." Most likely, she waded upright (rather than walked on dry ground) not unlike lowland gorillas or bonobos wading for sedges, frogbit, waterlilies, papyrus etc. in wetlands & forest swamps. Google "bonobo wading" or "gorilla bai" illustrations. Lucy might well have been a fossil relative of Pan or Gorilla rather than of Homo. It is traditionally assumed that australopithecines (because they had "bipedal" features) were human ancestors. This is an example of pre-Darwinian anthropocentrism. If all australopiths are closer relatives of us than of the African apes, 1 extant species (H.sapiens) has 100s or even 1000s of fossil ancestors or relatives, and the other 4 or 5 extant species (common chimps, bonobo, lowland & highland gorilla) have no fossil relatives. Statistically this is impossible, unless human ancestors are for some reason incomparably more prone to fossilisation than the African apes, but the Asian great apes (Pongo) do have fossil relatives: Sivapithecus, Lufengpithecus, Gigantopithecus etc. Logical conclusion: Pan & Gorilla were not less likely than Homo to have had australopith ancestors. Pan & Gorilla might well have had upright ancestors. According to C.Coon, African ape fetuses have humanlike feet, with long & adducted big toes: "Only as it approaches its birth size does its foot acquire the appearance of a hand." Probably, gorillas, bonobos & chimps had more vertical ("bipedal") ancestors, not for running, but simply for climbing vertically in the branches above the swamp (in the dry season?) & for wading upright in wetlands (in the flooded season?) as they still do sometimes.



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