Researchers say they’ve figured a cause of death for the 3.2-million-year-old fossil, and it could change how we understand her daily life.
By Nathan Collins
A re-construction of Lucy’s head on display at the Smithsonian Museum of Natural History in Washington, D.C. (Photo: Tim Evanson/Flickr)
It’s been a mystery ever since they found the young woman’s remains outside Hadar, Ethiopia, in 1974: How did Lucy, one of our earliest known ancestors, die?
Of course, it’s not an easy task, figuring out a cause of death after 3.2 million years, but a new post-mortem suggests an answer: Most likely, she fell from a tree. It’s an observation that adds to a long-standing debate over how it is we came to stand up and walk on two legs.
In case you need a quick refresher, Lucy is the nickname of a female Australopithecus afarensis, one of the earliest hominids to walk on two legs. Despite her exalted status in the evolutionary history of humankind, researchers don’t know a whole lot about how Lucy lived—in particular where she lived. Her long arms hint that she spent most of her time in trees, but her legs, clearly built for walking upright, suggest she may have spent more time on the ground. It’s a matter of “vigorous debate,” writes a team led by University of Texas–Austin anthropologist John Kappelman in Nature.
It’s not an easy task, figuring out a cause of death after 3.2 million years.
As is often the case, however, figuring out how Lucy died could reveal something about how she lived, so Kappelman and his team went back to the original skeleton, stored at the National Museum of Ethiopia. Their analysis revealed a spiral fracture on Lucy’s right humerus, or upper arm bone, in addition to evidence the head of the humerus had been crushed into the shaft of the bone, consistent with “an accident victim [who] consciously stretches out their arm in an attempt to break their fall,” the team argues. What’s more, the breaks are clean and show no signs of healing, indicating they occurred around the time of death.
“These humeral fractures were long thought to have occurred post-mortem, but their close match to clinical cases suggests instead that they represent perimortem injuries,” Kappelman and his colleagues write.
Beyond curiosity about how Lucy died, the results add some credence to the hypothesis that she and her Australopithecus afarensis relatives may have lived in trees. The Hadar region was a mix of grasses and trees at the time, and modern chimpanzees live in tree nests, sometime at heights upwards of 100 feet, making it at least plausible that Lucy died in a fall from a tree she called home.
“Close inspection of other fossil specimens for antemortem or perimortem fractures … has the potential to offer important information about their lifestyles through an understanding of the trauma that they suffered and the mechanisms by which they died,” the team writes.