A 3D x-ray has the ability to see inside an object to find a defect, crack, void, hole, or even porosity. They are so powerful that one x-ray even was able to solve a 3 million year mystery.

In 1974, a team of scientists from Arizona State University discovered the remains of an Australopithecus afarensi in a remote part of Ethiopia. Known as Lucy, this skeleton body is one of humanity’s earliest known ancestors to walk upright, and she was alive about 3.2 million years ago.

More similar to a chimpanzee than a human, Lucy had long arms, a protruding belly, a low forehead, and the ability to navigate trees. But the positioning of her feet, ankles, and pelvis were like that of a human and have given scientists unique insights on how humans started to walk on two feet.

Lucy was tiny, about three-foot six-inches tall, and weighed about 60 pounds at her time of death. Even though she was discovered 42 years ago, researchers have not been able to describe how the 15-year-old died, until now.

New x-rays of her bone fragments show that Lucy died after falling out of a 14-foot tree. She is believed to had hit the ground feet first while going about 35 miles per hour while stretching out her arms to brace her fall.

To come to this conclusion, University of Texas geologist John Kappelman and his team focused on a four-part fracture on Lucy’s humerus. The scans were consistent with modern day injuries of humans who fall at considerable heights. The team was unable to find evidence of bone healing, which leads them to believe this injury happened right at the time of death.

Kappelman expresses to PBS that he feels that this way of death was ironic for the first human ancestor to both walk upright and exist in trees died falling out of one. He explains, “Those adaptations that allowed them to move more effectively on the ground are not so good for climbing. It may have predisposed her to more frequent falls.”

Additionally, Kappelman believes Lucy was conscious when she hit the ground, but death was soon after.

Photo by Valerie A. Lopez and John Kappelman