Study suggests fall from tree killed human ancestor Lucy

LOS ANGELES — The famous human ancestor known as Lucy walked the Earth, but it was her tree climbing that might have led to her demise, a new study suggests.

An analysis of her partial skeleton reveals breaks in her right arm, left shoulder, right ankle and left knee — injuries that researchers say resulted from falling from a high perch such as a tree.

Lucy likely died quickly, said John Kappelman, an anthropologist at the University of Texas at Austin, who published the findings Monday in the journal Nature.

“I don’t think she suffered,” Kappelman said.

But several other researchers, including Lucy’s discoverer, disagree. They contend most of the cracks in Lucy’s bones are well documented and came after her death from the fossilization process and natural forces such as erosion.

How Lucy met her end has remained a mystery since her well-preserved fossil remains were unearthed more than four decades ago. Her discovery was significant because it allowed scientists to establish that ancient human ancestors walked upright before evolving a big brain.

Lucy was a member of Australopithecus afarensis, an early human species that lived in Africa between about 4 million and 3 million years ago. The earliest humans climbed trees and walked on the ground. Lucy walked upright and occasionally used her long, dangling arms to climb trees. She was a young adult when she died.

Tim White, a paleoanthropologist at the University of California, Berkeley, called the study’s conclusion a “misdiagnosis.” The Texas researchers “appear to have focused only on the cracks that they could attribute to an imagined fall, ignoring the additional abundant cracks,” White said in an email.

The split highlights the difficulty of pinpointing a cause of death from fossilized remains. Scientists rarely know how early humans died because skeletons are incomplete and bones tend to get crushed under sand and rocks.

Over the years, Lucy’s discoverer Donald Johanson has tried to solve the mystery.

Lucy’s skeleton, which is 40 percent complete, was recovered in Ethiopia in what was an ancient lake near fossilized remains of crocodiles, turtle eggs and crab claws.