LOS ANGELES (AP) – Scientists have long wondered how Lucy, the famous human ancestor, died.

Now a new analysis of her fossil bones suggests a possible answer – the upright-walking Lucy probably died after falling from a tree.

Some scientists including Lucy’s discoverer disagree. They contend the cracks in Lucy’s bones came after her death. The disagreement highlights the difficulty of pinpointing a cause of death from fossilized remains.

Lucy was a member of an early human species that lived in Africa between about 4 million and 3 million years ago. Her partial skeleton was recovered in 1974.

Lucy was a young adult when she died.

The new study was published Monday in the journal Nature and was led by researchers at the University of Texas at Austin.