50 Years Ago, Discovery Of This Fossil Changed Understanding Of Evolution

A fossilised skeleton, Australopithecus afarensis, best known by her nickname 'Lucy', was unearthed by researchers 50 years ago this month in the Afar region of Ethiopia. It eventually went on to transform scientists' understanding of human evolution.

Opening a new chapter in human history, the discovery by Don Johanson, an American palaeontologist and graduate student Tom Gray on November 24, 1974, provided proof that the ancient hominins could walk upright on two feet 3.2 million years ago — a trait thought to have evolved more recently, CNN reported.

Lucy had a mixture of ape and humanlike traits, suggesting she occupied a pivotal branch in the family tree of humans. Over the past few decades, she has encouraged multiple researches and debates, besides igniting a broader public fascination with human origins.

Although researchers have now unearthed fossil hominins twice as old as Lucy, she continues to remain a key subject for scientific studies.

At the time when it was found, Lucy had 47 bones and was the oldest known and the most complete skeleton of early human ancestors.

Reminiscing his 1974 Ethiopia visit, Don Johanson told CNN he was walking on sediment 3.2 million years in age to search for the fossilised remains of various kinds of animals, "but particularly the remains of our ancestors." 

"I happened to look over my right shoulder. If I had looked over my left shoulder, I would have missed it," he said.

At first, he witnessed a little fragment of bone, a little part of the elbow as well as a part of a forearm. 

He could tell "immediately that it was from a human ancestor," Johanson said, adding when he and his student, Tom Gray, kneeled to have a closer look, they saw "fragments of the skull and fragments of a pelvis and fragments of an arm bone and the leg bone." 

"I realized at that moment that here was the childhood dream... I'd always wanted to go to Africa to find something and by golly this was something. But we didn't know how much it would become an icon in the study of human origins," Johanson said.

At the time of discovery, Lucy's bones were "very fragile" because they had mineralised and changed into stone. So, the team did a "very careful crawl to pick up the obvious pieces," before they put them into the burlap bags.

Later, they water-washed them in the stream via fine screening. The whole process took two and a half weeks. 

Johanson recalled it was wonderful to see Lucy come together on the lab table in the field. "The femur there was only about a foot long, or 28 centimetres long. What is this? I thought. Is this a child? Well, let's look at the jaw. The wisdom teeth had erupted so she was an adult. But my god, if this was an adult, it had to have been only about 3 and a half feet tall, a meter tall," he added.

Asked how it got the name Lucy, Johanson said it had a delicate nature of the bones and the short stature, so they felt "she was probably a female."

He went on to say that while Lucy's species did not give rise directly to modern humans, "her pivotal place on the human family tree led to all later hominin species, most of which went extinct." 

"The Homo lineage persisted and ultimately gave rise to us, Homo sapiens," he concluded.