50 years of Lucy: see how the world’s most famous fossil was discovered

Lucy, a fossilized skeleton discovered 50 years ago this month, transformed scientists’ understanding of human evolution .

The discovery made by American paleontologist Don Johanson and graduate student Tom Gray on November 24, 1974, in Ethiopia opened a new chapter in human history, offering evidence that ancient hominids were able to walk upright on two legs 3.2 million years ago — a trait previously thought to have evolved more recently, in conjunction with brain enlargement and tool use.

Classified into a new species, Australopithecus afarensis, but better known by her simple nickname, Lucy possessed a mix of ape and human traits that suggested she occupied a crucial branch on the human family tree.

It inspired five decades of scientific research and debate, and sparked widespread public fascination with human origins.

Although today there are hominid fossils twice Lucy’s age, she remains a star of paleoanthropology. Composed of 47 bones of the same individual, she was the oldest and most complete skeleton known of an early human ancestor when found .

THE CNN spoke with Johanson, 81, founding director of the Human Origins Institute at Arizona State University, to hear the story of Lucy’s discovery and understand why her importance remains.

This conversation has been lightly edited and condensed for clarity.

CNN: Take us back in time 50 years.

Don Johanson: It was a Sunday morning, and temperatures were well above 38 degrees Celsius. I was in the Afar region of Ethiopia, which is one of the lowest places on the planet. There are ancient geological layers there, millions and millions of years old.

I walked through 3.2 million year old sediments looking for fossilized remains of various types of animals, but especially the remains of our ancestors. Then, I happened to look over my right shoulder. If I had looked over my left shoulder, I would have missed it.

What I saw was a small fragment of bone, part of the elbow and part of the forearm, and I knew immediately that it was from a human ancestor. It wasn’t from an antelope. It wasn’t from a baboon. It wasn’t from any other type of animal.

My student and I knelt down to get a closer look. We looked up the slope, and there were skull fragments, fragments of a pelvis, fragments of an arm bone and a leg bone. And I realized, at that moment, that this was my childhood dream… I always wanted to go to Africa to find something and, goodness, this was something. But we didn’t know how iconic it would become in the study of human origins.

CNN: How long did it take to excavate the skeleton?

Johanson: (The bones) were very fragile. They had been mineralized, turned into stone, so we carefully collected them to get the obvious pieces, then removed the top layer, square by square, placed them in burlap bags and washed them in running water with very fine sieves. The entire process took about two and a half weeks.

It was wonderful to see her compose herself at the lab table in the field. The femur was only about 30 centimeters long.

What is that? I thought. Will it be a child? Well, let’s look at the jaw. Her wisdom teeth had erupted, so she was an adult. But, my god, if this was an adult, she was only about a meter tall, about 90 centimeters.

CNN: How did the fossil get its name Lucy?

Johanson: Because of the delicacy of the bones and the short stature, we felt it was probably a female. (Subsequent discoveries revealed that males were much larger than females.)

That night at camp, we were listening to the Beatles album, “Sgt. Pepper’s Lonely Hearts Club Band,” and “Lucy in the Sky With Diamonds” were playing when one of the camp members suggested, “Why not call her Lucy?”

It was a coincidence, but the name stuck. It was, in many ways, an attractive name. People could identify with him. This gave those bones character. It invited people to be more interested. And she became the point of reference for the public on human origins.

CNN: What would the world Lucy lived in be like?

Johanson: It certainly wasn’t what you see when touring the Serengeti (national park in Tanzania) in a 4×4 vehicle today. They were not open plains. It was a forested area, but not a dense tropical forest — with some open bushes, where there were fruits, nuts and other foods, probably robbing nests of birds, crocodiles, turtles.

It really seems that upright walking emerged in much more wooded environments than we initially thought. The original vision was that when the forest disappeared, we went out onto the savannah and stood to look over the tall grass. However, there are carnivores in the savannah faster than a house cat, and you wouldn’t survive long. I think bipedalism, from a logical point of view, developed in the forest.

CNN: How important was Lucy at the time she was discovered?

Johanson: She was the oldest and most complete hominid known at the time. This was terra incognita (Latin for “unknown land”) in the 1970s.

Very few people had explored this region of Ethiopia, and other teams began launching expeditions and finding things that were even more exciting, in a way.

But I think Lucy was the spark. It ushered in a new phase in human origins research. The most important thing was that it broke the 3 million year barrier, and the site of Hadar, which is a local name, is very rich in fossils. He ended up producing a large number of fossils of his species and gave us an important reference point against which all other discoveries made in Afar could be compared.

CNN: In the field of human evolution, what has surprised you most in the last 50 years?

Johanson: One of the surprises is that we have Neanderthal genes in us. Many years ago, before we knew it, we thought of ourselves as a very different species from Neanderthals. We thought we couldn’t exchange genes with them.

Work in paleogenetics has revealed that we carry 1% to 4% Neanderthal DNA. I’m 2.1% — more Neanderthal than some people.

And, in the recent phase of human origins, in which we have Neanderthals living with Homo sapiens, a surprising discovery was made from bones found in Siberia. They found DNA, but it was neither human nor Neanderthal. It was from some other species that we know very little about. They call them Denisovans.

CNN: How have views of Lucy changed over the past 50 years?

In the early days, there was a question about how to know if it was actually more than 3 million years old. Argon dating (a method for dating rocks) was making very significant advances in the early 1970s. So that doubt disappeared very quickly.

There were critics who said that Lucy probably walked with a bow-hipped, bow-kneed gait. One of the most important discoveries that came later were the footprints found by Mary Leakey’s team in northern Tanzania in 1978.

Obviously, these people were not wearing shoes, leaving prints in the wet ash, like leaving a footprint in the beach sand. Here was evidence that they walked much like us.

CNN: Was Lucy a direct ancestor of humans?

Lucy’s species did not directly give rise to modern humans, but its crucial position in the human family tree led to all later hominid species, most of which became extinct. The Homo lineage persisted and eventually gave rise to us, Homo sapiens.

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This content was originally published in 50 years of Lucy: see how the world’s most famous fossil was discovered on the CNN Brasil website.

Source: CNN Brasil