By Katie Hunt, CNN

(CNN) — 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, providing evidence that ancient hominids were capable of walking upright on two feet ago is 3.2 million years old – a feature once thought to have more recently evolved in tandem with large brains and tool use.

Assigned to a new species, Australopithecus afarensisbut better known simply by her nickname, Lucy had a mix of ape-like and human features that suggested she occupied a central branch in the human family tree. It has fueled five decades of scientific research and debate and sparked a broader public fascination with human origins.

Although there are now fossil hominids twice as old as Lucy, she remains a paleoanthropological rock star. Made up of 47 bones Coming from the same individual, it was the oldest known and most complete skeleton of a primitive human ancestor when it was found.

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

This conversation has been lightly edited and condensed for clarity.

CNN: Take us back 50 years ago.

Don Johanson: It was a Sunday morning and the temperature was well over 100 degrees (Fahrenheit). I was in the Afar region of Ethiopia, which is one of the lowest places on Earth. There are ancient geological strata there, layers that go back millions and millions of years.

I was walking on 3.2 million year old sediments looking for the fossilized remains of various species of animals, but particularly the remains of our ancestors. And 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 bone fragment, a small part of the elbow and part of a forearm, and I could immediately tell that it came from a human ancestor. It didn’t come from an antelope. It wasn’t that of a baboon. It didn’t come from any other kind of animal.

My student and I knelt down to take a closer look. We looked up the slope and found skull fragments, pelvis fragments, and arm and leg bone fragments. And I realized at that moment that this was a childhood dream. …I had always wanted to go to Africa to find something and boy, this was something. But little did we know how iconic he would become in the study of human origins.

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

Johansson: (The bones) were very fragile. They had been mineralized, turned into stone, and we did a very careful exploration to pick up the obvious pieces, and then we removed the top layer, square by square, and then we put them in burlap bags, and then we washed them with water. in the stream thanks to very fine sieving. The whole process took about 2 ½ weeks.

It was wonderful to see it come together on the lab table in the field. The femur was only about a foot long, or 28 centimeters long.

What is this? I thought. Is it a child? Well, let’s look at the jaw. The wisdom teeth were out, so she was an adult. But my goodness, if it was an adult, it must have only been about 3 and a half feet, or a meter tall.

CNN: How did the fossil get the name Lucy?

Johansson: Due to the delicate nature of its bones and its small size, we thought it was probably female. (Later fossil discoveries revealed that males were much larger than females.)

That night at camp we were playing 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 said, “Why don’t you call her Lucy?

It was just a coincidence that it happened, but it stuck. In many ways it was an attractive name. People could relate to it. This made those bones a person. It drew you in and made you want to know more. And it has been the touchstone (of human origins) for the average person.

CNN: What kind of world would Lucy have lived in?

Johansson: This is certainly not what one sees today when traveling the Serengeti in a four-wheel drive vehicle. These were not open plains. It was a tropical rainforest that was wooded but not dense – sometimes with open bushes, and so you have lots of different kinds of fruits and nuts and so on. to feed yourself, probably stealing from bird nests, crocodile nests, turtle nests.

It really looks like walk upright is something that has appeared in much more forested environments than we (initially) thought. The original idea was that once the forest was gone, we would go out into the savannah and stand up and look over the tall grass. However, there (are) carnivores faster than your domestic cat (in the savannah), and you are not going to last long. I think bipedalism, logically speaking, developed in the forest.

CNN: How important was Lucy when she was discovered?

Johansson: She was the oldest and most complete hominin known at that time. It was terra incognita in the early 70s. Very few people had been to this area of ​​Ethiopia, and people began to launch their own expeditions and discover things even more exciting in some ways.

But I think Lucy was the spark. It triggered a new stage in research into human origins. What she did, most importantly, was that she crossed the time barrier of 3 million years and the site of Hadarwhich is a local name, is very rich in fossils. And this turned out to produce enormous numbers of fossils of its species and provided us with a very important reference point against which all other discoveries made in the Afar could be judged.

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

Johansson: One is that we have Neanderthal genes in us. Many years ago, before we knew it, we considered ourselves a very different species from Neanderthals. We couldn’t exchange genes.

Paleogenetic work has of course revealed that we carry between 1 and 4% Neanderthal DNA. I have 2.1% – more Neanderthals than some people. And for the recent period of human origins, where we have Neanderthals living with Homo sapiens, a surprising discovery was made (of bones found in) Siberia. They found DNA, but it wasn’t human or Neanderthal. This was another species about which we know very little. They call them Denisovans.

How have opinions about Lucy changed over the past 50 years?

At first the question really arose: how do we know it is over 3 million years old? And argon dating (a method of dating rock) was making very significant breakthroughs in the early ’70s. So that (question) disappeared very quickly.

There were critics who said that Lucy probably walked with a bent hip and knee gait. One of the most important things subsequently discovered were the footprints that Mary Leakey’s team found in northern Tanzania in 1978. Obviously these people weren’t wearing shoes, leaving footprints in wet ashes was like leaving a footprint in beach sand. It was proof that they walked almost like us.

CNN: Was Lucy a direct ancestor of humans?

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

The-CNN-Wire
& © 2024 Cable News Network, Inc., a Warner Bros. company. Discovery. All rights reserved.