Science Friday - 50 Years Of Science With Lucy, Our Famous Early Ancestor

Episode Date: November 25, 2024

On November 24, 1974—50 years ago this November—a pair of paleoanthropologists made the discovery of a lifetime: a set of 47 bones, hidden in the dusty, rocky hills of a fossil site in Hadar, Ethiopia. The skeleton belonged to a 3.2 million year old hominin, which came to be nicknamed Lucy.She marked the very first specimen of Australopithecus afarensis—a species of early hominins that were very likely our own ancestors. Lucy might be the most famous fossil in the world, and she’s transformed our understanding of human evolution.SciFri’s Kathleen Davis looks back at 50 years of Lucy with the people who know her best: Dr. Donald Johanson, founding director of the Institute of Human Origins at Arizona State University and the paleo legend who discovered her, as well as Dr. Zeray Alemseged, paleoanthropologist at the University of Chicago who discovered “Lucy’s baby.” They discuss what Lucy has taught us in the last 50 years, why she remains a scientific icon, and how understanding our ancestral origins helps us understand humanity.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

It's the 50th anniversary of the discovery of our very, very, very old ancestor, Lucy. And she doesn't look a day over 3.2 million years old. I certainly thought that she would be terribly important to the field of paleoanthropology. I had no idea that she would be the most famous skeleton found in the 20th century. It's Monday, November 25th, and you're listening to Science Friday. I'm SciFRI producer Rasha Iridi. On November 24th, 1974, 50 years ago, a pair of paleoanthropologists made the discovery of a lifetime, a set of 47 bones hidden in the dusty, rocky hills of a fossil site in Hadar, Ethiopia.

The skeleton belonged to a 3.2 million-year-old hominin named Lucy. She marked the very first specimen of Australopithecus aferens, a species of early hominins that were very likely our own ancestors. investors. Here's SciFri's Kathleen Davis with more. Lucy might be the most famous fossil in the world, and she's transformed our understanding of human evolution. So today, we're looking back at 50 years of Lucy with the people who know her best. The paleo legend who discovered her, Dr. Don Johansson, founding director of the Institute of Human Origins at Arizona State University, and Dr. Zerai Alemzegh Palaeo Anthropologist at the University of Chicago.

Welcome to Science Friday and welcome back. Happy to be here. Wonderful. Thank you. Thanks for having us. So, Don, I want to start with you. Can you believe it's been 50 years? How are you feeling this week? Well, you know, I went back to Ethiopia a couple of times this year and saw Lucy after 50 years. And she didn't look a day older.

But I look in the mirror in the morning when I shave and I realize that 50 years is quite a long time. it is amazing to think about how quickly that time has gone and how well-known Lucy has become and what an impact she's had not only on the average person's thinking about human origins, but on the science itself. Take me back to that day where you discovered Lucy. What were you doing? How did you find her? Well, it was a Sunday morning and my student, Tom Gray, and I were out recording the location of a discovery of a beautiful pig. We think pigs are beautiful at 3.2 million years. And on the way back to our

land rover, it was getting well over 100 degrees, and we were thinking about going for a swim in the river and having some lunch. But I am always looking at the ground. So I happen to look over my right shoulder, and I spotted a little fragment of bone, just about two inches long that had looked like a a wrench with a little notch in it. And it's part of the forearm bone that allows us to flex and extend at the elbow. And it looked peculiar to me because I thought at first it was probably a baboon. It was so small. But as I bent down, picked it up and looked at it, I could see that it was not a baboon. It was not from an antelope or a gazelle. It was from a human ancestor. And as we kneel down and looked closer at the ground, we saw bits of a skull, bits of a lower jaw, bits of ribs.

And I realized that right there at my feet was a partial skeleton, which I knew was older than three million years. I didn't know who it was. But I had no idea that she would be the most famous skeleton found in the 20th century. So Zerai, tell me how did you meet Lucy and how did she inspire you? Well, when Lucy was discovered, I was a little kid, so I was not aware of her impact. It was not until I was assigned to work at the National Museum of Ethiopia, where Don and his colleagues had steward Lucy that I started to spend time with Lucy and many other fossils that were discovered from across Ethiopia. So for me, the inspiration and the first contact was Lucy was actually hanging out with her physically on a daily basis.

So growing up in Ethiopia, was Lucy like a local celebrity? In Ethiopia growing up, she was not as popular as she is today. But clearly, you could find her name in textbooks, in lectures, in some places. But if you go to Ethiopia today, you will see Lucy restaurant, Lucy Cafe, Lucy, you know, So, yeah, she has now led to even the naming of the country's motto or logo, which is the land of origins, which I coined. And in order to do that, I obviously leaned on Lucy and many discoveries, including mine, the discovery of Salam, to show that Ethiopia is indeed one of the credulous of mankind, even though Africa broadly is the cradle of mankind. And Ethiopia is really one of the great centers of human origins research, but we also have to be reminded that she has her own Ethiopia name, which is Dinkadesh, which means that you are wonderful. But everybody seems to know her as Lucy, both here and in Ethiopia.

I've got to get myself to a Lucy Cafe. That sounds wonderful. And the coffee is good because not only the country is the origin of Lucy, but it's also the origin of coffee. So she goes to Lucy Cafe, you will have great coffee accompanied by Lucy. Wow, that's on my bucket list now. Let's talk a little bit about why Lucy was such an important discovery. Don, can you pick, let's say, two of the most profound things that we've learned from Lucy in the past 50 years? Well, I think one of the most profound things we learned was that she was a new species. She was a new kind of human ancestor.

She was an Australopithecus, that tongue twister, but she was very different from all other species. And with that recognition came the realization that we had to look again at the geometry of the human family tree. Where did she sit on the human family tree? When she was found, the predominant view was that the common ancestor to our own genus, Homo, we are Homo sapiens. And other kinds, other species of Australopithecus was Australopinicus Afrikanus in South Africa. Now she was placed at the pivotal place on the tree where she roughly around three million years ago gave rise to at least two, probably three different lineages. And one of those lineages ultimately led to us, Homo sapiens, through a very complicated

pathway, but she became the last common ancestor for all those later humans. Zerai, what is on Lucy's highlight reel for you? Well, you know, what Lucy did was a discovery of the small brain in Lucy and also upright walking. It's sealed the deal. That is, yes, upright walking came before small brain, and we did not need the large brains that we have today to become part of a member of the human lineage. I think that was one of the main contributions of Lucy. Don, have we learned everything that we can from Lucy in that time?

I mean, has her time come and gone, or is there still more to learn? Well, you know, when we talk about Lucy, we really talk about her species, Australopithecus operances. I would say that there will always be something new. There was a recent wonderful article that Sir Roy participated in, where they began to reconstruct brain capacities in virtual space, which was not really possible before that. We know that now they were about 30% larger brains than the average for a chimpanzee. So there is something going on in terms of selection for larger brains. So I would say that as new techniques become available, we will find a lot more information. And as we look at her through a different theoretical telescope, we may change your place of the tree.

I'm sure much more will be learned. Zerai, I want to ask you about this fossil that has been nicknamed Lucy's baby. Tell us about her and how did you find her? Yes, so I was working at a site called Dekka, which is not far from. Hadar where Lucy was found. And obviously, I expected to make discoveries, but I never would have thought of discovering such an amazingly complete skeleton. It is over 60% complete. It is a child that died at the age of 2 and a half, dated to 3.2 million years ago, which is 150,000 years older than Lucy. But what was important about the discovery,

is most of the bones that we find, including Lucy, come from adult individuals. And that is because the juvenile, the infants, their skeletons are fragile, so they disintegrate or get chewed by scavengers. So in many ways, when you work just on adults, the sample size you have is biased. Just think of someone from Mars coming to the planet Earth, and you would hide all the children, and they'll study only the ground. And they will go report, they say, well, humans are this high, this tall, this big, but they're ignoring the children. So in many ways, what Salam or Lucy's child did is brought

new information that completes the picture that has already been drawn by Don and his colleagues. So it's a unique and amazing addition to our knowledge of the Lucy species, but broadly speaking, early humans. After the break, what it means on a personal level to study our origins. Stick around. Don, you have had quite the career, and that's putting it mildly. What has motivated you to spend so many years searching for our origins? Well, it really came from reading about human origins when I was a teenager. And the book that startled me was Man's Place in Nature, which stated that we and the African

Ape shared a common ancestor. therefore our oldest ancestors should be found in Africa. And I think that the title continues to be exceedingly important to be and relevant today, man's place in nature, because for a long time people in anthropology have thought that culture makes us above the natural world. And I think that we are still part of the natural world. And I think every time we find one of these fossils, of course it was a missing, so it was a missing link, but I think more importantly, it's a link to the natural world in which we live.

And I think everybody has this question sometime in their lives, usually when they're very young, where did I come from, how did I get here? And we are fortunate on this planet as Homo sapiens to have the curiosity and the ability to go back and to actually find that evidence. And it deeply sets us in the framework of the natural world. In the grand scheme of evolution, Is our species all that unique, in your opinion? Well, we have a certain level of uniqueness. Each species does. We are unique because we are a combination of both biological evolution,

which is glacially very slow, genetic change is slow, but also cultural evolution. And we are a creature that is actually not because we wanted it, but we're in control of the future of the planet, and we're not doing a very good job. So I think every species is unique, and we have to recognize that and understand that we are not the end point

in evolutionary change. We were not destined to be. We're here because we have survived the whims and caprices of climate change, of challenges that we don't even know about. And we should cherish that. And really a pre-examined. the fact that we're alive because a few genes different and you wouldn't be you.

Zari would be Zari, I wouldn't be me. We have been given the gift of the universe. Zari, in studying human evolution, has it changed how you think about humanity? Oh, yeah, definitely. It's a privilege to study human origins. You know, as Don says, we are unique. Yes, but the fish is unique also, and the frog is as is the antelope. So our uniqueness should not dictate that we feel detached from nature

because we are integral part of nature. You know, I jokingly ask my students at the University of Chicago, are you more or less evolved than the fish? And all of them would answer, we are more evolved. Well, I will put you in the ocean and we will see who is more evolved. So unless we contextualize our understanding of being human, It is going to be difficult for us to interact, at least to continue interact with nature as we destroy it in terms of global warming and climate change and acidification.

As we destroy and kill any species, it's going to come back and haunt us. And that's why understanding our place in nature and really determining how we want to interact with nature is going to determine our own survival or not. the species that Lucy and Salam belong to, we call it primitive ancient species, but they managed to survive for close to a million years. Homo sapiens have been on the planet only for 200,000,000 years ago, so we need to be a little humble and have respect for the past and ensure that we can actually have the future. So it's a combination of understanding the past, and so we can work on present and then try to forecast the future is what

excites me and one inspires me to do what I do. How has Lucy's discovery changed the field of paleoanthropology in Ethiopia over the past 50 years? When I began in 1970, a long time ago, my first trip to Ethiopia, there were no Ethiopian scholars. There were only foreign scientists who came and did their research and left. And it's very, very gratifying that over the years, quite a number of Ethiopian-born scholars are now at the forefront of the research. And in addition to that, in the 1970s, there was really no place for us to work. There was a very old museum, but there was no place that was dedicated to storing and working on these fossils.

Today, there's a major building that was constructed by the government of Ethiopia that invite scholars from all over the world to come and study those fossils in contemporary modern laboratories. And as the rise said, it is now called country of origins and our origins, in fact, of many origins. Lucy and these fossils have dramatically changed the worldview of Ethiopia. Well, you know, just yesterday at the University of Chicago, my PhD student graduated he earned his PhD effectively working on the Lucy's species. So basically this would be Don's grandchild in some way. And if not for the inspiration that came from Lucy and many other discoveries, including mine,

I don't think you would be interviewing me today. I don't think you would be interviewing Don today. So, yes, you can make many discoveries. And Lucy is not the only fossil. We have so many hundreds and thousands of fossils, both human and human, non-human. But you always need that iconic specimen that is going to catch your imagination. So you can then think broadly and then ask the question, where do we come from? And in regards to what happens locally in Ethiopia, I think what Lucy did is inspired young people

like myself to not only train themselves, but train others, and inspire the government to invest in paleo-anthropology and build this lovely building for us to do research, but also inspires the public. So now in grade four textbook, you will see my name on page five or six where kids will say Ethiopian anthropologists are who discovers Salam. So it's just this, you know, gestalt, everything put together, the Lucy impact is simply huge and it never stops. Lucy continues to be the benchmark for any discovery. He cannot run away from Lucy. Well, what a wonderful place to end. I would like to thank you both so much for being here.

Thank you for having us. Yeah, thank you so much. Dr. Don Johansson, founding director of the Institute of Human Origins at Arizona State University and Dr. Zariahelmzeged, paleoanthropologist at the University of Chicago. That's it for this week's show. Lots of people help make it happen, including Santiago Flores. Emma Gomez.

Diana Plasker. Melissa Mayors. On our next episode, Wyatt took more than seven weeks for Asheville to get potable water after Hurricane Helene, and using oyster shell reefs to counter sea level rise in Louisiana. Join us. I'm CyFRAC producer, Rasha Aridi.