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IRA FLATOW, host:

Up next, a look at Lucy. At the age of 31, fresh out of grad school with a Ph.D., my next guest struck gold, well actually an anthropologist's idea of gold, anyway. He was in Ethiopia's Afar Region. He was standing in the hot sun, nearly ready to head in for the day, when he looked down and spotted a two-inch fragment of bone lying on the ground.

He instantly recognized it as part of an elbow and the rest, as they say, is history - well pre-history, actually. That elbow and a thighbone and ribs and a shard of a skull nearby belonged to a human ancestor later dubbed Lucy. At the time, Lucy was the first of her kind, and she filled in some very crucial blanks in the human evolutionary tree

And joining me now to talk more about that find, his work since then, is my next guest, Donald Johanson, anthropologist and director of the Institute of Human Origins at Arizona State University.

His new book is just out. It's co-authored with Kate Wong. It's called "Lucy's Legacy: The Quest for Human Origins." He joins us from KJZZ in Tempe. Welcome back to SCIENCE FRIDAY.

Mr. DONALD JOHANSON (Co-author, "Lucy's Legacy: The Quest for Human Origins"): Well, Ira, it's great to back on the show. I hope you're well.

FLATOW: Thank you, same to you. You're basically summing up the whole history behind Lucy in this book.

Mr. JOHANSON: Well, this is, in many ways, a sequel to my 1981 book, which was called "Lucy." I took a little while getting around to doing the sequel.

(Soundbite of laughter)

Mr. JOHANSON: But there was a long hiatus in Ethiopia when it was impossible for us to conduct field research, and we restarted research in the early 1990s with a whole series of questions that had been left hanging from the 1970s and since then have made some remarkable discoveries.

We now have a skull of what Lucy would have looked like. We have a female skull. We have a male skull. We have parts of another skeleton. We have exact ages for the geological studies, the geological deposits. So there's a lot to tell.

FLATOW: And Lucy is on exhibit in the U.S., is she not?

Dr. JOHANSON: That's right. Lucy has been in the U.S. now for well over a year. She premiered in Houston at the Natural Science Museum. She's now in Seattle at the Pacific Science Center.

FLATOW: Well, we're going to talk a whole lot more about Lucy with Donald Johanson, author of "Lucy's Legacy: The Quest for Human Origins," co-authored with Kate Wong.

Our number, 1-800-989-8255, your chance to talk with Donald and talk about Lucy and any other things about the history of humans with us. So stay with us. We'll be right back after this short break.

(Soundbite of music)

FLATOW: I'm Ira Flatow, this is SCIENCE FRIDAY from NPR News.

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FLATOW: You're listening to SCIENCE FRIDAY on NPR News. I'm Ira Flatow, talking with Donald Johanson, anthropologist and director of the Institute of Human Origins at Arizona State University, author of a new book, "Lucy's Legacy: The Quest for Human Origins," co-authored with Kate Wong.

Dr. Johanson, it's an amazing story in itself. I began to tell it. I wish you would recount it for us, just how you made that discovery that day.

Dr. JOHANSON: Well, it's a story - I can't tell you how many times I've told this - but every time I do tell it, I'm transported back to that day in November of 1974 when I was fortunate enough to look over my right shoulder and see a fragment of bone that belonged to an elbow of a human ancestor that I knew was more than three million years old.

FLATOW: That's not good enough for us, Dr. Johanson.

(Soundbite of laughter)

FLATOW: You have to set the stage, where you were, what you were doing, how hot it was, all that kind - we need the details.

Dr. JOHANSON: Well, I was co-directing an expedition in northeastern Ethiopia, in an area known as the Afar Triangle, which today is essentially a desert. And I had explored there in 1972 and realized that this was a place where we might possibly find some remains of early human ancestors.

I had just finished my graduate work at the University of Chicago, and I was out on a survey with one of my graduate students, Tom Grey(ph), and it was noontime. It was already, you know, 105, 110 degrees, time to think about getting back to camp, to jump in the river and cool down and have a little lunch. And as I was walking back to my Land Rover, always keeping my eyes to the ground, I looked over my right shoulder.

And there was a funny, little, wrench-shaped piece of bone sitting on the ground, and I knew it immediately it came from an elbow. It was so tiny. My first thought it was from a monkey, but when I kneeled down, picked it up, looked at it, I could see that it had the anatomy of your elbow, my elbow, the elbow of a human ancestor.

And I realized in that noonday sun at that moment, there at my feet, was my childhood fantasy that I had dreamed about since I was a young teenager, finding an important, ancient, human ancestor.

FLATOW: When did you know it was important?

Dr. JOHANSON: Well, I knew it was important almost immediately because it was from geological strata that we knew were older than three-million years. So I knew it was very ancient. And at that time, we had a handful of fossils of that antiquity.

I knew it was important because there were fragments of a skeleton, and normally, we're thrilled when we find a piece of jaw, a fragment of a leg bone, a part of a skull, but here were arms and legs and ribs and vertebrae and hand bones and foot bones, part of a skull and nearly complete lower jaw. This was an extraordinary discovery no matter how one measures it.

FLATOW: So did you stay right there and say we're not going home yet?

Dr. JOHANSON: No, I grabbed a little fragment, the first fragment I found. I wrapped it in my bandana, marked the exact spot where it was found, traveled back to camp, made the announcement to the rest of the expedition. And that afternoon we went back to the site and began to look more closely at it and spent the next two weeks collecting what is roughly 40 percent of a skeleton if you eliminate the hand and foot bones, of a skeleton that has come to be known popularly as Lucy and probably the single best-known human ancestor in the last century.

FLATOW: And how did Lucy change our ideas of the lineage and ancestry?

Dr. JOHANSON: Well, what Lucy did was she firmed up a number of things. She firmed up the idea that we stood up before we developed large brains, before we began to manufacture stone tools.

She showed us that natural selection had tinkered with the post-cranial skeleton, below the neck more than it had done any changes with the brain size, for example, that Lucy was upright-walking than in many respects. She probably had a striding, bipedal gait like we have, yet her brain was the size of a chimpanzee. And she presented us with a model of a species that is in between.

She sits at a very pivotal point on the family tree, between older ancestors that are very ape-like and more-modern ancestors or more-derived ancestors. So she is at a very pivotal point and appears to be the last common ancestor for all the later branches on the human family tree.

FLATOW: So how do you go about - I mean, this is a major find. Aren't you going to be upsetting the apple carts of some other archaeologists and anthropologists of that time, saying that…

Dr. JOHANSON: Well at the time when Lucy was found, we didn't know exactly who she was. We didn't know what species she belonged to. And it's interesting, if you open my new book, and you look at the end papers, there are almost a dozen new species of humans listed there, human ancestors, since my book, "Lucy," back in 1981.

We did know that she was a new species until several years of lab research. She's called Australopithecus afarensis. We didn't know exactly how old she is. We now know she's 3.2 million years old, and the first chapter of the book, interestingly, is entitled the woman who shook up man's family tree because she did prompt changes in the geometry, the shape of the tree.

For example, Australopithecus africanus - many listeners will know who that is. That was the Taung baby found back in 1924 by the late Raymond Dart - was considered to be the last common ancestor. Well, Lucy forced that particular species onto a side branch that became an ancestor to a bunch of creatures that ultimately became extinct.

So she prompted an enormous number of changes in the shape of the family tree. She has generated literally thousands of research projects, innumerable papers and a real glimpse at what one of our earliest ancestors actually looks like.

FLATOW: Now you get the sense from reading your book, although you don't say it explicitly, that there are a lot of egos involved in this kind of work, and your new find is going on the evolutionary tree, and if it's going get there, someone else's has to be bumped aside.

Can you tell us about the rivalries? You don't have to mention any names. But I mean, there are obviously, you know, there are obviously names that come to our minds. Can you tell us about the rivalries that go on there? Is there real competition in your field?

Dr. JOHANSON: Well, I think that individuals do have a lot of competition for finding the oldest, the most complete, the most important or whatever. I tend to look at the field in a more, I think, ecumenical way in the sense that each and every one of these discoveries, whatever it is, is vitally important for us to try to understand the details of how we became human.

It's certainly not like Cope and Marsh back in the 1800s, American vertebrate paleontologists who were out there sending telegrams back to their host institutions to beat the other one in the description and the naming of a new species and so on. But there is a lot of competition for funding. There's a lot of competition for access to sites.

There's a lot of competition for trying to find the most important fossil. But I think that we're seeing a change. There are a number of young scholars, Zeresenay Alemseged - wonderful name, Ethiopian scholar who was a post-doc here at Arizona State University - who made an incredible discovery of what would be Lucy's baby, something like Lucy's baby, a three-year-old baby.

He's shown that specimen to everyone. He's published it in a timely fashion. He has allowed people access to come into it. The real rivalry, I think, centers around people who keep fossils hidden. They don't share them. They don't show them with other people. And in that direction, recently there was a CAT scan done of Lucy's skeleton.

I had nothing to do with it, but the information from that is going to be made available online. It's going to be instantly available to scientists anywhere in the world. And I think that if there is competition and if there is rivalry, it's because not everyone in this field is as willing to share their fossils as they should be.

FLATOW: We actually have, Dr. Johanson, the CAT scan on our Web site, the (unintelligible) if anyone wants to take a look at it, they can see…

Dr. JOHANSON: I noticed. I looked at the Web site this morning.

FLATOW: Yeah. 1-800-989-8255 is our number. We're talking with Donald Johanson, author of "Lucy's Legacy: The Quest for Human Origins," co-authored with Kate Wong.

Let's see if we can go to the phones and get a few phone calls. Let's go to Anthony(ph) in Laramie, Wyoming. Hi, Anthony.

ANTHONY (Caller): Hi, I was hoping Dr. Johanson could address what other critters were around when Lucy was - in her time? And also any evidence that she was a social animal?

Dr. JOHANSON: That's a good question, both good questions. We have a group of paleontologists, people who study non-human fossils. And Kaye Reed is a member of that team here at Arizona State University and she has been working on trying to reconstruct the environment - the paleoecology, what kind of place it was. It was not a desert when Lucy lived there.

It was fairly heavily forested. There were rhinos, and all sorts of gazelles, and monkeys, and elephants, pigs. It was dominated by a large lake. So it was much like what you might see when you go on safari to East Africa today in several different places.

Whether she was a social animal, I would suspect she was. Imagine she was only three and a half feet tall. She probably followed a pattern not unlike what we see in the African apes today. We made a discovery in 1975 of a group of specimens from a locality called the First Family, where some 13 to 17 individuals died together. I suspect that they lived in multi-male, multi-female groups. That would be my best guess.

ANTHONY: Do we know how old she was when she died?

Dr. JOHANSON: Well, we know that they matured much more rapidly, more along the ape line than the human line. We are slow to mature and develop. It's part of our life history because we have so much learning to do as infants and juveniles. But Lucy was clearly much more like the ape that stood up. She was upright walking, but she still possessed an amalgam of features that were very ape-like. And people who study the dental anatomy and dental morphology and dental development - Gary Schwartz here at A.S.U. and others - have pointed out that it looks like from studies of the rate that the enamel is laid down that she was probably more like 11 or 12 years old when she died.

Probably a full adult, meaning that she had matured, her wisdom teeth had erupted, so the third molar, or wisdom tooth, was already in the jaw and beginning to wear but her rate of maturation was more like an ape rather than a human.

FLATOW: In your book, you give us a really good feeling for how long and tedious field work can take - the paper work, the bureaucracy - sometimes they go by before you can get back to the - years go by, before you get back to the work there. You also talk about the places where you work. And in Ethiopia, where there's a lot of unrest, at one point your camp is forced to be accompanied by military, you find yourself surrounded by men in foxholes with machine guns. We don't hear about that.

(Soundbite of laughter)

Dr. JOHANSON: No, that's exactly right. There are lots of challenges in doing this sort of work. But the reward is so enormous that all of us who are involved in the pursuit to understand the origins of humankind, will make many sacrifices, willingly, to be able to go out. And to fill in what is arguably one of the most interesting evolutionary stories we have.

FLATOW: So what is missing now? Where are the gaps in the human evolutionary tree?

Dr. JOHANSON: Well, there are a number of gaps that continue to haunt us. I think probably the most interesting one, the one that is receiving more and more attention, is that the gap between Lucy species - Australopithecus afarensis - and the earliest appearance of our own genus. We are placed in the genus of Homo which is Latin for man - Homo sapiens supposedly wise men. I sometimes think - wonder whether we really are wise men. But there is a period between roughly two-and-a-half and three million years, when there is a major gap.

We don't have the individual steps, the individual fossils, the individual species that show us the transition from the genus Australopithecus to the genus Homo. And that is a period of time when we probably began to see the initiation of brain expansion. We certainly see the earliest occurrence of stone tools, at 2.6 million years. We see the shedding probably the ape-like features, like curved hand bones and very long arms and small brain and so on, that evolve and change into that particular genus that ultimately leads to us. That's one of the major missing gaps.

FLATOW: Talking with Donald Johanson, author of "Lucy's Legacy" on SCIENCE FRIDAY from NPR News. 1-800-989-8255 is our number. Why - what is the advantage? And one of the things that you talk about in the book and anthropologists always talk about is the bipedalism - the fact that the -evolution made us standup on two legs, just two feet. What is the advantage to that evolutionarily speaking?

Dr. JOHANSON: Well, it's an interesting question and I think - in fact, thanks for asking me Ira. I just gave two lectures this week on bipedalism, so it is…

FLATOW: I missed them.

Dr. JOHANSON: …on the tip of my tongue. And by the way I'm looking forward to seeing you out here in Arizona next month.

FLATOW: We're going to be out there at the Origins.

Dr. JOHANSON: We have a wonderful Origins weekend and I know the tickets went on sale two days ago. I think there are about 50 tickets left for the big day.

FLATOW: Wow.

Dr. JOHANSON: It's in a huge auditorium. But at any rate, bipedalism is one of the defining features, of course, of what it means to be human.

Darwin recognized it, as something very special. It is one of our unique characteristics. And for a very long time, anthropologists have been asking the wrong question. They have asked why did we become upright. And the real question to ask from a Darwinian point of view - and we are celebrating his 200th anniversary of his birth this year. The right question to ask from a Darwinian prospective is what was it about bipedalism that was so advantageous? Why did it lead to a - why did that adaptation ultimately lead to a species Homo sapiens that has come to dominate the planet today with six and a half billion people?

The apes, the quadrupeds, those creatures walking on four legs, are all in decline. And it certainly opened up a whole new range of behavior and activity for us. From carrying food long distances back to home base. It allowed us to stand up and look over tall grass. It allowed us to reach up for fruit. It allowed us to do all sorts of things that together, I think in a multifaceted way, gave us a tremendous advantage over other creatures because it ensured in an interesting way that we were able to provision - to take care of, to look after our genes, our offspring.

And if we're going to leave an impact on the next generations, subsequent generations, we have to make sure that our offspring continue to survive, that our genes continue to be reproduced. And I think bipedalism was a key to provisioning, to carrying food back, to making certain that our genes did not die young, that our offspring did not die and take those genes with them.

FLATOW: (Unintelligible) used to always talk about opposable fingers and precision grip and things like that. Did bipedalism allowed us to develop that better?

Dr. JOHANSON: Well, certainly as we have moved through the evolutionary story, we see that we move from an ape-like hand that doesn't have the precision grip to one that does. These are gradual changes that have happened over time. But certainly they could have developed a precision grip without becoming upright and bipedal. But there was an interesting feedback model I think in the sense -even Darwin talked about this in 1871 in his "Descent of Man" where he said that bigger brains better tools, better tools bigger brains.

And once culture began to kick in, once we began to use our hands to manufacture tools, to open up new opportunities such as scavenging and hunting and exploit parts of the natural environment that were unavailable to us before, we began an evolutionary journey that has ultimately evolved into modern day humans.

FLATOW: Talking with Donald Johanson, author of "Lucy's Legacy: The Quest for Human Origins," co-authored with Kate Wong. We have to take a short break and we'll come back and talk back more with Dr. Johanson, our number 800-989-8255. Lot's of twitters coming in. Our tweet - you can tweet us at Sci-Fri. And lots of folks hanging out in second life and you can ask us questions there. We are taking questions from every direction today, so stay with us. We'll be right back after this short break.

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FLATOW: You're listening to SCIENCE FRIDAY from NPR News. I'm Ira Flatow, talking with Donald Johanson, author of "Lucy's Legacy: The Quest for Human Origins," co-authored with Kate Wong. Our number 1-800-989-8255. Lots of folks want to get in. David(ph) in Brooklyn. Hi David, welcome to SCIENCE FRIDAY.

DAVID (Caller): Good afternoon Ira, thanks for taking the call. Dr. Johanson, I was curious to know if you have any idea why you have not been able to discover the connectors between Lucy and the genus Homo. Is there something geological or environmental or the areas where these groups were living - that you haven't discovered where they are or where they were?

Dr. JOHANSON: What an interesting question. Geologically, the strata that would contain the remains between early hominids - between two-and-a-half and three million years - are exceeding scare in the Great Rift Valley. And it is an area that field geologists and paleoanthropologists in general are now in quest of. We are specifically looking for strata of that age. And we are hopeful that with very targeted and strategic research that we will be able to find strata of the appropriate age. But it is clear that during that period of time, there was probably a lot of erosion, periods of non-deposition, and it is going to be a challenge to find those strata.

FLATOW: Thanks David.

DAVID: Thank you.

FLATOW: Will you be looking in the same place?

Dr. JOHANSON: Well, we'll be looking throughout Africa's Great Rift Valley. The Great Rift Valley is one of those wonderful geological phenomenons on the planet that stretches from Mozambique in the south, all the way north into the Red Sea. But there is another area of fossil discovery in Southern Africa, called the Transvaal cave sites. These are sites that have accumulated other the last few millions years, accumulated remains of fossils. And I wouldn't be surprised if this might be an area in which we will find some early remains of the genus Homo.

FLATOW: Question…

Dr. JOHANSON: We shouldn't just restrict ourselves to the Great Rift Valley.

FLATOW: Sorry to interrupt. Question from Bete Noir(ph) in Twitter. I'm also curious about how Dr. Johanson views the aquatic ape hypothesis.

Dr. JOHANSON: Well…

FLATOW: Remember? Elaine Morgan wrote about that in the '70s - called the "Descent of Woman", I think it was.

Dr. JOHANSON: Yes. That was, of course, in response to Darwin's 1871 idea that - when he wrote the "Descent of Man".

FLATOW: Right.

Dr. JOHANSON: I'm not going to say it's all wet, but it is - it's sort of a construed idea. It's not really I think within the realm of what a theory is. And if we look at primates today, very few primates spend any time in the water. Both chimps and guerillas abhor being in the water. They will some times walk bipedal, as we've seen guerillas do in Central Africa, but primate adaptations are essentially terrestrial, arboreal adaptations.

And many of the features that Elaine suggests that are similar between us and aquatic animals are really not what we would call homologies - they're not something that come from a common ancestor. They're there for different reasons. They're there in an analogous way. So I think that to a very large extent the fossil evidence doesn't support it. But it is an interesting way for people to look at different ideas, of course. But Elaine's work has not really held up.

FLATOW: One last question I think we have time from Hannah in Minneapolis. Hi.

HANNAH (Caller): Hi. This question is for Dr. Johnson and my name is Hannah. I'm from Ethiopia. I just want to know more, you know, about Lucy. I have like three questions, the first one is why they bring Lucy because she's like over 300 years old, so why they bring her to the United States?

FLATOW: Three million years old.

HANNAH: We are not happy about it. You know most of us (unintelligible) then not to (unintelligible) but government do this, so we are not happy.

FLATOW: Alright. Okay…

HANNAH: My next question doctor, for you, what's the benefit for Ethiopia? And I want to know the third question, how much money, you know, the United States pay for bring the bones.

Dr. JOHANSON: Okay.

FLATOW: Hannah, I only have a minute left so I'm going to have to let him answer this.

Dr. JOHANSON: Okay, Hannah. (unintelligible) and it's wonderful that you called in. Lucy is traveling in the United States at the moment to show people one of the great wonders of the ancient world. And Ethiopia has been an extraordinarily welcoming and offering country. A country that is truly the cradle of humankind. They wanted to share that with the rest of the world. And the benefit is that people get to see her. The benefit is that we get see the real evidence for human evolution. And also to bring more and more attention to the wonderful country where I've had the privilege of working in since 1970.

FLATOW: Where is she headed next after she leaves?

Dr. JOHANSON: Well, I don't know exactly where she's headed. I've had very little to do with the exhibit. I've gone and lectured but I've not been involved with any of the transactions or venues or whatever. So, we'll have to see where makes her next visit.

FLATOW: We'll keep track of you Dr. Johanson. Thanking for taking time to be with us today.

Dr. JOHANSON: Oh, you're more than welcome. I look forward to seeing you here next month.

FLATOW: Thank you. Donald Johanson author of "Lucy's Legacy: The Quest for Human Origins," authors with Kate Wong - really, really interesting book. I recommend it all of you.

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