#1107 Donald Johanson: Lucy, Australopithecus afarensis, and Homo habilis

00:00 Ricardo Lopes: Hello everyone. Welcome to a new episode of the Dissenter. I'm your host, as always, Ricardo Lopes sent to the I'm joined by Doctor Donald Johnson. He is the Virginia M. Ullman Chair in Human Origins and the school of in the School of Human Evolution and Social Change and the founding director of the Institute of Human Origins at Arizona State University. He has conducted lots of field and laboratory research in paleoanthropology, most notably, he discovered that the, the 3.18 million year old hominid skeleton, popularly known as Lucy. And today we're going to talk about Lucy, uh, Australopithecuernzis more generally and also homo habily. So, Doctor Johnson, welcome to the show. It's a huge pleasure to everyone.

00:49 Donald Johanson: Well, it's a pleasure for me to be on your show. Thank you so much.

00:53 Ricardo Lopes: OK, so less remark than the 50th anniversary of the discovery of Lucy and that's one of the main reasons why I invited you on the show. So, start by telling us, uh, first about the history behind her discovery.

01:12 Donald Johanson: Well, uh, I was introduced to a, uh, geologist, a French uh geologist in Paris, uh, in 1970. Who unfortunately is no longer with us now. His name is Maurice Taeb. And he was working uh in the area you see behind me here, uh, which is the Afar region of northeastern Ethiopia, which is the largest expanse of the Great Rift Valley. And uh he was mapping the area. He was trying to understand the origins and evolution of the geology in this area. And during the course of his field work, uh, he brought my attention to the fact that this area was filled with all kinds of fossil remains of animals, elephants and rhinos, and pigs, and, uh, antelopes and so on, and no anthropologist, paleoanthropologist like myself, someone who studies human origins, had ever visited that region. And he asked me if I wanted to go with him. And I was a young, uh, anthropologist at that time. I had just gotten my doctorate, uh, from the University of Chicago, I was getting my doctorate from the University of Chicago. And I was in Ethiopia with my, uh, professor from the University of Chicago, working in the absolute opposite end of Ethiopia in southern Ethiopia. So, I was, um, Just beginning my career in human origins research and uh surprisingly, he, he offered the opportunity uh for me to accompany him there. And uh finally, after a couple of years of uh organization and planning and uh finding financing, we made a visit in 1972. Uh, I was still 2 years away from getting my doctorate, so I was just a graduate student. And I was absolutely amazed at how. Filled this area was with fossils. You could walk along and find a complete elephant skull. It was more than 3 million years old. We knew that they were very old because we looked at the, the teeth and the, especially, uh, and they're good indicators of time. They evolve very quickly over time. And uh uh so we decided to form an an expedition, a formal expedition called the International AFA Research Expedition. And uh to systematically work in this area, which was really terra incognita for anthropologists. And uh in 1972, we, we undertook this, um, you know, exploratory expedition, and finally in 1973, we had uh arranged for funding. And an organization of a number of people to go and to sort of say, plant our flag there. We, we got a permission from the Ministry of Culture in Ethiopia, uh to go to this particular place, which is called Hadar, H A D A R. And uh I had not a great deal of money. It was a, a really small amount of money and the pressure was on because I was hoping we could find the remains of a human ancestor. And, and you can see there are no signs that say dig here or look here, uh, and uh I was very fortunate in late October of 1973. Where I spotted a few bone fragments on the ground that uh constituted part of a human knee. And we could tell it was from a human knee because of the anatomy. And the anatomy told us that that knee worked the same way that your knee and my knee works. In other words, it was from a creature that was walking upright. And, uh, within the world of mammals, as you well know, uh, humans really stand out because we get from here to there by walking on two legs. All other mammals walk on four legs. So we knew this was from a human ancestor, and Maurice said, geologically, it looked like it was from below a volcanic lava. That eventually was dated at over 3 million years. We now know that that knee was 3 is 3.4 million years. In in age. So all of a sudden we had the proof we needed that these beautiful deposits behind me contained remains of humans. We didn't know who that human was. We didn't know it it got the name Australopithecus, eventually, which, as you said in your introduction, and named after the Aar region called Afaensis. But uh at the time, all we knew was it came from a creature that walked upright, and that For the very first time, was the proof we needed that this huge geological region contained fossils of our human ancestors, not just all kinds of mammals, but also those that were an ancestor to later humans. And that was what really launched uh our expeditions to this arena.

07:11 Ricardo Lopes: And why were or even are still Lucy's fossil remains so important.

07:19 Donald Johanson: Well, Lucy, uh, we have to, you know, we have to look back a little bit, uh, to understand that, uh, in terms of what what we knew at the time of her discovery. She was discovered the following year in 1973. Uh, WHEN I was out with one of my graduate students, and I happened to Look on the ground, I'm always looking at the ground and uh spotted a little piece of uh of elbow. Hm. And uh it was just a small fragment, and I, I thought this is not a monkey, this is not an antelope, this has to be from a human ancestor, but it's so tiny. Well, I then thought the knee was very small. Are all these pygmies or small people or what, what are they? And um at that time, in the early 70s. In terms of our understanding of human origins, everyone placed uh the South African fossils, Australopithecus africanus, at the base of the human family tree that gave rise to everything from Homo habilis, uh, to robustus and Boisea, and so on. And uh this discovery of Lucy was going to be very critical in more closely examining that hypothesis, because Lucy was 40% complete. It wasn't just a fragment of jaw. Uh, WE now knew that from the teeth, it belonged into the genus Australopithecus. Uh, WE didn't know until 4 years later, or announced till 4 years later. That she represented a and she and the other fossils frompa represented a new kind of human ancestry, more primitive, but walking upright, very small brain. That was a much better candidate for the common ancestor. So, uh, she. Really Caused us to reexamine the shape, the geometry of the human family tree. And remove Africanus from a common ancestor to all the later branches. And uh she led us to uh other fossils at the site, which indicated to us that this was an early human species. We now know one that lived close to a million years in eastern Africa, you know, you and I as Homo sapiens, and maybe we've been around for 200, 250,000 years. And that her species lived in Kenya, Tanzania, uh, Ethiopia, and probably also in North Central Africa in Chad. So it was a very widespread species, geographically widespread, and it lasted a long time. Which meant that it was highly adaptable, that it could adapt to different kinds of environments. And also, we learned that the small individuals like Lucy, And like the need. Uh, WERE from females. Uh, AND the males are much larger, that there was a large degree of what we call sexual dimorphism that males were much larger, females much smaller. So this unleashed decades of uh re-examination of the earliest stages of uh our our origins. And Lucy has continued to be at the focal point. Of this research. Uh, WHENEVER someone thinks about early humans, uh, and they pick up their newspaper, I don't know what your local newspaper is, but, um, and a new discovery is made, uh, in, in Africa, they always say, oh, it's older than Lucy, or younger than Lucy, or the same as Lucy, or different than Lucy. So, Lucy continues to be that important comparison, comparison to everything that is discovered. So she has become the benchmark by which all other discoveries are compared and evaluated. And uh it seems that uh Very frequently, there are people who who find new aspects about Lucy. For example, there's been recent research on the size of her brain, which was really quite small, but the size of a good size orange. You know, our brains are 3 or 4 times as large as her brain. And um it it we've been able to reconstruct those using technology in virtual space to determine size of brain in bluey species. And it has shown us that uh already there seems to be some natural selection for somewhat of an increase in brain size. So, she, uh, and all of her other, we have more than 500 specimens of her species now. So we have a good understanding of her biology, and uh she continues to be the real focal point of paleoanthropological research in this time period.

13:06 Ricardo Lopes: And what do we know about Australopithecus afarens? You mentioned, for example, the places where these species lived in Africa, uh, but what other information do we know about it in terms of, for example, anatomy and sociality? I mean, what other things do we know about it?

13:28 Donald Johanson: Well, um, from, uh, there's, there's controversy about many of these topics, but, uh, we have not found any stone tools, uh, in association with any of the human fossils at Hawor. Uh, I think that her species, uh, was not fashioning stone tools like later species like Homo habilits, but we do know from uh discoveries at one fossil locality. Uh, WHICH is called the first family. There are remains of 250 fragments of bones, including parts of skulls, uh, a child's skull or baby skull, who died probably around 3 years old, and so on, that there are large specimens and small specimens, and there are young specimens, and there are old specimens in this one geological layer, which means that they were certainly living in groups. Uh, LIKE modern chimpanzees, and I think when you are a biped like this, uh, and, uh, particularly in the case of females, Uh, you need this protection of living in a group. So they were living in a group. Uh, WE don't know exactly why this group died and was buried in this geological layer, but I suspect that they, their group size was not dissimilar, or may have been very similar to what we see in in chimpanzees, maybe 30, 40 individuals. So, uh, and we know that uh there is some extension of, of uh childhood, that they, uh, their brains continued to grow. For a number of years after birth. Uh, AND, uh, it means that there probably was some particular care given to these offspring. They had more to learn about their world, let's say, than a, than an average chimpanzee. Uh, WE know that, uh, from, uh, studies of isotopes. That uh they were um. Essentially vegetarians. Uh, WE know that, uh, they didn't just survive on vegetarians, because at the, the, the particular locality where Lucy was found, uh, it's interesting, uh, during our excavations, we found a number of things that were surprising. We found uh crocodile eggs. Uh, WHICH are more or less the shape of the eggs we have in our refrigerators, and we found round eggs, uh, which are turtle eggs. Uh AND uh what that suggested to us, uh, was that Lucy had actually been buried in a beach sand. Uh, IN the old, in the ancient lake that was there, and perhaps she was down at the edge of this lake, not only to get a drink, uh, humans have to drink every day, primates drink every day. And uh. But she may have been collecting turtle eggs or crocodile eggs, uh, and including them in in her diet. She probably was climbing trees to eat and collect birds' eggs and small vertebrates, uh, and, uh, I remember very vividly, one of our students on the trip, uh, brought a a strange looking thing to me. Looked like an enormous canine, and upon further examination, we realized it was a a claw of a crab. So maybe they enjoyed a nice crab dinner from time to time. Uh, BUT predominantly, uh, the trace elements and the environment in which they live suggests and the and the wear on their teeth suggests that they were essentially vegetarians, but they certainly uh could have eaten um turtle eggs, crocodile eggs, and so on. And in a documentary I did uh in the early 1990s. Uh, IF you've seen that, uh, I, uh, reconstruct had reconstructed Lucy using a, a, a, a twig or a blade of grass, taking termites like chimpanzees and eating the termites, which are a great source of protein, amino acids, and so on. So, uh, I, no one ever had thought about that before, but of course if chimpanzees do it, why couldn't, uh, Australopithecus have done this. So, uh, they were living in troops. They probably weren't very dense on the landscape. There weren't a huge number of them on the landscape. They were not big herd animals like the antelopes and gazelles. Uh, SO they, they did live near a lake, a permanent source of water. And I suspect uh that in many ways, uh they were very similar to uh chimpanzees and their behavior. Uh, BUT they were beginning to Probably move in a different direction in terms of social interaction with one another. We don't know for certain, um, we know they were lived in multi-male and multi-female groups. Uh, AND we would love to know more, but, uh, there are no, there are no signs of burials, there are no signs of elaborate tool making, so that, um, they were still, from our perspective, you know, walking around with things like this, uh, quite different. And technologically nowhere as uh close to us in terms of their uh cultural artifacts.

19:45 Ricardo Lopes: And what do we know about uh its phylogenetic relationships? I mean, in terms of ominent species, what were, or what are its closest relatives and how does it relate to the homogenus?

20:02 Donald Johanson: Well, this is, this is a, a very exciting time, uh, in paleoanthropology. Uh, YOU know, the 1970s in my first book, uh, called the, uh, the Golden Decade, you know, when my colleagues like Richard Leakey and uh his mother Mary Leakey were working in Tanzania and in Kenya, finding fossil footprints of Lucy's species in Tanzania. Uh, THE late Richard Leakey finding a new species, and, uh, some more complete specimens of the early genus Homo, uh, up at Lake Rudolph, Lake Turana, as it's called now. And, uh, there has been an increase in the number of specimens of various species, but today, One of the, when, when I was asked uh uh during the 80s and and 90s, what, what I thought was perhaps one of the most exciting aspects was what is the relationship between Ahoensis and our own genus Homo. Uh, SO your question is, is was a question that all of us had for many years. And um we hypothesized, my colleagues and I hypothesized that Lucy was a common ancestor to one branch that led to our own genus, and led also to other Australopithecus species. But the problem was it was a million years separating Lucy from the genus Homo. And uh what was happening in that period? Well, scientists, I just spoke with one yesterday, Kay Reed, who was at the Institute of Human Origins Emeritus now. But her team Uh, has found a a lower jaw. Uh, THAT is, uh. About 2.8 million Lucy's species went extinct about 3 million years ago. So this is not long after Lucy's species vanished, and in the front of the jaw, you have a very angled chin. Uh, IN the back of the jaw, you have a very homo arrangement of the teeth and jaws. So this appears to be A descendant of Lucy, but it's placed in the genus Homo. And uh it means that uh there is a anatomical morphological connection between Lucy species oferensis and early Homo. And in the mid 80s, uh a skull was found uh at Lake Turkana by uh Richard Leakey's team. Uh, THAT was an Australopithecus, but it was a peculiar Australopithecus. It, it was called the black skull. It had a very strong crest on the top of its skull, but it had a very projecting face and enormous teeth. Luy species did not have huge crushing and grinding teeth. So this specimen known as the black skull, or 17,000 is its Catalog number had a projecting face like Lucy. But Massive muscles for mastication for chewing and enormous crushing and grinding teeth, and it was at 2.5 million years, so it was halfway between the disappearance of Lucy's species and the appearance of something we call nutcracker man, the skull that was found in 1959 at Oldvai Gorge by Mary Leakey, which was this robust Australopithecus called Australopithecus Boisea. So now we have a few connections. Between Lucy and later species of Homo, and later species of Australopithecus. So, uh, this is uh uh an interesting hypothesis that we're working with right now. And uh so that was one of the real focal points one of the real questions, you know, reporters would always say, what are the remaining questions? I said, well, there are, there, there are many questions that I won't remaining questions that I won't bore you with, but the two major areas is where did our genus come from? Homo Which ultimately led through some superorous route through phylogenetic changes to us, Homo sapiens. And uh what was the ancestor to uh Lucy's species? BECAUSE Lucy was the only species we had at that time between 3 and 4 million years. And it also seemed to me that it was very strange that there were not other species. So if we shift forward to today, Uh, Richard Leakey's wife, Meeve Leakey, working south of Lake Turkana, found uh a series of jaws and teeth. Uh, THAT are clearly Australopithecus, and to evaluate those and to put them in perspective, or put a forensis in perspective relative to them, they all came to, uh, uh, M came with some of her colleagues to my lab in Arizona, brought casts of everything. And we uh wrote a, a very important paper which showed that her fossils, which she called Australopithecus animensis, was an immediate precursor to Aerensis. It was Afareis, but even more primitive, had a very strong buttressing in the midline here. Uh, IT had very straight tooth rows like you have in apes, much straighter than what we see in our arns. And uh so this, this was suggested to be a common ancestor or an ancestor to Lucy's species. So, uh, most recently, uh, a team working in the middle Awash area of Ethiopia found something. That is still uh under consideration by many people, because we don't know uh if it really were really, if it really was an ancestor to Animensis. And this was something called Ardipithecus ramidus. And it is um a strange creature in many ways. It, it appears to be the beginnings of bipedalism. Uh, THERE are suggestions in the pelvis, but when you examine the foot, it has a foot like that. It's a grasping foot. For climbing, not necessarily adapted like our foot, if we look, take our socks off and look at our feet, our big toe is in line with the rest of the foot, and all these toes are shortened. So our foot is not a grasping foot, but a way of helping us move forward. And uh it's got very long arms that come down uh below the knee, so, uh, it was probably living a great deal in the trees. Uh, AND, uh, there are not many specimens well known of it. It's about 4.4 million years in age. Animensis uh goes back now very close to 4.3 million years. So is that enough time to evolve from a very ape-like creature to uh a creature that is more human-like? That's one of the big questions. And my colleague at the Institute of Human Origins, uh, Who is now director, uh, I'm very uh happy that we got him as a director. I'm, uh, will be retiring very shortly from university, but I stepped down as a director, and, uh, this is a, uh, fantastic, very accomplished, uh, Ethiopian uh scholar named Johannes Haile Selassie. He is, uh, he actually found the first bone of Ardi Pitaggus Rainus. And um he is working in an area uh that I've known about since the early 70s, um, northeast of where Lucy was found, and uh he's finding uh one or two, maybe three different species at about the same time as Lucy. And the big question is why was there such diversity there and now no diversity at Hat art. Uh, AND he found, he found a foot, a partial foot that shows that divergence. To that is contemporary with Lucy. Does that mean that that was the Ardipithecus was a separate, independent lineage, it lasted a long time, or was this just parallel to it having given rise to Australopithecus? So there, there are a lot of new questions being asked, and uh talking to my colleague Kay yesterday, they found some new things uh at about 2.8 million. Uh, THAT support the idea that perhaps, uh, there are more specimens of the genus Homo. It has not been put into a species yet because there's not enough diagnostic material. But uh they find stone tools. At 2.6 million years, uh, hoping to find them a little bit older. Uh, SO we're, we're, we're looking at an exciting time in paleoanthropology, when we're beginning to look at that very opaque period of time between, say, 2.9 million and 2.5 million. And uh there are uh numerous uh scholars uh working on this problem. And there's been a major development in Ethiopia. Uh, WE had a huge conference last summer to celebrate the 50th anniversary of uh Lucy's discovery. I can't believe that. I was 31 when I found that, today I'm 81, but um I remember as if it was yesterday, and at that conference, what was so amazing, if I went to a conference like I did in Africa in the early 1970s. There there were no African scholars in the audience. Uh, AND, uh, just like in, uh, in the United States, uh, we wouldn't want all of these excavations of, uh, you know, Native American sites and so on being conducted by foreign scholars. We'd like to be participating in that work. It's only natural. And over those many years, there have been efforts, uh, not just by me and my institute, the Institute of Human Origins. But by many other scholars to train uh African scholars. And this has been particularly uh notable in Ethiopia, where there are uh Ethiopians, a number of Ethiopians who are undertaking their own expeditions and making their own discoveries. And making their own breakthroughs. Uh, Johannes is a is a prime example of that. At the University of Chicago is a a close friend of mine who did his postdoctoral work at the Institute of Human Origins. His name is Zaa Alamseed. And uh he was born and raised in uh in Ethiopia. And uh he developed a real interest in uh human evolution. And uh made a discovery of a partial child skeleton, which is uh which is 3.4 million years, 3.3 million years old, a little bit older than Lucy, but the kind of baby that Lucy would have had. So he's now trying to understand how does a baby offers grow up to an adult offererances? Is it slow? Is it fast? Is it delayed, and so on. So, um, there are, and the Ethiopian government, the Ministry of Culture in particular, uh, I met, uh, members of the ministry when I was there in August to give a, a very important paper, uh, to open this big conference celebrating Lucy, and there are, there are laboratories. Uh, THERE'S a major building that's been built to invite scholars from around the world to come and study these fossils. So, uh, as we look back, uh, as it takes a long time to study and understand and interpret these fossils, it, you know, I always, I have an expression in that I use in my life that the road to success is always under construction. No matter how hard you try, there's something happens. And uh it took a long time for this to happen in Ethiopia. It took almost 50 years. But now there are Ethiopian scholars who are doing cutting edge research, are as qualified as any researcher in the world. Uh, AS opposed to when I first began in Ethiopia in 1970, uh, there were no laboratories, there was no real place to store these fossils. There was no place to study them. There, there were, there were these fossils were taken abroad to be discovered, but everything has been returned to Ethiopia. It's all housed in the National Museum in Addis Ababa. So, we're seeing the results of uh years of study of the fossils, and years of efforts to to bring African scholars into the research arena so that they themselves can organize their own teams, raise their own funds, make their own discoveries, and interpret the fossils that they themselves and their teams have discovered. So, Lucy was not only important for our understanding of human origins, not only important as a benchmark. If uh it seems that no matter where I go, if I'm getting my by going to my doctor, for example, and the doctor will say, well, now your name sounds very familiar to me. What, what, what do you do? And I said, Well, I'm an anthropologist. And he said, well, what kind of anthropologist? I say, I know Lucy, you know, she brought it all to the public. She brought human origins, the subject of human origins to a worldwide audience. And thirdly, these early discoveries uh stimulated uh all of us, as well as the Ethiopian government to see how important it was to develop this research in Ethiopia itself with Ethiopian scholars. So, um, there is, there are people who have just come back from the field. Johannes just came back from the field. I haven't spoken to him as to what he and his team have discovered. But, uh, certainly there, there are going to be many more discoveries made in Ethiopia to help us understand that transition from, uh, for instance, to Homo, and from Homo, whatever it is, we don't have a name for that earlier species yet, uh, to the emergence of things like Homo habilis and so on.

37:10 Ricardo Lopes: OK, so let's talk then now about Homo habilis. Uh, YOU have also done some work on it on this species. What do we know about it and its phylogenetic relationships?

37:24 Donald Johanson: Homo habilis, it probably goes back to about 2.4 million years, 2.3 million years. Uh, WE found, uh, at the site of Hadar, uh, a complete, fairly complete upper jaw. Which is completely different from an Australopithecus jaw. It has a very high dome to the top of the mouth. There's a palate, for example, uh, the teeth are very different, uh, the shape of the front of the nose is very different. So it belongs in the genus Homo. Uh, WE'VE been reluctant to put it into a species, but there are aspects that are similar to Homo habilis. It was originally named in 1964. With discoveries at Olduvai Gorge in Tanzania by uh Louis Leakey and uh Philip Tobias and John Napier. Uh, AND, uh, It is, uh, it, it has a larger brain size, um, it's probably, you know, A few 100 cubic centimeters larger than what we're seeing in Australopithecus, maybe as much as uh twice the size of Australopithecus, uh, associated with stone tools. Uh, ASSOCIATED with butchered bones. Uh, CONTROVERSY as to whether or not they were really doing much hunting or just scavenging, but they were now including a significant amount of meat in their diet. And uh meat is very important because it is a high energy food. And as opposed to um predominantly being a vegetarian. We think that real hunting, that is having a strategy to go out and hunt and kill an animal, uh, really only traced back to about 1.5 million years in things like homo or gastro, that Homo habilis was, uh, probably more of a scavenger. But it was making regular tools, which are called Ooin tools after old divide. And those old one tools can now be traced back to about 2.6 million years. So they were making uh stone tools for quite a long time. We don't have any cranial material from this 2.3 to 3 million year time period, so we don't know what their faces looked like, how large their brains were, how their bodies were built, and so on. But uh and what is interesting about Homo habilis is that. The one specimen that uh a team I led to Tanzania found. Uh, IN the, in the 80s. Uh, WHICH is called Olvi hominid 65. Uh, IS that it's got, um, Relatively long arms like you see in. Australopius. So that ties Homo there again to Australopithecus. And um so there's a big discussion as to whether there is only one or more species than Homo habits living in contemporaneously. Uh, AND the suggestion is that, uh, the hypothesis right now is that to havelis did give rise to the African, uh, Homo erectus, which is called the Homo ergaster. Uh, AND, uh, in Homo orgaster, the Turkana boy found at Lake Turkana is a fairly, it's so wonderfully complete specimen. I just saw it, uh. A couple of months ago when I was in Nairobi. And I've, I've seen it over the years, but it's, it's, it has a body like us. It has a long, narrow body. It has a very long legs, relatively short arms, it has a larger cranial capacity, close to 1200 cubic centimeters, almost 3 times the size of Lucy's. Uh, AND is associated with stone tools and butchered animals. So Homo habilis, uh, as always seems to be going undergoing some sort of revision. There's this specimen along. In Homo habilis or should it be in homogaster and uh. We do need further materials to see if there were multiple species living at that at that early time. But uh once we began to include meat in our diet, Um, it, it was very important for the development of, uh, Our most important organ, which is our brain. Uh, OUR brains are, are one of the hungriest parts of our body. We use a lot of calories. And um you, if you look at vegetarians, Uh, within mammals. Generally, uh, and I'm not talking about humans, uh, my wife is a vegetarian, but, uh, But uh uh animals that are vegetarians, they're not very Intelligent, they're not very bright. Um, YOU know, they, it, it doesn't take a lot of intelligence. To for for herbivores. To run down bushes or grass, right? It's just there. But they have to eat all the time. They're eating all day long. You go out, I, I was out yesterday and there were a bunch of sheep, uh, nearby, and, uh, you know, they're out there to cut the grass down, and they're just eating all day. Um, BUT her but carnivores on the other hand, whether it's your family cat, uh or uh a coyote, which we have in California, uh, and Arizona. Um, THEY, they're, they, they're brighter animals because they have to strategize, and it takes more brain cells to do that, to hunt down and kill their animals. And uh I think that as our earliest ancestors were tied so closely to the African, a common ancestor with the African apes, that they were vegetarians, there were dietary restrictions on feeding a brain. But once you had a high energy food source on a regular basis, like. Uh, ANIMAL meat. Uh, THERE was natural selection for larger brains. I mean, larger brains, better tools, better tools, more meat, larger brains in that feedback circle. So, uh, meat eating became very, very important, uh, after, uh, 2 million years ago, and, uh, certainly is evident in the bones we find. Associated with Homo habits. For example, uh, at Olduvai, uh, have you been to Africa?

45:13 Ricardo Lopes: Uh, NO, not yet.

45:15 Donald Johanson: OK. Well, when you go to Olduvai, as I hope you will someday, uh, you will see that the animal bones, the antelope bones and hippo bones and whatever, are all broken up. You know, they're smashed, and if you look closely, you can see cut marks on them. So those cut marks were made by stone tools, which were obviously in the hand of Homo habilits probably. Uh, DID Australopithecus Boisia use stone tools? I don't think so, but We'll see. And um so they were uh beginning to scavenge carnivore kills. And if you, uh, as I've uh seen uh animal kills in Africa many times. Uh, EVEN the hyenas can't get into some of these bones that have a very thick, uh, cortex to them. But if you've got a, a, a, a hammer stone. And small flakes to disarticulate the skeleton and run away with a leg or whatever, and you smash these bones and you open them, there's bone marrow inside. And that was a meat, it was a source of protein and energy that uh even other animals couldn't. Get to Uh, but early humans could. And, uh, meat, once meat comes into the diet, I think we largely move in a very different direction to a much more sophisticated uh groups living together, more sophisticated technology, um, and, uh, of course, uh, when we look around the world today, uh, we were hunter gatherers until Well, 1214 1000 years ago, very good hunter gatherers worldwide. Uh, EVERYBODY was a hunter gatherer or a hunter fisher or fisher gatherer or whatever. But once agriculture came in and gave us even more leisure time, Uh, our cultural innovations just rose asymptotically, uh, just in my lifetime of 50 years, when I think back to, you know, typing my doctoral dissertation on an old typewriter, um, and today I have this wonderful computer in front of me. Uh, SO, culturally, we're evolving very, very quickly. Um, SO, uh, the innovations, early innovations that were made, uh, set the stage for advancements, and I think that the inclusion of, of even scavenged meat, uh, had a very important impact on uh our evolutionary trajectory.

48:18 Ricardo Lopes: Mhm. So, let me just ask you one final question because we've already done around 50 50 minutes. Do we know which was the first species of the Homo genus? I mean, we have Homoaboles, you mentioned Homo ergaster. We also have Homo erectus. I mean, was any of these species the first one of the homogeneus or not?

48:47 Donald Johanson: Well, I, I, I think, uh, I think that the, the mandible I mentioned at 2.8 million. Uh, IS, uh, Really almost half a million years older than Habilis. And uh I would suspect it was a different species, but we, we don't have enough of it to conclusively show that it's that different from Homo habits. So we have to, we have to get we have to get more material, um, but I, I, I would go as far as to say. That the earliest homo. WAS A descendant of Lucy's species of forensis. And That as far as we know, this was an event. That happened in eastern Africa. And We are beginning to understand much more completely. Uh, THE, uh, a very important boundary. In our evolutionary record. That before 3 million years, we have only Australopithecus. After 3 million years. More recently, we have Australopithecus and Homo. So Homo arrived around 3 million years ago, was my estimate. And that uh Why did Afarensis disappear? Why were there new species of Australopithecus, and why did Homo appear around 3 million years? Well, what we know is that there was a significant climate change around 3 million years. And that climate change. Uh, Generally speaking, was a period when there was a drier period. And uh many of the more forested areas were beginning to disappear. And more open areas. I don't wanna say, you know, grasslands, woodlands, uh, began to appear. And We also interestingly see. That there were uh there was a uh explosion in the diversity of herbivores. Uh, BIG herd herbivores like antelopes and gazelles that came in from Asia. And uh a diversity of some primates like baboons, which were essentially herbivores and perhaps grass eaters. Uh, IN some instances are seed eaters. And um. There was a there was a period of competition for for those vegetarian food sources. And some of them specialized in strict vegetarianism, like robustus or Boise I or Nutcracker man, that that group of robust Australopithecus, but they made the evolutionary mistake. That so many species do. They don't know where they're evolving to. They became so specialized that when uh they had competition from herd animals like gazelles and antelopes and baboons, um, They lost out Because they were just outnumbered, and they had less uh availability for the vegetarian diets that they had developed. The other lineage that evolved into homo. That we get the earliest tools at 2.6 million years, and there are supposedly tools at 3 and 3.3 and these large tools at at Olduva or at uh Lake Jacana, but they're not Oduin tools, they're just bashing tools. Uh, THERE are cut marks on one bone from afarensis layer, but there are no tools nearby. Were those really made by purposeful stone tools or? Were they made by some other agency we don't know. But uh once tools came into the record, it, it changed significantly. Um, THE availability of certain kinds of food. Um, WHICH, uh, I think early homo was beginning to exploit. And uh when you, uh, as I said, when once you, if you go to all the, all the bones are broken up because they're getting marrow and meat and so on. And I think this begins uh fairly early, around just after Lucy's disappearance. And uh if that's the case, um, It means that there was a really different behavioral change, a very significant behavioral change, that was ultimately influenced by competition for food sources, which was brought about by changes in the environment. So, uh, I am eager to see a team find more complete homo, uh, at 2.5 to 3 million, to see what that creature looks like, uh, to see if it retains a lot of our creatures. What changed first, uh, we know with the robust Australopithecus that the first thing that changed were the sizes of teeth. And the huge chewing muscles, and only later did the faces become flat. So we're beginning to understand the sequence, and it's very important to understand not only uh the tempo, the speed of evolutionary change, but the the kind of evolutionary change. And that is where I think the field will be the fieldwork will be so vitally important to help us understand the emergence of Homo and its uh diversity.

55:16 Ricardo Lopes: Uh, SINCE you mentioned that, uh, as a last question, let me just ask you then, apart from what you mentioned there, what would be other questions about the ominent evolution that you would like to see answered in the near future?

55:35 Donald Johanson: Well, I think, uh, uh, one of them is uh very specifically where Johannes is working with 2 or 3 species, uh, between 3 and 4 million years. Uh, WHY are there so many species there? And in Hadar there was only 1 species of Australopithecus. That's one. Crucial question. Um, THE other crucial question is, um, What is the relationship of Ardipithecus to later humans? And, uh, you know, once you get back over 4 million years, uh, I think we're going to find some surprises that there may be different species there. Uh, AND, uh, so I think we're still focused on, um, species diversity, different adaptations, uh, and, uh, ancestor descendant relationships between these early Pleo Pleistocene hominids. Mhm.

56:39 Ricardo Lopes: Great. So let's leave it there, Doctor Johanson. Thank you so much for taking the time to come on the show. It's been an honor to talk with you.

56:48 Donald Johanson: Well, you're very welcome. Um, I have never visited your wonderful country. My wife and I are certainly going to come and visit someday.

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