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Science Talk September 20, 2006 -- Human Evolution Fossil Find; and Oil Company Conservation Comments
Welcome to Science Talk, the weekly podcast of Scientific American for the seven days starting September 20th. I am Steve Mirsky. This week on the podcast, it's a girl—a very young, very old girl. A major paleoanthropological find was announced today. The discovery of the extensive remains of what is being called the Dikika baby. She was discovered in Ethiopia not far from where her famous relative—the fossil known as Lucy—was found. Donald Johanson discovered Lucy more than three decades ago. He is now the director of the Institute of Human Origins and professor of human origins at Arizona State University. He joins us to talk about the new finding and what it means for our understanding of human evolution. We will also hear some very interesting comments that John Hofmeister made last week in a talk he gave. He is the president of the Shell Oil Company, but these particular comments might be some unexpected fuel for thought. And we will test your knowledge about some recent science in the news. First up, Donald Johanson on the big fossil find from Ethiopia.
Steve: Dr. Johanson, thank you very for talking to us today.
Johanson: Well, it's a pleasure to be here to talk about this exciting new discovery from Ethiopia.
Steve: A major paleoanthropological find that's being announced today. Can you tell us exactly what it is and talk about why it's so exciting?
Johanson: Well, the discovery made by [the] Dikika research project under the direction of wonderful Ethiopian scholar Zeresenay Alemseged. We refer to him usually as Zaray as I will do
so in this interview. The remarkable discovery that Zaray and his team have made in Ethiopia is of a 3.3-million-year-old partial skeleton of an immature individual—a baby virtually—that died at about age three. And what is so remarkable about it is that there is a virtually complete skull; and by that I mean the brain case, the face, and the lower jaw, or mandible, is still in articulation with the face. There are numerous rib fragments. There are both collar bones, both shoulder blades, there are number of vertebras such as those from the neck, from the chest, and even a few from the very low down in the back and lumbar region. There is a piece of arm, there are some hand bones and enough of the lower limb, the thigh bone, and tibia, or shin bone, that shows us that this creature was certainly upright walking [upright]. So, it's a remarkable discovery, because of its completeness, because of its age—its geological age, 3.3 million years—and also the fact that it is such a young individual or was such a young individual when it died.
Steve: Why are juvenile[s] so valuable to find?
Johanson: Well, one of the important questions that we all ask ourselves is whether or not the features, the anatomy, of adult specimen[s] that we traditionally use in giving a description or diagnosis to a new species—for example, this specimen belongs to a species already very well known from discoveries that I have made in Hadar, Lucy of course being the most famous. But how do we know that these specimens all belong to Australopithecus afarensis? And we usually see these features in adult specimens because those are the ones that preserve the best, and we want to know if some of those features, such as [a] curved hand bone, for example, are actually genetically driven or are they part of what happens through activity throughout the individual's life? Is it something that you acquire by holding onto a branch? Does that curve the fingers or is it something genetic? And here in this individual—as young as three years old—we see every single feature that clearly defines Australopithecus afarensis in a very young individual, so it means that these are genetically determined characteristics. So that makes this specimen incredibly important from that point of view. But it's also important because there will be differences in the shape of the face and proportions of the mandible and so on that will change throughout the growth of the individual. For instance, if we look at a baby chimp today, it looks much more like an adult human than does an adult chimpanzee.
Johanson: So that the changes that occur that make chimps very distinct from us are part of the growth process; and what Zaray and his group will be doing obviously is looking very closely at those changes that occur during growth and development—what you call androgenetic change.
Steve: You get two for one when you find a juvenile—you find out what characteristics are genetically—I hate the word programmed, but you know what I mean—and which ones are then [acquired and] get some insights into what happens during the development of the individuals in that species as well.
Johanson: That's exactly correct.
Steve: Can you tell me—people might not know that when you are out there fossil hunting, to find an almost-complete or, you know, half-complete skeleton is incredibly rare, is that correct?
Johanson: Oh, it's unbelievably rare. If I get back in my own career, I have worked in Ethiopia since 1970 and my discovery of the now-very-well-known skeleton popularly called Lucy nothing—like it has been found since, and that was found in 1974. So,
that it is an extraordinarily challenging endeavor. The probability of finding something like this is very low. So, of course I tip my hat to Zaray and his group for discovering this specimen, which—interestingly in a geographic sense—is just across the river from where I found Lucy; in fact as the crow flies, or I suppose in the African sense, as the vulture flies.
Johanson: It's about—they are separated by only about four kilometers. So, they are very close to one another. Lucy was 3.2 million years old, so this is a little bit older than the Lucy specimen by about 100,000 years. But from the description which Zaray has provided in this very important Nature paper, there is no question that Lucy and this new baby from the Dikika region, as it's called, belong in the same species.
Steve: There is a term that gets used a lot—intermediate forms—and I hate this term because I think it's almost disrespectful to the individuals that you are talking about, because when they were alive, they were not an intermediate form, they were whatever they were. Do you have that same opinion, by the way, about that expression?
Johanson: Well, I think that the term intermediate form is better understood from the perspective of time.
Johanson: If we look;—for example, we published an article of Bill Kimbel—who is the lead author, a colleague of mine here at the Institute of Human Origins—an article in the Journal of Human Evolution in June, and there we looked at nearly a million years of time from about four million to about three million; and there are two well-known species of Australopithecus, or ape man, as they are sometimes called. One of them is known as Australopithecus anamensis, about four million years, and one well-known one, Australopithecus afarensis. And when you look at features, you see that they change over time in a sort of a systematic way; and we interpret that as being a lineage in a strict Darwinian sense. Darwin suggested that species evolve out of other species along a lineage over a slow changing process. So that you could look at that million-year time slice and see that some of the specimens are intermediate in their anatomy as opposed to ancestral or descendant or primitive and advanced. So, I think if you have enough specimens over enough of a range of time, one can begin to talk about the intermediate nature of some anatomy. But you are absolutely right when you say these are not species or specimens that are going anywhere, they are not intermediate between anything at that time because they are fully adapted, fully in tune with the natural world around them; and it's only much later with the perspective of a time slice that we can actually appreciate the trends—for example, evolutionary trends—that might make some species more ancestral, others more derived, and some intermediate.
Steve: With that in mind, can you talk just a little bit about where afarensis is as a form that we now in retrospect
and think of as intermediate? It seems like you have a lower body that [is] this familiar for upright ambulation and an upper body that['s] still sort of climbing around a bit.
Johanson: I think this is certainly one of the great contributions of the Dikika baby
and[in] that, more clearly than ever—we have never had a complete shoulder blade or scapula, and both of them are preserved. And what's remarkable about it is that when you look at the little cavity, it's called the glenoid cavity on the side that points outward; it points directly outwards in modern humans, Homo sapiens. But in chimps and gorillas, that little cavity points more upward—more cranially, as we would say—because they were swinging around in the trees a lot using their arms. Well, in the Dikika individual, you can see clearly that that little cavity is pointing much more upwards and because of the breadth and the length of the shoulder blade itself, it looks more gorilla-like than anything we have ever seen. And the Dikika baby does substantiate the view that the evolution of hominids, like all animals was, in fact a condition, which we would call mosaic evolution—that they didn't sort of magically turn in overnight from an ape to a human; that natural selection sort of targeted its certain parts of the body. And it appears that the first major thing to change was bipedal locomotion; but those other features that were left over from the days of our far distant ancestors [who] were living in the trees are still seen in the skeleton, such as relatively long arms, curved hand bones, a gorilla-like scapula, a small brain, a projecting face, and so on. So, we are looking at a creature in afarensis—Lucy['s] species or the species of the Dikika baby—as being intermediate between ape and human. So, that I think is very important. The other part of the article by Zaray that is interesting is, they do suggest that those features in the scapula tend to be correlated with climbing behaviors. Traditionally, I think many people—including myself when we first found Lucy—thought that she was strictly a terrestrial creature, walking bipedally on the ground and never traveling in the trees. It seems now that more and more evidence s [is] suggesting that climbing behavior may have been part of their activity pattern and they may have been climbing into the trees to gather fruits or perhaps build sleeping nests at night.
Steve: What's next here? Are there other things percolating? I mean it takes years really between the time that the discovery is made and the publications come out. Are there other things that we don't know about yet that are still coming out that you have heard about?
Johanson: Well, there certainly are. There are colleagues who have made discoveries of various places who are working on them. We are still waiting for announcements of things that have been found way back in the early 1990s; and it does take a long time to process this information. I think that Zaray has done a splendid job of pointing out the highlights of this individual, highlights of this specimen. But it will be some years before a detailed monograph, as well call them—a book that is dedicated solely to the specimen—[will] appear; and by that time, I think, we will have tremendous insight into the growth and development of Lucy['s] species Australopithecus afarensis.
Steve: Dr. Johanson, thank you very much for your time. We really appreciate it.
Johanson: It's been a pleasure. Thank you so much.
Steve: For [a] collection of Scientific American articles on the subject of human evolution, go to our digital archive, www.sciamdigital.com, and check out the volume called "Becoming Human".
Now it's time to play TOTALL.......Y BOGUS. Here are four science stories, but only three are true. See if you know which story is TOTALL.......Y BOGUS.
Story number 1: Some have predicted future wars over water. Archaeological evidence now points to numerous conflicts over water supplies in the distant past.
Story number 2: If you are easily angered, it looks like you have an increased risk of lower lung function later in life.
Story number 3: The boy scouts of America now offer a merit badge in nuclear science.
Story number 4: The first complete g[e]nome of a tree has been sequenced, and this poplar has more genes than you do.
We'll be back with the answer. But first, John Hofmeister is the president of the Shell Oil Company. He gave a speech [in St. Louis] on September 7th at Washington University['s] Weidenbaum Center on the economy, government and public policy. I saw some brief articles about this speech and called up the university, which sent over a DVD of the entire talk. There were a couple of passages I thought were particularly interesting coming from the president of an oil company. Hofmeister made it very clear that Shell was in no way getting out of the oil and gas business, but he also addressed the benefits of alternative fuels; and then he said this.
Hofmeister: We believe at Shell that we have to change the hearts, the minds, the values and the behaviors of Americans toward a culture of conservation, to use energy differently and to use energy more efficiently in the world of tomorrow. Eight percent of the world's population today in this country uses 25 percent of the world's energy supply every day. That is not a sustainable formula for lifestyle and use of energy into the future when we know for a fact that the other 92 [percent] of the world wants their fair share of energy. And if you travel today to China, travel to India, travel to other parts of the world, you see increased use of energy in ways and means that we are accustomed to in our lifestyle; and you realize that we can't deny Chinese, Indians, Africans, Malaysians, other people from different parts of the world from also wanting their opportunity to use energy in different ways. And so the unsustainability of the 8:25 formula will only be satisfied in the current lifestyle by higher cost; and at some point cost is too great for the social requirements of our communities and our cities, and as a consequence people get frozen out. They can't afford energy, they can't pay the bill, they can't fill up the tank because it's too expensive. So, a culture of conservation to us deals with hearts, minds, behaviors and beliefs; and it leads to different ways of managing energy in terms of how we design our homes, how our cars are designed, how
are[our] factories, offices, and lifestyles are designed. I don't mean to be critical, but this morning, coming down the elevator in the Hilton, next to the ballpark, waiting for colleagues, you looked at the fireplace— is[it's] a gas fire heating an air-conditioned lobby. (Laughs) It looks great, it feels great—little chill in your back and a little warmth on your front—but is that an efficient use of energy in the world of tomorrow? The answer is obvious. A culture of conservation is much more in our view and Shell's view than simply moving the thermostat one or two degrees or driving slower or driving less. It's much, much more than that. Those are, of course, available options to every one of us today, but it's not enough. We need different designs and different mindsets around the engineers and the technicians and the technologists that work on these things; and we need to move forward as a society in a way that is different.
Steve: At the end of his prepared remarks, Hofmeister took questions from the audience. Here is his response to the question: Can you give us your thoughts on the science of greenhouse gases and that whole issue?
Hofmeister: For Shell, the debate is over on greenhouse gas emissions for two reasons. We believe the science is mature in terms of measuring greenhouse gas effects on the world as we live in it; and secondly, when most of the policymakers around the world have decided the greenhouse gas emissions are at a level that is not acceptable due to manmade issues, who are we to say they are wrong? They run our governments, they run our countries and we are citizens. So, we follow what our policymakers tell us to do, and so we think the debate is over. Let's instead get on with the solutions.
Steve: Anyway, I thought you would be interested in hearing those remarks. Thanks again to the folks at Washington University in St. Louis for supplying a copy of the speech.
Now, it's time to see which story was TOTALL.......Y BOGUS. Let's review the four stories.
Story number 1: Many examples of wars over water throughout history.
Story number 2: Easily angered may have lower lung function later in life.
Story number 3: The boy scouts are for a nuclear science merit badge.
Story number 4: A poplar tree has more genes than a human.
Story number 4 is true. The first complete genome of a tree was announced this week, and the poplar in question has about 45,000 genes compared with only some 30,000 for you. For more, listen to the September 18th Scientific American 60-Second Science podcast at www.sciam.com/podcast or at iTunes.
Story number 3 is true. The boy scouts do have a nuclear science merit badge. The journal Physics Today reports that the revised merit badge replaces the old atomic energy merit badge, and if you want one, be prepared to go through a 95-page booklet of requirements.
Story number 2 is true. A study in the journal Thorax followed 670 men taking part in aging research. Men who had high levels of hostility had consistently poor lung function. Remember—breathe.
All of which means that story number 1 about, numerous wars over water throughout human history is TOTALL.......Y BOGUS, because it now looks like the last war over water was fought between a couple of Samarian city states 4,500 years ago. Apparently, water is so important that countries—even those who may already technically be in a state of war—find ways to cooperate over H2O. For more, see the article titled "Water Wars Loom, but None in the Past 4,500 Years" at our Web site, www.sciam.com.
Well, that's it for this edition of the Scientific American podcast. Our email address is email@example.com. And also remember that science news is updated daily on the Scientific American Web site, www.sciam.com; and check out the new daily SciAm podcast, 60-Second Science, at our Web site and over at iTunes. For Science Talk, the weekly podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.