 For this morning music we give thanks to the Gustavus Wind Orchestra and their director, Dr. Wines, through the prairie, we find ourselves in this great tent of meeting. Welcome to Gustavus Adolphus College as we turn the page to the 39th chapter of our Nobel Conferences. This year, as we gather for the story of life, let us begin with silence and prayer, which is ineffable, and that which is ultimate. We stand before you, O God, joining with the psalmist who sings of your love in the morning and your truth at the close of the day. We give thanks for Alfred Nobel's generosity that has kindled the spirit of inquiry. We give thanks for the persistence of scientists and teachers who have dedicated and committed themselves to explore the evolving historic record in their pursuit of truth. We give thanks for all who come this day to also explore their place in this grand story. Keep us mindful of the fragility of this ecosystem we share. Keep us vigilant of issues of equity and privilege. Keep us aware of our common concerns and our shared hopes. This we pray. It's my distinct pleasure to introduce you to the new president of Gustavus Adolphus College. Dr. Peterson is a Gustavus graduate. He studied entomology at the University of Nebraska and did post-doctoral work at the University of Wisconsin. Forsaking academia at this point of museology and became associated with a science museum in Philadelphia and then before returning to assume the role of president of the Minnesota Science Museum here in Minnesota. Welcome to the 39th annual Nobel conference here at Gustavus Adolphus College. This year's conference, The Story of Life, has been planned to explore some of the most profound questions we can ask. How did life on earth begin? Where do humans come from? How did humans and other species evolve? What responsibilities do we have to each other into other species on earth? What are the implications of these questions? And the implications of some of the answers? I welcome you to what promises to be two days of thought provoking and insightful sessions of discussion, questions, and yes, even a few answers. While I have attended past conference, this is a first in my relatively new role as president of Gustavus. Given my long-term interest in science and education, including my years at the Science Museum of Minnesota, how wonderful it is for me to see this extraordinary range of people, high school students, teachers, college students, faculty, residents of our local communities, and for many others from throughout the Midwest and beyond, all of you lifelong learners. To help fuel that lifelong journey to challenge our thinking and our assumptions, the Nobel conference has dealt with topics recently in genetics, virology, astrophysics, and material science, along with last year's timely conference on the nature of nurture. This year's conference on the story of life is, I think, perpetually timely, as we ask the most basic questions about the origin and history of life on earth and by extension, our connectedness to the natural world and to each other at a time of global stress and uncertainty and division. My hope as we leave this conference is that we might continue these conversations about how a greater understanding of our past and our present can inform our deliberations, our discussions, and our decisions about the future. We are very fortunate to have with us for these two days persons of extraordinary achievement and wisdom who can help us both ask and answer significant questions. These annual Nobel conversations with some of the most renowned thinkers at the forefront of their own fields underscore the commitment that Gustavus has to the full and lively exchange of ideas that has become the hallmark of a liberal arts education at this college. These conferences could not be what they are without the relationship that Gustavus enjoys with the Nobel Foundation of Stockholm, Sweden. We are also indebted to the Nobel Laureates who nearly 40 years ago played a role in shaping and planning the first Nobel conference and to the many other laureates and speakers, distinguished speakers who've added to the intellectual vibrancy of these conferences. We have a number of special guests with us today, friends of the college and leaders in their respective communities. Welcome to you. Several sponsors are here who have assisted in underwriting the cost of this conference. There are costs of doing this, you know. Including an American Express financial advisors, Cambria, the 3M Foundation, the Kelvin and Diane Miller family. It is my pleasure also to make special acknowledgement of the financial support of the Nobel Conference Endowment, first established some years ago by the Russell T. Lund family and augmented by the United Health Foundation and the Mardag Foundation in memory of a long time friend of this college, Edgar Ober. And special thanks to doctors Robert and Susan Riedel whose generosity has brought to Gustavus classrooms leading scholars as Robert and Susan Riedel distinguished Nobel conference professors. Again, on behalf of the entire Gustavus College community, it is my great pleasure to welcome you to this special telling of the story of life. Let me close with the simplest of versions of the story of life. It's from a children's book by Lisa Westberg-Peters. It's on sale over the bookstore by the way if you want to stop there. We began as tiny round cells and we've changed a lot since then. But we carry with us reminders of each step of our past. That's how it is with families. And ours goes back. Dr. Robinson, let's start the conference. Thank you, Jim. For those of you who are first time Nobel conference attendees, a special welcome. The next two days, and I hope like the rest of us, you'll have some fun while you're here. I'd also like to, those of you who have attended before, we've come informally to refer to this group as the usual suspects. Attend this gathering with astonishing regularity. Our president can recognize some people. I want to ask if there's anyone in the audience who has attended. Over here is Bruce Gray. Mr. William Harvey, longtime high school teacher here at St. Peter High School. The success of this gathering is due in large part to the extraordinary dedication of you folks and they're extremely appreciative of it. It's now my pleasure to introduce our panel to you. Introducing our final speaker first. Our final speaker is Dr. Christian Dedeuve. He is a Nobel laureate in 1974 in physics and medicine. And if you've been with us before, at this point you would probably expect us to have an honorary degree ceremony. Well, as it turns out, this is Dr. Dedeuve's second trip here. Matter of fact, he was with us in 1975. A very special Nobel. We considered the future of science and we invited all living Nobel laureates at the time and 25 of us were in the T5 laureates. Again, if you're familiar with our operation here, we always have a theologian on the panel too. And we generally figure that the appropriate ratio is about one theologian per five or six Nobel laureates. And so at this gathering, we had 25 Nobel laureates and six theologians. And in the course of the event here, we had four featured speakers. Sir John Eccles, Flynn Seaborg, Polycarp Kusch representing science and the theologian from the University of Chicago Langdon Gilkey representing theology. After each of the talks, we broke down into discussion groups and we proceeded to hash out the question of the future of science. Couple of things were memorable also about that. One was that this was the first year that we held the conference in this building. It was not yet completed from the first week in January to the first week in October in hopes of better weather. Look closely at this photograph here of the audience and notice that they're sort of huddled together for warmth. It was 48 degrees in here, we had no heat and actually the back end of the building was not yet completed. So it was memorable for that. It was also memorable from another standpoint in that one of our guests, Nobel laureates, was William Shockley, a prize-winning physicist who at that time was advancing controversial theories of racial genetics. And actually the night before our Nobel conference, he gave a presentation in Minneapolis which as the press reported, he was roughed up by the audience. And this caused us some concern because we had some worry about his safety. And so for the only time that I can remember with Nobel conferences, we had to take extraordinary measures to protect the safety of one of our extraordinary measure actually was to deputize Professor Lawrence Potts from our chemistry department who served as William Shockley's bodyguard for the time he was here. His only regret was that they didn't allow him to pack heat for the event. But it was indeed a memorable time. Gets together to consider planning these events. We always try to assemble a gathering of the best experts on campus that we can. And this year we're extremely fortunate to have as our leader, Dr. Keith. We know him as Joe Carlson, 30 some years and just recently retired and took over the job of chair, faculty chair of the Nobel conference in retired. The question I asked them if we're going to tell the story of life from the beginning to present, what do we need? One of the first things that came to mind was that we need somebody who can talk about the original conditions under which life, the person who immediately can do as a molecular biologist to spend his life studying the workings of the cell for his work, the transition from prokaryotes to eukaryotes in the process of evolution. But one of the things made us also attracted to, Dr. Keith, is that he's recently published, Dr. Dust. And just last year he goes beyond purely scientific and considers some of the truly big questions in life. And we considered who better to tell the story of life than Dr. Dutu. Would you please give a special warm welcome to him? So I said, what else do we need? He said, we need an evolutionary theorist, somebody that can give us the big picture about what's going on in evolution. Natural history in New York City. My colleague, Russell Shapiro, will introduce him in just a few minutes here. But he will be our leadoff speaker here this week. So what else do we need? Italogists get to have their person, biologists have to have their person. And so the biologist said, we have to have somebody that continues in Darwin's footsteps, looks at the population of species and how they adapt. And the names that immediately came to mind there were Peter and Rosemary Grant from Princeton University. And at one o'clock this afternoon, they will give us a talk entitled The Evolution of Darwin's Finches. Another thing that we consider at this conference is what my predecessor, the former chaplain of the college, Richard Elvie, used to say is where is God in all of this? In addition to having a science-based conference, we always do deal with the topic of how God relates to these issues. And this was a very serious topic here. And one of the things that the committee and I concluded was that what we did not want to do was to put on a creationist-evolutionist debate. We felt that the time was to move forward from that. And instead we elected to look for some thoughtful people who were looking for some sort of common ground between science and religion. And I think we were extremely fortunate. Our theologian this year is John Hout. He comes to us from Georgetown University and will give us a talk called God After Darwin, Evolution and Divine Providence. And for those of you who are interested in sort of expanding on these issues here, we do have a special event planned this evening. Some of you will remember our firing lines from previous conferences. At 6.30 this evening, Dr. Hout has graciously agreed to sort of preside over a meeting dealing with issues in science and religion. This will be held at 6.30 in Alumni Hall. We also have a couple of other special things here. Since we were talking about fossils, we thought wouldn't it be nice to have some examples on campus here. And our friends at the Minnesota Science Museum were kind enough to loan us some absolutely spectacular fossils. These fossils, which includes a carnivorous dinosaur skull and very large crocodile skull are located in the forum, which is the next building over where our lunches will be served. And we invite you to inspect their exhibit there. We'll conclude the evening with a special concert at 8 o'clock in Christ's Chapel. Everyone is welcome to that as well, okay. Tomorrow, said the anthropologist on the committee said we have to have somebody who can talk about human lineage. And the question there was who to invite and our anthropologist was quite definitive in her answers. He says, Tim White is the person we want here. We will hear about his work in Ethiopia and hopefully he'll tell us about the 150,000 year old Homo sapiens that he discovered there just recently. And of course, you have to have somebody who does the fossil record. And doing that will be Dr. Phil Curry. He's a dinosaur hunter, okay. We had to have somebody who does dinosaurs on the panel here. And he's gonna tell us about some rather unusual ones. He's gonna talk about feather dinosaurs and the origin of birds. And finally, our last speaker at three o'clock tomorrow afternoon is Sean Carroll. We asked the panel, what's new in the field of evolution? And their answer was evo-devo. And of course, I had no idea what they were talking about. But some people on the committee says that Sean Carroll has the coolest website of any scientist out there. He has these spectacular pictures of insect larvae showing how they develop and how this in turn determines the body shape that they produce as they mature. And so our final speaker will be Sean Carroll speaking on butterflies, zebras, and fairy tales. Genetics in the making of animal-deserved diversity. Okay. And so it's time to begin. Let me begin by calling our first speaker up and I'll introduce you to my colleague, Russell Shapiro, who will introduce Niles Eldridge. Russell is new to our geology department. He's our new paleontologist. He deals with very, very old species. And Russell prevailed upon his friends in the industry to provide us with some very old fossils. And so if you are interested, in the lower level of the Nobel Hall of Science is a collection of some of the oldest rocks and fossils ever collected together. We have a three and a half billion year old stromatolite from Western Australia. And if you wanna know about stromatolites, talk to Russell. He's positively passionate about stromatolites here. So, Russell, take over. Any time you wanna talk about stromatolites, please look me up. Thank you. Recently, a colleague lamented that our students can earn a degree without knowing who Hegel was. Likewise, I think it's also regrettable that they can leave college without having read the theory of punctuated equilibrium. That seminal paper, although that paper was published in 1972, co-written by Niles and the late Stephen J. Gould, I feel it's still important, and not because it provides an alternate explanation that better fits the fossil data of evolution, but it's important because it was one of the key papers that forced paleontologists and biologists to critically reevaluate what Darwin had written. In the years since, Niles has spent his time at the American Museum of Natural History in New York, continuing to tease patterns out of the fossil record. Notably, he has published on the dark side of the story of life, Extinction, by looking at how the theory of punctuated equilibrium applies to these large-scale die-offs and the role the environment plays in those changes. He's also addressed fundamental issues for society in his writings on biodiversity, reminding us what Darwin professed a century and a half ago, that we must not forget that humans, too, are subject to the whims and the rules of nature. As a scholar, Niles has spent much of his career applying hierarchical theory to evolution, a radical, yet a very realistic approach. He wrote in 1996 that every kid knows the universe is hierarchically structured. Well, that's true. It is not difficult to conceive of any number of artificially constructed hierarchies to explain a variety of phenomenon, from symphonies to motorcycles. What's novel about Niles' approach is that he does not construct a hierarchical system but elucidates and gives names to real biological entities. And like his lovely trilobites of days gone by, hierarchical theory is itself evolving, and we all look forward to an anticipation to learn what Niles and his colleagues come up with next. He may produce a clodistic analysis of trumpets, but I'm sure he will take us to the next level, as my jazz friends would say. For now, it's time to turn over the lectern, and the last thing I'd like to say is in a nod to the other passion of your late colleague, it gives me great pleasure to introduce the 2003 Nobel lead-off batter, Dr. Niles Eldridge. Thanks very much, Russell. You know, lead-off batter gets dangerously close to mentioning baseball, and I just came in from New York, so I don't know if I wasn't gonna go there, but Russell started, it's indeed a pleasure and an honor to be here, starting off this symposium. I also wanna give a nod. I was very glad that the orchestra didn't have to sit there during my entire lecture, but I thought they did a fantastic job, easily the best music I've ever heard before I gave a talk. And what better person to start off our entire story of life two days here than Charles Robert Darwin, the man who wasn't the first to come up with a notion that all life has descended from a single ancestor, which will be the definition of evolution that I'll use, but certainly the first one to convince the thinking world that life has indeed evolved. We still debate, there's debate that was alluded to, largely over, actually completely over, has been for a long time within the cannons of science. There's no doubt that life has evolved, but there's still a debate in society at large and we're not going to, and I'm glad of it, spend much time, if any, talking about that aspect of things. Darwin is up here though, not just because he symbolizes the beginning of our study, of our scientific study of the history of life, but because he, well he was the first kid on the block to discover things and so he was so right about so many things that he remains integral to our understanding about how the evolutionary process works and of course the thing that he's most famous for is the notion of natural selection, which in a nutshell is that more organisms within any species in a local population are born each generation that can possibly survive and reproduce, so those that are best equipped to eke out a living and existence, statistically speaking will be leaving more copies of their genes behind to the next generation. Darwin knew nothing about genes, but he knew that they would be a relative reproductive success that would be caused by statistically, on average, by the relative success that organisms had in eking out a living and I'm very happy that the next talk will be all about this and this remains the core, I think, mechanistic concept of evolution. My theme today though is basically the importance of the environment and evolution, it's kind of interesting to me, I didn't know until I got here that last year's Nobel conference was actually on nature and nurture and in a sense this is nature and nurture writ large because I honestly feel that the rhetoric of evolutionary biology, certainly theoretical of evolutionary biology ever since the 1960s has been gene saturated, it's almost, if you read Richard Dawkins, for example, on the selfish gene, that it's a competition amongst genes themselves to shoulder each other aside and make it to representation into the next generation that is sort of a redefinition, a sort of a narrow, I think, definition, redefinition of natural selection and is the core essence of what's going on in evolution, it's how evolution works, it's competitiveness, competition amongst genes for representation in the next generation which is in fact driving the evolutionary process. Now, I'm a paleontologist, I know about genes, I've installed a molecular lab at the American Museum of Natural History, I think genetics is very exciting and obviously it's the relationship between genetically based information and something else which is going to give us the evolution of life and our understanding of how life actually does evolve and that's something else, however, is the physical environment. I was trained as a geologist, as indeed was Charles Darwin and many of our intermediary forms in the history of thinking about this subject and I'm going to put it to you, I'm gonna try to make a case for you today that it's actually the physical environment without which changes in the physical environment and its effects on living systems, particularly already up and running organized ecosystems. Unless and until you've got disruption of ecosystems, you're going to get very little evolution of the kinds that a person like myself can spot in the fossil record. It's very intriguing, I've got a working group established with half geneticists and half paleobiologists out in Santa Barbara and they tell me and I believe them that they see a tremendous amount of genetic change on a generation by generation basis within and between local populations. So in a sense what they're seeing is almost genetic chaos at least at some level in their populations. Those of us who are paleontologists tend to step back and look at the fossil record and we see great stability, we see almost intransigence resistance to change in many instance. And so the question then becomes, what is the context? Natural selection, yes, is going to give you evolutionary change but it's not inevitable with a mere passage of time. It's in certain kinds of situations where you're going to find it. And I think we've been able to pinpoint with great degree of accuracy and success in recent years what those ecological contexts are that actually do result in evolutionary change. So that's basically the drift of my story. The next, this is the only other person I'm going to be showing you in the course of this talk. This is a hero of mine, George Gaylord Simpson. He was a predecessor of mine at the American Museum of Natural History. I only glimpsed him from afar. I corresponded with him but I really, our careers actually did not overlap at the museum. He was a mid-century paleontologist, probably more than anybody else. He was responsible for keeping paleontology in the mix of trying to figure out how life actually evolves. So he's a practicing paleontologist but an evolutionary theorist as well. And one of the founding fathers of the evolutionary synthesis in the 1940s. And I bring him up for two reasons. I just characterized a sort of gross outlines, the kind of disparity in views or tension between a person like Richard Dawkins on the one hand and people like Gould or myself on the other hand who take radically different departures and have rather different takes on the nature of the history of life. And just to show you that this is nothing new, George wrote a book called, one of the great books in evolutionary history. Temple and Mode and Evolution was published in 1944 during World War II when he was an intelligence officer in Patton's army and giving Patton fits because he refused to shave off his beard for example and Patton told him to shave it off. So this guy was tough minded and he stood up for himself obviously. But he wrote this book in bits and pieces during World War II and the preface of the book has got some very arresting passages. I'm gonna read one for you. It's the only quote I'm going to read. But it characterizes the tension back in the 1940s, late 1930s, early 1940s that Simpson felt as a paleontologist vis-a-vis paleontology on the one hand and genetics on the other. I'm not trying to set up a warfare here, it's all true. We're gonna try to look for how it all fits together but the tension was there. He says not long ago, paleontologists felt that a geneticist was a person who shut himself in a room, pulled down the shades, watched small flies disporting themselves in bottles and thought that he was studying nature. A pursuit so removed from the realities of life they said had no significance for the true biologist. On the other hand, the geneticist said that paleontology had no further contributions to make to biology, that its only point had been the completed demonstration of the truth of evolution and that it was a subject too purely descriptive to merit the name science. And here's his punchline, the paleontologist they believed is like a man who undertakes to study the principles of the internal combustion engine by standing on a street corner and watching the motor cars whiz by. And indeed, how do you frame a testable hypothesis involving evolutionary processes when the material at hand are things that have been dead for hundreds of millions of years and they don't have any genes preserved typically with them and so forth. You've got the anatomy, you can see in fossils how the anatomy is the same through periods of time or it changes through periods of time or it varies in time and space and so on and so forth. And that's what he meant by geneticist saying that paleontologists merely document what happened but they are not privy to looking at that motor of change. And Simpson himself though was brilliant I thought and it's really the inspiration for all of my work. I didn't realize it until I was halfway through my career but what he says in this Temple in Modern Evolution is that there are repeated patterns in the history of life. That we as paleontologists can see them in the Cambrian with trilobites, we can see them in the Mesozoic with dinosaurs, we can see them in the tertiary with mammals and indeed, and I'll give a very brief example at the end, I do believe at least parts of this story of human evolution and Tim White will tell us a lot more about that, can actually be looked upon in this same sort of way. So no matter where you are in the last half billion at least years in the history of life, you can see patterns that are hauntingly familiar up and down throughout the history of life. And the question is how do you explain them and how do you integrate them with, and this was Simpson's I guess, great contribution of what is known about the genetics and the ecology of populations and of species. The idea is not to discover new processes that nobody ever dreamt of before but as Simpson says again in the preface to this book, what happens to 100 rats in the course of 10 years might be rather different if you blow that up to 100 million rats over 10 million years of time. The patterns might not exactly be the same. And even though I disagree in detail with what Simpson concluded about the major patterns and the major mechanisms in the history of life to a great degree I do disagree with him, it's the approach that he took, it's the how do we know. So I do think, and I agree with George and I agree with Darwin, that patterns in the history of life have a great deal to tell us about how life actually evolves. Not just the story of life, but how it actually evolves. I'm not gonna spend much time on this. Russell has got a display, is it in the Nobel building, yeah, on stromatolites. I can't resist but to mention, this is a stromatolite, these are so-called blue-green algae, they're actually bacteria, they're colonial, they come out every day and they photosynthesize and you see these laminy building up because every night when the sun goes down or actually the earth turns away from the sun, photosynthesis stops. Well, we must be accurate about this and the photosynthetic machinery stops and there's a deposition or a sort of a collection of particles just raining down from the seawater that's trapped in this sort of slimy mat and then the next day at all the bacteria burst forth again, these things are still being formed in places in Australia and so forth around the world but they're the oldest evidence, macroscopic evidence of life and I was just reviewing this yesterday with Russell, he tells me they're actually stromatolites. I thought they were simple bacteria three and a half billion years ago. The earth, by the way, was formed, gotta get this in, about four and a half to 4.6 billion years ago and one thing that I should leave you with is the notion that life is intrinsic to the earth because the oldest rocks that we find, sedimentary rocks where we might expect to find fossils, we find fossils and that's Wararuna group in Australia. It implies that life began earlier than this and of course it must have and we'll hear more about this from Dr. Dadoof because these are bacteria, simplest forms of life that we know because I'm excluding viruses at the moment but they are very complex compared to the first interactive sets of, if you will, economic and information molecules that must have been the nature of the very earliest living systems. So life is intrinsic to the earth and my only demonstration that to you is that the oldest sedimentary rocks you can find are virtually the oldest you do find traces of life in them. I'm not gonna push this too far but nothing was known about this when I went to graduate school so I'm really entranced with it and there was a huge bombardment of the earth by extraterrestrial objects about 3.8 billion years ago. Another Nobel laureate, Francis Crick, has said well perhaps life came in from outer space in the dirty snowballs of the meteors and so forth that might have been colliding with the earth back then. Nobody knows for sure but the possibility has arisen that life actually, I don't believe it, I think life probably most likely arose here on earth. I find it just sort of pushes the problem back if you follow Crick out that far and then as I say we'll hear more about it but it's kind of interesting that right around the time you find your first fossils and the first definitive evidence for the origin of life or the beginnings of life, you do get evidence of a major environmental episode on the surface of the earth. I already heard very briefly today, again in conjunction with Dr. Dedeuve, that the next big step in evolution, maybe 2.2 or a little bit older billion years ago, you got the first complex cells appearing and that's taking a bacterial cell with a single strand of DNA that's not in a nucleus and now having a much more complex cell with a nucleus, a double bounded nucleus and the genetic material arranged on the chromosomes and lots of complex organelles in the cell system themselves. Again I can't really go into this, it's not really the topic but now people are saying that there was environmental events going on around 2.5, 2.4 billion years ago that seemed to be correlated with this next major step. Is it cause and effect? I don't know. What were those events? There's a spike in oxygen which may or may not be related to a massive global ice age called Snowball Earth. It's a very exciting new topic. It comes in later on about 700 million years ago but back about 2.2, 2.3 billion years ago there was apparently at least one maybe more episodes where the entire earth froze over and that would have an enormous effect of course on whatever forms of life were around and as far as we know all that was around by that time were bacteria. So there's a pattern emerging here but again I'm not insisting on cause and effect. This is a trilobite, let me see if I have this down right. You touch this, yeah. In life there would have been antennae coming out and there would have been a pair of legs under each of these thoracic segments. I'll probably get good at doing this by the time the lecture's over. These are complex animals. This is an eye, whoops, the arrow's here. This is an eye here and another eye over here, yes. Primitive for trilobites but complex, they're arthropods that are related to crabs and shrimp and flies and so forth. All of a sudden appearing on the earth 543 million years ago people are still arguing whether this is sort of an artifact of the fossil record, the so-called Cambrian explosion. I'm one of those people who really think the evidence is there to show that it's a very real evolutionary event. It's an explosion, a proliferation of life and as again I was telling Russell coming in yesterday, one of the reasons why I'm back to thinking that, not that I ever really doubted it but if you look at the, there's a tree of life issue of Science Magazine last May and it's sort of a consortium of all the world's leading molecular systematists and other kinds of systematists but it's an infusion of knowledge brought to us from the genetic world about how different branches of life actually are related to each other. There have been some surprises because of this kind of work. For example, I think it's amusing to know that the closest relatives now amongst the five major groups of organisms on the planet, closest ones to us animals are actually fungi which I think is amusing but anyway. And this has been known for a while so if you open that issue of Science Magazine you'll see that that's in there and that's an accepted, not interpretation but that's the best map now of how those portions of life actually join together. But if you look at that section where the trilobites, these arthropod things here, the kindiderms, starfish and so forth, the mollus, these sort of higher developed invertebrate organisms and there's plenty, you all are familiar with them even though you don't live on the coast and stuff like that. They mostly live in the sea, marine invertebrates but we have them as arthropods flies and so forth and worms and so forth in the terrestrial biome as well. When I went to school we learned that there was no way to tell the arthropod anilid worm lineage that sort of converged down to the lineage that we're in, the deuterostomes and the echinoderms, the starfish and their relatives in a hodgepodge of things called brachypods. Some of you are studying brachypods with Russell right now, I know that, the so-called loafoforates. And the assumption has always been and I think it's a reasonable assumption that the more we know and in particular opening up these new avenues of analysis that we can get from molecular biology we'll be able to tease these apart and find out more details about who is precisely related to whom. And if you look at this May issue of science you'll find out that absolutely zero progress has been made in resolving that. And there can only be one explanation for that and that is that at about 543 million years ago which is erroneously because it's an old slide says 570 here, I apologize for that. There was a literal explosive proliferation of the major forms of animal life. Not your corals, not your sponges, they had already diverged somewhat earlier but these things like arthropods and the echinoderms are group basically being part of the deuterostomes, the anilid worms and so forth. Exploded, proliferated so rapidly at the base of the Cambrian giving us our first dense fossil record where the apologies to Russell where you can actually go out and see some fossils and pick them up and not have to hunt quite as hard as Russell does for his pre-Cambrian algae. It's a real event. And also in May in science, Andy Noel at Harvard and some of his colleagues published a paper that said there's a spike in oxygen there. So oxygen seems to be correlated. Now is that a cause? I don't know. There's also this notion that we're four or five or maybe even more snowball Earths that might have caused the oxygen spike. All I know is that we're getting these patterns of association which do not mean cause and effect. I'll get to the cause and effect in a moment but which I find very, very intriguing. Every time you get a major event in the early history of life there seems to be something weird going on with the Earth's environment, something very different and something rather extreme. All right. Now that I have the slide on, even though some of the numbers are inaccurate, this chart of geological time was devised pre-dark, most of the names were in place before Darwin published in 1859 on the origin of species. It's empirical. It's noticing what bodies of rock occur below what and above what and making the assumption that the rocks with the same fossils or very similar fossils are about the same age. And so you can recognize a Devonian rock who was named for rocks in Devonshire. Devonian was where I spend most of my time pulling around but there's a lot of Devonian in North America. We call it Devonian because the fossils are so similar and they occur above Solerian rocks and again in the Solerian it happens to be an unusual time in the Earth where the fossils in England and the fossils in North America virtually identical. They probably having to do with the changing distribution of the continents and so forth. So you always know you're in the Solerian in most parts of the world and these things occur in a regular sequence that remains the same wherever you go around the world. I will say, I said I wasn't going to say anything about creationist but one of the things that makes me maddest about creationist is that they claim that this geological time scale here, I'm supposed to run like that, is a device created by evolutionists to show the course of evolution. In other words, a non-random, systematically lying organization of rocks to show a growth from primitive to more complex forms of life as you go through time. Nothing can be further from the truth. Adam Sedgwick was Darwin's mentor in geology. Adam Sedgwick was a reverend. Darwin was studying to be a reverend when he went out with Adam Sedgwick. He changed his mind but there were a lot of the early 19th century intelligent people some of whom went into and founded the science of geology were in fact were Dane clergymen who were very distressed when Darwin later on went on and announced and then convinced the world that life hadn't de-evolved. Sedgwick didn't like that at all, never accepted it but Sedgwick taught Darwin how to go out there and Sedgwick is the man who named the Cambrian for example because it was empirical and this is the way, basically it's an empirical thing that has nothing to do with trying to prove evolution. That was one point about this. Those of you who have taken geology here or anyplace else also realize that this is just the sort of the tip of the iceberg. There's lots more divisions that a specialist can name of Devonian rocks for example or of Cambrian rocks and on and on it divides and divides and divides down but it has to do with the distribution of fossils in fairly discreet layers. This was understood in the 19th century after Darwin we tended to go away from that and think that maybe these are sort of convenient divisions that geologists, paleontologists recognize rather than actual units or divisions, natural divisions in the history of life that are there and we can go out and find them and then go out and make our subdivisions of geological time. So I'm taking the position that the fossil, I always have, my whole career that's what punctuated equilibrium was all about, the fossil record should be taken a bit more seriously, a bit more literally than it ever has in the last like 100 years, in fact ever since Darwin and that's those, these are the kinds of patterns that allow us to make some, I think some accurate statements about how life evolves. Now this is a very abstract slide in a sense I apologize, well I don't apologize for it, I'm an abstract kind of person. There's no trilobites on this. What this means, here's three patterns. These are essential for understanding the history of life. Each vertical line in white on the screens is the history of a species. It's shown as being like this, it's a straight line. It doesn't show us any of the variation that we're going to see in the very next lecture from the grants and we all know and I certainly agree that life is very, very variable. You get variation within populations of a species and if you follow a species out over its geographic range you're going to find a lot of geographic variation. That is not expressed in this particular diagram. What it really says though is that if you go to the fossil record of one of these trilobites that I work on or anything else, basically, you're going to find, you get a collection and you understand the nature of the variation of the anatomy of the fossil. But if you go five million years later, which is not an unreasonable number for Paleozoic invertebrates, which is what I really work on, and sample up near the top, the end of the history of this species, you can't tell them apart. And this was the underlying empirical basis or the problem that the whole notion of punctuated equilibria was set out to really investigate and try to explain that. Darwin pushed that problem underneath the rug, basically, and said when paleontology grows up and we know more about fossils, we'll find a lot more examples of gradual change in a directional sort of matter or maybe oscillating through time. So although this picture cheats a little bit in not admitting or not showing that there's a lot of variation, there is, but the point is that the variation is about the same width five million years later, very typically as it is when you begin in the early history. These are additive, these three patterns. This is meant to be the splitting of a lineage, so-called speciation, where I do believe another nice little molecular paper in science, finally corroborating what we've been saying in paleontology, that most, if not all, anatomical change that accrues in evolution, permanent anatomical change, tends to occur in rather rapid little bouts of lineage splitting, speciation. It's not intuitively obvious why this should be. I'll get into it a little bit as I go along, but this is the pattern that I'm mostly excited about now and which has been occupying most of my attention and my colleagues' attention the last 10 or 15 years. It's called turnovers, or some people call it coordinated stasis, but I like the reference to the actual turnover. It's an amalgam of these two previous patterns where you have some species going extinct. This is a timeline running across here. This is a speciation thing that happens to coincide with that particular timeline. This species just runs right through it. It's not affected. This has a slightly variant pattern, and so on and so forth, and there's a number of subdivisions, permutations, and combinations of this particular pattern, but this is ecological because these are not all closely related species. This might be a trilobite, but this might be a clam. This might be a brachyopod species in the diagram, and it begins to bring in very explicitly the notion of ecology and of ecosystems. Let me just spend a moment telling you what the latest thinking is. I got this, as I mentioned, the study group in Santa Barbara, half geneticists, half paleobiologists. The geneticists say, my God, our populations are changing almost on a daily basis. The genetic variation's wild, and sometimes we can't even come to grips with it, and we're saying, well, if you look at the fossil wreck, nothing much is happening out there, and so we're saying it's all gotta be true at some level, or we're giving each other the benefit of the doubt, and we're looking for common ground, and how do you explain this? This is, just to have this up here, this was sort of the original example of punctuated equilibria. I'm not gonna go into the details of the example. Again, there were been antennae, these wonderful compound eyes on this animal, so later trilobites more advanced than the one I just showed you. I have it here just because I wanna have a trilobite up, but basically, this is where I first stumbled into this concept or this empirical pattern of stability, and that's what these arrows here really are. Two or three million years of relatively little change as you go through time. Now, how do we explain that? One of the most exciting things that has happened to me in the last 10 years anyway, at least professionally speaking, I mean, what has a life outside of one's profession was to sit in Santa Barbara, and the geneticists actually said to the paleontologists, all right, you guys shut up, and we're gonna list everything that we know from mutations and aspects about mutations all the way up through population level processes on a blackboard. They exhausted three, in fact, all of the blackboard space that was available to us in the room, in the seminar room, listing absolutely every genetic process that known to promote and or hinder genetic change, changes in the genetic information, and they listed, so as I say, everything from very small scale, mutational sort of molecular sort of phenomenon, all the way up to population level phenomena, and then one of them, Rich Lensky from Michigan State, leans back and he says to the guy who was up there drawing John Thompson, he says, all right, cross out the first two boards. It's obviously something at the population, maybe ecological level, that's causing the stability, that's dampening down this variation, that's causing the variation that we know that is there not to get established and completely modify the entire genetics of an entire species or be passed along even to descendant species. A lot of this stuff as ephemeral doesn't get established. Why is this? All right, the two favorite explanations, they're not the invention of this group, one of them though is this notion of habitat tracking that paleontologists have been sort of hip to for quite a while. Consider this place just, I don't know, I didn't look it up before I came here, but up to, I don't know, 16, 18,000 years ago, maybe even more recently than that, was covered with a sheet of ice. It was the last major pulse of the Pleistocene glaciation. What happens when you get such enormous environmental change? Obviously the temperature drops, but you don't have any trees, you don't have any grass, if you've got a half a mile thick sheet of ice sitting where you are, you don't have any buildings either, but there were no buildings at that time to be destroyed. But that's radical environmental change in terms of what was there prior to that and what gets re-established later. What happens? When glaciation was first discovered by Louis Agassiz in Switzerland, he was an anti-evolutionist too, by the way. Darwin loved it because it showed, yeah, well, in Lyell too. I mean, it proves that the environments are bound, the physical environment is bound to change on Earth as you go through time. And this was great because Darwin needed not only a lot of geological time for his ideas to work, but he needed to show that there was environmental change. But the assumption that he made, and other people made too, was that you changed, say, global temperature and drop it, say, 10 degrees centigrade over a relatively brief period of time. His notion was that the organisms that were then present on the Earth would modify, as we would say now, if the genetic variation were there, natural selection would modify the properties of the organisms and they would track that environmental change. We're gonna see patterns like that on the population level coming from the Galapagos. I'm not saying they don't happen, but what really happens on a large scale, you get a little of that, but you basically have glaciers coming down, the tundras coming down in front of it, the boreal forest in front of that, and the mixed hardwood forest, such as we have here, to the extent that we haven't removed it through agriculture and city building, all move south. Not in a nice, neat, circular pattern. Sort of hodgepodge, but the point is, is the longest species that are up and running and have their own adaptations in place can track, can find and occupy habitats that are recognizable, in a sense, to their adaptations, they'll move there. Even trees can move because they send out seeds and reestablish themselves there and there is no impetus, real impetus for evolutionary change, and you can ask virtually any plant, any Pleistocene plant paleontologists, and they'll tell you, that's exactly what happened. We have a great record of the plants because we know about their pollen, we find the pollen in the glacial pools and so on and so forth. So what happens is you get this great waxing and waning of the glaciers, lots of environmental change, but very little evolution, including very little extinction as these, because the biotic world sort of swings with it and moves around and establishes ecosystems that are sufficiently similar to the previously existing ones that they're just in a different place and the emphasis is really on survival and the toughness of life rather than the ineluctable urge or need or indeed just the fact of evolving to meet the changing conditions. And in fact, if you push that system too hard too fast, and I hope I have time to give an example at the end, the second most likely outcome is actually extinction rather than evolving into something new. Now, this is not to say there was no evolution in the Pleistocene, the hominids that evolved and Tim will be telling us about that. The famous Ice Age fauna did evolve in the steppes of Asia with long coats of hair. So there is adaptation, adaptive change going on in some parts of the system, but by and large most of the species that were present in the Pleistocene on land and in the sea didn't change, at least not all that much and did survive even though there was this tremendous amount of environmental change that they had to cope with. So that's one reason why you can get stasis because you can move basically is what it is and swing with the changes that are being, environmental changes that you're being confronted with. But I think the favorite particularly amongst the geneticists but also with me explanation for why you get this tremendous stability is that yes, you get a lot of local adaptations going on within populations. But if you look at a species and most of the species in the fossil record are fairly successful far flung species, they're not species that tend to be located in just one particular place and specialized to one particular environment because you just don't tend to find those kinds of things or sampling basically isn't that good. But on my way over today, walking from the guest house I saw an American robin, I should say big deal but I like American robins. American robins live in the deep woods in the Adirondacks, deep wet woods in the Adirondacks during the summertime. Of course they fall back because there's nothing to eat for them and it gets beastly cold during the winter time. But they're up there and I was surprised because I'm a suburban guy, I grew up, I know about lawns and I know robins hop around on lawns looking for worms but they also really like deep wet woodlands in the summertime. But then I was down in Santa Fe a few years ago and you're up at 6,000 feet, there's cacti all around the only water that you can see is leaking from a garden hose, that type of a thing. There's different plant foods, there's different insect foods for robins to eat and I'm sure there's a little bit of a variation between the sort of body size and proportions and so forth of the robins in Santa Fe versus the ones up in Maine or indeed in Oregon or down in Mexico. But they look awfully similar and nobody's split them up and made different subspecies out of them or not. I'm not saying they're not differentiated but they have such different lives that they're leaving. They have different temperature regimes, different water availability, probably different parasites on them, different diseases to cope with. So if you start thinking about, I would say the bulk of the world's species and we think we have maybe 10 million species on earth right now and maybe as a standing crop, maybe few or maybe more, some people think a lot more, if you take most of those species and recognize that they're distributed over large areas in very different kinds of habitats then you start asking yourself how is natural selection going to modify that melange that are locally adapted in one particular evolutionary direction? The answer is it's highly unlikely, it's not impossible but it's highly unlikely that it's going to happen and even if you change the global environment for all of them, like temperature, we've already seen that mostly what happens is an oscillation back and forth of the distributions of species rather than a concerted directional evolutionary change. Well, that's an old hobby who are stasis, it's very important though and it was good for us to sit down as a group with our such different backgrounds and understandings about the nature of living systems and try to come to grips with modern understanding of a pattern that we've known about ever since Darwin but we've tended to ignore because it didn't make a great deal of sense. Russell says I'm interested in hierarchies, this is an almost impossible slide to decipher so there will be a quiz, particularly for those of you who are enrolled in Russell's class but without going into any great detail on the abstract thinking about it but it's been apparent to me and a number of my colleagues for at least 20 years that organisms do two and only two basic kinds of things. Organisms obtain energy and nutrients to differentiate and grow and maintain their bodies and they do or at least some of them do reproduce. Okay and the consequences of those two different categories of behavior are enormous. You need to eat and maintain your body in order to reproduce. You do not need to reproduce to live. I mean you won't leave any offspring but for you yourself to live you don't have to make babies. Organisms of the same species, with the same adaptations, same food requirements, same temperature tolerances and so forth tend to live together and either cooperate or compete or it varies depending on what we're talking about in local populations. The presence of an American robin, local population in a wet woodland and not an artificial setting that we're in there is actually what most ecologists mean most of the time when they use the word niche. It's the role that these local populations of birds, of plants, of snakes, whatever you're talking about are playing in that local ecosystem. Energy flows, matter and energy is flowing between organisms and when a robin eats a worm, when a hawk takes a robin. That's energy flow going on there and you get these local ecosystems very often hard to define. If you're in the Galapagos you've got these islands and maybe even I will see but I think you can even recognize environmental subsets on these islands so it's not cut and dried but local ecosystems are sort of networked into regional ecosystems and eventually all of the world's ecosystems are intertwined and interconnected in one big matter energy network. Now with a possible exception of the deep sea vent faunas but all of the solar driven ecosystems that we know of. So there's an ecological organization of the sort of economic side of life and just by dint of the fact and humans are an exception because we stepped outside of local ecosystems entirely different lecture. All other things squirrels and robins and so forth just by dint of eating or warding off predation are engaged in economic behavior. They're parts of ecosystems and it falls out that way. On the other hand at least sexually reproducing organisms and that includes almost everything because I include most single cell eukaryotic organisms there. There's at least usually some sexual reproduction going on there. Are parts of populations in which males and females can exchange genes. The word for that is deems on a local level. Deems are parts of species. Species in my view are collections of organisms, males and females which potentially at least can recognize each other as mates. They share the same reproductive adaptations and you can also view them as collectivities, as collections of genetic information. They're not economic entities and I think a lot of mistakes have been made but that's again something more esoteric in thinking that species are actually economic machines. They're not, they're actually genetic machines or genetic information not even machines but repositories. Species give rise to new species. We already saw this in a diagram and so you get these sort of lineages developing of species and you get a hierarchy of life. You get January, you get families and so forth up to the kingdoms of life and then that is basically the evolutionary or the genetic or the genealogical hierarchy. Natural selection tracks on this because it's how well you do as an organism ecologically speaking inside a local ecosystem that has to do with your reproductive success and your reproductive success with the implications of that ecologically is that you're making babies and you're replenishing the supply of organisms in the local ecosystem. Now I wanna play a little game with you. I wanna, this is what I call the sloshing bucket, notion of evolution. I think there's a lot more to evolution than what I'm about to tell you but I think there's a tremendous amount of truth here. If you play the game and we know a lot about the lower level and the highest level of the game and just ask yourself what happens if you perturb a local ecosystem? What are the consequences genetically speaking on this side and what are the back consequences over? And then if you look at the mass extinctions of the geological past and ask that same question, then I think we're in a position we would predict that there'd be an intermediate mid-range which is what I'm gonna tell you is where I think most of the evolutionary action in the history of life has resided at least in the last half billion years. I'm gonna leave this slide on but let's just say for the moment I'm gonna start out with local perturbations of ecosystems, fires, oil spills that's artificial, volcanoes going off, earthquakes. My favorite example actually is Ralph Gordon Johnson who was a paleontologist at the University of Chicago who's now no longer with us but a editor for a while of the journal Evolution. Went out to Tamales Bay in California and studied the ecosystems on the seaborn in Tamales Bay and in particular he was interested at the migration of a sandbar across Tamales Bay. Now this was going slowly but he went back every summer and he documented patient man and he didn't let the sand go. I mean he couldn't control that if he wanted to but he was documenting the obliteration of the mollusks and the worms and so on and so forth, the benthic fauna of this section that was being affected by this growing sandbar as it crossed over the ecological community and it just totally wiped out everything as you might imagine, utter devastation but it was localized and so all of these species that had members in this sort of mini microcosm of this ecosystem being obliterated slowly but surely because they couldn't move around and so on had other populations of reproductive populations in immediate vicinity. So as soon as the sandbar crossed over you get the familiar phenomenon of ecological succession. You get these larvae are coming in from all these different species and there might have been a little bit of a structure to this succession. Some species might have gotten there first and so forth. Sometimes there's a great regularity to it. Otherwise there's not but the end results sooner rather than later is that you end up with a community that looks as though it were the same thing. I mean the organisms are not exactly arranged in the same way, maybe even the relative abundances are slightly different but you've got basically that same community back there. And now here's where my genosis friends step in and correct me. Then I always like to say, well, and there's no evolution because from my perspective of looking at the anatomies of these creatures you can't tell the difference between the clams that were once there of a particular species and the ones that came in and migrated back in. But yes you can maybe genetically. So there might be some genetics changes that have accrued there. Maybe some new genetic information actually through mutation might actually have become established. You can't see that though. I'm not saying it's not real. I'm not saying it's not important but you don't see it. As far as the anatomy of the creatures was concerned you're not getting any evolutionary change at all. And I think that's interesting because it shows amongst other things that species are these repositories of genetic information. And species are supplying, this way I'm looking at it, always supply side over here, the players to the ecological systems. And particularly if the ecosystems are disrupted you're gonna get recruitment coming in from the outside. There is a counter example actually. Coyotes are coming back in the east now and up in the Adirondacks they shot the last coyotes out in I don't know. I think the 19th century, the latter part of the 19th century if I'm right about that. They've been slow to come in and get reestablished timber wolves are going now too. So now we're getting coyotes that are bigger than the ones that were presumably that were shot out and I think this is based on actual specimens. And even their behavior is a little bit different because they'll take down deer now in packs. Sort of like the way timber wolves will. So you do get, I'm not saying you don't get any interesting changes. You do potentially get some. But by and large it's a reestablishment of the status quo if you're perturbing down here at this level. What about up here at the extreme level? There's been at least five, some would say six or maybe even seven, global mass extinctions that have occurred in the last half a billion years that we know about. The granddad evolved 245 million years ago where at least according to Dave Raup at least 70% of the world's species and perhaps as many as 95 or 96% of the world's species became extinct. Life nearly bit the dust back then, 245 million years ago. There would be no Nobel conference. There would be no playoff baseball. There would be nothing in terms of life. A bacteria undoubtedly would have gotten through and that would have been interesting in and of itself. But in terms of the kind of life that we know, let's take the extreme scenario, 4% of the genetic information is the basis for everything that came afterwards and some of these lineages came out. So what is, this has an enormous effect. Now, some evolutionary biologists including some famous ones have said to me, well, that just means stuff happens. What I'm saying, I'm trying and you know, and so things happen every once in a while and it resets the clock so what? But what I'm saying is that this is part of, this is a large scale and extreme version of a set of patterns that are absolutely symptomatic not only of the way life is organized but of what happens to it and how life actually evolves. So I use these as the clarion example of the most gross and easy to understand examples of what happens. Let me quickly give you two examples and I gotta cut to the chase here. Back in the Paleozoic we had corals and there's a lot of corals you can find. They're important in Michigan and in Saskatchewan as oil reservoirs even. There's just huge coral reefs back in the Paleozoic. So we're talking about maybe 500 million years ago up to about 245 million years ago. There are two different kinds of corals. This is a tabulate coral. It's not the best, I pick this like as it's pretty. It looks like ribbon candy. This is from Niagara Falls. It's salurian in age. The Paleozoic corals particularly the other kind other than this had mineral shells of calcium carbonate but of the mineral calcite. Their internal arrangement of their septa and I can't get into it right now is four-fold. They were called tetrachorals and these were a similar version of it. Each one of these little holes was an individual coral so this is a compound colonial coral. After the big mass extinction 245 million years ago you get a different kind of coral. You get six-fold symmetry corals, calcium carbonate but it's the more delicate mineral form called aragonite. These are the corals that we have around us. Today this is a modern coral. This genus is still alive. This is a fossil from the myosin of the East Coast but this particular coral species is still alive today. People used to turn themselves into pretzels trying to understand how 245 million years ago the four-fold symmetry coral turned into the six-fold symmetry coral. And the quick answer is that it never happened that way. Molecular analysis just show recently what people long suspected which is that these six-fold symmetry corals are actually most closely related to sea anemones, naked corals if you will which we're all familiar with from the seashore. Fossil record of naked animals is bad but we do know that we get some squished things every once in a while and we know that there were anemones back in the Paleozoic. So what happens, what seems to have happened is that the corals evolved but they were from a different branch if you will of the selenirate phylum, of the Nidarian phylum. And it was only after those two kinds of Paleozoic corals, after a large run of whatever that is, 250, at least million years of building reefs all over the world and so forth became extinct that evidently the opportunity then to become a coral and this sounds very teleological. I know there's a problem with the way I'm expressing myself right now but in a sense, corals were reinvented by evolution from a collateral line, the sea anemone line. It took, there's a gap of about five or seven, I think it's seven or eight million years before you start getting our modern corals after the demise of these Paleozoic corals. So you get this haunting theme and you get this, you get a replacement in ecological terms of sometimes from nearest relatives and other times from completely different branches but there's a sort of a reinvention of the ecological wheel. I don't want to push it too far. I don't want to say a Tyrannosaurus, not a Tyrannosaurus but a triceratops and a rhino are ecologically the same. I mean they look sort of vaguely similar and that rhinos eventually replace triceratops. Nothing that sort of precise but you get whole new groups evolving that are in effect in some meaningful sense and an ecological sense replacing groups that fall prey to these mass extinction events and very quickly, the most famous example of all, this is Tyrannosaurus, one of the last along with triceratops, one of the very youngest of the terrestrial dinosaur species and I'm treading on Phil's territory here. They survive vicissitudes. There were mammals and dinosaurs going back well into the Triassic period, something that was known to Charles Lial and for some reason it was the dinosaurs and their collateral reptilian kittens that basically dominated, kept proliferating, they were cut back by extinction events, proliferated again and the mammals remained relatively undiverse and unequologically differentiated until you finally do lose at the end of the Cretaceous and again, I know Phil's going to be talking about the origin of birds specifically but this is his territory. You don't get large mammals until after the large terrestrial dinosaurs finally bit the dust. Even though mammals have been around for I guess about 150 million years, only after the dinosaurs disappeared do you find a proliferation into small ones, medium sized ones, large ones, herbivores, carnivores, scavengers and so on and so forth and mammalian history then as we know it starts taking off including human history. Now I don't want to impinge on Tim either but one of my, well, so here's the patterns. I'm saying ecological succession is sort of this but you get the same things replacing the things that are wiped out down below. That's below the species level, above the species level, way above the species level, orders of things like terrestrial dinosaurs or corals or something like that, you get extinctions but you get replacements in the evolution of something new but not using these particular dynamics. You can feel it. There's got to be an intermediate level where you are disturbing regional ecosystems to the point where you start losing entire species and that really is to me what the history of life really looks like. I just took this, it's not at random, I obviously deliberately chose this but this is a trilobite, it's not my work, this is the work of Susan Longacre I think, from the upper Cambrian of some place in the western United States. This is her chart of the distribution of individual species, mostly of trilobites but I think there's some brachypods and so forth in there as well. It's ecosystems and it's the persistence unchanged of many species. I see in my own work in the middle paleozoic of the Appalachian Basin, the tabulations are from Carl Brett and Gordon Baird though. I think there's eight successive faunas that live about five to seven million years, 70% or so the species are there throughout, they're all in stasis, they're not changing at all and only 20% get through to the next succeeding level. So there are these extinction events. This I tell you is you just sort of memorize this pattern because that is actually what the history of life looks like and we can tie that into speciation mechanisms and the last example I'm gonna give you Tim Territory here but this is the town child and nobody knows how old that was but these Australopithecus Africanus creatures live to, now I was gonna say two and a half million years ago that they're a little bit younger than that I think as I'm hearing in South Africa now but here's the idea. This is Elizabeth Verba's work. I think it's holding up rather well those consistently and persistently being criticized. This X is about two and a half million years ago and what she has said is that beginning about 2.8 million years ago there was a global, there was the beginnings of a global decline in global mean temperature which ended up being 10, 12, maybe even 15 degrees centigrade global mean temperature and that the ecosystems of Eastern and Southern Africa were able to absorb this. They were mostly wet woodlands, a lot more than they are now and all of a sudden they transformed into grasslands. You started getting habitat tracking in of organisms that were already adapted to grass animals, already adapted to grasslands and you apparently got true extinction and true evolution so you get this mixed thing and this looks like a sort of a cartoony I admit fleshed out version of that diagram I just showed you and I think it fits it perfectly well and she claims that human evolution also fits it and I wonder actually what Tim thinks but it is true that just not too far after two and a half million years and the dates are sort of being debated right now you get two lineages at least of humans you get these robust australopithecines again I don't wanna steal or step on Tim's territory and also the first tools and maybe something like homo habilis that might have made them with increased brain size and I wanna push this too hard and I'm gonna actually leave you I'm gonna put this last thing on but even up to and including I think the early phases of human evolution you get these environmental pulses and these ecological and evolutionary reactions to them which can be understood in conventional biological genetic terms and notions of speciation and extinction I'm just saying basically the context of natural selection then is very important is not sort of sort of intrinsically obvious but you're not basically things or natural selection will stabilize unless and until somebody really throws a joker in the deck with a physical environment really gets shaken up and you start getting true extinction going on at the regional level I think most speciation events and hence most anatomical change in evolution including perhaps even in our own ancestral species take place in that kind of a context and not just simply the march of time changes of environments in natural selection tracking environmental change and bear this in mind because we're going to see these wonderful examples of natural selection tracking environmental change in the Galapagos I'm just saying that there's a larger context for understanding what happens when you get the truly new that gets really established typically speaking in evolutionary history thank you very much. At this point I'd like to call the rest of the panelists up to the front here and we'll get ready for our Q&A sessions. People in the audience are invited to fill out question cards pass them to the center aisles and they'll be collected and what I'll do here is to begin by asking other members of the panels to react and then we'll get to your questions after that and I understand that people have to leave for various reasons we'll wait just a few minutes but then I hope you can be considerate of everyone else in the audience here so that we can all hear the answers to the questions.