Revolution #130, May 25, 2008
| REVOLUTION Interview |
A special feature of Revolution to acquaint our readers with the views of significant figures in art, theater, music and literature, science, sports and politics. The views expressed by those we interview are, of course, their own; and they are not responsible for the views published elsewhere in our paper. |
Neil Shubin: The Quest to Uncover the History of Life on Earth
Neil Shubin is one of the world’s leading paleontologists—scientists who study fossils to learn about the evolution of life on our planet. He is also a professor and associate dean of organismal biology and anatomy at the University of Chicago and provost at the Field Museum. In 2004, Shubin and his team discovered a fossil in the Canadian Arctic that made headlines around the world when it was publicly announced two years later. This was Tiktaalik roseae—a 375-million-year-old fossil of a creature that was an intermediate between fish and land-living animals.
Earlier this year, Neil Shubin came out with his book Your Inner Fish: A Journey Into the 3.5-Billion-Year History of the Human Body (Pantheon Books)—a lively and accessible work that is full of fascinating science…and downright fun!
Revolution interviewed Neil Shubin at his lab at the University of Chicago, where his research involves the study of genes and the development of embryos along with fossils.
Revolution: Would you give a brief general overview for our readers of the significance of the Tiktaalik fossil you discovered, and what your book, Your Inner Fish, is about?
Neil Shubin: Tiktaalik, along with other fossils of lobe-finned fish and amphibians, reveals a critical time in evolution. What we see is how the descendants of fish with fins evolved to inhabit land. This is a big event in the history of the earth and also is a big event in our own history. Many of the features that originally evolved in fish like Tiktaalik are parts of our own bodies and our own history. The neck that is first seen in Tiktaalik is something that became our own neck. The functional wrist in Tiktaalik is something that became our own wrist. This is the general theme of Your Inner Fish. Each of us carries over 3.5 billion years of history inside of us. In every organ, cell, and gene in our bodies is a deep connection to the rest of life on our planet. And the story of our bodies is written in the fossils, bodies, and DNA in creatures as different as worms, fish, and sponges. That is the story of the book.
Revolution: You’re preparing for this summer’s field season in the Canadian Arctic. Are you going to the same area where the Tiktaalik fossil was found? And are there specific types of fossils that you are looking for?
Neil Shubin: We have two goals this summer. The first goal is to return to the Tiktaalik site, which is a site about 20 feet long that we've opened up a bit, with fish skeletons one on top of another. So we know there are more Tiktaalik to find at that site. So we're going to go there for about two weeks. The whole field season is about five weeks long. So for the remainder of the time—there will be six of us going—we'll divide into two camps of three. Small camps, very mobile, like sort of reconnaissance teams. And our goal will be to identify new sites.
Revolution: You said you hope to find more Tiktaalik. What other kinds of fossils do you expect to find?
Neil Shubin: What is really great about the Tiktaalik site itself is that there are all kinds of fish there, it's not just Tiktaalik. So we have a chance by working the Tiktaalik site in more detail, and by studying the geology of that site in more detail, as well as the rocks above and below it, we'll have a sense of what the environment that the Tiktaalik lived in was like. Was it swampy? What other fish lived with it? What was the ecosystem like? Really what we want to do, in several years' time, is to be able to state with a degree of confidence, what the ecosystem that Tiktaalik lived in looked like. And the only way we're going to do that is by really working the site in some great detail, bringing in people who have different expertise than mine, which might be more geological, things like that. So we'll spend a few weeks there.
And then, we're always itching for new things. So the idea will be, we'll divide up into these two camps, two teams of three, very mobile—and we'll go up in time, into younger rocks. Tiktaalik is about 375 million years old. The rocks we're going to go into are about 370 to 365, five million years younger, more recent. The idea is to find something that was more tetrapod-like than Tiktaalik. [Editors' note: Tetrapods are animals with four limbs.] So it's a never-ending quest to some extent. Each time we find answers we get new questions. And that's what makes it fun. And there's so much to still discover up in the Arctic. To some extent, we've been victims of our own success. When you find a place, that's the one place you work, the Tiktaalik site. But there's this vast Arctic that we still haven't looked at, much of it, in great detail. And so we're going to get back to that a bit this summer.
Revolution: In Your Inner Fish, you point out that our world is so “highly ordered” that it’s possible to predict the kind of fossils that lie in different layers of rock around the world, and that those predictions can bring about discoveries that tell us about ancient events in the history of life. At the same time, you talk about the role of chance and serendipity in your work. How did those two aspects relate to the discovery of the fossil of Tiktaalik?
Neil Shubin: It took us all kinds of planning to get to Tiktaalik sites. First of all, we needed to figure out that we wanted to work in the Arctic. Then where in the Arctic we wanted to work. Finding a fossil in the Arctic is like finding a needle in a haystack. The Arctic is a pretty big place, and fossils are pretty small. So how do you do that? It took a lot of planning. It took learning about the geology of the area. There are two essentials, obviously. Learning from the work that preceded us, the geologists who worked there in the '70s, Ashton Embry and his teams from Canada, did a great job mapping those sites. But there's no getting around the experience of actually seeing the rocks for yourself. And so it took us a long time actually of learning the local geology, from our own viewpoints, that we were able to narrow down the particular patch of the Arctic that would be the most productive for us. We knew that because the best places up there are places that were in ancient streams. And so we were basically looking for rocks that had the characteristics of ancient streams. So that was planning. We planned like crazy to get there. And it takes a lot of planning in terms of permits, working with local governments, trying to raise money—these expeditions are not cheap, and we live in a time where funding for science, particularly basic science, is very challenged. So it took a lot of planning.
But then the actual moment of discovery is usually some dumb, bizarre luck-chance thing that happens, it really is. You're walking one day, and you see a little glimmer of something that doesn't look like it should be there on the ground. You pick it up and there's a bone. Well, what if that day was cloudy instead of sunny? What if the light was coming at a different angle? Or what if your head wasn't in it, and you're thinking about home or something, you know what I mean? There's all this serendipity that happens at that final moment. For us, in fact, the moment when the site for Tiktaalik was discovered, there was a degree of serendipity. Jason Downs was the one who discovered it. Jason was a college undergraduate who joined us. He happened on the site, and golly-gee, had he walked 10 feet in another direction, he wouldn't have seen the site. So you plan like crazy to get to some place. But then usually the act of discovery, that moment, is usually kind of random [laughs]. And funny—sometimes they're hilarious.
Revolution: How so?
Neil Shubin: For instance, when I was a graduate, back in the ’80s, I was working in Nova Scotia. And we had planned like crazy. At that time I was really interested in the origin of mammals—an evolutionary event that happened around 200 million years ago. So we had made all kinds of plans to go to the Bay of Fundy in Nova Scotia. And it was great for fossils, but we weren't finding exactly what we were after. It turns out this place has super-high tides. If you didn't plan your trip to the beach right, you would get stuck. It wouldn't be terribly life-threatening, but you'd be sitting on a pinnacle of rock for a couple of hours, skipping stones or whatever. So one night we were called to judge a local beauty contest for this town we were staying in. And we stayed up way too late and woke up the next morning too late because of that, and missed the tide. So we got stuck on this one pinnacle. And here, all this planning it had taken to get us to this site which was on the other end of this pinnacle of rock, but here we're stuck on this place for two hours. So we got bored and started looking at the rocks there. And the rocks there are not the kind that you'd ever look for fossils in, they look like they're volcanic. But it turned out there were fossils in them. And boom—if we'd never judged that beauty contest, we'd never have been stuck, we would never have found these really cool fossils that came out of that pinnacle of rock.
Revolution: You write in Your Inner Fish of a biological "law of everything"—"that every living thing on the planet had parents"—and how this law is "so profound that most of us take it completely for granted." Why is the fact that every living thing had parents so important?
Neil Shubin: What it means is that each of us as individuals can trace a biological lineage. We have biological families. And you can make a biological family tree. Now my children are adopted. They're part of my family, but they have a biological lineage that's separate from their social one. Regardless, we have a biological lineage that we can trace, from my parents to grandparents, my biological great-grandparents, all the way on. And that's true because I'm a modified descendant of my father and mother. My parents are modified descendants of their parents. Well, it turns out we can use the same techniques that we use as biologists to decipher our own family trees—like the DNA mapping projects that you read about, or the forensics that put people in jail, things like that. We can use them to find a broader family tree, the family tree that's the family tree of our species, to show that we as a species are modified descendants of another species, and so forth. So this tree of life concept, which we're so familiar with in our own personal lives, actually has a deeper meaning for us, because it means there's a deeper tree of life that relates us to everything from apes that are walking the earth today to jellyfish to squid…you name it. And it's interesting that oftentimes the techniques that do these things are very identical. The beauty of this is that we're intimately connected to the rest of life. Not only that, we're part of a family tree with the rest of life. We're relatives. That family tree is knowable—that's the fun thing. We can decipher it. We can do it by looking at molecules, the DNA. Or we can look at bones or fossils.
Revolution: Some animals have only one parent instead of two.
Neil Shubin: Yeah, some are clones. But you can still trace their genetic history. So let's remove the parent concept for a second and think genetic lineage, that you can trace the genetic continuity. And you can even do that to things that are not living, all the way back in time. That is, the DNA molecules, the RNA molecules—the molecules themselves have a lineage from a simpler molecule. So lineage is the very important thing, genetic lineage if you will. That doesn't mean that nurture, the way we're raised, is not important. But we have an internal lineage inside of us, a family tree.
Revolution: In the 1800s, the anatomist Richard Owen made, as you describe it, a "remarkable discovery"—that the limbs of creatures as different as frogs and humans are very similar, essentially "variations of a theme." To Owen, these similarities showed the plan of a Creator. Then came Darwin a short while later with an "elegant explanation" for these similarities. What was the leap in understanding that Darwin brought forward? Why do you describe it as “elegant”?
Neil Shubin: The leap is, essentially, that Owen's plan—one bone, two bones, little bones, and limbs, which is the arm of a bat, wing of a bird, arm of a human—that pattern to Darwin was evidence of common descent. That the reason why creatures had that similar pattern is not because of a highly organized creator, but it's material evidence of the fact that these creatures share a common ancestor in the distant past, that they're related. Now the reason why that's elegant is because it not only explained Owen's pattern, but it made predictions, which then you can go out and test. That's the beauty of it. With Owen's plan, it's just there. Oh, the Creator made it, good, let's move on, find the next plan. This one's different. This one says: here's the material reason. And now knowing that, well, you know what—you should be able to find how that plan was assembled in fish, or before that, in creatures that we call worms today, and so forth. It should have a history. And that history you should be able to find. That's what led to Tiktaalik.
Revolution: Your book goes into many fascinating examples of how various structures of the human body can be traced back through evolutionary history in often unexpected ways. For instance, you point out that one might think that our skeletons began with features like the backbones or body armor of earlier creatures, but that is not actually the case. Can you go into how the skeleton actually evolved?
Neil Shubin: Our skeleton is hard, right? I knock on this table, and it's really hard. And it's good, because if we didn't have a skeleton that was hard, we'd be just like a mass of goo, and we wouldn't be able to live on land, it'd be lots of blobs moving around. There are a lot of theories about why hard parts developed. Did they evolve to protect animals—like bony armor? Did they evolve to support the skeleton, or for mineral balance? But it turns out that the first things we find that are hard in our lineage (there are other things that are hard—clams are hard, and things like that), but our kind of hardness, which is brought by a particular kind of molecule which we have called hydroxyapatite, that kind of hardness originally appeared in a tooth-like structure. So the first things that were hard were not there to protect creatures—they were there to chew them up [laughs]. Teeth are really important.
Revolution: Related to the tooth question, there were these common fossils in ancient oceans, called conodonts, that, for a long while, were a mystery to scientists.
Neil Shubin: Yeah, they didn't know what they were. If you go to certain places in the world and you crack rocks, say over 250 millions years old, like go to the era of oceans when Tiktaalik was around, you'll find places where there are these conodonts. You crack the rocks, you'll find these really tiny…put them under the microscope and they look like tiny little teeth for all the world. For a long time people didn't know what they were, because they never found an animal that had these things. Turns out that what we call conodonts are actually the teeth of a larger creature which we now call the conodont animal. The mystery was solved when people discovered whole animals, and it turns out they're teeth, the earliest known.
Revolution: You note that "One of the joys of being a scientist is that the natural world has the power to amaze and surprise." Would you give us a particular example of this—what has really amazed and surprised you?
Neil Shubin: When I was in graduate school in the early ’80s, people were beginning to work on flies. People were looking at development—embryology—by looking at frogs, flies, and mice. I remember at the time thinking, what is the development of a fly going to teach us about how our own bodies are made? Well, here's the power of surprises. Many of the versions of the same genes that build our bodies from front to back, that define the body axis, are present in flies, doing versions of the same thing. So what surprised me, as well as a lot of other people, was the discovery in the mid- to late-'80s of the common genetic tool kit to build bodies—bodies as different as flies, humans, and worms. I would not have predicted that. And there's a beauty to that when it's more elegant than just the surprise—it's the order of it. Our world is not put together piecemeal. When you start to learn more and more, we start to discover that the more we know of the history, the more things become ordered to some extent—you can make sense of stuff. Just like you can make sense of your own pre-disposition to diseases if you know your genetic lineage, or the environments you were raised in. It tells a lot about yourself.
Revolution: As a part of the title of your book notes, the human body has a 3.5-billion-year-history. Now, three and a half billions years ago, the only living things on earth were microbes with just a single cell. By contrast, there are trillions of cells that compose the human body. In what sense can we speak of our "inner microbe"?
Neil Shubin: Oh yeah, the choice of the title was completely arbitrary. Well, not arbitrary. As a scientist, I could have called it "Your Inner Worm," "Your Inner Microbe," a lot of things. But I work with fish. Fish are a wonderful way to think of our own bodies. That's why I called it "Your Inner Fish." But I could have chosen many different points of our evolutionary past and given the title there. It's just for me, personally, the entry point has been fish. So that's my fishy bias. But the thing is, if you want to understand yourselves, you have to understand different parts of our tree to explain different parts of ourselves. If you want to understand what makes us unique relative to other primates, well then you have to understand our humanity. If you want to understand why our head is shaped the way it is, well you have to understand the history we share with primates, but you also have to understand the history we share with other mammals, with reptiles, with fish. So it's these deep layers upon layers of history that make us.
Revolution: But how can we trace our history back to single-cell microbes?
Neil Shubin: It's beautiful because if you look at the structure of our DNA, if you look at how our DNA works, if you look at how our cells work, how we metabolize oxygen, if you look at the molecular machinery that guides the workings of our cells, and how our cells interact with one another, that's the microbe bit. So again it's layers after layers of our history buried inside of us. So the fish-like bits of us, you see in our skeletons. You see in our nerves, and so forth. But the microbial bit, you actually find in the machinery of our cells, of our genes. So that's an example of our three-and-a-half-billion year history. Well, there's stuff from a billion years ago. How our cells make energy—we breathe oxygen and eat food, we work our muscles, we're using energy. Well, the whole machinery to do that is a microbial feature. In fact my ability to talk to you right now, and your ability to hear me, and our ability to move—thank you, microbes [laughs].
Revolution: You write that life in your research lab can be very "schizophrenic," because it is split directly into two, half devoted to fossils and the other to embryos and DNA. You've talked about this some, but how are these different areas of study linked?
Neil Shubin: To decipher a family tree, what you need are many different lines of evidence. Think of solving a mystery. There's a murder. How does a good detective solve a murder mystery? Well, they're going to pull in as many lines of evidence as possible. Hopefully they have some eyewitnesses. But short of that, they're going to need a ton of independent lines of evidence. Well, it's the same thing with us. We pull in as many lines of evidence to understand our history as possible. Fossils are one line of evidence. The DNA records are another line of evidence. But the fact of the matter is that it's strongest when both those lines of evidence point to the same thing. When the DNA inside the cells of living creatures gives us the same story as the fossils that we find up in the Arctic, then we know that we're on to something very powerful. That's the idea.
Revolution: There is a very poetic passage in your book: “If you know how to look, our body becomes a time capsule that, when opened, tells of critical moments in the history of our planet and of a distant past in ancient oceans, streams, and forests. Changes in the ancient atmosphere are reflected in the molecules that allow our cells to cooperate to make bodies. The environment of ancient streams shaped the basic anatomy of our limbs. Our color vision and sense of smell has been molded by life in ancient forests and plains. And the list goes on. This history is our inheritance, one that affects our lives today and will do so in the future.” How does this inheritance affect our lives now and in the future?
Neil Shubin: I was born with a hernia which had to be corrected [laughs]—that's a good example. We evolved in many different environments. Our common ancestors that we share with the rest of life on the planet lived in starkly different environments than today, which sometimes leads to problems. Fish don't walk on two legs, we do. Yet we use some of the same structures that originally evolved in fish. So what you have is a body that can be seen as sort of a jerry-rigged device. Every piece of us has been modified or re-purposed in different ways through evolutionary time. And what that means, when you re-purpose things, it's not the ideal solution. We're not very intelligently designed. We're very unintelligently designed in a lot of different ways—we're historically designed. Our bodies are a testament to the power of history. Nowhere is it more clear than in the bizarre loops and turns some of the vessels and nerves in our bodies take. And one of those loops is in males, unfortunately, the spermatic cord, which gives males, as compared to females, a greater tendency to develop a certain kind of hernia in the lower part of the abdominal wall. So that history is our inheritance, and oftentimes that inheritance causes us a little bit of grief [laughs], because we live in a different world. I'm sitting in a very soft chair for eight hours a day. I can guarantee you the common ancestor we share with other mammals did not sit in a soft chair for eight hours a day [laughs].
Revolution: What about your point about that inheritance affecting the future?
Neil Shubin: Think of what we humans are as creatures. We're so different in some ways with our cognitive abilities. We're able to devise gizmos and technologies to sort of overcome our inheritance, to some extent. I had that hernia I was born with. OK, that was my past, but guess what, our technological present led to technologies that fixed that hernia. I have nearsightedness, pretty severe nearsightedness. Which would mean, if left to my own devices, natural selection would have weeded me out. But we have this wonderful technology [pointing to his glasses] which has helped us—that kind of thing.
And so what that means is, if you think about our future, it's increasingly going to be driven by the choices we make with our social structures, our technologies, how we're going to deploy them, how we're going to use them, what they are. Frankly, the more we understand about our bodies, the more we can change them. It's not inconceivable that in the future we can have technologies which affect our ability to think, to recall things, to run, to jump, to leap, to hit home runs [laughs]. We're already seeing that—human performance can change based on our technology. So frankly, our own evolution, to some extent, in terms of our performance, is going to be very much affected in the future by our ability to change ourselves—consciously. And those decisions are going to have all kinds of ramifications. We're going to have to make choices in how to deploy those, or whether we want to deploy them. More likely than not, they're just going to happen, and then we'll look back and think, we should have done something about that. Come back in 150 years and I guarantee you, humans will be running faster, thinking more—like, you want to learn French, here's a chip, put it right here in your brain, that kind of thing.
Revolution: At the end of your book you speak to “the power of science to explain and make our universe knowable,” and that “the unknown should not be a source of suspicion, fear, or retreat to superstition, but motivation to continue asking questions and seeking answers.” Could you expand on this?
Neil Shubin: For me, I was always raised in a tradition that the unknown should become known. A dark room is scary for a kid, but when you turn on the light it's not scary. And that's how knowledge is. It's like turning on a light in a room. You think about how the moon was thought to be, for years—there was all kinds of mythology about the moon. But once humankind made the trip to the moon and back, it became part of our world. You can go on the Internet and see pictures of the moon. You can see people walking on the moon. You can see moon rocks in the Museum of Science and Industry. The same thing is true with all branches of science. The more we learn about the DNA, the more we learn about how our bodies are built, our evolutionary history, we remove the chance for myth and superstition. The more we do that, the more we gain power over our own lives. Now, that means we face choices with things. But those shouldn't be scary—those should be informed choices. I see science as a light in a dark room. When my son is scared at night in a dark room, I'll turn on a little night light. Well, that light is knowledge in my own world.
Revolution: At the same time, there will always be more mysteries—a question is answered, then there'll be more questions.
Neil Shubin: Exactly. My world is full of questions. How do you think I'm approaching Tiktaalik? We answered some questions with Tiktaalik, but there are more questions that are opened up. Science is never-ending questions. We humans are never going to understand 100 percent of everything, obviously. It's always a battle to learn the truth. And scientific truth is different from most other kinds of truth in that it's a truth that we strive for. We never actually claim we have it entirely, because it sometimes slips out of our grasp. What we have is a method which can get us there. Scientific truth is important because it's truth that you and I can share. I can put it on the table, and I can tell you why that is a truth. And we can agree on principles to falsify it or confirm it, right? That's something that's important about science. Other forms of truths, you either accept it, based on your own background or belief system. In scientific truths, there is a right and a wrong. And that's what attracts me to it.
Revolution: You’re a provost at the Field Museum in Chicago, which has a very popular exhibit called "Our Evolving Planet," among other things. You’ve written a best-selling book. You’ve taken the Tiktaalik fossil to schoolrooms. How do you see the importance of people broadly in society understanding science and the scientific method?
Neil Shubin: We have to do that, scientists have to get in the role of communicating what we do. It's important in several ways. Not only communicating the fact of evolution, the facts of the fossil record and of DNA. There's something else there—two other things. One is, science is a process. How do we scientists do it? It's not that we just open a book and say, aha, there's the fact. My “book” is in the Arctic, and we have to work really hard to find that stuff. We have to take some risks. So the “books” of science are in the test tubes and in the field and so forth. But the other piece of it is conveying also why it's fun. I love nothing more than receiving a letter from teachers or kids who want to learn more. If they're lucky to live in an area that has a great museum, that's fine. But the Internet is a great tool, and that's been a great equalizer in a lot of ways in giving people from remote areas the chance to see museums or encounter fossils and so forth. It's ever more important in our society. Look, we live in a society, United States, I don't know the current statistics, but over 60 percent believe in the story of the Genesis over the science of evolution. I think there's a gap there. Here we are in an increasingly technological society—look at what I just said about technology and our future. Yet we as a society are completely unequipped to evaluate that. So we owe it to our children and to our population, not just children—to people who might be scared of science because of experiences they had in school and so forth, to communicate its power and what we do. That was the spirit of my book. And that's also why I think museums are very important places.
Revolution: What do you see as some of the key questions and controversies in paleontology and evolutionary science today?
Neil Shubin: There's a lot of good stuff. Cutting-edge issues include, I think, understanding the dynamics of extinction—how species go extinct, and why. There is an ongoing question about why are certain areas of the world or certain time periods more diverse in species than others? Why is there more diversity of species in the tropics than there are in other places? Why do we see that pattern of diversity—what explains that, what's the mechanisms? Those kinds of questions are very important. And paleontology is actually making strides on those as we speak, but those are very important questions. And the other really big one, in terms of my own patch of the world, is understanding bodies. How bodies came about in the first place. We know a lot more than we did five years ago, and we're going to know a lot more five years from now. And that's going to be exciting to watch as we learn more about how cells came together to make bodies and other big questions.
Revolution: That goes back to the point about microbes—single-celled microbes were the only form of life for billions of years on earth, before multi-cellular creatures came about.
Neil Shubin: They had been coming together for a long time. But they hadn't been coming together in bodies. They had been coming together as mats or sheets of cells. What's a body, and what's really important about a body, is those cells had to have a mechanism where they could interact with one another. Bodies have an integrity to them that other kinds of organization don't. The way that happens is that these cells, these microbes, actually evolved over time ways to interact with one another. And it's interesting, microbes do that. Microbes interact. Microbes sense the outside world. And really what we have—the tool kit that makes bodies—is actually a modified version of that, which helps microbes interact with each other and the outside world. So that's why the continuity is still there. For me as a scientist, there's no doubt that that happened. The interesting puzzle comes down to how that happened, over what time frame, and so forth.
Revolution: Why did you decide to become a scientist, and how did you come to pursue your particular areas of research? Were you interested in science from an early age?
Neil Shubin: I was this kid—still the same way—I would have a hobby of the month. It would drive my parents nuts. They bought me a telescope—"I'm really into astronomy." So I subscribed to Sky and Telescope and I learned a lot about astronomy. Four months later I got bored of it. So I got a stamp collection, got really into it. So I would go from hobby to hobby to hobby to hobby. I would eventually loop back to old hobbies—the telescope never got thrown away; in fact, I still have it somewhere. So I was always curious, and science has always been an outlet for my curiosity. But the actual paleontology end of things—it combines a lot of cool stuff for me that I like to do. It combines strengths—it's important to find a career where you can use your strengths, not your weaknesses [laughs]. I enjoy going out in the field. I enjoy finding fossils—my strength is the ability to find fossils, I've always been good at that. It's nice to have a career where I can put that to good use. But the important thing is, you have to really enjoy it. Because most of the time I'm not finding anything. It's the hunt. It's the exhilaration. I like starting a new expedition, having the expectation and the risk. That's kind of fun. But for paleontology, one of the immediate appeals is the "eureka" moment—there is a moment in paleontology, if you're successful, you find something. And that's something you can hold and say, "aha"—like Tiktaalik. That's what you look for. Now I'm looking for the next one.
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