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Once We All Had Gills: Growing Up Evolutionist in an Evolving World

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In this book, Rudolf A. Raff reaches out to the scientifically queasy, using his life story and his growth as a scientist to illustrate why science matters, especially at a time when many Americans are both suspicious of science and hostile to scientific ways of thinking. Noting that science has too often been the object of controversy in school curriculums and debates on public policy issues ranging from energy and conservation to stem-cell research and climate change, Raff argues that when the public is confused or ill-informed, these issues tend to be decided on religious, economic, and political grounds that disregard the realities of the natural world. Speaking up for science and scientific literacy, Raff tells how and why he became an evolutionary biologist and describes some of the vibrant and living science of evolution. Once We All Had Gills is also the story of evolution writ large: its history, how it is studied, what it means, and why it has become a useful target in a cultural war against rational thought and the idea of a secular, religiously tolerant nation.

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1 Space-Time

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I am enthralled by time. As long as I can recall I’ve wanted to know how the familiar world we take for granted came about. This has been a lifelong fascination because the past is truly not just another country but a chain of linked and ever stranger other worlds. Our evolutionary origins lie in these former worlds, which grow not only more alien but also fainter and more elusive as we look ever deeper. The passage of years and the eclipse of memory also obscure our personal origins. Like detectives, we have to tease out our pasts from imperfect and concealed evidence. On the greatest earthly scale, the geological record of the planet and the record of the evolution of life upon it have been likened to a book left to us with most of its pages torn out. On a personal level we suffer from lost family records, deceased witnesses, and the erroneous illusion that our own so-certain memories are accurate. Our efforts to answer questions on these vastly different scales will succeed with some, but others will remain elusive, and new questions will arise like dimly seen specters, shyly but persistently standing at the edge of our vision.

 

2 Layers of the Past

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My mother, Therese Dufresne, was the daughter of a well-liked local physician, Albert Dufresne, who practiced from 1930 onward in Shawinigan and the surrounding countryside. His house calls could mean anything, including grueling trips into the backcountry by horse-drawn sled or canoe. By the time he retired, my grandfather had delivered or treated most of the living citizens of the town. He once estimated that he had delivered eight thousand Shawinigan babies. In 1966 he was made a Commandeur de l’Ordre de Saint-Gregoire-le-Grand, a papal award for his charitable acts to his many patients unable to pay in hard times. A street in Shawinigan now bears his name.

Going to visit Shawinigan during summer vacations was the highlight of my early life. Shamefully, it was not because I liked spending an entire vacation in my grandparents’ rather formal house. I was too energetic for that. What I cherished most was any time I could spend out in the woods at a lake. My Uncle Gérard Dufresne’s family had a remote cottage on Lac des Îlles, where on one visit I was impressed to see the hole where an enterprising bear had clawed its way through a soil-filled double-log wall into the icehouse. What a frisson to realize that wooden doors would be as paper to hungry bears (not that they bothered cottages with people around). Most of my cottage experience though was at Lac Souris (Mouse Lake – had they run out of better names?). Here the vast Quebec forest lapped the edge of civilization. On the far side of the lake, inaccessible from the end of the rutted lake road, my uncle Guy Ricard (the husband of my mother’s sister Margot) and my grandfather had built a summer cottage. To get to the cottage from the road head, we would uncover my grandfather’s old motorboat, drag it over the wet sand into the shallows, load up supplies and gas, and push off with battered oars to get into water deep enough to lower the outboard. Then, with some boat rocking, repeated pulls of the starter cable finally got the balky engine going. We’d head off at two miles per hour in a cloud of fragrant blue smoke. If there were just the two of us, I’d be allowed to run the engine and steer with my grandfather’s nervous guidance. Once steady, I could throttle up enough to leave a discernable wake across the usually glassy surface. I have a photograph of one of those days – me a skinny ten year old wearing an oversized old raincoat of my grandfather’s belted around my waist, he with his inevitable cigar in his mouth.

 

3 An Age of Dinosaurs

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We left Canada for Pittsburgh, a mysterious city in Pennsylvania, during the fall of 1949. I know this move was an enormous break in the lives of my parents, hopeful for my father, wrenching for my mother. The trip was just a big adventure into the unknown for me, a train journey to the faraway exotic South. Rail service was efficient and comfortable in those days, with sleepers, dining cars, and authoritative conductors wearing neat blue uniforms. There were lots of windows to gaze out from. The trip was long, and not understanding just how near the equator we were headed, I watched for hours in hopes of seeing exotic creatures by trackside as we crossed into tropical Pennsylvania. Despite my hopes, I was to be disappointed by the scarcity of coiled rattlesnakes and waving palms – but not by Pittsburgh. How could it fail to satisfy? I had never seen a city before. We lived for a couple of months in the Webster Hall Hotel just across the street from Mellon Institute, where my father’s research lab was then located. At night the horizons were lit a lurid orange by the blast furnaces. The glow of the furnaces would fade out to extinction in Pittsburgh by the 1980s, and the steel industry would follow. Best of all, our first temporary home was also just two blocks from the Carnegie Museum with its wonderful gallery of dinosaurs. My first visit to that vast, gloomy exhibit hall was unforgettable. I was eight and had never been in such a cavern. The hall contained towering chocolate-colored skeletons, monsters like nothing living today, standing silent, mouths armed with impressive teeth, leg bones the size of trees. Like most children, I was enraptured by dinosaurs. Naturally, I knew none of the scientific drama and wonderful megalomania that lay behind those skeletons. The dinosaurs themselves were enough for my eight-year old sensibilities.

 

4 A School a Minute

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My mother never really adapted fully to life in Pittsburgh or felt completely at home with American customs. She always pined for Quebec and for French-speaking friends. Although she spoke English as well as any native speaker, all her life she would emphasize her origins by occasionally using an outrageously fake French accent or interspersing her conversation with “How do you say it in English?” accompanied by a Gallic shrug. She painted avidly and encouraged me to draw and paint. I enjoyed it without being inhibited by the least sense of angst. I knew I didn’t have the talent to contemplate becoming a professional artist. My father took enthusiastically to living in Pittsburgh and thoroughly enjoyed being in the United States, which he found amazingly open and free of onerous restrictions. He told me how liberating it felt to live in a country where everything was permitted unless specifically forbidden, as opposed to the authoritarian system he had grown up in which everything was forbidden unless explicitly permitted. Having come to America as an adult, he did find some of the cultural idioms puzzling, however, and never lost his strong Austrian accent.

 

5 In the Natural World

ePub

I was an inveterate naturalist. Each year I anxiously awaited the return of spring (and, truthfully, the end of the time-crawling endless school year). I felt a strong curiosity and an intense attraction for the look and feel of natural forms and creatures, the stranger the better. At various times my interests settled on hunting salamanders, insects, turtles, snakes, and fossils in the forested hills near our house. I had read that snakes had no eyelids, so I had to look a snake in the eye. Sure enough, their eyes are covered by the clear window of a single modified scale and can’t be closed even in sleep. All snakes are carnivores. I kept snakes and watched them feed using independently attached lower jaws armed with sharp, curved teeth. A snake engulfs its prey by walking each jaw alternately down its victim’s body, and there is no escape once a snake begins to swallow. It happened to me. I was handling a middling sized garter snake, about eighteen inches long and about as thick as my index finger. It bit the tip of that finger and held on. This posed a quandary to both of us. The snake couldn’t let go because of its recurved teeth, so it began to work its jaws up my finger, committing itself to swallowing a nearly full-sized human – a new frontier for a garter snake. I carefully disengaged its independently movable lower jaws, and slid my finger free without hurting the snake. Fortunately, its upper jaws hadn’t secured much of a hold because my fingernail was in the way. I got to keep a few tiny punctures as souvenirs.

 

6 Transformations

ePub

After one more family move, I did my last year before college in another new school, Gateway Senior High in the Pittsburgh suburb of Monroeville. As many of my classmates were also new students who had just transferred there with the metastasis of suburban sprawl, no cliques of cool kids had built up and the teachers were good. Perhaps the best was our exceedingly sarcastic English teacher, who supplied just the right attitude for reading about the oddities of the Macbeth family and Julius Caesar’s unfortunate misjudgment of his friends. Two of my Gateway friends eventually took doctoral degrees in science. Tom Taylor became a mechanical engineer, and Mary Boesman became an immunologist. She died in 2007. Mary and I both read history and lent each other books. This was the best of my twelve-year run of schools, and I remember it fondly.

But that pleasant year also included the looming matter of where I should go to college. Given what my family could afford, my choices were limited. I could attend a university in Pittsburgh and live at home or attend the state university and live away. Not much of a contest. Despite the good universities around Pittsburgh, living at home would suffocate my becoming independent. After all the adventures of filling in applications, taking College Board exams, being interviewed, and sitting in on a sprinkle of college class lectures, I left for Pennsylvania State University in the fall of 1959. My parents took me to State College and helped me move into my first dorm, but I was anxious for them to leave. I now had to make my own triumphs and my own missteps (ludicrous missteps outnumbered triumphs that first year). Our first assembly as freshman students included an address by the president of Penn State. He told us to look at the person on our left and the person on the right. One of them would be gone before the year’s end. Perhaps that encouraging invitation to embarrassed sidelong glances constituted what might be described as a subtle preparation for life.

 

7 Going South

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Near the end of my undergraduate life, I set about blissfully applying to graduate schools, including Duke. There was lurking a possible slight hitch to entering this dream world; I had a commitment to serve two years of active duty in the U.S. Navy after commissioning as an ensign (the naval term for what the army calls a second lieutenant). However, the navy seemed to have had an excess of young officers entering at the time and readily allowed anyone qualified to have eighteen months in the inactive reserves to get a master’s degree before going on active duty. The master’s degree limit seemed like a constraint, but I hadn’t met Bill Byrne yet. Bill was a biochemistry professor at Duke who served as the departmental graduate program director. He was undaunted by both the department’s and the navy’s rules and worked out an acceptance for me to take a master’s degree, which the navy approved. He then produced a second letter to convince the navy that as Duke didn’t really like to give a master’s in biochemistry, it would be far better to let me stay on for a Ph.D. In a miracle of bureaucratic accommodation, they approved that too.

 

8 Learning to Love the Bomb

ePub

As I was completing my Ph.D. dissertation in the spring of 1967, I uneasily awaited my orders to report for active duty in the U.S. Navy. The anticipation was tense because I was a line officer and thus could have been sent to serve in a warship cruising off the Vietnam coast, a depressing thought. The Vietnam War was every day becoming ever more obviously a futile exercise made up of empty victories and doctored body counts. Each night statistics were reported in television briefings featuring confident and heavily be-medaled generals who jabbed pointers at authoritative-looking multicolor charts. No matter how glorious the assertions, effective victories were elusive. The war was a waste of life without any claim to a valid purpose. There were fevered references to hapless countries succumbing to communism like falling dominoes if American troops went home, but in reality combat churned on only to protect the reputation of a president who couldn’t admit defeat. The fateful orders finally arrived. The envelope lying on my desk held my future – orders were orders. It seemed like the famous box containing Schrödinger’s cat, which existed in an undecided state between life and death. I opened the envelope; the cat was alive. I had been assigned to a research institute at the National Naval Medical Center in Bethesda, Maryland, which had a slot for a line officer. With my assignment to active duty, Beth got a booklet in the mail called Welcome Aboard to the Navy Wife. She was incredulous at the instructions about when and how to wear white gloves and, worst of all, that she should respond to the wishes of her commanding officer’s wife as her husband did to his commanding officer’s orders. Actually, nothing of the sort happened, and we shared social occasions with friends serving similar tours of duty.

 

9 On the Road to Chiapas

ePub

As 1968 bloomed, we watched in dismay the growing ferocity of the Vietnam War with the shattering surprise of the Tet Offensive at the beginning of the year, the decline of Lyndon Johnson’s hold on the presidency, and the depressing inevitability of Nixon’s election that autumn. However, my time in the U.S. Navy would come to an end early in the summer of 1969, and exciting science beckoned. One enticing new discipline bubbled up about that time from the sudden re-awakening of developmental biology: the study of how organisms develop from the fertilized egg to the adult, with the marvelous unfolding of the elaborate form of an organism from the apparently structureless spherical and homogeneous egg. I looked for postdoctoral opportunities in this new molecular developmental biology being pioneered by just a few labs. Developmental biology had made famous discoveries earlier in the twentieth century through ingenious microsurgical experiments but had languished by the 1960s because of a lack of tools to penetrate further into how embryos work. This was about to change in a completely unexpected way as genes became better understood and ways to study them were found.

 

10 The Masked Messenger

ePub

When Beth and I returned to State College at the end of the long, anticlimactic journey back from Mexico via Oklahoma, we packed our car full of our possessions and set off for Boston to start postdoctoral work. We moved into the entire middle floor of an enormous frame house in Watertown, built about 1900 by a prosperous dentist who had an expansive family to accommodate. Our only pet at the time was a gopher tortoise we had rescued from the highway in Oklahoma. He was charming in his own reptilian way. We’d off er him lettuce and he’d go for it. Once a bite was taken, he’d drift off absentmindedly, lettuce forgotten until he’d catch a glimpse of the green. Then he’d frantically charge back for another bite. We found him a good home with a herpetologist. I settled into Paul’s lab, and Beth started as a postdoc in biochemistry at Tufts Medical School. Boston was an entirely new experience. We quickly found the Boston Museum of Fine Arts and the Isabella Stewart Gardner Museum. Both had wonderful collections and were places we could aff ord to visit on postdoc salaries in an expensive city. Hal White, our friend from Penn State, was now a postdoc at Harvard. His wife Jean was a graduate student at Brandeis University. With them we discovered close-by canoe and swimming streams in New Hampshire and the wonderful Ponkapoag Pond in the Blue Hills nature preserve.

 

11 Evolution as Science

ePub

When I was a kid and enjoyed collecting fossils and fantasizing about live dinosaurs, I was completely, even magnificently, ignorant when it came to grasping what evolution is, beyond a vague notion of one kind of dinosaur following another through time to their inevitable doom. There were many things I didn’t even know that I didn’t know – like what science itself is. Then there were other gaps in my knowledge, most critically of the historical origins of evolutionary biology and, most difficult to grasp, what the living science of evolution is all about. Much education happens by accident and curiosity. I have never had a formal course in evolution, and my becoming an evolutionary biologist came as a result of my reading as I became a molecular developmental biologist. I only later came to do research on the relationship between developmental biology and evolution. Now, as a whim of fate, I teach evolution to students who have no idea that I never took the course myself.

Science is about understanding the natural world. As scientists, we assume that nature operates under the actions of consistent natural forces; no miracles or other supernatural phenomena are involved. This is not to suggest that scientific reality will necessarily correspond to commonsense reality. The bizarre world of quantum mechanics makes no connection with common sense, nor can we have personal comprehension of the vast geological times we have to think about in studying evolution. Scientists assume that we can extract a consistent understanding of the natural world, and that we can test our working models, hypotheses, under tough criteria. Hypotheses should seek the least convoluted assumptions; they should not require special fudge factors; they should explain existing knowledge; and finally, they must predict the results of experimental test or new observations. Only hypotheses with a high degree of explanatory power and a history of surviving all challenges are promoted to the status of a theory. But science is always conditional. Even theories may be susceptible to being overthrown if a better model of the world becomes available. Some theories, like the rule that matter is composed of atoms, that the Earth revolves around the Sun, or that life has evolved, are strongly established and are unlikely to be incorrect.

 

12 Dining with Darwin

ePub

Biologists like to have a sense of connection with places or events associated with Darwin. That comes mainly from reading Voyage of the Beagle, which along with the great Darwin biography industry has given us an amazing sense of intimacy with him, a sort of feeling of kinship. I feel it, too, and I have enjoyed my contacts with Darwin’s traces even though I’ve never tried to follow his Beagle travels. The first Darwin site I saw happened to be the place where he spent most of his post-Beagle life and where he wrote Origin of Species. That was Down House in Kent, about sixteen miles south of London, which Beth and I visited in September 1974. Our trip there was long before Darwin’s popularity peaked again. Down House was empty of visitors, so we could look around the garden in solitude and stroll the famous sandwalk where Darwin walked for exercise and to think. As we were alone in the place, the custodian opened the cord blocking casual entry into Darwin’s study and showed us around, a treat that may be harder to come by now. The room was preserved pretty much as it had been in Darwin’s time. We stood in front of his desk, his mantel, and his bookcases. I put my hand on his desk. This was the room he wrote in. You might imagine that you could speak to him there, but you can’t reach across time except in imagination.

 

13 Life with Sea Urchins

ePub

My former postdoctoral advisor, Paul Gross, liked to say that “your graduate students are your friends, but your postdocs are your enemies.” This was because graduate students would go off to do postdoctoral work in new areas of research but departing postdocs would want to kick-start their independent careers by continuing the research they had developed during their postdoctoral years. Thus they were virtually destined to become competitors with their own former mentors. Nonetheless, Paul was generous about allowing postdocs to take their projects with them. For several years at Indiana, I continued the study of how protein synthesis was stimulated at fertilization of sea urchin eggs. By 1978, we had published our main findings on the “masking” of mRNAs of eggs and on the regulation of protein synthesis from these mRNAs in embryos following fertilization, and I began to get restless. I was ready to start a new direction of research. I thought it was time to return to my early interest in evolution, but now with a better understanding and better methods, and a view toward thinking about evolution and development. Developmental and evolutionary biologists had diverged in their research objectives to the point where neither thought much about the role of the other. My first approach to the experimental study of the evolution of development would be based in Indiana but was boosted by priceless summers in Woods Hole, Massachusetts, where I learned about marine embryos as creatures with life histories and their own evolutionary careers. Those evolving larvae have occupied my scientific life for three decades.

 

14 Embryos Evolving

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At Indiana I began thinking about evo-devo as something that should move beyond its mid-twentieth-century form. Over a period of time I developed a parts list of essential elements we would need in order to be able to both ask and answer questions about the evolution of body form. It seemed that it would take a synthetic combination of ideas from several disciplines. These eventually would include developmental genetics, molecular evolution, and genomics on the mechanistic side. But more was needed. The historical disciplines of paleontology and phylogeny would allow us to include the events of the long ago evolutionary past in our analyses. Paleontology would allow us to envision ancestral conditions and patterns of change, and evidence from phylogeny would allow us to map a history of descent. The second essential element was a suitable research organism for addressing experimental questions. That would require an organism that presented concrete evo-devo problems stemming from its evolutionary history and was amenable to experiments designed to answer those questions. The third was to seek mechanisms of evo-devo that were comparable in explanatory power to those of modern developmental and molecular biology. This would allow us to understand the mechanistic bases for particular evolutionary changes. I considered phylogeny to be crucial to the experimental effort, because it is only by incorporating the pattern of descent of evolutionary changes that evolutionary changes in development can be interpreted as arising once in an evolving lineage or evolving independently in separate lineages. We should be able to set mechanistic explanations into these phylogenies.

 

15 Evolution in the Tasman Sea

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In the early 1980s, I started earnestly hunting for the right organism as an experimental system for delving into evo-devo. I thought the ideal animal would be one in which the evolution of early embryonic and larval development could be readily studied because embryos and larvae are crucial stages in development and are simple in cell numbers and types compared to adults. My first efforts were made using the familiar sea urchins of the Northern Hemisphere. I found that we could explore evo-devo at the gene level in sea urchins and published our first evo-devo paper in 1984. In it we showed that a major innovation in the expression of histone genes in sea urchin eggs had taken place with the origins of advanced sea urchins in the Mesozoic, while brontosaurs munched their way across the landscape. We could thus correlate a unique gene regulatory mechanism with a set of macroevolutionary events in sea urchin evolution. But the events were too distant in the past to help unravel ongoing developmental evolution. So I’d have to look farther afield.

 

16 An Alternate Present

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I was drawn to Australia because of the extraordinary possibilities it offered to study evo-devo in a marine embryo that had evolved with abandon. Everyone knows about kangaroos and a few other oddities such as giant fruit bats, photogenic koalas, and good beer. So it was for me when I first went Down Under. But as a biologist, I was soon overwhelmed by the endless strangeness of Australian life forms. I still am, as a matter of fact. What many return visits have taught me is that the weirdness is more than koala deep. Australia is not lost in time; it is an alternate, living evolutionary outcome on planet Earth resulting from millions of years of evolution in isolation. Australia’s last direct links to the rest of the world started being ruptured by inexorable plate tectonics about 80 million years ago, when dinosaurs still roamed Antarctica and Australia. A connection to Antarctica and from Antarctica to South America persisted until about 40 million years ago and then was severed with the final drift of Australia to the north. The ancient plants of Australia were derived from a forest that extended from South America through South Africa and Antarctica to Australia, and the botany of that long-dispersed Gondwana forest has left its mark. The Antarctic beech that long ago grew in the forested vales of Antarctica still grows in the cool highlands of Australia. The exotic banksias and grevilleas that bloom in Australia are the evolutionary cousins of the South African proteas beloved of flower arrangers. The state flower of New South Wales is the gorgeous red waratah, which has close relatives in South America.

 

17 Biology Meets Fossils

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I’ve never lost my interest in fossils or my love of tracking them down in their rocky haunts. Sometimes that haunt lies in the splash at the foot of seaside cliff s. Standing there, I’m lost in time, the fossils merging with the heave of a sea in which an imagined swarm of alert, large-eyed ammonites still float with colored tentacles projecting from the mouths of their graceful chambered shells. Disentangled from fantasy, fossils are priceless tools for seeing through time in order to answer questions in evolution. In particular, I’ve wanted to see far back beyond those beautiful ammonites to the origins of multicellular animals, the organisms that include our ancestors.

In the past decade there has been a revolution in discoveries of Precambrian and Cambrian animal fossils; a whole half-billion-year-old zoology is appearing before our eyes and thought. These fossils are extraordinary enough, but even more amazingly, fossil embryos from the dawn of animal life have turned up as well. The flash in the fossil record that marks the origin of advanced animals has been variously called the “Cambrian explosion” and the “metazoan radiation,” names that come from the observation that the animal body plans found in the animals that live today appear with relative suddenness in the fossil record, in strata deposited during the Early to Middle Cambrian time. The official start of the Cambrian was 542 million years ago, and this fabled geological period closed up shop 488 million years ago. The “explosion” had ended by about 520 million years ago. In fact, the metazoan radiation had begun slowly 100 million years before that and reached a crescendo in the Early Cambrian.

 

18 Darwin’s Day in Court

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When Galileo turned his telescope to the sky in 1609, he revolutionized our thinking about our place in the universe as surely as in modern times Darwin’s natural selection would give us a new view of our biological origins in nature. Galileo’s startling discovery was that Copernicus had it right. The Earth was not the center of the solar system, nor was a fixed Earth the center of the universe. In 1632 Galileo published a defense of his work and was tried for heresy and condemned by the Catholic Church to spend the remainder of his life under house arrest. In 1992, Pope John Paul II acknowledged the church’s errors in the matter. In 2009, the Pontifical Academy of Sciences concluded, “The extraordinary progress in our understanding of evolution and the place of man in nature should be shared with everyone. . . . Furthermore, scientists have a clear responsibility to contribute to the quality of education, especially as regards the subject of evolution.” The validity of science does not depend on religious approval, but amicable understanding doesn’t seem like a bad idea. That’s an unfortunately iff y proposition for science co-existing with at least some of religion in America.

 

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