Science: The Last Frontier
President Shirley M. Tilghman
February 28, 2006
Dehejia Lecture, presented at Sidwell Friends School
Thank you and good afternoon. I am honored and delighted to speak to you today in the role of a Dehejia Fellow. Dr. Dehejia, before his untimely death, was a life scientist committed to understanding the genetic basis of Parkinson's Disease, one of the most common yet poorly understood neuromuscular degenerative diseases. He was also involved in one of the most daring and ultimately successful scientific projects of the 20th century – the Human Genome Project. As a student at Sidwell Friends, Dr. Dehejia had the advantage of a first-class education, and I have no doubt that it was here that his fascination with the natural world was kindled.
Today, as never before, there is a pressing need in the United States for children to be instilled with a passion for discovery. If one considers the advances in the 20th century that left the world a better place, they grew almost exclusively out of fundamental and applied scientific research, much of it conducted in our nation's research universities and government laboratories, like those where Dr. Dehejia worked and studied. The evidence for this sweeping statement is all around us: in the dramatic increase in life expectancy and particularly the reduction in infant mortality; in the virtual eradication of a disease like smallpox through systematic world-wide vaccination; in the generation of household conveniences that have freed us from punishing manual labor; in the provision of safe drinking water and sanitation; in the availability of world travel and its potential to foster greater understanding among people of different cultures; and in the development of the Internet, a powerful tool that provides global and instantaneous access to everything from the world's great literature and art to mindless chatter on blog sites. Everyone from The New York Times' Tom Friedman in his powerfully argued book The World is Flat to President Bush in his State of the Union address last month is publicly speaking out about the critical importance of the United States remaining pre-eminent in the fields of science and technology. Just as the launching of Sputnik in 1957 sent shockwaves of self-doubt through the corridors of Washington, the potential emergence of India and China as technologically advanced world powers is forcing us to question the inevitability of our post-Cold-War position as the lone world power. The response in the 1950s was to begin a massive federal investment in scientific and technological research and to inspire a generation – my generation – to see science as one of the most exciting and rewarding callings imaginable.
My fear today is that we are no longer instilling in our children a sense of curiosity about the natural world that would lead them to choose to devote their lives to revealing its many wonders, and that we are failing to provide them with the knowledge to make them good scientists and engineers. What is the evidence for this? According to the National Assessment of Educational Progress conducted in 2000, only 18 percent of high school seniors correctly answered "challenging" scientific questions, and only 53 percent had a handle on the "basics." When the scientific and mathematical knowledge of American twelfth-graders was recently compared with that of students in 20 other countries, only two, Cyprus and South Africa, had average scores significantly lower than the United States, and most countries outperformed us. As an educator, I am haunted by the words of that great sage, Pogo: "We have met the enemy, and he is us."
Now one might argue that the lackluster performance of American students in science and engineering reflects the absence of something as exciting as sending a satellite – much less a human being – into space to inspire them. Indeed, every so often, with a periodicity of about 25 years, someone claims that everything worth knowing has already been discovered, and all that is left are clean-up operations in which "i"s will be dotted and "t"s will be crossed. The first time I heard such a provocative statement was in the late 1960s. Gunther Stent, a distinguished molecular biologist at the University of California Berkeley, published a book called The Coming of the Golden Age: A View of the End of Progress, in which he posited that it was precisely the rapidity of recent progress that predicted the demise of science, possibly within a few decades. He pointed out, for example, that the discovery of the double-helical structure of DNA in 1953 and the deciphering of the genetic code left few profound questions to answer. He did admit that we still did not know how life began on earth, how a fertilized egg gives rise to a fully formed embryo, or how the central nervous system processes information, but he was sanguine about the short period of time it would take to answer those questions. Stent may have been a fine scientist, but he left something to be desired as a prognosticator, as we have yet to answer those questions 37 years later.
In fact, I would argue that we are still very much at the dawn of science, with far more profound questions to address than we have answered to date. As the American physicist and Nobel laureate David Gross put it, "Some wonder whether some day we will arrive at a theory of everything, and run out of new problems to solve – much as the effort to explore the earth ran out of new continents to explore. While this is conceivably possible, I am happy to report that there is no evidence that we are running out of our most important resource – ignorance. How lucky for science. How lucky for scientists." Like David Gross, I am confident that the discoveries we will make in the next 50 years will be even more dramatic than those I have witnessed in my lifetime. I am equally confident that the process of making those discoveries will be great fun and enormously rewarding for those involved – which is something we need to convey to the next generation.
Today I would like to reflect on the notion of science as mankind's last frontier, a place of profound change and infinite possibilities, much like the geographic frontiers that have always captured the popular imagination. From my perspective, the excitement to be found on the frontiers of science springs from three primary sources: the lure of the unknown, the extraordinary rush at the moment of discovery, and the satisfaction that comes when scientific progress transforms the lives of our fellow men and women for the better.
Let me start with one of Stent's unanswered questions. If I was 18 years old and just beginning a life in science, I would choose to become a neuroscientist, like Dr. Dehejia. Many of my Princeton students have chosen that path over the last decade, and it is one with which I have a great deal of sympathy – and a little envy. From the deepest questions about the nature of human consciousness to specific questions about perception – how does the brain distinguish the odor of a rose from that of a skunk, and why is the universal emotional response so different? – neuroscientists are posing questions with profound implications for all of us. After all, the essence of being human lies in the way in which the human brain functions. As Stent clearly failed to appreciate, the magnitude of the challenge is daunting even today. It is not so much that the brain is composed of more than 100 billion neurons – a frightening number that would intimidate even Carl Sagan. But each of those neurons is connected to upwards of a hundred thousand other neurons in a pattern that is so complex that it defies our computational firepower at the moment. In fact, each neuron is a computational device in its own right, with the ability to communicate internally and externally with chemical and electrical signals that fire at nanosecond speed. Unraveling the complexity inherent in this magnificent machine we call the brain will be the great scientific achievement for this millennium. Imagine the fun of trying to answer age-old questions like "What is the nature of memory? How is information stored in the brain and how are we able to retrieve it so rapidly –at least if you are under the age of 50?" We have begun to get some traction on this question by studying simple organisms – including Aplysia, the sea slug. You may not think that a sea slug is capable of learning anything, much less recollecting it at a later date, but, in fact, a friend of mine, Eric Kandel, won the Nobel Prize in Medicine in 2000 for doing just that – for showing that these extremely ugly animals are capable of undergoing both conditioning and habituation, and then uncovering the molecular basis for those responses. This is the ultimate example of turning a sow's ear into a silk purse.
If for some reason I were prevented from becoming a neuroscientist, I would next choose to become a cosmologist. Today we are living in one of the most extraordinarily productive times in the history of astrophysics and cosmology, when explorations with satellite space telescopes such as the Hubble Telescope, the Wilkinson Microwave Anisotrophy Probe, and the ground-based Sloan Digital Sky Survey, as well as unmanned space missions like Voyager, are providing us with breathtaking insight into the structure of the universe and our solar system. We are learning that our cosmos is much stranger than we thought. It is flat, not round or spherical, a fact that would come as a surprise to Christopher Columbus, I am sure, and it is flinging itself apart at an accelerating rate. To explain these observations, cosmologists have invoked a new force, to which they have given the Darth Vader-like moniker of "dark energy," to counteract the forces of gravity that we understand much better. Can you imagine that only 4 percent of the universe can be accounted for by the atoms and molecules we know and understand? The rest is composed of "dark matter" and this strange dark energy. We have a very accurate age for the universe – 13.7 billion years plus or minus a few hundred thousand years – but the origin of the universe remains a complete mystery. What existed just before the Big Bang? As someone who has always been fascinated by stories of exploration – whether it was Columbus and the New World or Amundsen and the South Pole – I see space as the ultimate frontier. With the development of earth-controlled space probes, we are beginning to fill in remarkable details about our solar system. New galaxies, planets, and moons are being discovered almost monthly, to the point where we are beginning to reconsider what constitutes a planet in our lexicon. Just last month the remarkable journey of Stardust, a spacecraft launched in 1999 to capture particles from an orbiting comet, ended safely in the Utah desert. Comets are believed to consist of the oldest and most pristine material in our solar system, and scientists hope that Stardust's precious cargo will help to explain our solar system's origin and, maybe, even that of life itself. These discoveries comprise a golden age of space exploration – and should capture the imagination of aspiring scientists.
If budding scientists are drawn to mankind's great unanswered questions – and I have touched on only two examples – they are also attracted by the possibility and, in many cases, the certainty of doing good, whether that means developing new vaccines, connecting the world through information technology, or creating nanodevices that are small enough and smart enough to enter and monitor human cells. But for my money the most compelling – and urgent – societal need today is to curb the release of greenhouse gases and ameliorate their subsequent impact on our planet. The evidence that the pace of climate change exceeds what one could expect from natural variation is convincing to the overwhelming majority of the scientific community. Twenty-one of the last 25 years have been the warmest of any period in the last 150 years, and the levels of atmospheric CO2 are unlike anything measured in the last millennium according to ice bores; the Greenland sea ice and the Arctic permafrost are melting; glaciers like those on Kilimanjaro are receding; and as we saw so tragically in the case of the Gulf Coast, weather patterns are becoming far more violent.
At the moment there is no credible alterative to the hypothesis that these changes are directly correlated to the increase in greenhouse gases in the atmosphere. What can we expect if we continue with business as usual? The best estimates are that the average global temperature will increase between 2 and 4° C by the end of this century, which is warmer than it has ever been over the last 2 million years. This will mean the extinction of polar bears and coral reefs, severe decades-long droughts and crop losses in the tropics, and the drowning of most of Florida. What a challenge for a bright young person to find a way to slow down greenhouse gas emissions by devising methods to capture the carbon before it is released! What a challenge to turn the promise of fusion energy or hydrogen fuel cells into practical reality so that when we run out of fossil fuels, as we surely will sometime in this century in the absence of serious conservation efforts, world commerce does not come to a grinding halt! The young should be pounding down the doors of science classrooms to get their teeth into these monumental problems that threaten our way of life.
Yet they are not. Despite the fascinating nature of these questions and the critical urgency of finding solutions to societal problems, American students are not rushing to become scientists and engineers. Just 6 percent of undergraduates major in engineering nationally, a percentage that is the second lowest among developed countries. To give you some sense of the magnitude of the differences, 12 percent of European students and 40 percent of Chinese students are concentrating in engineering today. To fill the void, foreign students comprise approximately 40 percent of all graduate students in science and engineering in this country. On the one hand, the participation of foreign students has historically been one of the great strengths of our scientific enterprise. A healthy competition between American and foreign students produces the most talented pool of students. However, the demographic trends clearly suggest that some fraction of the increase in foreign students is the result of the decline in the number and quality of American students. There are many steps I believe we must take to reverse this worrying trend, but as a university professor and a former high school teacher speaking at one of the nation's finest private schools, I would like to focus on just two things – changing the way we teach science and improving the quality of who does the teaching.
If I think back on why I became a scientist, it was the pleasure I derived from solving puzzles. From early childhood, I loved puzzles of any kind – mathematical puzzles, jigsaw puzzles, Rubik's Cubes, clever murder mysteries. I was attracted initially to all things mathematical but eventually migrated to organic chemistry because of the challenge of starting with one compound and transforming it, through a maze of possible chemical reactions, to a very different final end product. This was fun – a form of mental gymnastics – but what turned me into a scientist was discovering a big idea. I was a chemistry major in university in Canada, and by my junior year I was a bored chemistry major. I stumbled by chance on a paper in the chemistry library that described a very recent finding of two scientists named Matthew Meselson and Frank Stahl, in which they reported on the mechanism by which DNA is replicated. The first thing that struck me about the paper was the importance of the question being posed, for each time a cell divides, it must faithfully replicate all its DNA and deposit equivalent amounts into each of the two daughter cells. Now there was only a finite number of possibilities for how this could happen, and whether the answer was A, B, or C was not particularly interesting, frankly. But what was absolutely gripping was how Meselson and Stahl distinguished among the options. The experiment they devised was clever, indeed elegant, and it led to an unambiguous answer. What entranced me, what so entranced me that I ran over to the biology department to sign up immediately despite the fact that I had never had a course in biology in my life, was not what they learned but how they went about it; how they discovered new knowledge about the natural world. It was a thing of beauty and worthy of a life's work. And, most importantly, because I understood how they arrived at their answer, I never forgot it.
I take two important lessons from my own awakening. The first is that we must introduce students to the big ideas early in their education. Too often the operating metaphor for science education is a pyramid. At the bottom is a group of foundational facts – often discovered hundreds of years ago – that must be learned by heart. These are often taught as a laundry list and from an historical perspective, without much effort to explain their relevance to modern problems. Only after you have successfully conquered those facts are you allowed to move up the pyramid to the next set of slightly more complex facts, and if you have the persistence of Sisyphus and the patience of Job, you will finally reach the summit and be shown the reasons why you have been learning those facts – that they are the tools you need to solve exciting problems. I think we need to invert that pyramid and begin with the big ideas – like those that I mentioned a few minutes ago. And then we need to continually connect the facts and theories and hypotheses and theorems we teach to solving the questions behind the big ideas.
I tried this approach a few years ago with a group of eleven Princeton freshmen in a seminar called "The Role of Asymmetry in Development." At the time I taught this course – in 1992 – Princeton had a Freshman Seminar program in which a senior member of the faculty explored for a semester a deep question, often arising from his or her current research interest. To this day it is considered one of the most memorable teaching experiences by students and faculty alike, but no one had ever tried to teach a Freshman Seminar in the scientific disciplines. The reason? The pyramid! Dogma held that you could not possibly engage a group of freshmen with complex scientific ideas because they were standing at the bottom of the pyramid and were completely unprepared to appreciate what lay at the pinnacle. I was not persuaded, and I began the semester by posing one of the central questions in developmental biology: how can you go from a perfectly symmetrical cell – it could be a fertilized egg or a stem cell – and after a single cell division have two daughter cells that are different from one another? Without the generation of asymmetry, no differentiation and hence no development can occur. The assignment I gave to the students for the first three weeks was to think about ways in which asymmetry might be introduced into a biological system, and they were forbidden to consult any textbooks or sources. I wanted them to think originally about the problem. For three weeks we discussed their ideas – weighing the pros and cons of each. Once they had learned that they could invent hypotheses themselves, we spent the rest of the semester reading papers from the professional literature in which their ideas had been tested. Yes, we had to begin each class with a vocabulary lesson because of the propensity of scientists to use arcane language when simple words would do, but once armed with the dictionary, the students were able to understand the concepts and, most importantly, the ways in which scientists go about designing experiments to test big ideas – their ideas. From that I learned that it is possible to invert the pyramid.
The second lesson I take away from my own experience is that the two most important questions for students to ask are "How do you know that?" and "Why?" Science is, at heart, an exercise in asking questions, and in the course of my career, I have always found designing and carrying out clever experiments to be far more engaging than the answers to which they ultimately lead. Answers are, of course, important, too, but the real excitement and the lasting rewards of a life in science come from the journey, not the destination. This suggests that we educators need to abandon the practice of reciting the facts that reside at the bottom of the pyramid and replace them with questions – why they are important and how they were answered. This also suggests that we need to give students research opportunities as early as possible. In fact, there are studies that establish a positive correlation between an early research experience and the likelihood of persisting with a career in science. This is hardly surprising since one of the greatest motivators for a scientist is the thrill of discovery – at the risk of sounding like Bob Costas.
In my own case, I experienced the addictive rush of discovery as a sophomore at Queen's University, where all honors students were required to conduct research. My organic chemistry professor asked me to explore whether anhydropenicillin, an inert chemical, could be converted into biologically active penicillin. To this day penicillin remains one of the most powerful antibiotics we have to combat bacterial infections, but at the time the only source of the drug was the penicillin mold made famous by Sir Alexander Fleming, who won the Nobel Prize for his discovery. If we could develop a strategy to synthesize penicillin in the laboratory, we could potentially improve the purity of the drug and reduce its price to consumers. I spent the semester trying to effect the chemical conversion using an infinite variety of concentrations, solvents, temperatures, salts, incubation times, all to no avail. Then one morning I arrived in the lab to discover that the lawn of bacteria on which I tested the outcome of each chemical reaction was not growing as usual. Instead, there was a clearing in the lawn where the bacteria had been killed. The hair on the back of my neck stood on end, and my heart started beating wildly. I experienced the joy that comes from discovering something, and as of that day nothing could have stopped me from becoming a scientist.
But, of course, inspired education cannot happen without talented teachers. And it almost goes without saying that it is impossible to teach well a subject that you do not know inside and out. Yet, in 2000, 2/3 of public school physics teachers in the United States did not major in the subject, and 61 percent of chemistry teachers and 45 percent of biology teachers were not prepared in those fields. The critical lack of technically trained K-12 teachers in biology, chemistry, mathematics, and physics creates what in biochemistry is called a futile cycle – unprepared teachers fail to inspire students, who pursue other studies but return to public schools to teach science. We need to break this cycle because, as the Center for the Study of Teaching reports, the most consistent predictor of student achievement in science and mathematics is teachers who are fully certified in the scientific discipline they teach.
In a report released last fall by the National Academy of Sciences entitled Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future, a panel of experts from academia, industry, and government warned Americans – and I quote – "that the scientific and technical building blocks of our economic leadership are eroding at a time when many other nations are gathering strength.... We fear the abruptness with which a lead in science and technology can be lost – and the difficulty of recovering a lead once lost, if indeed it can be regained at all." The authors zeroed in on the key role that education plays in international competitiveness – "History is the story of people mobilizing intellectual and practical talents to meet demanding challenges" – and concluded, "If our children and grandchildren are to enjoy the prosperity that our forebears earned for us, our nation must quickly invigorate the knowledge institutions that have served it so well in the past and create new ones to serve in the future." This will be the only way to compete in our new flat world. The Gathering Storm makes a number of strong recommendations that are focused on teachers – including a new four-year scholarship program to attract at least 10,000 of our best college graduates to the teaching profession each year, and incentives to colleges and universities to develop rigorous science degrees that come with teacher certification. Master's programs and summer institutes for continuing education of middle and high school science teachers – like the one that the Howard Hughes Medical Institute supports at Princeton each summer for high school teachers in New Jersey – need to be made affordable and consistent with ongoing professional and family commitments. But perhaps most importantly, the profession of teaching needs to be recognized for what it is – the bedrock on which the United States rests, and teachers need to be respected, their working conditions improved, and their compensation adjusted to reflect the critical role they play, not just in the lives of our children but in the future of America. There are no silver bullets that will keep Americans in the forefront of global scientific progress, but if the panel's recommendations are taken seriously and adopted in thoughtful ways, we will be heading in the right direction.
Scientists themselves have a pivotal role to play in inspiring and motivating the next generation of scientists. Despite the general esteem in which American scientists are held, there are many members of the public who regard us with benign incomprehension, and there are others – and I fear their number is growing – who view us with out-and-out suspicion. For the first of these conditions, scientists must shoulder much of the blame. All too often we take refuge in our labs or limit our scientific conversations to our peers and a privileged group of graduate students and post-doctoral fellows. In his farewell address to the National Academy of Sciences last spring, outgoing president Bruce Alberts warned that "most people have never encountered a working scientist, nor do they understand how science works or why it has been so successful. Far too many think that we are weird geniuses, when in fact the vast majority of us are neither.... I am absolutely convinced that the scientific community will need to devote much more energy and attention to the critical issue of educating everyone in science, starting in kindergarten, if we are to have any hope of preparing our societies for the unexpected, as will be required to spread the benefits of science throughout our nation and the world."
This is not an easy task, but I believe it can be accomplished if we are prepared to venture into non-traditional settings and engage the public in a conversation that will help us to understand each other better. And when we conduct this conversation, we cannot take refuge in bewildering jargon or rarified arguments and hope that our audience will stay awake. Science need not be difficult or opaque if we choose our words carefully. We also need to invest our message with passion. It is true that we take pride in being objective, in collecting and interpreting our data in a dispassionate manner, and I suspect there is more of the rational Mr. Spock than the histrionic Captain Kirk in most of us. Yet none of this should prevent us from communicating the inherent wonder of the natural phenomena we study. We can demystify the heavens without destroying the enchantment of a meteor shower. We can explain the genesis of the giraffe's extraordinary neck or the millipede's bounty of appendages without reducing these animals to a collection of data sets. We can do what I have tried to do today and convey the excitement and ultimate fulfillment to be found in advancing human knowledge through scientific means.
Thank you very much for giving me this opportunity to share my thoughts with you today.