The Assault on Evolution
President Shirley M. Tilghman
May 10, 2005
Presented at the Memorial Sloan-Kettering Cancer Center Academic Convocation
Thank you, Harold and Sandy, for your kind words and to everyone at Sloan-Kettering for the honor of receiving the Memorial Sloan-Kettering Medal for Outstanding Contributions to Biomedical Research. This award is especially meaningful, coming, as it does, from someone I admire as much as my dear friend Harold Varmus — who is a particular hero of mine. It should be sufficient for one’s lifetime achievement to discover that cancer arises when specific endogenous genes are mutated or highjacked by viruses. No one would have argued if Harold had rested on those Nobel laurels. Instead he has gone on to lead not one, but two of the most important institutions in the nation that are devoted to improving human health, Memorial Sloan-Kettering and the National Institutes of Health — and to do so with great distinction and integrity. Not too shabby for a former English major — it gives me faith in a liberal arts education.
I am delighted to be invited to address you at this convocation, but cannot help but be sensitive to the possibility that you were hoping for Jon Stewart, who is apparently the most sought-after convocation speaker in the country this year. The great playwright Tony Kushner began his Class Day address last year at Columbia College by saying that while he understood the audience’s disappointment that he was not Jon Stewart (who happened to be Princeton’s Class Day speaker last year and was thus unavailable), they should imagine how he feels having to face that sad truth every day of his life. I am reminded of the Harvard students’ reaction to your own Harold Varmus in 1996 — I believe the common response was “Dr. Who?” — when they discovered that Princeton had President Clinton as Commencement speaker. That reaction speaks volumes for the impact of a Harvard education, in my mind.
All that notwithstanding, I welcome the opportunity to address the extraordinary corps of students, fellows, scientists, physicians, and especially those of you who have completed your studies at Memorial Sloan-Kettering this year. As you prepare to start the next phase of your scientific careers, I would like to take a moment and reflect on what it means to be a scientist in America today. Charles Dickens might have put it as follows: This is both the best of times and the worst of times to be a scientist. Never before have we known so much about the natural world and our fellow human beings: Through the Wilkinson MAP satellite, astrophysicists are looking back in time to nanoseconds after the Big Bang to infer the properties of the elementary particles that make up the universe, biotechnology is being applied to the development of entirely new disease- and drought-resistant crops that will make it possible to feed the world, and we are even finding answers to age-old questions such as “how did the leopard get its spots?” Never before have the benefits of long-term investments in scientific research been so omnipresent: from therapeutics like Herceptin that dramatically reduce the recurrence of breast cancer to the stunning ability of Google to find just what you were looking for.
On the other hand, what concerns me most as I survey the scientific and social landscape of 2005 is the increasing assertiveness of elements within American society who wish to blur the distinction between science and religion. The two offer fundamentally different means of understanding the universe and must be clearly differentiated if they are to fulfill their respective and, I believe, fully compatible roles in our society. Scientists, as all of you know, pose questions and test hypotheses, always with a healthy dose of skepticism, until the evidence is overwhelmingly in favor of one solution over others. Believers, in contrast, are asked to trust without the proof, which is what makes faith at once so daunting and inspiring. There are, to be sure, enormous gaps in scientific knowledge, black holes, if you will, where scientists have only fragmentary clues to guide them. However, as Bruce Alberts, president of the National Academy of Sciences, recently wrote, “The entire success of the scientific enterprise has depended on an insistence that these gaps be filled by natural explanations, logically derived from confirmable evidence.” By its very nature religion cannot demand factual certitude. As Thomas is reminded in the Gospel of John, “Happy are those who have not seen and yet believe.”
Unfortunately, notwithstanding our nation’s debt to the Enlightenment, religious principles are increasingly being used to weigh the validity of scientific conclusions, and religious beliefs have cloaked themselves in the language of science. Under the banner of “intelligent design,” creationists have launched a well-publicized but scientifically deficient assault on the theory of evolution, suggesting that the complexity and diversity of nature is not the product of natural selection but rather of supernatural intent. For those of you who are not conversant with the intelligent design literature, the argument usually begins with Darwin himself, who said, “If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.” From there advocates such as Michael Behe, a professor of biochemistry at Lehigh University, declare that “natural selection can only choose among systems that are already working, so the existence in nature of irreducibly complex biological systems poses a powerful challenge to Darwinian theory. We frequently observe such systems in cell organelles, in which the removal of one element would cause the whole system to cease functioning.”
What is wrong with this thesis? To begin with, it reflects a fundamental misunderstanding of how evolution works. Nature is the ultimate tinkerer, constantly co-opting some molecule or process for another purpose. This can be spurred on by frequent duplications in the genome, which occur at random but are selected upon as evolution tinkers with the extra copy without disrupting the pre-existing function. In other instances, entirely new functions are found for existing proteins. My favorite example is the use of lactate dehydrogenase, a metabolic enzyme, as one of the proteins that makes up the transparent lens of the eye. In one cellular setting the protein has a catalytic function, in the other a structural one. The evolution of two different promoters, one constitutive and one used only in the lens, accomplishes this regulatory feat.
Of course, the real test of whether intelligent design is a scientific theory, comparable to Darwin’s theory of natural selection and worthy of equal consideration in the biology classroom, is whether it poses testable hypotheses. Here the answer is self-evident — it does not. Rather than searching for explanations for the complexity that is surely present in each living organism, it accepts that the complexity is beyond human understanding because it is the work of a higher intelligence. That suggests no experiment, and thus it creates an intellectual dead end.
Yet, as strange as it may seem, we find ourselves today, eighty years after John T. Scopes was convicted of teaching the theory of evolution, still debating the merits of Darwin’s theory, despite the fact that it has stood up extraordinarily well to experimental tests. In a recent survey conducted by the National Science Teachers Association, 31 percent of respondents reported feeling pressure to include “creationism, Intelligent Design, or other alternatives to evolution in their science classroom.” More worrisome still, 30 percent of respondents confessed to feeling pressured to “de-emphasize or omit evolution or evolution-related topics from their curriculum.” These data should come as no surprise if one considers the results of a nationwide CBS News poll conducted last November. Not quite two-thirds of respondents favored the teaching of both evolution and creationism, while more than a third expressed the view that only creationism should be taught. Perhaps the saddest report I have read on this issue concerns the decision of a number of IMAX theaters, including some in science museums, to refrain from screening films that allude to evolution for fear of offending the religious sensibilities of viewers. Documentaries that have met this fate include “Cosmic Voyage,” “Galapagos,” and “Volcanoes of the Deep Sea,” which suggests that life could have originated in the vicinity of underwater vents in the ocean’s floor. And the State Board of Education of Kansas is once again holding hearings in which Darwinism is described as “a dangerous dogma.”
Of course, scientists have found themselves at odds with the guardians of religious orthodoxy for centuries. The Copernican revolution, which dethroned the earth from its central place in the universe, was regarded by many as heretical, as Galileo discovered to his cost. From the splitting of the atom to the creation of so-called test tube babies in the 20th century, scientists have been accused of usurping the role of the Almighty. As Albert Einstein himself would say of Ernest Rutherford, scientists have “tunneled into the very material of God,” and for many men and women, these advances have been both alarming and disorienting. As the pace of scientific discovery quickens and no corner of the cosmos or the human body is exempted from scientific inquiry, the perception that we are distorting — rather than explicating — the natural order of things will only intensify. Inevitably, this perception will find political expression, and thanks to our system of government, in which power is widely diffused, the views of even a small minority can carry disproportionate weight on Capitol Hill or in the White House.
How, then, do we — and you who are poised to join the ranks of professional scientists — respond to the millions of Americans who do not accept evolution as a scientific theory and are happy to invoke the power of the state to ensure that their views prevail or, at the very least, get equal billing? How do we reassert the line between science and religion? There is no simple solution to this challenge, and no matter what we do, some of our fellow citizens will regard us as the enemy of all they hold most sacred. This should not, however, deter us from rising to the defense of science, and this means speaking out. Public advocacy, other than for grants and fellowships, does not come naturally to most of us, but this must change if the pressures I have described this afternoon are to be resisted. If the debate over the merits of evolutionary science tells us anything, it is that our work cannot be conducted in a vacuum. We must convey the nature and purpose of scientific inquiry beyond the realm of scholarly symposia and academic articles, and we must do so respectfully, clearly, and passionately.
I fear that many of us fail to keep these adverbs in mind when we do speak to non-scientists. We must, for starters, avoid the suggestion that science and faith are mutually exclusive — they are different manifestations of the human experience. As long as we maintain an unambiguous distinction between science and religion, neither domain should feel threatened by the other. And so, when we shout foul, as shout we must, it should always be in nuanced terms. I think that Kenneth Miller, a professor of biology at Brown University, set the right tone when he wrote, if an exponent of intelligent design “wishes to suggest that the intricacies of nature, life, and the universe reveal a world of meaning and purpose consistent with a divine intelligence, his point is philosophical, not scientific. It is a philosophical point of view, incidentally, that I share.... [But] in the final analysis, the biochemical hypothesis of intelligent design fails not because the scientific community is closed to it but rather for the most basic of reasons — because it is overwhelmingly contradicted by the scientific evidence.”
The clarity of our public message is also critically important. We cannot take refuge in esoteric arguments and bewildering jargon and hope our audience will embrace the positions we espouse. Science need not be difficult or opaque if we choose our words and practical illustrations wisely, and the concept of evolution is no exception. Finally, we need to invest our message with passion. By passion I mean a willingness to convey the extraordinary beauty of the natural phenomena we study. We can demystify the heavens without destroying the wonder 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 call evolution what it is: a magnificent and beautifully elegant explanation for the extraordinary diversity of life that we enjoy on this planet.
Thank you, congratulations, and the very best of luck wherever your research leads you.