by Bill Mesler
Carl Sagan was fond of recalling a story from a public panel discussion he had taken part in Chicago in 1960. A member of the audience had asked the panelists when scientists would solve the mystery of the origin of life by actually duplicating the process in a test tube. The first panelist said it would be in about a thousand years. The second said three hundred. Gradually, the numbers got smaller and smaller until one scientist said it had already been done.
The question of the origin of life has always provoked unrealistic expectations in those who look to science to explain the natural world. Similar to the early Christians who waited for a Rapture they were sure was just around the corner, so, too, have believers in science expected that the solution to one of its greatest mysteries was on the verge of being revealed. And so have they waited for hundreds of years.
Depending on one’s perspective, the answer to the question of how life began has always been right around the corner—or so incredibly difficult that it may never be definitively answered. Science has no doubt made enormous strides toward understanding the transition from nonlife to life. The mystery has attracted some of the world’s greatest minds; no doubt it will continue to do so. It could well be that definitive answers are just around the corner. There is likewise a good chance that the question will remain unsolved, at least in our lifetimes. We simply do not know whether the transition from nonlife to life took a week or a month or five hundred million years. A process like this may require such a vast amount of time that it will never be observable in a laboratory.
We do know that science will never stop searching for the answer. Perhaps that search has already yielded something important. Perhaps it has told us something about the nature of science and even of ourselves.
* Venter and his team encoded a series of quotations in the synthetic genome as a puzzle. These included a quote from James Joyce’s Portrait of the Artist as a Young Man, “To live, to err, to fall, to triumph, to recreate life out of life.” Two other quotes included were “See things not as they are, but as they might be,” from American Prometheus, the story of Robert Oppenheimer and the creation of the atomic bomb, and “What I cannot build, I cannot understand,” reportedly the last words left written on the physicist Richard Feynman’s blackboard at the time of his death. They also encoded a link to a website where amateur cryptologists could report their having unraveled the puzzle. Venter and his team had a good practical reason to include the quotations: the coded messages were proof of the bacteria’s synthetic origin.
† There has been some progress in synthesizing such a molecule. In 2011, a British team led by Philip Holliger announced the synthesis of an RNA polymerase, made out of RNA—not protein—that could copy another RNA molecule ninety-five nucleotides long.
EPILOGUE
Men in their generations are like the leaves in the trees. The wind blows and one year’s leaves are scattered on the ground; but the trees burst into bud and put on fresh ones when the spring comes round. In the same way one generation flourishes and another nears its end.
—HOMER, The Iliad, c. 1250 BC
IN HIS FAMOUS LECTURE at the Sorbonne, Louis Pasteur made an observation about the nature of science and the role of the scientist. Science, he said, is an impartial arbiter. The true scientist must strip himself of all preconceived ideas. About the subject at hand, spontaneous generation, Pasteur said one could come to no other conclusion through science than to arrive at the necessity of a divine role in the creation of life.
Roughly a century and a half later, the evolutionary biologist Richard Dawkins stood in the laboratory of one of the world’s most influential geneticists and delivered a speech that began in almost identical terms. Science, he said, does not take sides; it looks only for objective truth. But here Dawkins, an ardent atheist, diverged from Pasteur, a Catholic and vitalist. For Dawkins, one could draw no other conclusion than to say that the first emergence of life was purely the product of natural laws, completely devoid of the supernatural.
Dawkins was standing in the laboratory of Craig Venter, who had helped map the human genome and had led a team that actually reverse-engineered a living organism. Pasteur delivered his lecture at a time when there was as yet no notion of the existence of nucleic acids and the gene was no more than a concept. The world has changed dramatically since Pasteur’s day. Synthetic biology has opened up the inner machinery of living organisms. The engines that drive life can be seen, scrutinized, and manipulated. In our lifetimes, the cost and ease of making a synthetic living thing may become so trivial that it can be something amateur scientists do in their garages. We understand the world and the forces that govern it far better than human beings just a century ago could ever have imagined.
In many ways, our understanding of the origin of life has always been a function of the available tools and technology with which we could make sense of the world. The microscope opened up new worlds to the human beings of the seventeenth century. The printing press of the nineteenth century opened up those worlds to vastly more people. The explosion of technological innovation in the twentieth century—radiometric dating, gene sequencing, exploration of the solar system, to name just a few—has likewise transformed our understanding of biology, and of the origins of biology on this Earth.
But technological progress is not all that has changed since Pasteur’s famous Sorbonne lecture. Speaking at Francis Crick’s funeral in 2004, Michael Crick said that his father had wanted to be remembered for finally putting to rest the theory of vitalism, the idea that some uncrossable chasm existed between the living and nonliving. Noting that the word “vitalism” was not recognized by Microsoft Word, he said, “Score one for Francis.”
The balance of power between science and theology in society has shifted. Nothing symbolizes that shift more than a trip Sidney Fox made to the Vatican in 1964 to advise Pope Paul VI on evolution and the most modern scientific concepts of the origin of life. The pope’s predecessor, Pius XII, had already announced that evolution was not incompatible with church teachings, marking a slow but steady return to the spirit of Saint Augustine, who some two millennia earlier had said that the church would not be served by appearing ignorant of the natural world. The march toward an acceptance of scientific explanations for the origin of life seems inevitable. In 1996, Pope John Paul II alluded to the “recognition of evolution as more than a hypothesis.” Less than two decades later, Pope Francis warned against thinking of God as “a magician, with a magic wand able to do everything.”
In a sense, the world has come full circle. With the notable exception of the United States, religion in most of the developed world has largely ceded to science much of the responsibility for explaining how the physical world functions. Gone are the days when Redi and van Helmont had to tread carefully in the shadow of religious authority, or a man like Robert Chambers was forced to publish anonymously for fear of religious retribution. Even in America, where biblical literalists remain an influential minority, scientists are almost entirely free to follow the pursuit of knowledge wherever it may lead.
TODAY, TENS OF MILLIONS of dollars are spent researching the problem of the origin of life at scores of eminent labs around the world. Every year, new results generate a great deal of excitement that scientists may finally be on the brink of solving the central mystery of biology. A never-ceasing drumbeat of stories appears in the press about every new idea. Often these are given outsized significance. Even the notion of panspermia is routinely resurrected as an exciting and somehow new idea. We want to believe that science has a firm grip on the central problem of biology. The reality, though, is that it is very difficult to say how close we are to understanding the answer to this most vexing of questions.
Yet the search for answers has already taught us an enormous amount about the world and the way it works. Since the Reinaissance, scientists involved in that search have transformed our understanding of biology. They have driven our first steps into the cosmos and spurred our exploration of the
microscopic workings of molecular biology. Along the way, our vision of the universe and our place within it have been fundamentally reshaped.
The long saga to understand the origin of life may hold some subtler lessons as well. It may tell us something deeper about the nature of science, even something about our very nature as human beings. Most of the characters in the great saga to unravel the origin of life did not merely set out to answer a question. Many of them used science to prove or disprove a worldview.
Redi didn’t drink snake venom just to make a point about the deadliness of snake venom. He was trying to show that reason was superior to superstition. The atheist supporters of John Needham did not look at his work and say, “This is good science.” They looked into his microbial broth and saw a pathway around the need for God. The religious looked at Needham’s broth in much the same way, and saw a threat to the existential meaning upon which they had centered their lives. Sidney Fox looked at his proteinoid microspheres and saw a vindication of his life’s work, something he could never let go of, even when faced by a mountain of opposition. Nearly every scientist who attempts to explain purported microbial fossils—in ancient rocks or in meteorites—sees something different. These tiny structures often become the scientific equivalent of a Rorschach test.
Champions of experimentally derived knowledge can look at the same evidence and see something completely different, even diametrically opposed, because science and the scientist do not exist in a vacuum. They exist in a real world of constantly changing ideas and beliefs. Much has changed since Pasteur’s time. Society is different. Religion is different. What we know or believe we know about the world is different. How humanity sees its relationship to that world is different. And consequently, so is what humanity sees in science.
This is evident in no field of science more than the study of life’s origin. Most people cannot seem to simply disregard the question, cannot simply say, “I do not know,” as people might once have responded to a question about why lightning occurs, or might now answer a question about the nature of dark matter. We may not know or claim to know the exact details of how life began, but we hold in our heads answers based on philosophy, religion, conjecture, even wishful thinking. We hold these answers because we have to, because the origin of life strikes at the very meaning of what it is to be alive. Scientists are no different. They often cling to their particular answer even in the face of contradictory evidence, even when, in cases like those of Sidney Fox and Charles Bastian, their intransigence means professional loss.
Yet science remains the best method for understanding the world. There is a process of scrutiny, a process of provando e riprovando in the spirit of the Medicis’ Accademia del Cimento. In the end, the truth is often arrived at. Or, at least, something closer to the truth. Today, almost everyone would agree that flies come from eggs, not rotting meat. Pasteur was right about the existence of airborne germs. Bastian was wrong. One man’s views became accepted as common sense; the other’s were forgotten. We can say these things are true because, in the long run, science does work in the impartial fashion described by both Pasteur and Dawkins. Its history is filled with figures who chose evidence over their own beliefs or what may have been convenient. Darwin took no pleasure in his role as what he called the “Devil’s Chaplain,” pitted against pious men whom he respected and the church that he attended. He shared his science with the world at large only with great reluctance. Yet ultimately, he did. Our understanding of the natural world has grown exponentially since then.
In the end, science will weed out old falsehoods and will reveal new truths. But the path to such understanding might not always be as clear and straightforward as it appears, and the winners and losers might not always be immediately evident. Writing in Scientific American in 1954, biologist George Wald made that observation about Pasteur’s great “triumph” in the spontaneous-generation debates of the late nineteenth century:
It is no easy matter to deal with so deeply ingrained and common-sense a belief as that in spontaneous generation. One can ask for nothing better in such a pass than a noisy and stubborn opponent, and this Pasteur had in the naturalist Felix Pouchet, whose arguments before the French Academy of Sciences drove Pasteur to more and more rigorous experiments. When he had finished, nothing remained of the belief in spontaneous generation. We tell this story to beginning students of biology as though it represents a triumph of reason over mysticism. In fact it is very nearly the opposite. The reasonable view was to believe in spontaneous generation; the only alternative, to believe in a single, primary act of supernatural creation. There is no third position.
The history of science is filled with “losers” who clung to a conclusion despite the rejection of their peers. They all possessed a stubbornness that, for some, led to professional disgrace. Nevertheless, they took that road. On the surface, their inability to simply abandon their positions in the face of intense criticism or even contrary evidence smacks of hubris.
Their doggedness may serve a purpose. The naturalist Alexander von Humboldt once remarked that there are three phases of scientific discovery. The first is denial. The second is denial of importance. The third is crediting the wrong person. It takes a certain kind of fortitude to overcome the first step. Truly novel thinkers are often treated as crackpots. When proved wrong, history decrees that they remain crackpots. When proved right, history recasts them as visionary geniuses. The crackpots of the past may become the visionaries of the future.
THE SCIENTIFIC SEARCH for the origin of life continues. Meanwhile, we see that science, like history, tends to repeat itself. Every generation finds a new messenger with a definitive answer to the question, and every generation finds a new debate. Some bold scientist will push his or her Sisyphean answer up a hill only to find it rolling down again. Something will be seen in the lens of a microscope or in some test tube or fossil or rock, only to be reexamined, rescrutinized, and eventually reinterpreted. And in their search for answers, scientists often find themselves returning to the once-discarded solutions of the past. The debates of Needham and Spallanzani bear a striking resemblance to those between van Helmont and Redi, and between Pasteur and Bastian. During each epoch a definitive “victor” is proclaimed, only to see victory overturned by future discoveries.
For now, the “losers” have all but disappeared from textbook science. But science can have a short memory. Their sagas will be told again and differently, and we do not yet know how the tale will end. The forgotten may be resurrected. New scientists will take up where the old left off. We may still find answers in a discarded idea or discovery that is presently thought to have little, if any, relevance.
WHEN OR IF an explanation to the problem of life’s origin is found, a solution capable of withstanding all the rigors of scientific scrutiny, we might find that the real answer we have been looking for continues to remain elusive. That is because there has always been a bigger question looming over the search for life’s origins. It is the reason the debate has engendered such strong emotions and visceral reactions, and why the question has led so many scientists to throw scientific caution to the wind. For as human beings have searched for the origin of life, what they often seem to have been searching for is the meaning of life. That, perhaps, is something that science alone will never be able to answer.
APPENDIX: RECIPES FOR LIFE
Johannes van Helmont’s Recipe for Mice
Place a dirty shirt or some rags in an open pot or barrel containing a few grains of wheat or some wheat bran, and in 21 days, mice will appear. Adult males and females will be present, and they will be capable of mating and reproducing more mice.
Henry Bastian’s Recipes for Microbes
1. Boil a flask containing beef juice for 15 minutes, and then place it under vacuum and hermetically seal it. After 12 days the liquid will contain actively moving bacteria and several monads.
2. Boil a flask containing a rather weak infusion of beef, carrot, and turnip for 15 minutes
, and then place it under vacuum and hermetically seal it. After 14 days the liquid will contain yeast-like cells.
3. Boil a flask containing a neutral solution of white sugar, ammonium tartrate, ammonium carbonate, and ammonium phosphate for 20 minutes, and then place it under vacuum and hermetically seal it. After 9 days the liquid will contain yeasts, bacteria, and monads.
4. Boil a flask containing a solution of ammonium oxalate and sodium phosphate for 20 minutes, and then place it under vacuum and hermetically seal it. After 61 days the liquid will contain fungal spores, as well as monads showing “tolerably active movements.”
Sidney Fox’s Recipe for Proteinoid Microspheres
Heat 10 grams of L-glutamic acid at 175°C–180°C until molten (about 30 minutes). Then add 10 grams of DL-aspartic acid and 5 grams of a mixture of the sixteen basic and neutral amino acids. Maintain the solution at 170 ± 2°C under an atmosphere of nitrogen for a few hours. During that time, considerable gas will have evolved, and the color of the liquid will have changed to amber. Rub the mixture vigorously with 75 milliliters of water, converting it to a yellow-brown granular precipitate. This material will form protocells, which should be capable of division and self-replication. Most of these materials can be obtained at your local health food store. We estimate the cost of this experiment to be about a hundred dollars.
Craig Venter’s Recipe for a Cell
You will need a DNA synthesizer and a fairly sophisticated molecular biology laboratory. You will need to make, base pair by base pair, a complete bacterial genome, involving the construction of a chain of several million chemical linkages one by one. You will then need to insert this molecule, which, at today’s prices, will cost you upwards of a million dollars, into a living bacterium. If you have placed the appropriate markers into the genome you made, you will be able to purify the synthetic descendants of your creation from the natural ones.