The Impact of the Gene; From Mendel's Peas to Designer Babies

by Colin Tudge

• ISBN13: 9780809057436
• ISBN10: 0809057433
• Format: Trade Paper
• Copyright: 2002-05-30
• Publisher: Hill and Wang

Summary

How genetics, and the technologies that arise from it, will affect the way we live in the twenty-first century In the mid-nineteenth century, a Moravian friar made a discovery that was to shape not only the future of science but also that of the human race. With his deceptively simple experiments on peas in a monastery garden in Brno, Gregor Mendel was the first to establish the basic laws of heredity, laws from which the principles of modern genetics can be drawn. In this fascinating account, acclaimed science writer Colin Tudge traces the influence on science of Mendel's extraordinary ideas, from the 1850s to the present day, and goes on to ask what might happen in the coming century and beyond. A comprehensive and entertaining work that combines scientific history with a compelling discussion on the future trends of genetic technologies, The Impact of the Gene examines how the ideas that underpin the spectrum of all genetic issues are interrelated, and proposes that with a basic understanding of Gregor Mendel's theories and discoveries, all modern genetics falls easily into place. From a monastery garden to the laboratories of the twenty-first century, The Impact of the Gene provides a vital overview of the science of genetics, at once "enjoyable and informative . . . readable and entertaining" (The New York Times Book Review).

Author Biography

Colin Tudge is the author of, most recently, The Variety of Life: A Survey and a Celebration of All the Creatures That Have Ever Lived and The Second Creation: Dolly and the Age of Biological Control, with Ian Wilmut and Keith Campbell. One of Britain's leading science writers, he is currently a Fellow of the Linnaean Society of London and a Research Fellow at the Centre for Philosophy at the London School of Economics. He lives in Oxfordshire.

Table of Contents

The Future of Humankind and the Legacy of Mendel	3	(10)
The Peasant and the Scientist	13	(36)
Breeders, Scientists, and Philosophers	49	(35)
From Mendel to Molecules	84	(39)
What Genes Are and How They Work	123	(37)
Mendel and Darwin: Neo-Darwinism and the Selfish Gene	160	(12)
Genes for Behavior: Evolutionary Psychology and the Nature of Human Nature	172	(59)
Genes Rearranged and Genes Conserved	231	(34)
The Shaping of Homo sapiens	265	(44)
Epilogue: What Should We Do With All This Power?	309	(46)
Sources and Further Reading	355	(4)
Index	359

Excerpts

Chapter One

The Future of Humankind

and the Legacy of Mendel

* * *

Heredity matters. It is perhaps the central obsession of humankind, and indeed of all creatures. We care who our ancestors were, and--probably even more--who our descendants will be. If it were not so, there would be no arranged marriages, no patricians and plebs, no feudalism or apartheid, fewer random beatings in lonely parking lots, and a great deal less genocide. Great swaths of modern law and politics and many thousands of hours of fraught debate would instantly become redundant.

    Nowadays, it seems, we understand heredity. Of course, understanding can never be complete: that is a logical, as well as a practical, impossibility. Any feeling of omniscience that may creep over us from time to time is always an illusion, and a dangerous one at that. Our understanding, nonetheless, already gives us enormous control over the shape, size, color, and even the behavior of our fellow creatures. Soon we might have crops like metaphorical Christmas trees: a basic plant whose species hardly matters (it might be a wheat, it might be a carrot), genetically adorned with whatever extra capabilities and quirks our fancy cares to impose. In a hundred years or so (technology takes longer to come on-line than its proponents are wont to suggest!) we might produce livestock like balls of flesh, churning out milk and eggs like termite queens; at least we could do this, if we allowed expediency to override sensibility. Most shockingly of all, we could, in the fullness of time, redesign ourselves. We might refashion the human species to a prescription: a height of eight feet for better basketball; an IQ of 400 to talk more freely with computers, win lost and unjust causes in courts of law. Plastic surgery will seem childish indeed when we can restyle ourselves from the genes upward.

    Clearly, such technical power--not present-day, but pending in principle--has implications that stretch as far as the imagination can reach. No aspect of economics, politics, philosophy, or religion is untouched by them. What prospect could possibly be more momentous than the redesign of humankind? It is hardly surprising that the notions that have to do with heredity--its theory and the technologies that spring from it--account for much of the content of every modern newspaper. In the past few years in Europe and America, consumers, farmers, politicians, bankers, environmental activists--everyone--has been talking about "GMOs": genetically modified organisms, which, in effect, are the first generation of crops qua metaphorical Christmas trees. The birth of Dolly, the cloned sheep, at Roslin Institute near Edinburgh in 1996 (and the birth the year before, though fewer people noticed, of Megan and Morag) raised the possibility of human cloning. Far more importantly--though most commentators missed this point--the technology of human cloning paves the way for the "designer baby": the human being that is genetically "engineered" to a specification. More broadly, the emotions that spring from matters of heredity continue to ferment and fester: racism and genocide, which surely are as old as humankind (and probably much older), dominate the world's international news.

    Yet at the same time, on a more positive note, scientists known as evolutionary psychologists are using what are essentially genetic insights to reexplore the principal theme of the Enlightenment: the true nature of human nature. Already there are encouraging signs that evolutionary psychology can improve on the forays of the eighteenth century, noble as they often were. The point is not to be "genetically deterministic," suggesting that human beings are run by their genes, as the critics continue to proclaim. The point is that if we can understand ourselves more fully, then we have a greater chance of devising social structures that are humane and just on the one hand and robust on the other; social structures, that is, that can persist through time and retain their basic humanity and justice through all of life's setbacks and vicissitudes. The criteria of humanity and justice must of course remain the products of human intellect and emotion, as has always been the case: they will not derive directly from greater knowledge of our own biology. But social robustness does depend on such knowledge. There really is no point in devising utopias that require people to behave in nonhuman ways. Many have tried to do this, throughout the twentieth century, and millions died as a result. The possibility of utopia, or something very like it, seems a proper ambition. But it will not be achieved unless we first understand how we really are . The vociferous critics of evolutionary psychology should do some homework, to find out what it is really about. If they did, they would surely be ashamed of their own obduracy.

    Then, of course, there's the matter of our fellow species: wildlife conservation. I believe this ranks in importance with the fate of humankind itself. The nature of the task for the twenty-first century and beyond is to create a world in which we can thrive alongside our fellow creatures. If we succeed at their expense, then this will at least be a partial failure; but of course it is absurd to suggest (as some unfortunately do) that other creatures should survive instead of us, as if human beings should or would commit mass hara-kiri. We and the rest of creation must be catered to, as harmoniously as possible. Wildlife conservation has a huge and necessary emotional content and is indeed driven by emotion, for if people do not care about other creatures, then they are doomed. It's unfortunate, though, that some of those who profess to care most deeply also feel that emotion is incompatible with what they see as the cool rationality of science. Yet poetry alone will not save our fellow creatures, either. Wildlife cannot survive without good science. Genetics, the science of heredity, is not the only discipline that's needed, but it is certainly essential. To focus our efforts effectively, we need to know which species are most endangered and in greatest need of immediate help. We cannot begin to make that judgment without knowledge of genes. Sometimes, too, we need to supplement all efforts in the field with specific breeding plans, and these are bound to fail unless guided by genetic theory.

    Overall, the present discussion of all these issues, sensible and otherwise, must be welcomed. Nothing can be more important to life on Earth. No human concern is left untouched. In democracies, at least, and most people apparently prefer democracies, we should all talk about and have some input into the ideas and policies that affect our lives. The idea that we should leave everything to "the experts" is an invitation to revert to the worst of the Middle Ages. In the bad old days, the peasantry were expected to take the word of the priest as gospel, while we are now invited to take our lead from scientists and politicians. At least, this is sometimes the case, although some scientists, more sensibly and humbly, are content to take guidance from the societies of which they are a part, and to contribute merely as citizens, like the rest of us. We might indeed argue that it's our duty to discuss these issues. The effort is the price we pay for democracy.

    However, the issues that now need to be discussed are hugely various: breeding of crops and livestock, cloning, genetic counseling, designer babies, conservation, animal welfare, the nature of human nature. Worse: each of them is, or can be, highly technical. There are entire institutions devoted to each. Specialists in any one field disclaim any worthwhile knowledge of any other. How can the rest of us, who aren't experts at all, hope to keep up? Worst of all: much of the discussion is heavily overlaid with politics of one kind or another. Most perniciously, some biologists seek openly to misrepresent some of the current endeavors, or at least display a sublime lack of understanding; and yet they are believed because they are perceived to have authority. Thus confusion is loaded onto what is already complicated. So what hope is there? Perhaps we should be content to mount discussions in the manner of a party game, to chatter away in the pub for the fun of it, but let "the experts" run the show after all. We could do this, except for the nagging suspicion that the experts aren't as expert as they sometimes make out, and they don't all agree with each other so they can't all be right, and they often seem to say things that leave us feeling uncomfortable. Besides, we don't live in the Middle Ages any more, and although we may feel that priests are important (I certainly do), we should not be content to let them, or scientists masquerading as latter-day priests, tell us what to do. That way of running society is no longer acceptable. But how can we improve on this, if the issues are so disparate and difficult?

    Well, I have been looking at aspects of genetics and related issues for about four decades (I am alarmed to discover) and have concluded, after so many summers, that the problems are not as disparate and difficult as all that. It's important only to grasp the underlying principles. Once you see how genes really work--or seem to work, in the light of present knowledge--then all the biology seems to fall into place. The ethical issues require further input, but at least we need not be waylaid by the technicalities. I am not a professional geneticist: I have never plucked the anthers from an antirrhinum, or calculated "gene drops" on a computer, or even tracked some inherited blight through the royal houses of Europe. But I did study genetics and evolutionary theory thoroughly, during my formal education in the 1950s and 1960s, when the world was celebrating some significant centenaries, the new science of molecular biology was undergoing its spectacular birth, and genetic engineering had yet to begin. Over 35 years of work I have had prolonged and significant dealings with medicine, agriculture, and wildlife conservation, and--particularly of late, at the London School of Economics Centre for Philosophy--plenty of involvement with many aspects of genetic and evolutionary theory and the philosophy of science. So I haven't worn a white coat since undergraduate days and am not knee-deep in snails and fruit flies, but I have had the opportunity to take a very long, bird's-eye view of the whole caboodle. It's a matter of swings and merry-go-rounds: what you lose from daily contact with roundworms and oscilloscopes, you gain (I hope) in intellectual mobility. In short, I want in this book to provide an overview of the whole shooting match.

    More specifically, I want to show how much the modern world owes to the nineteenth-century Moravian friar Gregor Mendel. As all the world knows, in the 1850s and 1860s Mendel carried out some irreducibly simple experiments with rows of peas, in the monastery garden at Brno. Most people know less about his subsequent experiments--with scarlet runner beans, snapdragons, the hawkweed Hieracium , and many others and his final, brilliant flourish with bees--but never mind: peas carry the day. It's often suggested, however, that because Mendel's experiments were simple he was a simple man, driven by simplistic thoughts. Because his results were so precise, too, it has been suggested that he cheated, or--more often--that he was lucky. If he had looked at other plants, or even studied the hereditary pattern of different characters within garden peas, he would not have achieved such tidiness.

    But he did not cheat (I can't prove this; but that really wasn't his style, and there are various alternative explanations that seem far more likely). Neither did he rely on luck. He achieved such clarity because he was, in principle, a very modern scientist and knew, as the great British zoologist Sir Peter Medawar observed a hundred years later, that "science is the art of the soluble." While others, including Darwin, pondered the huge complexities and confusions of heredity, Mendel perceived that no one would make any progress until they first identified and worked out the simplest possible cases. He did not stumble upon peas by accident. He chose them from the mass of candidates because he knew they would give simple results. He did not study the particular characters he did--the shapes of the seeds and the colors of the pods--by chance. He knew before he began that the pattern of inheritance for these particular characters was relatively straightforward. Failure to "breed true" is the bane of all commercial breeders and experimental geneticists: all creatures often give rise to offspring that are strikingly and apparently randomly different from themselves. But Mendel knew that his peas would breed true. First, he selected the species for this very quality; and second, he carried out at least two years' preliminary work to produce especially true-breeding lines.

    Never, in short, in all of science, have experiments been more beautifully conceived and executed. This is the simplicity not of a simple man but of a genius, who sees the simplicity that lies beneath the surface incoherence; he had the deftness of touch that we associate with Newton, say, or Mozart, or Picasso. Experiments that reveal so much with so little fuss are said to be "elegant." Such elegance--so much derived from so little--has been matched only by Galileo.

    Neither did Mendel move on to beans, hawkweeds, and bees out of stupidity. With peas, the simplest possible case, he worked out the ground rules. But he knew, as well as Darwin did, that most cases are more complicated. He wanted to find rules that were universal. I am sure he felt in his bones that the rules he derived from his peas were universal, and that with a little tweaking they could explain the odd patterns of inheritance in beans and bees and, indeed, in human beings. But he was one man working more or less on his own, and he ran out of time. In the twentieth century, it took hundreds of scientists several decades to work through the problems Mendel set for himself after his work with peas was done. He also, I think, lost heart--for so few people recognized the greatness of his achievement, and many fail to do so even now.

    In truth, the complex patterns of heredity seen in beans and bees and human beings do follow straightforwardly from Mendel's unimprovably simple case. Skin color in human beings is a far more complex character than the shape of the seeds in garden peas, but the theory that explains the latter also fits the former perfectly easily, once we add a few conditional clauses. We see in this some of the essence of the mathematical concept of chaos : the notion that very simple rules, once given a small twist, can lead to endlessly various outcomes. Most breeders and biologists were bogged down with the outcomes: Mendel saw the rules beneath. That is genius.

    Once we combine Mendel's ideas of heredity with Darwin's concept of evolution "by means of natural selection," we have two thirds of the basic theory of all modern biology. Mendel's and Darwin's ideas together form "the modern synthesis," otherwise known as neo-Darwinism. Add one more set of ideas from the twentieth century--the science of molecular biology, which is the study of what genes are and how they behave--and we have virtually all of the hard core of modern biology. That is not quite true, of course. Ecologists and some psychologists will argue that their disciplines also belong to biology, and that they contain much that cannot simply be thrust into the canon of neo-Darwinism-cum-molecular-biology. But the canon is the hard core nonetheless, the spring from which all may drink.

    The English philosopher A. N. Whitehead famously argued that "all moral philosophy is footnotes to Plato": in the same spirit, it could be said that all genetics is footnotes to Mendel. Of all the experiments that he began, only the ones with peas were really completed. But they will suffice. Once we understand what he did, and why he did what he did--his background thought and the details of his irreducibly simple method-- all the modern debates that seem so confusing start to fall into place.

    Chapters 2 and 3 of this book make the general case: they describe Mendel's background, the society in which he worked, and the people he knew; the science of his day, why heredity is so difficult, and how he cut through the knots with his rows of peas. The fourth chapter discusses the twentieth-century contribution: how Mendel's proposed "hereditary factors" were given the sobriquet genes , and how the chemistry and modus operandi of the genes were revealed. Chapter 5 describes how scientists worked out what genes actually are , and how they operate, leading to the science of "molecular biology."

    Then the thesis bifurcates: first into theory, and then into practicalities--the modern biotechnologies. So chapter 6 describes the synthesis, the fusion of Mendel's genetics and Darwin's evolutionary theory, and chapter 7 examines how the notions of neo-Darwinism are now being applied to the Enlightenment issue of human nature through the discipline of evolutionary psychology. Chapter 8 then discusses the practical issue: how modern genetic theory is applied to the "improvement" of crops and livestock for economic purposes, and, in sharp contrast, how it can be pressed into the service of conservation.

    Chapter 9 shows how the two arms of the discussion, the deep theory and the practice, are being brought together again to make the most fundamental changes to human life that are conceivable. It is rapidly becoming possible to redesign human beings: to create the "designer baby."

    We have already reached the point, indeed, where we might reasonably argue that all the conceivable ambitions of biotechnology should be considered possible, provided only that they do not break what Medawar called the bedrock laws of physics. There is nowhere for biotechnology to hide, in short. Scientists can no longer dismiss public misgivings with the peremptory comment that this bogeyman or that need not be considered because it is "not possible" or mere "fantasy." Such dismissals just will not do. Anything that a physicist would allow, the biologists of the future might do. When anything is possible, we have to ask as a matter of urgency: So what is right ? That is the subject of the last chapter.

    Mendel has much to teach us here, too. Much less is known of his life than we should like. Most of his personal notes were destroyed. The literature of Mendel ought to be as rich as that of Darwin, and it simply is not. So we do not know in detail much of what he thought or did, day to day. The little that is known, though, suggests that he was courteous, humble, generous, and certainly conscientious. These are qualities our descendants will need in abundance if they are to come to terms with their own extraordinary power.

Copyright © 2000 Colin Tudge. All rights reserved.