The Impact of the Gene : From Mendel's Peas to Designer Babies
by Colin Tudge

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by Colin Tudge

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The Impact of the Gene , by Colin Tudge

The Impact of the Gene by Colin Tudge

Hardcover - 375 pages
First Edition, July 2001
Published by Hill and Wang,
A division of Farrar, Straus and Giroux,
ISBN 0-374-17523-3 / 0374175223

Table of Contents

1. The Future of Humankind and the Legacy of Mendel
2 The Peasant and the Scientist
3. Breeders, Scientists and Philosophers
4. From Mendel to Molecules
5. What Genes Are and How They Work
6. Mendel and Darwin : Neo-Darwinism and the Selfish Gene
7. Genes for Behavior : Evolutionary Psychology and the Nature of Human Nature
8. Genes Rearranged and Genes Conserved
9. The Shaping of Homo sapiens
Epilogue : What Should We Do With All This Power?
Sources for Further Reading

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From Mendel's Peas to Designer Babies
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Reviewed by Mike Lepore for

            The Impact of the Gene , by Colin Tudge is an expertly balanced work, combining biography, history, science, sociology, civics and ethics. Anyone who wishes to discuss either scientific issues or controversial social issues intelligently will benefit much from reading it, and will find every part of it to be enjoyable.

            375 pages. 17-page 2-column index. 3 page list of suggestions for further reading. No illustrations. My comments about each chapter follow. [Page numbers in brackets.]

1. The Future of Humankind and the Legacy of Mendel   (10 pages)

            Before jumping back to the 1800s and telling the story of the first heredity experiments, Colin Tudge compels us to face the future. Having already developed a number of genetically modified organisms (GMOs), humanity is on the threshold of inventing the technology for creating "designer babies." What it means to be a human being may itself be redefined. The author takes no pleasure in this, and expresses moral apprehension. We cannot leave the momentous decisions to experts. "It is our duty to discuss these issues. The effort is the price we pay for democracy." [6]

            After this chapter, the book is approximately 2/5 about the history of the development of genetic science, and 3/5 a discussion of social and moral considerations which accompany this new power.

2. The Peasant and the Scientist   (36 pages)

            Gregor Mendel (1822-1884) was a friar of the Augustinian order of the Catholic Church, who lived most of his years at the monestery at Brno, near Prague, Czeckoslovakia. He was extremely well educated in physics and mathematics, but had acquired a love for botany while studying and teaching at the University of Vienna. There was some ambivalence in the Church about sponsoring the study and teaching of science. Mendel was attracted to the problem of how it occurs that offspring resemble their parents and grandparents. Mendel used rigorous scientific methods and discovered universal rules of heredity which are valid for all plants and animals. Mendel's understanding of heredity would not be improved upon until much later, with the eventual discovery of the molecular basis of genetics.

3. Breeders, Scientists and Philosophers   (49 pages)

            This chapter is an overview of various scientific discoveries that had to interact in order for us to understand genetics.

            In the early 1800s it wasn't agreed upon that both parents contribute heredity information. Ovists maintained that an egg determines the heredity makeup, while the sperm is a sort of nutrient, and the spermists insisted on the reverse hypothesis. [51-53]

            It had only been a hundred years since mammal eggs and spermatozoa had been discovered by Anton van Leeuwenhoek, the inventor of the microscope. [52] In 1839, for the first time, a spermatozoon merging with an egg was observed, and to determine the significance of this was put forth as a great scientific problem. [55]

            Some researchers not only wondered why "like begets like" (dogs have puppies, etc.), but also wondered why the resemblance isn't exact, such that brown eyed parents occasionally have blue eyed children, or why siblings who are not twins are not identical. Furthermore, what mechanism could account for crossbreeding, resulting in white dogs with brown spots?

            Another matter of confusion was what, if anything, the pollen produced by flowering plants has to do with reproduction. Carolus Linnaeus, inventor of the binomial or two-name convention (genus and species) for naming plants and animals, and an entire system of taxonomy (classification of species), made another discovery that was quite controversial. He discovered that plants have two sexes. In the Catholic Church there was some some resistance to the idea of sex in plants, since the concept seemed immoral. [70-71]

            Ironically, while scientists and philosophers argued in the abstract about such things, breeders were far ahead of them in knowledge. In their practical and daily work, breeders had already settled such issues, and even took the answers for granted. [71-75]

4. From Mendel to Molecules   (35 pages)

            Before Gregor Mendel could even begin his experiments on plants in the monestery garden, he had to spend two years (1854-1855) on preliminary sorting to determine which plants were pure breeds. Then he experimented for nine years (1856-1864) with crossbreeding. He crossed plants of the same species but different strains according to plant color, seed color, seed texture, and other observable factors.

            Mendel continuously produced data that seemed to be approaching very simple ratios. For example, when he crossed plants with round seeds and yellow colyledons with plants that had wrinkled seeds and green colyledons, a group of 556 seeds and offspring turned out to consist of 315 round and yellow, 108 round and green, 101 wrinkled and yellow, and 32 wrinkled and green. It was apparent that the proportion 315:108:101:32 is close to the proportion 9:3:3:1. [pages 98-99]

            Mendel formulated the rules to explain these proportions and published them in a scientific paper. The scientific community ignored his paper and his discovery, until the paper was "rediscovered" decades later.

            The remaining 14 pages of the chapter explain the later 20th century developments in genetics, from the time when genes were visualized abstractly as beads on a string, until the time it was learned that the heredity information is contained in structures called chromosomes in the nucleus of every cell.

5. What Genes Are and How They Work   (39 pages)

            In the 1950s it was learned that genes are strands of a type of molecule called DNA, which consists of four nucleotides (A,G,T,C) bound into a three dimensional structure with the shape of a double helix. This chapter is a semi-technical, but also historical and biographical, essay on DNA.

6. Mendel and Darwin : Neo-Darwinism and the Selfish Gene   (12 pages)

            Neo-Darwinism is the name given to Darwin's principle of evolution by means of natural selection, combined with the later discoveries in genetics. Not only physical characteristics, but also behavior, must evolve. In the late 1800s, sociologist Herbert Spencer proposed the concept of "social Darwinism.", and this in turn led to the field of evolutionary psychology. This chapter introduces these concepts, which are more completely explained in the following chapter.

7. Genes for Behavior : Evolutionary Psychology and the Nature of Human Nature   (59 pages)

            Evolutionary psychology, attempting to explain the way people think and interact in terms of evolution, clashes with philosopher John Locke's concept of tabula rasa (blank slate), that the human mind is blank at birth and then molded by environment and experience. Locke's theory could not explain why almost all mammals and birds are "obsessive child rearers" [174] or why all humans of all cultures, and only humans, communicate through vocal language which they always learn "within the first few years of life, given only a minimum of of always rather scrappy clues." [175]

            Two philosophical sects attack each other. Believers in a fixed human nature accuse those who emphasize environmental influence on behavior and thinking of practicing "environmental determinism," while the latter group accuses the former of practicing "genetic determinism." In the centuries-old "nature versus nurture" debate, extremists in both factions are partly right and partly wrong.

            Toward developing an understanding, Tudge embarks on a 19-page analysis of the four basic premises of evolutionary psychology [182-199]. Then he looks at "strategies for living, mating, and reproduction," [199] and cautions us about some common errors in thinking, such as the "naturalistic fallacy" [282], where one asserts that anything "natural" is therefore morally justified.

            Next, Tudge looks at features which have evolved for the purpose of attracting mates, such as the male peacock's feathers, and some features of human beings as well.

8. Genes Rearranged and Genes Conserved   (34 pages)

            This chapter is fascinating essay about all types of heredity changes, "the craft and science of 'improvement' [235], such as intentional breeding and, since the 1970s, genetic engineering. The text contains both facts and insights.

9. The Shaping of Homo sapiens   (44 pages)

            We will very soon reach the point in technology when it will be possible to fully specify "designer babies." Colin Tudge has a strong moral sense, and argues that not everything than can be done should be done. It should be acceptable at once to adjust specific genes to delete tendencies for diseases and deformities, but that doesn't mean that parents should go to the laboratory to tinker with their offspring to produce genius intelligence, which is not a correction of a crippling abnormality. We already practice a form of eugenics merely by choosing our mates, but is there a rule to define which forms of eugenics, and for what objectives, are ethical?

            "Finally, decisions on genetic counseling or gene therapy should be made by individuals on behalf of themselves or the children they intend to have. This is not always the case.... Many governments in the twentieth century took such decisions into their own hands." [281]

Epilogue : What Should We Do With All This Power?   (45 pages)

            The epilogue is a mini-course on the branch of philosophy known as ethics. What determines which human actions are morally right? Is morality fixed and given, or are we supposed to judge actions by what appear to be their likely consequences? Should government decide such matters in lieu of the individual? Some of the questions that were kicked around that the time in vitro fertilization (IVF, or so-called testtube babies) first appeared are now resurfacing in reference to the debates about gene therapy and human cloning.

            But let's not forget the practical problems. Tudge gives reasons to conclude that we can never know all their is to know about our genome. An attempt to change the gene for a single characteristic might, through gene linkage, cause an abnormality in another part of the anatomy. We cannot tolerate the production of deformed babies or stillbirths as part of an ongoing experiment to figure out how to increase intelligence by a few points.

            "This book has focused on Gregor Mendel,", says the author, and "all that has followed since is footnotes." [353] And yet I see that this biography of the early 19th century friar has quite naturally moved into a discussion of events in the 20th century, likelihoods in the 21st century, and the sociological and moral challenges which they bring. In fact, Mendel was "courteous, generous, socially conscious" and therefore "has a great deal to teach us." [353]

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The Impact of the Gene , by Colin Tudge

Book Description From the Publisher

          How genetics, and the technologies that arise from it, will affect the way we live in the twenty-first century.

          Every day a new development in genetics seems to make headline news: genetically engineered crops, cloned sheep, the Human Genome Project. Some scientists and entrepreneurs are even contemplating cloned and genetically engineered human beings -- "designer babies." And while advocates of evolutionary psychology suggest that their findings provide essential insight into "human nature," opponents level charges of "genetic determinism." Much of the world's politics is rooted in primitive notions of heredity -- of tribe and race. Confusion reigns, even among acknowledged "experts" and political leaders.

          The Impact of the Gene traces how the ideas that underpin the spectrum of controversies are interrelated and flow naturally from the insights of a mid-nineteenth-century Moravian friar, Gregor Mendel, who first established the principles of modern genetics with his deceptively simple experiments on peas in the monastery garden at Brno. Acclaimed science writer Colin Tudge shows that if we can understand what Mendel did and why, then all modern genetics fall easily into place. Tudge also addresses the ethical implications of the modern genetic technologies, seeking to define the criteria by which to judge good and bad, and showing why we must find ways to contain our new and awesome power.

About the Author

          Colin Tudge is one of Britain's leading science writers. A research fellow at the Centre for Philosophy at the London School of Economics, he is the author of, most recently, The Second Creation (FSG, 2000) with Ian Wilmut and Keith Campbell.

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