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The End of Sex and the Future of Human Reproduction

The End of Sex and the Future of Human Reproduction

Copyright Date: 2016
Published by: Harvard University Press
Pages: 340
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  • Book Info
    The End of Sex and the Future of Human Reproduction
    Book Description:

    Within 40 years many people will stop having sex for reproduction. After IVF and preimplantation genetic diagnosis, parents will pick embryos for implantation, gestation, and birth. It will be easy, safe, lawful, and free, Henry Greely predicts. He explains the new technologies and sets out the deep ethical and legal challenges facing humanity.

    eISBN: 978-0-674-54575-5
    Subjects: Health Sciences, Biological Sciences, Law, Ecology & Evolutionary Biology
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  1. Front Matter (pp. i-vi)
  2. Table of Contents (pp. vii-x)

    This is a book about the future of our species, about the likely development of revolutionary biological technologies, and about the deep ethical and legal challenges our societies will face as a result. But the best way to sum it up, I think, is to say that it is about the coming obsolescence of sex.

    It is not about the disappearance of all the things we mean by the word “sex.” Humans will still (usually) appear at birth having physical attributes of one sex or the other and will be loudly pronounced as either baby girls or baby boys, with...

    • [PART I Introduction] (pp. 7-14)

      This part of the book sets out, in six chapters, the scientific background that I think is useful for understanding Easy PGD and its implications. The chapters cover basic information about cells, DNA, and genes; “normal” reproduction among living things, including humans; assisted reproduction in humans, genetics, genetic testing, and stem cells. I have tried to write about them to make the information understandable to anyone interested, even those of you who, like me, last took a biology course at the age of fifteen.

      Some of you will have educational and professional backgrounds that give you far more knowledge of...


      Nineteenth-century author Samuel Butler wrote, “It has, I believe, been often remarked, that a hen is only an egg’s way of making another egg.”¹ Butler could not have known it, but his statement could have been made more foundational by saying “a hen is only chicken DNA’s way of making more chicken DNA.” Richard Dawkins’s famous term “selfish DNA” encapsulates that idea.² Deoxyribonucleic acid—DNA—is the thread that connects generation with generation.

      This book will have quite a lot to say about DNA, but some basic knowledge of cells, chromosomes, DNA, genomes, and genes is essential at the very...


      To discuss the end of sex, we need to talk about what sex is. It is actually at least three different things—and each much more diverse in nature than we normally realize. First, sex is a method of reproduction in which the new organism gets a new mixture of genetic material from two parents. Second, sex is a condition of having either male or female reproductive organs—is an organism male or female? And, third, sex is a male and a female acting in ways that can, in the right circumstances, lead to reproduction. Each is first discussed below...


      This book is about the broad future use of techniques of assisted reproduction by fertile people who don’t “need” to use them, but that future will strongly rely on techniques established to help infertile people have “children of their own”—children made from their own DNA. This chapter starts with some background on infertility and the history of treatments for it until 1978. It then describes in some detail the history and practice of in vitro fertilization (IVF), the crucial method that will lead to the end of sex.

      Doctors define infertility as a condition occurring when at least one...

    • 4 GENETICS (pp. 61-73)

      After starting the book with a chapter on the basics of DNA, chromosomes, genomes, and genes, I have spent the last two chapters on reproduction—it is now time to return to genetics. The power of genetic testing to tell us about our future children will drive the revolution in human reproduction. Understanding that revolution will require some background on genetics.

      DNA makes RNA makes proteins. That is the central dogma of molecular biology. Although exceptions and qualifications have been found, it remains largely true. It is also true that variations in DNA can lead to variations in RNA, which...

    • 5 GENETIC TESTING (pp. 74-88)

      All this information about the relationship between DNA and various diseases and traits is only useful if we can know not just the relationships but exactly which DNA variations particular people, fetuses, embryos, or gametes have. Genetic testing is the process of finding that out. Genetic testing of humans has taken place for over sixty years. During that time, the methods used have varied enormously but have consistently become more precise and less expensive. This chapter will first explain five methods relevant to this book: karyotyping, fluorescence in situ hybridization (FISH), array comparative genomic hybridization (aCGH), SNP chips (often called...

    • 6 STEM CELLS (pp. 89-100)

      Stem cells provide the last piece of the puzzle that assembles into Easy PGD. This chapter provides background to stem cells and their possible uses. It will first outline what stem cells are, then describe the development of human embryonic stem cells (hESCs), and, after a brief digression into the immune system and human cloning, explain human induced pluripotent stem cells (human iPSCs).

      Our bodies are all about cells. Except for water-based fluids, our bodily components are either made of cells or, in the unusual instances where they are not made up of cells, like cartilage, bone, or hair, they...


      The first six chapters of this book have given you some background on various parts of biology and human medicine—molecular biology, reproduction, infertility treatments, genetics, genetic testing, and stem cell research. Those threads will soon be woven together to make a new pattern, one that will change fundamentally how our species reproduces.

      I call the process that will emerge from these developments Easy PGD. It is basically just an extension of preimplantation genetic diagnosis, but an extension that will turn PGD from an uncommon curiosity to the way many if not most babies will be conceived, at least in...

    • 7 GENETIC ANALYSIS (pp. 107-120)

      For Easy PGD to become a clinical reality, PGD will not only need to get easier, but also to get better. For that to happen, two genetic technologies will have to be improved—DNA sequencing and DNA interpretation. This chapter will discuss each.

      Each embryo has a set of genetic variations that will provide information—sometimes powerful, sometimes weak—about the traits of the person that embryo might become. Those variations need to be determined through analyzing the embryo’s DNA. Genome sequencing is the best tool we have for this kind of analysis.

      How we have done genome sequencing has...

    • 8 MAKING GAMETES (pp. 121-136)

      If the science stops with the genetics advances detailed in the last chapter, we will have substantially improved the cost, speed, and effectiveness of PGD, but as long as PGD requires egg retrieval, it will remain an uncommon procedure. The cost, discomfort, and risks of egg retrieval make it unlikely ever to be popular. How to get eggs without retrieving them? There are several possibilities, some easier and some harder. The best solution would be to make eggs from iPSCs, but other possibilities exist. And some of them offer other benefits—an effectively unlimited number of eggs (and sperm) that...


      Many things that are technically possible do not happen or, at least, do not become common. Consider flying cars. Or, more realistically, supersonic commercial flight. The first supersonic human flight was achieved nearly seventy years ago in 1947. A supersonic commercial jet, the Concorde, went into service in 1975, offering trips from New York to Paris in three and a half hours instead of eight. Only twenty Concordes were ever built and the last supersonic Concorde flight came twenty-seven years later, in the aftermath of a fatal crash in July 2000 and air traffic declines after 9/11. The service had...

    • 10 LEGAL FACTORS (pp. 153-165)

      The current American legal framework contains no insurmountable obstacles to Easy PGD—at least if the science works. This chapter discusses how existing law is likely to allow Easy PGD in the United States, with a few comments on other countries. In the United States, the procedure will face some significant challenges with the FDA about the safety and efficacy of the process, but at least under current law will be largely free from other limitations.

      The United States is an odd place in many ways. The most relevant for present purposes is that it has almost no direct regulation...

    • 11 POLITICS (pp. 166-177)

      Current American laws may not prevent Easy PGD but laws can be changed. Will political forces prevent the rise of Easy PGD? That question cannot be answered with confidence, even in United States, the one country I know something about. Nevertheless, my unconfident guess is that Easy PGD will not be subject to significant regulation in the United States or in very many of its individual states. For an explanation, we need to start with some discussion of the American politics of IVF.

      As discussed above, most developed countries have significant substantive regulation of IVF and other assisted reproductive technologies....


      This part has, so far, laid out a case that Easy PGD is likely to be possible, accepted, and common sometime in the next few decades. But the revolutions the biosciences may bring to human reproduction will not necessarily stop with Easy PGD. Four other possible technological advances lying farther down the path deserve mention. Each could profoundly affect human reproduction and at least the first three seem plausible within something close to our twenty- to forty-year time window: human reproductive cloning, genome-edited embryos, synthetic chromosomes, and artificial wombs.

      Remember the uniparents and the “unibabies” from Chapter 8? They would...


      The last six chapters have laid out one likely pathway to the near future, as well as a few more distant possibilities. Where will that path have led us in, say, forty years? I believe to a world where most pregnancies, among people with good health coverage, will be started not in bed but in vitro and where most children have been selected by their parents from several embryonic possibilities based on the genomic variations of those embryos and hence the genetically influenced traits of the eventual children.

      This will not—and should not—happen overnight. Even if all the...

    • [PART III Introduction] (pp. 203-206)

      This part of the book explores the implications of Easy PGD. It mainly looks at problems with Easy PGD. Some of these problems are speculative and will never come to pass, and others might be avoided by wise policy, but some will be real and inevitable. I have grouped the risks into six chapters, looking at safety, family relationships, equality, coercion, naturalness, and a last category, which I call “implementation,” but which might be called “other.”

      Many of these issues have been explored at great length and depth since well before the technologies for even primitive prenatal genetic testing were...

    • 13 SAFETY (pp. 207-224)

      “Is it safe?” sounds like such a simple question. It is certainly an important one, to me the single most important question Easy PGD raises. But answering that question is anything but simple. We need not only scientific evidence about safety but also a conceptual understanding of what we mean by safety—and, ultimately, a process that can assure us about safety. This chapter will start by discussing what we should mean by the safety of Easy PGD. It will then lay out the questions (and evidence) about safety—the safety of current uses of PGD and IVF, the safety...

    • 14 FAMILY RELATIONSHIPS (pp. 225-237)

      “Happy families are all alike; every unhappy family is unhappy in its own way.” Tolstoy’s start toAnna Kareninais one of the most famous opening sentences of any novel.¹ But would it be different for families built with Easy PGD?

      The day-in, day-out happiness of families is rarely a concern for law and policy except at the most dysfunctional extremes. And yet it is, for many of us, the single most important issue in our lives. How would Easy PGD affect families, and the joy, pride, and comfort—or the pain, embarrassment, and hatred—we take from them? This...

    • 15 FAIRNESS, JUSTICE, AND EQUALITY (pp. 238-252)

      Fairness, justice, equality—these terms, and the relationships between them, have been contested for at least 2,500 years. No one has yet produced a unified theory of these concepts that has gained general approval. This book will not try. Yet some of the hardest and most important issues raised by Easy PGD are issues of fairness, justice, and equality. This chapter sets out some of those concerns. To set a foundation, it looks first at just how much “better” children conceived through Easy PGD would likely be. It next considers issues raised by differential access to the technology before moving...

    • 16 COERCION (pp. 253-270)

      “Three generations of imbeciles are enough.”¹ The great “liberal” Supreme Court justice Oliver Wendell Holmes Jr. penned that memorable line in his majority opinion inBuck v. Bell, finding constitutional the forced sterilization of the feebleminded. Today, it is a chilling reminder of the eugenics movement. “Eugenics” is a term that has come to mean many things, all of them negative, and some of them only a synonym for “bad.”

      But what was the evil of eugenics—the mere fact of genetic selection, the inaccurate early genetic science that guided it, the sterilization that negative eugenics used to avoid “bad”...

    • 17 JUST PLAIN WRONG (pp. 271-282)

      I’m not sure how to characterize the last major category of objections. These objections are from people who think the whole idea—Easy PGD, PGD, or any genetic selection—is “just plain wrong.” Sometimes they say, in a triumphant voice, “well, that’s just eugenics,” as if a label is a trump card, or even an argument. For some it is against God’s will; for others, it is unnatural. Still others will ask, “Are we wise enough to make these decisions about our children and the future of our species,” or will just say this is “playing God.” Often people will...


      Any utopia might be possible—except for the mundane problems of enforcement and implementation. Those problems must always be considered seriously before making any major change and Easy PGD is no exception. This chapter discusses the many problems of enforcement as well as the single most serious implementation problem of Easy PGD.

      Laws are easier to pass than to enforce. This is not a definitive argument against laws. It is clearly wrong to require perfect enforcement of any law. I am willing to say that laws against murder are a good idea, even though, in spite of their ubiquity, murders...

  7. CONCLUSION: CHOICES (pp. 299-316)

    The future is coming; there is no way to prevent it. The question is whether and how to try to shape it. I believe that future will include substantial use of Easy PGD or, if not that particular technology, some method that allows intentional selection or modification of babies’ genetic traits—that allows those to be chosen. What do we want that future to be and how can, or should, we go about trying to achieve that goal?

    This final chapter does not argue for any particular answers to those questions. Instead, it sets out futures I think some readers...

  8. NOTES (pp. 317-360)
  9. GLOSSARY (pp. 361-368)
  10. ACKNOWLEDGMENTS (pp. 369-372)
  11. INDEX (pp. 373-381)