Brutes or Angels: Human Possibility in the Age of Biotechnology

6. Genetic Enhancement: Humankind Healing and Redesigning Itself

6 Genetic Enhancement Humankind Healing and Redesigning Itself We embrace technologies that tame and harness nature because we think they improve our lives, and we will accept or reject human genetic manipulation on the same grounds. —Gregory Stock, Redesigning Humans: Our Inevitable Genetic Future Michelangelo did a wonderful thing when he sculpted the David (fig. 6.1). This single creation embodies the confidence, courage, and creative potential of Renaissance Florence and of humankind today. Michelangelo’s chisels are now genes, and humans are simultaneously the artist and the block of stone. In the decades ahead, we will override natural selection and sculpt our genomes. According to what? Our own best judgment? What gives us pleasure? What sells best? In this chapter we explore how humankind can direct its future evolution and what choices, promises, and perils lie ahead. These questions guide our explorations: 1. What is genetic engineering? 2. What are the different types of human genetic engineering? 3. What human genetic engineering is already performed? 4. How might humans genetically alter themselves in the future? 5. What does the pub­ lic think about genetically engineering humans? 6. Is human genetic engineering safe? 7. At what point does gene therapy become genetic enhancement? 8. Is it morally wrong to tamper with the human genome? Genetic Enhancement / 159 9. Should parents genetically alter their children without the children’s consent? 10. Will human genetic engineering lead to a new eugenics? Human Genetic Engineering: The Biology What Is Genetic Engineering? Genetic engineering is the intentional and directed altering of an organism ’s genome, usually involving just one or a few genes. In plants, this includes putting a daffodil gene, which confers resistance to a chemical herFig . 6.1. Michelangelo’s David, Florence, Italy. Photograph by James T. Bradley, 1983. 160 / Chapter 6 bicide, into soybean plants so farmers can spray to kill weeds without harming the bean plants. In humans, it can mean inserting a normal gene for an important enzyme into the DNA of white blood cells to restore normal function to a patient’s immune sys­tem. In the future, it might mean inserting genes into eggs or early embryos to increase the cognitive abilities of upcoming generations. This chapter is about genetically engineering human cells. In it we consider some examples of human cell genetic engineering already performed, some successful and some tragically unsuccessful. Then we look at the prospects for human genetic engineering in the future. Finally, we explore moral issues that come with vari­ ous types of human genetic engineering. What Are the Types of Genetic Engineering? All human genetic engineering involves manipulating DNA in living, human cells. Depending upon the kind of cell being altered and the motive for doing so, there are four types of human genetic engineering. Since human motives are of­ ten difficult to define, the boundaries between some types of genetic engineering are also elusive. Nevertheless, categorizing genetic engineering into four types helps us to think about the vari­ ous ethical issues arising from the technology. One way to classify genetic engineering is by the cell type being engineered : somatic (body) cells versus germ cells (eggs and sperm). Somatic cell genetic alterations last only for the lifetime of the person receiving the genetically engineered cells; the alterations are not passed on to future generations . By contrast, germ-­ line genetic alterations are potentially immortal since they can be passed on to future generations. A sec­ond classification of genetic engineering is based on motive: therapeutic versus enhancing. Gene therapy aims to cure a genetic disease or treat some other genetically based health problem. Genetic enhancement, not yet performed in humans, would aspire for cosmetic changes in non-­ health-­ related traits. For example, increasing the stature of or diminishing the fat deposits in a normal person would be enhancements. In their 1997 book, Ethics of Human Gene Therapy, bioethicist LeRoy Wal- Genetic Enhancement / 161 ters and molecular biologist Julie Palmer use the following matrix to illustrate how combining the above categories yields four types of human genetic engineering: (1) somatic cell therapy, (2) germ-­line therapy, (3) somatic cell enhancement, and (4) germ-­ line enhancement (table 6.1). Considering how each of these is performed and when they might be used will help us think about the moral issues that they raise. Somatic Cell Gene Therapy (Type 1) Somatic cell gene therapy (type 1) is the only kind of genetic engineering currently...