Regular newspaper readers likely have noticed a steady stream of articles outlining the options available to infertile couples who want a child. A recent New York Times story by Gina Kolata, for example, discussed the difficulties such couples living overseas encounter in gaining local access to donor sperm, eggs, and the means to bring them together - the basics of what is known in polite circles as "assisted reproduction technologies." As a consequence, many foreigners are taking advantage of the relative ease with which these services can be obtained in the United States. Some services combine World Wide Web sites that allow prospective parents to screen for donor characteristics (height, weight, eye color, SAT scores) with express-mail delivery in a kind of Amazon.com shopping experience. Assisted reproduction technology has become a growth industry in this country thanks to the market forces of supply and demand operating in the absence of significant regulatory oversight.

Obviously, many aspects of this trend raise fundamental questions about human biology, genetics, and sociology. These questions are addressed with a great deal of insight in Lee M. Silver's Remaking Eden: Cloning and Beyond in a Brave New World. After reading it, one envies the Princeton University undergraduates who have participated in Silver's seminars on the biological, ethical, and public-policy issues surrounding the latest advances in reproductive biology and genetics - "reprogenetics," as Silver refers to it. He has produced a clear, thoughtful survey of his subject that even manages to entertain despite the gravity that these matters entail. He lays out a series of sometimes dizzying hypothetical situations and then, through reasoned arguments based on current science and past experience, shows the reader how feasible these scenarios are, and how much (or little) there is to fear from them.

He delves into such procedures as surrogacy, in vitro fertilization (IVF), cloning (of course), prenatal diagnosis, genetic manipulation, gamete and embryo freezing, embryo fusion, spermatogonial transplantation, and a whole range of technologies whose acronyms are slowly entering the field's lexicon, like ICSI (intracytoplasmic sperm injection) and ROSNI (round spermatid nucleus injection). Silver brings to the discussion not only his expertise in the technical aspects of the field as a working geneticist at Princeton, but also his broader experience as a member of a task force on new reproductive technologies established by the New Jersey Bioethics Commission during the 1980s.

Silver asserts that a thorough understanding of the biology of human reproduction is indispensable for avoiding common misunderstandings, even if it cannot answer all of the prickly questions raised by new technologies. He devotes the first part of the book to an overview of the key stages of human embryology, from fertilization to the development of a nervous system. The chapters have titles such as "Does Your First Cell Deserve Respect?" - a section that contains discussions of the status of early human embryos from both scientific and philosophical viewpoints.

Silver draws distinctions between human life in the general sense, which describes any living cell, and human life in the special sense, which denotes the kind of life that is associated with a functional nervous system. By combining some underappreciated biology with common sense, he also analyzes the assumptions underlying the claim that a fertilized human egg deserves special status based on its potential for developing into a human being. For example, the assertion that a unique genetic identity is created at conception is undermined by the fact that the maternal and paternal pronuclei don't fuse until the two-cell stage of development. Moreover, for about two weeks after fertilization, each of the individual cells of the embryo has the potential to give rise to a complete and distinct developing embryo. Despite the acknowledged potency of each of these cells, their lost potential is not mourned when one of them is plucked off from an early embryo in order to carry out prenatal genetic diagnosis. Finally, since cloning by nuclear transfer allows for the creation of a new embryo from any somatic cell in the absence of conception, the act of conferring respect or elevated status on biological potential is not supported, Silver argues, by the modern facts of human reproduction.

Another major theme of Remaking Eden is Silver's conviction that most of what can be done in the area of reprogenetics will be done. He reaches this conclusion because these technologies address a powerful human need - the desire to have and raise a child. Since certain procedures such as IVF have overcome initial resistance from the public and bioethicists, Silver asserts that infertile couples will continue to take advantage of reprogenetics to fulfill this desire. He sees this dynamic at work in the field of commercial surrogacy, now a booming practice despite the well-publicized and notorious example of Baby M., whose surrogate mother backed out of the original contract. He writes: "What the brief history of surrogacy tells us is that Americans will not be hindered by ethical uncertainty, state-specific injunctions, or high costs in their drive to gain access to any technology that they feel will help them achieve their reproductive goals."

In addition to discussing the growing number of methods available to infertile couples that will allow them to have a child of their own, Remaking Eden also catalogues the many ways in which molecular biology will likely affect our ability to select or avoid a particular embryonic genotype, or to alter it to our liking. Silver is most effective in demonstrating the difficulty of making intellectually coherent distinctions between embryo selections or manipulations that we can all agree on and those which at first glance we might think should be off-limits. In the end, he argues, having accepted IVF - now routine - along with a wide variety of postnatal environmental, social, and pharmacological attempts to affect our children's lives, the arguments against the newer reproductive technologies become less and less persuasive. "As is so often the case," he states, " . . . the real objection lies in the realm of spirituality, not science."

Many will not agree. Still, in spite of the rebuttals to many of Silver's arguments that have been and will continue to be put forth as this debate continues, it is hard to imagine a better, more comprehensive, and more scientifically grounded account of the "brave new world" of baby-making. While it is aimed at a general audience, biologists will certainly find insightful arguments, and true cognoscenti will enjoy at least two lovely inside jokes in which the names of four prominent biologists are inserted deftly into the text. Reprogeneticists should be pleased with the arrival of a thoughtful, skillfully written book like Remaking Eden that engages the public in a conversation about the potential consequences of their work.

Silver Lab - author Lee M. Silver's Web site at Princeton University.

The American Surrogacy Center - claims to offer the most complete source of surrogacy and egg donation information on the Web.

National Bioethics Advisory Commission - a useful Web site with links to items such as its report on cloning.

Voluntary Moratorium on Cloning Human Beings - arguments in favor of a cessation of such research, from the Society for Developmental Biology.

"Embryonic Stem Cells Debut Amid Little Media Attention" - a September 29, 1997 article in The Scientist describes the establishment of human embryonic stem cells, which opens up a whole range of possibilities in reprogenetics and medicine.

Three relevant books available from Amazon.com: The Lives to Come: The Genetic Revolution and Human Possibilities by Philip Kitcher; Clone: The Road to Dolly, and the Path Ahead by Gina Kolata; A Child is Born by Lennart Nilsson.

"Science and Ethics of Mammalian Cloning" - HMS Beagle's Cutting Edge Debate, moderated by Jon W. Gordon.

"Celluloid Genetics" - HMS Beagle's Press Box review of the movie Gattaca, by Jim Kling.

Web Book Reviews - a listing of selected Web sites that offer science book reviews.