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The question of when human life commences is one of longstanding philosophical and scientific interest. In our day it has been thrust into the realm of immediate urgency by advances in embryonic stem cell and cloning technologies. The question is taken up by Jane Maienschein in Whose View of Life? The book examines the matter principally from a historical perspective, asking how scientific, secular, and (to a lesser extent) religious views about the onset of life have changed over time as the scientific understanding of embryonic development has expanded.

Maienschein is a well-published writer in the history of science, and this book has been warmly welcomed by many. Publishers Weekly says the “book should be required reading,” Garland Allen calls it “essential reading,” Jonathan Weiner describes it as “timely, sensible, and clearheaded,” and in a very friendly interview with the author posted on the New York Academy of Sciences website she is praised her for a perspective that “casts doubt on the certainties of anti-research thinkers.” In her introduction, Maienschein declares that she will take a balanced and neutral look at “how to define when a life begins and what the appropriate boundaries and constraints on human embryo research should be.”

This is a worthy goal, but one finds that balance and neutrality are not evident in the product of her efforts. Though she is an historian of science, there are serious problems with her presentation of both history and science, and in the end she settles the question of her title by appealing to the self-evident correctness of her own preferred answer: we are to resolve the question of when life begins by rejecting the “extremism and absolutism” of those who believe life begins at conception, and by cleaving instead to the “wisdom” of “meta-experts” (these are apparently academic historians of science). Such meta-experts will help us to “forge a compromise explicitly responding to our best science and our best moral thinking.” The reader will note that it is a curious sort of “compromise” that explicitly denies any role for the “extremism and absolutism” of those who reject Maienschein’s own viewpoint.

The majority of the book deals with the history of thought about human embryonic development, beginning with the views of Aristotle and proceeding in rough chronological order to the present day. The presentation of historic viewpoints is at times inexplicably disjointed. (Why, for example, are topics as divergent as Mendel’s genetic experiments with pea plants, the eugenics movement of the early 1900s, and the cloning of frogs all covered in a single chapter?). Yet the text is still reasonably informative and entertaining. A major theme that emerges from Maienschein’s historical studies is that two opposing opinions on the origins of human life have coexisted since ancient times. One is the “preformationist” view, which asserts that life is present in some form from the earliest stages of development (the modern form of this view being the belief that life begins at conception). The other is the “epigenesist” view, which asserts that life comes into existence gradually over time. Maienschein would have us believe that these two views have come down more or less intact to the present and that understanding the changing historical preeminence of one position versus the other enables us to see that the question of when life begins is finally unresolvable.

Yet Maienschein’s historical presentation is flawed in important ways. While maintaining ostensive neutrality regarding the relative merits of the preformationist and epigenesist views, Maienschein indulges in a less than even-handed characterization of these two positions. Modern-day preformationists (those who believe life begins at conception) are “absolutists” who hold “extremist” views that are “vague and unsustainable” but who advance these views as “immutable, without possibility of compromise or accommodation,” and thereby contribute to “the politics of hate.” By contrast, even highly dogmatic statements by proponents of the epigenesist view are not similarly condemned. For example, Michael West, the president and CEO of Advanced Cell Technology, is quoted as saying: “You can’t say that making and destroying a pre-implantation embryo is the destruction of a human. Because it isn’t. If it was a human life, I wouldn’t touch it. Absolutely not. A human individual does not begin at conception. It begins at primitive-streak formation.” (The “primitive streak” forms approximately fourteen days after fertilization and marks the beginning of a period during which cells of the embryo organize into three primary tissue types.)

Clearly, an opinion as strong as West’s could be fairly described as “immutable, without the possibility of compromise or accommodation,” but Maienschein presents this statement without qualification and goes on to laud West for his conviction that “the research must go forward.” Similarly, the inflammatory advice of Nobel Prize“winner James Watson about embryonic stem cell research”“We’ve got to go ahead and not worry whether we’re going to offend some fundamentalist from Tulsa, Oklahoma””is presented without comment; Watson is not charged with advancing “the politics of hate.” This is hardly a balanced and neutral look at today’s debate.

Maienschein’s exposition of scientific information (particularly modern findings) is similarly biased. Considerable factual inaccuracy and distortion arise from Maienschein’s selective omission of scientific findings that cast a less than kindly light on embryonic stem cell and cloning research. It is notable, for example, that despite devoting an entire chapter to the topic of cloning, Maienschein glosses over the well-established and significant fact that the vast majority of cloned animals either die before birth or are physically and genetically abnormal. This fact certainly calls into question the wisdom of using such abnormal cells for the therapeutic treatment of human disease. Similarly, despite the promisingly even-handed title of her final chapter, “Hopes and Hypes for Stem Cells,” Maienschein fails to discuss the well-established drawbacks of using embryonic stem cells for therapeutic purposes (See my article, “The Basics About Stem Cells,” FT January 2002). The effect of these omissions is to present embryonic stem cell and cloning research as therapeutically promising technologies that are uncompromised by significant scientific limitations. The best that can be said for such a presentation is that it is disingenuous.

Maienschein’s portrayal of history also suffers from a number of conceptual flaws. Maienschein paints a picture of the historic debate over when life begins as a series of inconclusive battles between the preformationist and epigenesist views, a continuing controversy in which neither position has achieved clear victory. She goes on to argue that, because the available science has sometimes favored one view and sometimes the other, science will never resolve the debate. She concludes that while we must take scientific information into account, science itself cannot define the beginning of life.

This picture is interesting, but it is also profoundly inaccurate. Maienschein’s argument explicitly denies the possibility of real advance in science and falsely suggests that the question of when life begins is simply beyond the realm of scientific inquiry. On the contrary, the historical facts strongly argue that although there were limitations in scientific understanding and method that precluded a clear resolution of this question in previous eras, such limitations no longer exist. While the inability to “look inside” the womb may have led early scientists to favor the epigenesist view that life gradually comes into existence from inanimate matter, we simply know better today. Once we came to understand that embryos arise from the fusion of living sperm and egg cells, the debate over spontaneous generation of embryos from inanimate seminal and vaginal fluids was forever closed to serious scientific discussion. Real and substantive progress has been made, and in no circumstances will further research prove capable of causing our understanding to revert to a disproved concept.

Suggestive comparisons may, of course, be made between earlier epigenesist-preformationist controversies and our current debate over when life commences, but such comparisons do not “inform” the current debate in any meaningful sense. Indeed, they have no bearing on the real issue, which is whether our current scientific understanding substantively and permanently resolves this question. The modern discussion of when life commences must proceed from the answer to following question: Given what we know with certainty, what type of new information is it currently possible for us to discover”and could such information substantively change our present understanding of early embryonic development?

What we know with certainty, despite Maienschein’s insistence that the “jury is still out,” is that the facts inarguably support the preformationist view she so vehemently rejects. We know, for example, that single-cell embryos are unambiguously organisms, for the defining feature of an organism, as compared to a simple collection of cells, is that it is “organized” to accomplish a “purpose” that exceeds mere cellular life. Talking about “purpose” may make some readers (including some scientists and perhaps some historians of science) nervous, yet in the context of developmental biology, an organismal “purpose” means nothing more than the playing out of a game plan that we know, by observation, results in the formation of increasingly complex, integrated structures, all of which work together for the continued life and health of that organism as a whole. Embryos manifestly behave as organisms and as nothing other than organisms from the single-cell stage onward. This conclusion is true today, will be true forever in the future, and will at no point be subject to substantial revision by further scientific research or discoveries.

Maienschein, like many other proponents of using stem cells from embryos as research material, denies the organismal nature of single-cell embryos by simply asserting the opposite. However, such denial is contrafactual. Maienschein states, for example, that single-cell embryos only function as “cells dividing into other cells that are just like them.” This assertion is patently absurd; single-cell human embryos ultimately produce babies, not merely multiple copies of themselves. Early embryos can be destroyed to yield embryonic stem (ES) cells that do indeed simply reproduce themselves, yet once the embryo is destroyed, the cells that once composed it lose their organismal character. If early embryos are nothing more than ES cells, and if human organisms “spontaneously” come into existence at some later developmental stage (the primitive-streak stage, for example), then embryos and ES cells should be interchangeable. That is to say, it should be fully possible to aggregate ES cells together and reconstitute an embryo that will develop into a normal baby. The fact that embryos cannot be “made” from ES cells alone demonstrates that ES cells are qualitatively different from em-bryos. ES cells are “organized” to the purpose of maintaining and replicating cellular life, but not to the purpose of generating a baby.

Aristotle, of course, knew nothing of single-cell embryos or ES cells, but an Aristotelian distinction between the two can be made quite clearly: the single-cell embryo fully possesses a substantial form that is organized toward the generation of increasingly complex systems, ultimately culminating in an adult individual, whereas the ES cell possesses a qualitatively different substantial form that is organized toward the maintenance of cellular life and generation of other cells like itself. (Maienschein’s apparent confusion of accidental form and substantial form causes her to erroneously assign Aristotle to the epigenesist side of the debate, thus lending that side a somewhat more distinguished pedigree than it deserves.) The radical difference in kind between ES cells and embryos exists from the earliest stages of embryonic development and does not magically come into existence at the primitive-streak stage”regardless of how convenient such a mystical event might be for the argumentation of those who favor doing research on early human embryos.

The ultimate issue for Maienschein is not so much when life begins; it is, rather, when do we as a pluralistic society choose to value and defend life? Maienschein believes that human life is worthy of defense at some point and that our definition of when human life begins should be informed by scientific evidence. Yet she also believes that research on human embryos is valuable and should therefore be allowed to proceed. To reconcile these beliefs, Maienschein ultimately rejects the scientific facts regarding when life begins and resorts to the purely utilitarian argument that human life is valuable and worthy of protection so long as some other goal (in this case the hope of curing human disease by destroying human embryos) does not exceed the value she personally chooses to assign to human life at a given developmental stage. The answer to her question “Whose view of life?” turns out to be “Maienschein’s.” Society’s interests will be better served by answering the question of when life begins by appealing to scientific fact.

Maureen L. Condicem is an Associate Professor of Neurobiology and Anatomy at the University of Utah; she is currently conducting research on the regeneration of embryonic and adult neurons following spinal cord injury.