The aim of Jane Maienschein’s book is to show that “We can best understand what embryos are by putting them under the microscope and looking at them carefully” (p. 287). The author wants to show that, in order to understand the complexity of the ethical challenges of embryo research, we need first to know the “facts” of embryology; and the best way to present the facts about embryos is to understand the conceptual history of developmental biology. In order to do so, Maienschein partitions this history in seven stages that represent different historical periods, each characterised by a particular conception of the embryo and by peculiar epistemological challenges. She then narrates the history of embryology in chronological order by showing that our understanding of embryos has radically changed since, more than two thousands years ago, Aristotle observed the development of chicks with the naked eye. Unsurprisingly, the engine of change has been technology, first with the invention of the various instruments that make embryos “visible” (e.g., from traditional to electronic microscopes) and subsequently with the development of various techniques allowing us an ever increasing power of manipulation over embryos (e.g., from traditional tissue transplantation to nuclear transplantation). 

Synthetically, this is how the history of embryology unfolds. While during antiquity the embryo was a hypothetical construct, with Aristotle it started to be observed. The stage of experimental embryos had to wait until the end of the 19th century. During this period embryology became a science and many of its glorious experiments were performed (e.g., those of Roux with frog embryos or Driesch’s with sea urchin’s) and the first transplants achieved by Harrison, Spemann and Mangold. The emergence of genetics transformed embryology and shifted the focus on inherited embryos and the role of DNA in development, while in the 60s, also due to concomitant theoretical developments in cybernetics, information theory and computer sciences, the embryo was even considered computable (the rationale being that, by knowing the embryo’s genome, it would be possible to “compute” the morphology of the adult organism). At this point the book’s narrative changes and the focus moves primarily on human embryos and the technological innovations (such as IVF in the 70s) that first rendered them visible and that then led to the tremendous achievements of our age of constructed embryos. Maienschein argues that contemporary research is marked by the ideal of engineering life originally advocated by Loeb. This ideal is represented by a plethora of technological achievements (e.g., preimplantation genetic diagnosis, cloning, embryonic stem cells) that have revolutionised our conception of embryos. Today, Loeb’s ideal is epitomised by the prospect of not solely engineering but synthesising and creating embryos from scratch, which is not a mere science fiction scenario.

Maienschein’s historical reconstruction is also aimed at showing which cultural forces have influenced our moral attitudes towards embryos. These attitudes have changed through time. Perhaps surprisingly, only relatively recently (in 1869) the Catholic Church changed position concerning the ontological status of the embryo, proclaiming that life begins at conception. Maienschein reminds us that this position is in contrast with the views of St. Augustine and Aquinas, who both advocated the thesis of “delayed hominization”, according to which the embryo cannot be considered a person. It remains an interesting question why the Catholic Church changed its conception of the embryo. Was it because of empirical advances in embryology? From what Maienschein tells us, this hypothesis seems unlikely, as embryo research was at the time still in its pre-experimental phase. It is more likely that the Catholic Church tried to correct some perceived theological incoherence rather than promulgating a view informed by the science of the time (after all, the theological zealous of Pius IX also produced the dogmas of the immaculate conception and papal infallibility). In this sense, the Catholic Church preferred and still prefers to stick to metaphysical dogma instead of revising its position in the light of the available evidence. This attitude is constantly criticised by Maienschein. In fact, that science should inform our moral views is the underlying theme of the book.

Maienschein claims that, by refusing to watch a material embryo developing under a microscope, the risk is that of becoming glued to metaphysical beliefs that should be expunged by the progress of science. Her position is eminently sensible, but at times scientistic (every science is coated in a metaphysical husk). This occasional scientistic attitude unnecessarily loads her overall argument when dealing with ethical issues, for instance when she treats (too quickly) the hypothesis of fetal pain. Maienschein makes some bold assertions such as “Researchers have solidly established what neural wiring is necessary to allow sensation, the perception of those sensations, and the ability to interpret them as pain” (p. 285) and concludes that “We know that an embryo cannot feel pain because it does not have any neurological system or any pain receptors or processors” (p. 283). I find her argument unconvincing: perhaps feeling pain “like adult humans” requires a specific neurological apparatus, but whether neural wiring is essential to allow sensation is a totally different issue; in a way, any cell “senses” many aspects of its environment through its complex and varied receptors. Maienschein seems to push a flimsy argument in name of what she considers a good cause, but we simply do not know whether and how cells, plants, ticks, bats, cows, small children etc. experience pain. Above all, contrary to what the researchers cited by Maienschein seem to suggest, nociception seems to be a common biological phenomenon.

Maienschein’s narrative strategy constitutes the virtue but also the limit of the book. It is its virtue because the historical chapters are the clearest and most accomplished: Maienschein is an eminent scholar who is best suited to tell us the extraordinary history of classical embyology, the continuous struggle between preformationism and epigenesis, the development of our conceptions of heredity etc. But the more we approach our contemporary times, the more Maienschein’s narrative loses fluency.  For example, in chapter 8 the author gives us a tour de force through synthetic biology, regenerative medicine, stem cell research and microbiomics in a dozen pages: I doubt that most readers would get much out of it. This brings me to a more general issue: after reading the book, it remains unclear to me which readership the author aimed to target. She seems sometimes more interested in castigating loony neocon U.S. politicians for advocating “unscientific” views rather than reaching a less local and wider readership. Without a doubt, Maienschein is ideally placed to explain well the science as well as the societal implications of embryo research. But she does not totally succeed in this otherwise absorbing, though overambitious, little book.

 © 2014 Davide Vecchi

Davide Vecchi, Department of Philosophy, University of Santiago, Chile