Manipulating the human embryo.

• Author: Nusslein-Volhard, Christiane
• Position: Science & Technology

GENES AND EMBRYOS have become the subject of intense public discussion, as the achievements and scientific discoveries in the fields of embryology and genetics not only increase our knowledge, but open up new possibilities to influence human life in a principally novel way. In addition, these achievements give rise to speculations and scenarios that indeed would change the world substantially should they ever be realized. Although several medical applications of new technologies, in particular gene technology, now are widely accepted, there is a widespread fear of the dangers of unpredictable consequences of such technologies.

At the center of these debates is the issue of the extent to which human embryos should be manipulated in vitro and whether to interfere with their genetic constitution. Among different countries, the regulations relating to this issue are diverse, ranging from very restrictive, for instance in Germany and Ireland, to quite permissive in the United Kingdom and Sweden.

What exactly is the issue? Since 1978, it has been possible to fertilize human eggs outside the female body and cultivate the embryos in vitro for a short while before they are transferred back into the uterus to achieve pregnancy. The current procedure for this in vitro fertilization yields surplus embryos that are not transferred back. This opens up the possibility to use these embryos for medical research rather than discarding them. For instance, embryonic stem cell cultures could be obtained that could be used to develop therapies for several severe diseases. By genetic screening of such early embryos, congenital diseases could be avoided, even eradicated. However, according to the generally accepted moral conviction of our culture, every human being possesses dignity and, therefore, must not be used solely for the benefit of others. Opponents and supporters of embryo research share this moral position. The conflict therefore does not concern the acceptance of human dignity and protection, but rather the moral status of the early embryo.

From which point on is a human embryo a human being? Are the very early embryos human beings, which have to be protected just like growing embryos during pregnancy, or is their moral status different, and gradually changing until birth? The view of such a graded increase in status in many ways does reflect our natural feeling, which is manifested by our customs of birth control and laws of abortion. This difference in status is the bone of contention. The German law of 1990, for instance, defines the beginning of a human being at fertilization, while others consider the actual time of implantation into the female organism as crucial. In the U.K., in vitro is allowed until the 14th day. A human being becomes a legal person only by birth.

Although the criteria used for the definitions rely on biological events, they are not a scientific, but a moral, issue. Dignity, right to life, and protection are not biological, but moral categories. Therefore, these issues should be decided not by scientists but by our society as a whole through our political representatives. The big differences among nations even of very similar cultural backgrounds indicate that there is no single correct solution. However, in order to guarantee efficient research, we need clear regulations that are respected widely. The legal definition of the beginning of a human being should be reasonable, plausible, and consistent. It is at this point where scientific knowledge and judgment may help by describing grades and steps of embryonic development. It also is the obligation of scientists to reveal the potential applications and consequences of embryonic research. As there are conflicting moral issues--such as the right to life on the one hand and the pain and suffering caused by yet untreatable diseases on the other--these regulations demand great care and foresight and will have long-lasting consequences to our societies.

Using early human embryos for medical therapy merely is part of the debate. Additional issues include the ability to interfere with the processes of reproduction, and diagnostic procedures such as the selection, or even the genetic manipulation, of children with desired attributes. A particularly controversial issue is that of cloning. It is remarkable that, in this debate, or rather in the representation of this debate by the media, there is little or no distinction between what is real, what is plausible, and what is utterly utopian. Sometimes the impression is conveyed that science not only could accomplish anything we desire, but actually would test the limits of the possible without any ethical considerations. This attitude is not new. There is a long tradition on both sides: blind belief in scientific progress and its flip side, the utter distrust in science.

Utopias of man creating man have existed since antiquity, handed down through the generations by way of myths and religions. Even though most people would acknowledge that the creation of woman from Adam's rib or the creation of Pallas Athena from Zeus' head are meant purely as symbols, things look different if such ideas are supported by contemporary biological theories. A good example from the Middle Ages is the recipe of the creation of the Homunculus (Latin for little human) by Paracelsus of Hohenheim, a scholar of alchemy and various other sciences in the 16th century. The story of the Homunculus is based on the popular idea of preformation, which prevailed for a long time. This idea implies that the sperm already harbors a completely formed human being, a Homunculus, which unfolds in the mother's body in the way a plant's seed would develop in the earth. Paracelsus' 1537 "recipe" replaces the mother's organism...