From mice to men? On cloning and the challenge of the new biology

Test-tube babies, cloning of identical individuals, rewriting genetic "blueprints": such prospects of modern biology raise profound questions. Do an improved understanding of, and control over, the mechanisms of biological reproduction threaten people's sense of identity? Should limits be put on the application of this knowledge?

These twin questions challenge people to think again, and to think deeply, as to what they consider life itself and humanity in particular really to be. This challenge cannot be ignored. The questions are insistent, arising again and again with each new development in research in genetics and reproduction.

At this writing, the latest scientific milestone to be announced was the successful cloning of mice. Karl Illmensee at the University of Geneva, working with Peter C. Hoppe from the Jackson Laboratory at Bar Harbor, Maine, has used genetic material taken from mouse embryos to reproduce three mice genetically identical to the three respective embryos.

Nuclei containing the genetic instructions for "making" a gray (or in one case agouti) mouse were used to replace the genetic material in the fertilized egg cell of a black mouse. Eggs prepared this way were then cultured for four days and transplanted into white-mice surrogate mothers, which later gave birth to the cloned mice.

This experiment, reported in the journal Cell, is the first successful cloning known in mammals. Cloning had already been demonstrated with frogs and fish.

While this is a significant research milestone, it does not mean that the cloning of mammals, including humans, is imminent. There is much research to be done before this could be considered a practical possibility.

Also, this work is no more portentous than is the successful "editing" of genetic instructions reported last summer by Jon Gordon, Francis Ruddle, and George Scangos of Yale University. They injected the DNA of a virus into mouse embryos. DNA is the molecule that carries genetic instructions. This was incorporated into the embryos' genetic material.

Such research has the immediate benefit of giving bologists powerful new ways to study basic genetic processes. In the longer term, it holds the promise of such things as improving crop plants and animals, endowing them with inheritable qualities deemed valuable. But it also raises the questions noted above.

These issues of the concept one holds of life and human identity are essentially philosophical and spiritual. And, as such, they are as ancient as humanity itself. The injunction to love one's neighbor as oneself or the commandment "Thou shalt not kill" did not have to wait for molecular biology to be relevant to human welfare.

These age-old issues are with us always. The challenge of the new biology emphasizes the need t o reexamine them in today's context.