Last week I described the work of the American group that identified the minimum set of genes essential to sustain life in the simple bacterium Mycoplasma genitalium. A leading member of that group has declared it is now possible to create a living M. genitalium by synthesising the essential set of genes and the minimum other pieces of essential cellular machinery and putting the lot together under the right conditions. In my opinion this claim grossly underestimates the difficulties involved in synthesising life given our present limited knowledge of cell functioning. However, it seems equally clear the synthesis of life will become possible in time, and I may well be over-estimating the time frame involved.
J.B. Gurdon, at Oxford University, successfully cloned a frog in the 1960s, using a tadpole cell as his starting material. The clone developed into a normal adult frog. Despite the fact that, at that time, huge difficulties clearly lay in the path of duplicating this work in mammals, and even greater difficulties opposed its duplication using a cell of an adult animal as starting material, it nevertheless didn't require a Herculean feat of imagination to foresee that, before too long, an adult mammal would be cloned.
In 1997 the cloning of Dolly the sheep was announced to an amazed world. There seems to be no technical reason why the Dolly technique would not be successful in cloning a human being. Human cloning is a subject that bristles with ethical questions. But, prior to 1997, little or no consideration was given to these questions. After Dolly the whole world was suddenly agog over the matter. But, the whole area could have been under consideration since Gurdon cloned the frog 35 years ago. It is most unwise of us to allow big ethical issues to spring suddenly on an unsuspecting world where this can be avoided. Thankfully we may be getting wiser - the same issue of Science that announced the possibility of synthesising life also carried an article on the ethical implications of such a move. Also, the scientist, Dr Craig Ventner, who declared he now feels confident that he could synthesise a living cell, has declared he will take no action in this regard until an ethical debate has been finalised.
The perceived advantages of synthesising living cells are manifold. The genetic content of such cells would be designed to produce precise results. For example, organisms could be specifically designed to secrete valuable medical biochemical products at high yield and with no unwanted by-products. The ability to construct a wide variety of new organisms with precisely defined genetic content would also revolutionise the study of molecular cell biology.
Would such developments pose new threats to human health and/or to the environment? They probably wouldn't pose new types of threat additional to the perceived threats associated with current practices of genetic engineering. However, the capacity to synthesise new types of living cells would greatly speed up developments in genetic engineering and therefore would magnify the extent of whatever threats are already inherent in this technique. Strong majority scientific opinion holds that genetic engineering poses little or no threat. Suppose the capacity to synthesise life magnified these threats by five-times. The net result might then be, as a colleague once remarked to me about another type of low risk: "Five times damn-all is still damn-all".
The cloning of Dolly was followed by a public outcry against the idea of human cloning, which is widely considered to be unethical. Is it ethical to synthesise life? There has been little public reaction against the idea. I presume this is largely explained by the fact that the proposal is to synthesise a bacterium, not a human being. One might imagine that the Churches would object to the synthesis of life. The mainstream Western Churches were represented on the panel that wrote the paper on ethical considerations published in Science. These Churches voiced no major objections. I quote from the paper: "The prospect of constructing minimal and new genomes does not violate any fundamental moral precepts or boundaries, but does raise questions . . ." One of these questions concerns our reverence for life.
Despite circumscribed specific exceptions, we humans still have reverence for life. To some extent this is engendered by the fact that, up until recently, the mechanisms that underpin life were a complete mystery. Over the past 50 years many of these mysteries have been explained. If we reach the stage where we can synthesise life from basic chemicals, what mystery will remain as to the physical basis of life? At that stage that fraction of our current reverence for life that depends on our ignorance of life's processes will vanish. That day is coming anyway, whether or not we synthesise life, as our knowledge of the molecular biology of the cell increases exponentially. Any lessening of reverence for life is a bad thing so we would do well to start replacing that fraction so far dependent on ignorance with a new reverence based on an appreciation of how the wonderful molecular organisation of life arose naturally.
The synthesis of life would be a major triumph for reductionism. Reductionism is the dominant approach used in modern science i.e. complex systems are studied by reducing them to their simplest component parts, studying the parts and then trying to understand the whole as the sum of the parts. Reductionism has been a most fruitful approach but it seems almost certain that its power to explain is limited to systems at lower levels of biological complexity. We need to develop more sophisticated approaches in order to understand systems like the brain. Impressive as the synthesis of life would be, an unwanted by-product could be to canonise reductionism as an all-powerful approach at a time when it is fast approaching the limits of its usefulness.
William Reville is a Senior Lecturer of Biochemistry and Director of Microscopy at UCC.