Just how many genes does it take to be human?

Imagine an amoral but technologically highly competent medical scientist who has created a potential embryo by removing the nucleus from the egg of a rabbit and replacing it with the nucleus from a human skin cell.

Being highly competent, the scientist has managed to do what others have so far found impossible: the hybrid embryo has started dividing and has the appearance of an early stage embryo. Being amoral, the scientist has arranged to implant the embryo into an unsuspecting woman to allow it to develop. The embryo duly grows into a fetus and goes on to be delivered by Caesarean section.

Though you may have many questions around this thought experiment, the one I wish to ask first is this: ‘What would the offspring of this union be — fully human or something not quite human?’

As a thought experiment, this scenario assumes a great deal, including the deliberate breaking of the law forbidding reproductive cloning of human beings. It also assumes a huge amount in terms of what might be possible technologically and biologically. But, in my view, what it does is get to the heart of a key issue in the government’s white paper reviewing the Human Fertilisation and Embryology Act published in December 2006.

The government has proposed a ban which includes experiments aimed at creating embryonic stem cell lines by transferring human DNA into enucleated animal eggs. Yet the white paper does not close the door permanently on such procedures; it is envisaged that they might be permitted in the future, subject to regulation by a body such as the Human Fertilisation and Embryology Authority (HFEA). Indeed, the HFEA are conducting a consultation around this kind of research which will be completed in the autumn of this year.

In its recent sessions, the Science and Technology Committee of the Commons heard evidence from a number of witnesses maintaining that a ban is unnecessary and could be detrimental to the advance of our knowledge in the field of stem cell research. They argued that the regulations on the use of human eggs and embryos could easily encompass research involving human nuclei being transferred to animal eggs.

Their reasoning was that if the ‘products’ of the technology could be considered human then the procedure was in essence no different from the transfer of human nuclei into human egg cells. On the other hand, if the cell lines were ‘animal’ then they need not be considered by the HFEA at all — if such research required regulation then the Home Office was the appropriate department.

At one level, this seems reasonable. But it neglects the very obvious fact that in creating a human-animal hybrid (or cybrid as these embryos have also been called) we are dealing with a wholly different set of parameters. As the thought experiment shows, the nature and status of the embryos that scientists propose to bring into being takes us into territory that demands very careful thought and attention.

If the thought experiment above did ever become a macabre reality my guess is that the entity produced would be a human being — albeit a severely genetically disabled human being if the example of the cloned sheep, Dolly, is any guide.

From a Christian perspective, such an individual would be both a full person and carry the image of God. Yet most people would also acknowledge that in creating such a person we were beginning to lean on the boundaries of what it might mean to be human. Many would share a sense that something fundamental about the sanctity of what it meant to be human had been violated in several ways.

Of course, the research that is being proposed to create hybrid embryos does not intend for them to live past 14 days and there is certainly no intention to implant in a human being. The technology itself is considered incredibly difficult and may yet prove a fruitless avenue for progress in research. But that does not mean that we should not take time to ask deeper philosophical and moral questions about it.

Christian churches like my own, as well as other religious groups, need time to reflect on this and contribute to the ethical debate without unreasonable time pressures. It is not only the science that is complex and demanding — we are crossing into territory which in the view of many seems to be raising totally new philosophical questions. ‘How many genes does it take to make a human being?’ is not the speculative intellectual game it might once have seemed.

In the light of these considerations, I find it hard to understand why some politicians and scientists are pushing so hard for a permissive change to the white paper. The HFEA itself acknowledges that the construction of human-animal embryos is a complex and controversial issue. Its opinion is that such research would involve a significant step change in UK science and should not be permitted before there has been proper public debate and consultation.

We would do well to remember what happened with genetically modified crops. The rather ‘maverick’ way in which acceptability of the technology was assumed by those who developed it probably set the field back a decade or more and some potential benefits may have been completely lost. It seems to me that a more cautious approach can pay dividends and this appears to be the government’s view.

Appropriate and wise regulation should act as a protective shield for many parties. Effective regulation ensures that the public are reassured and this is crucial in such a sensitive area as the creation of human-animal embryos.

There is an undeniable ‘yuck’ factor around this kind of experiment which should not be overlooked or ignored. As the philosopher of science Mary Midgely has observed, the ‘yuck’ factor is not to be dismissed too lightly; it has been described as an ‘amber light’ in ethical discourse. Widespread unease and distaste for a procedure cannot be the last word in making decisions, but failing to address it can be interpreted as arrogance.

Effective regulation should also be seen as an aid to scientists rather than an unwelcome hurdle to be negotiated. Ethical review by expert bodies which include lay women and men should ensure that promising research is nurtured and protected; an overly permissive culture can backfire when things go wrong. This has been true in the field of gene therapy where in the US research suffered a huge setback through an inadequate regulatory framework. In the UK we have a reputation for thoroughness for working with scientists in developing our regulations. Let us not throw that away lightly.

We also must eschew hype, which is far too prevalent in the field of embryonic stem cell research at present. As those in other fields such as gene therapy know to their cost, overselling the possibilities is harmful; raising expectations and not delivering tends to immunise people. It is prudent for patient advocate groups who see promising possibilities to be positive but realistic.

As a Christian and a former medical scientist, I am committed to developing medical technologies that will bring relief from suffering. I do not want opportunities to be squandered.

However, that means ensuring that the ethical basis is sound and acceptable and that the regulatory framework is firm. In the case of hybrid embryos formed between human and animal cells I believe that the initial ban on such work proposed in the government’s white paper is correct. The ban should be relaxed when there has been wider consultation and the moral, philosophical and theological issues have been explored more thoroughly.

When the decision was made to allow the use of human embryos for research it was a crossing of the Rubicon. Many people, including a high percentage of practising Christians, are still not sure that was the correct decision, especially in respect of creating embryos purely for research. If we are going to preserve the ‘special status’ of the human embryo it would be wise not to rush into crossing another Rubicon.

Right Reverend Dr Lee Rayfield, Bishop of Swindon, is an ordained scientist and member of the Gene Therapy Advisory Committee, but the views expressed here are not to be taken as representative of that body. He gave evidence to the Science and Technology Committee on behalf of the Mission and Public Affairs Division of the Church of England.