The work I was involved in had no obvious therapeutic benefit. It was purely of scientific interest. I hope the country will continue to support basic research even though it may have no obvious practical value.
It is particularly pleasing to see how purely basic research, originally aimed at testing the genetic identity of different cell types in the body, has turned out to have clear human health prospects.
If you took some famous religious leader, for example, and said it would be nice to clone them indefinitely so you have a dynasty of leaders, my own guess would be that each time the cloning takes place, they would become more and more defective, presumably mentally defective and subsequently worse.
My first attempts to transplant nuclei in Xenopus were completely unsuccessful, because the Xenopus egg, unlike those of other amphibians, is surrounded by an extremely elastic membrane and jelly layer that make penetration by a micropipette impossible.
I wondered whether the nuclear transfer techniques could be used to introduce purified macro-molecules into an egg, and hence into embryonic cells.
Within six months of starting my Ph.D. work in 1956, I had already obtained feeding tadpoles derived from transplanted nuclei of embryonic cells.
For my part, I have worked all my life with eggs and embryos of frogs. Compared to other small animals, these have figured prominently in the world of literature.
As a brand new graduate student starting in October 1956, my supervisor Michail Fischberg, a lecturer in the Department of Zoology at Oxford, suggested that I should try to make somatic cell nuclear transplantation work in the South African frog Xenopus laevis.
I take the view that anything you can do to relieve suffering or improve human health will usually be widely accepted by the public - that is to say, if cloning actually turned out to be solving some problems and was useful to people, I think it would be accepted.
The aim of a nuclear-transplant experiment is to insert the nucleus of a specialized cell into an unfertilized egg whose nucleus has been removed.
As with most animal eggs, the early events of amphibian development are largely independent of the environment, and the processes leading to cell differentiation must involve a redistribution and interaction of constituents already present in the fertilized egg.
I must have been born with a strong attraction toward, and possibly even an aptitude for, doing things on a small scale.
I left my frogs, which I had grown, with my supervisor, who had moved to Geneva, and he and a technician grew them up. So by 1962, they were adults, and one could publish a paper to say that these animals, derived from nuclear transfer, really were absolutely normal. So it took a little time to get through.
Within one year of starting work, I had found that the nucleus of an endoderm cell from an advanced tadpole was able to yield some normal development up to the nuclear transplant tadpole stage.