For all the millions of words expended on Dolly the cloned sheep since her birth in the summer of 1996, most commentators have missed the main point. It isn't just that we can replicate prize livestock, or even human beings. As late as 1984 the great embryologist Davor Solter declared that "cloning mammals by simple nuclear transfer is biologically impossible" - and most biologists took it to be the case that he was absolutely right. Even John Gurdon of Oxford, who cloned adult frogs from tadpole cells in the 1960s, was amazed by Dolly - for she was a mammal, not a mere amphibian, and she was cloned from an adult cell (from the udder of a long-dead pregnant ewe), and not from a mere larva or an embryo. The deep point is that after Dolly, the expression "biologically impossible" no longer seems to have meaning. From now on it is most prudent to suppose that anything we might care to contemplate in the field of biotechnology is possible in principle, provided only that it does not breach what Sir Peter Medawar has called "the bedrock laws of physics", or defy the rules of logic. Just let your imagination run. Scientists who say "it can't happen" are dissembling, or have failed to keep up with the literature.
Why not - just to be obvious - designer people: human beings who have been altered genetically to a prescription? Genetic transformation - "transgenesis", "genetic engineering" - is not related directly to cloning, but in fact the creators of Dolly, Ian Wilmut and Keith Campbell at the Roslin Institute near Edinburgh, were never interested simply in replicating prize livestock but always saw cloning as an aid to transgenesis. At present, animals can be transformed only by adding DNA to young embryos, but it is far easier and more efficient to produce an array of cultured cells and work on them a thousand at a time, and then clone whole new animals from the cells that have been transformed most effectively. Neither Wilmut nor Campbell seek to apply their technique to humans - both abhor the idea - but although scientists may patent their methods, they cannot control what others do with them and many, elsewhere, are keen both to clone people and to manipulate their genes. The process has begun and now there are no obvious technical barriers.
Human cloning and transgenesis may appal at first blush, but it's largely a matter of image. Cloned Hitlers - a common image in the wake of Dolly, already floated by Ira Levin in The Boys from Brazil - seem ghastly but are an obvious nonsense. Clones are born as babies, so it would take 50 years to replicate the full-blown monster of 1939 and by then the political moment would surely have passed. Besides, nuclear clones are not strict replicas. Hitler-clone-fils might as soon become a priest, something Hitler-pere once longed to be, as a tyrant. Clones, like all offspring, can be a great disappointment. Far more realistic, as Professor Lee Silver of Princeton suggests in Remaking Eden (Weidenfeld & Nicolson, 1998), is that cloning will be seen as a natural extension of the increasingly exotic reproductive technologies that already help millions of couples - for one in eight may have fertility problems. Honest desire and a loving home are surely what count, says Silver, not the details of the reproductive process. We quickly get used to technicalities. In 1978 the world's first "test-tube baby", Louise Brown, caused as much stir as Dolly has done and provoked the same kind of arguments. But IVF now is so commonplace that if you don't know somebody with an IVF child, you probably know someone who does.
Transgenesis will creep in as serious therapy. At the Royal Society last week, Lord (Robert) Winston of Imperial College was surprisingly bullish when discussing gene therapy for Duchenne muscular dystrophy - not simply for the somatic (body) cells but for the whole young embryo, so that germline cells (gametes) will also be transformed and affect all subsequent generations. Transgenic techniques that are perfected through such life-and-death therapy will one day be used to titivate genomes that are normal but a bit too ordinary. Indeed, Lee Silver envisages a future of what he calls "genrich" people so laden with ancillary genes that they form a new species. Lord Winston has roundly criticised such visions, but Silver warns us never to underestimate the power of market forces. Those who lay out $100,000 on their offspring's education might spend as much again on genes that will help them make best use of it; and the US bursts with hungry physicians and molecular biologists, keen to offer their services.
But - and here's the big but - there's nowt so queer as folk. Technologies don't necessarily catch on just because they are there. People may even throw them out when they already seem established. High-rise flats are now biting the dust, and nuclear power could go the same way. On the reproductive front, artificial insemination has been available for 200 years (in 1790 the Scottish surgeon John Hunter used a syringe to inseminate a woman with the sperm of her husband, who had a bent penis) and could in theory transform the way we live and the genetic prospects of the entire human race. But it hasn't. Feminists have urged women to live in prides like lionesses, consorting with chaps only for social reasons and buying in the sperm of basketball players with four-figure IQs for the serious business of reproduction, yet women on the whole prefer their smelly, couch-potato husbands. The reasons are partly social - society is geared to couples - but are also, surely, biological. On the face of things it makes biological sense for a woman to link her genes to those of a super-stud, but way-of-life and infant care count for at least as much. The in-house slob may be a genetic second-rater but he is good for a laugh, brings home the wages and takes the children to the zoo, and would be less inclined to do so if those children were not his own. Our psychology is at least rough-hewn by our evolution, and evolution is not stupid: partners on hand really are better, usually, than anonymous, distant paragons.
So the new technologies will come on line, if not in the next decade then the one after, or the one after that. There is plenty of time, and they are not going to go away. But they will not take over the world, or give rise to a new human species. Our social institutions will change, but our evolved predilections, our deep-set instincts, will keep us the way we are. At least for a time. Probably.
Colin Tudge's latest book, "Neanderthals, Bandits and Farmers", is published by Weidenfeld & Nicolson at £4.99