How should we remember the 1990s? Well, as the decade of the sheep perhaps. Damien Hirst pickles one, prompting the inquiry: "What is art?" A research team outside Edinburgh clones another, and we all start asking: "What is life?" Dolly is a Finn-Dorset ewe that was delivered in 1996 from a Scottish Blackface surrogate and named after a well-endowed American country and western singer. However, though the cultured cells from which she came were indeed mammary in origin, Dolly made news because the cells were adult. The donor had died long before the headlines. Her name was Hannah. This is the story, then, not so much of Dolly herself as of the long sequence of developments and experiments that preceded her arrival. Ian Wilmut and Keith Campbell (Colin Tudge is a science writer) were the leading figures in a research collaboration between the Roslin Institute and a biotechnology company, PPL Therapeutics. They are not quite as excited about this ewe as you might expect. As scientists, they find as much, if not more, importance in earlier cloning experiments and in a sheep called Polly, which was also cloned but genetically modified to produce a human blood factor in her milk.
Dolly is now a mother, and in the usual way - with the help of a Welsh Mountain ram. And she has not been repeated, which many may find curious. Despite some concerns about the rate at which her chromosomes are ageing, Dolly is fine so far, but if something odd did happen, sorting chance from catastrophe would be tricky. The recent death of one patient in a human gene therapy study is causing all sorts of problems for this promising line of therapy. Still, other species have since been cloned the Dolly way, and before her the cloning of animals had been studied for years. Older readers may recall the media attention given to research with frogs that was done in Oxford in the 1960s. No one then was thinking of supplies of blood factor IX to treat a type of haemophilia. A big scientific question was whether, in specialised cells of, say, a frog's intestine, genes not needed for the tissue's overt purposes were lost for ever, or merely switched off. Cancer research wanted the answer more than biotechnology companies did.
In around 200 pages, before we get to Dolly proper, Wilmut and Campbell explain the background biology. Readers who cannot differentiate a morula from a gastrula should not be put off, and there is a glossary to keep them on track. The authors would, I think, argue that one cannot have a fully informed debate about the uses and abuses of cloning without some understanding of the science. Last month, newspapers recorded yet another "first". Tetra, a cloned rhesus monkey, is a primate - non-human, but getting close. Yet Tetra came about by embryo-splitting, while the Dolly experiment was a nuclear transfer. If, in public debate about the ethical, social and other issues that the new pharming (no, not a misprint) and the potential human cloning are raising, we do not want scientists to blind us with their jargon, then we will have to acquire some grasp of it. For example, about 3 per cent of DNA, the genetic information store, lies outside the cell nucleus, in mitochondria, so nuclear transfer cloning does not achieve total identity. Dolly and Hannah are not identical twins, a point well explained here. But this is not a dry, academic text. How the credit for the clarity of writing should be shared between Tudge, Wilmut and Campbell is not easy to judge, but it has clearly been a successful collaboration. With the science behind them (and the reader), the authors end with a non-sensational discussion on "cloning people". That was the issue that, inevitably, became the focus when Dolly's birth was announced in the journal Nature in 1997.
The dust jacket's "most important science book of our generation" had become, by the launch on 20 January, the more humble "most important science book to be published in 2000". Either way, do not come down for or against cloning until you have consulted it.
The author is deputy editor of the "Lancet"