Clone: the road to Dolly and the path ahead by Gina Kolata Allen Lane, pounds 15.99; Could human clones already exist?
Last year, in March, I wrote: "cloning people - adults, anyway - is just not possible." I had it on good authority. Reputable scientists said it was "a biological fantasy". Yet in July 1996, Dolly the lamb was born in Scotland. She was a clone of an adult sheep - genetically identical to an elderly ewe. Someone had done the impossible: taken the DNA from a ewe's udder cell, and reprogrammed it so that it could direct development of a new life. When news of Dolly's birth was announced this February, the shock was genuine. "They said it couldn't happen before 2050," said one bioethicist.

This is the starting-point of Gina Kolata's Clone. Why did this remarkable breakthrough take most of us by surprise? And why, Kolata covertly enquires, didn't it happen in America? Her quest makes fascinating, if controversial, reading. This gripping account of science in action keeps you wanting to know what happens next. Yet it is a decidedly American-eye view of the path to cloning.

As a science writer for the New York Times, Kolata endeavours to be at the cutting-edge of research. Yet, before the cloning story broke, she'd never heard of Ian Wilmut and Keith Campbell, Dolly's creators, nor the Roslin Institute near Edinburgh, where they work. US scientists are known to suffer from a peculiar syndrome that makes it difficult for them to a) take note of, and b) believe research findings from elsewhere. Kolata finds it remarkable that Wilmut completed his PhD in three years - the standard length of the British degree - and calls a salary of pounds 37,500 "modest". She gets the name of our Human Fertilisation and Embryology Authority wrong. More seriously, she never mentions that Britain and other European countries outlawed human cloning in 1990.

Yet she avoids sensationalism and lets her interviewees make the controversial claims. This makes her final chapter all the more powerful, as she describes the ideas flooding in from pro-cloning scientists, who have lobbied the US government against a ban, the "Luddite option".

Kolata leaves us with the uneasy feeling that the drive to clone people is unstoppable, if only because scientists and doctors are intrigued by what they could do with the technology. Indeed, perhaps humans have already been cloned by accident. This startling suggestion comes from Steen Willadsen, a brilliant Danish scientist who did much of the groundwork for Dolly in the 1980s.

Willadsen now works in a clinic in Florida, where he injects sperm from infertile men directly into human eggs. The treatment, known as ICSI, is designed to enable men who do not produce mature sperm to father children. But as immature sperm cells are removed from the testicles, similar-looking non-sperm cells could contaminate the sample, and be inadvertently injected. Should the egg spontaneously jettison its DNA, as can happen, you'd be left with an egg that bears only the father's genes. If it developed normally, you would have cloned the father.