REMAKING EDEN: CLONING AND BEYOND IN A BRAVE NEW WORLD
BY LEE M. SILVER | AVON | 317 PAGES

CLONE: THE ROAD TO DOLLY AND THE PATH AHEAD
BY GINA KOLATA | MORROW | 288 PAGES

BY ANDREW BROWN | I went to school with a clone 30 years ago, and you may well have done so, too. The experience was not a memorable one: In those days they were always called "identical twins." But such twins are completely identical genetically, whereas it is a curious fact that artificially produced clones are not genetically identical, since they do not quite share all their DNA: A few genes (about 60 out of 100,000) come from the host cell into which the nucleus to be cloned is placed.

But how much does genetic identity matter? We have no difficulty in recognizing identical twins as separate and distinct people. Even when we cannot always tell which is which, we know the distinction between them matters. Genetic identity is not personal identity, as the story of Tim and Terry Twomey shows.

In 1977, Tim Twomey, a Sacramento, Calif., policeman who had lost his testicles in an unfortunate developmental accident in the womb, received a testicle transplant from his identical twin brother so that he could impregnate his wife (also a police officer, though this detail is not strictly relevant). In 1980, Tim and his wife duly had a son, named -- with a worrying lack of irony -- Christopher Gene. Christopher Gene's parental genes are exactly the same as they would have been if dad had been equipped with his own testicles rather than his brother's spare one, since Christopher Gene's father and uncle are genetically identical. But it must have been clear to all parties in the story at every moment which distinct brother had which testicle, even though it would be impossible to tell this by genetic analysis.

Considerations like this go some way in explaining why the scientific world was less shocked by the cloning of Dolly last year than by the tremendous public reaction to it. There was some surprise that it had been done. The Roslin Institute, in a quiet town outside Edinburgh, Scotland, is not a place from which cutting-edge science might be expected. But the feat seemed to most scientists a technical breakthrough, not an ethical or conceptual one. Ian Wilmut, who cloned Dolly from the udder of an adult sheep, had made the real breakthrough the previous year, when he cloned two other sheep, Megan and Morag, from embryonic cells that had already started to differentiate into particular kinds of tissue. Other scientists working in the field had already produced beasts such as sheep-cows, made by mixing sheep and cow embryos together, to produce a sheep with such oddities as wool patterned in black and white patches, like a cow's hide. One sheep cloned from an adult cell seemed a logical and unsurprising development.

There were exceptions to this scientific phlegm. Lee Silver, a professor of molecular biology at Princeton, was told about Dolly by Gina Kolata of the New York Times. "It's unbelievable!" he said. "It basically means that all of science fiction is true." She got her quote, and he got to appear on 23 talk shows in the next 14 days. Now both of them have published books on the subject: His is called "Remaking Eden"; hers (not a title copied from anyone else) is "Clone." Kolata thanks Silver for his help and advice -- and also reveals that an early draft of his book had a chapter explaining why cloning from adult cells was impossible.

When he had to revise that opinion, Silver appears to have abolished every other limit on his imagination. By the end of "Remaking Eden," he has gone into complete raving mad-scientist mode. He foresees a long-term future in which humans will have fitted themselves with genetic accessories from all over the animal kingdom: We will have magnetic direction-finding systems like birds, built-in batteries like electric eels and, should we want them, luminous bottoms like fireflies.

Of course, these are long-term plans. Before then, he tells us, "Alcohol addiction will be eliminated, along with tendencies towards mental disease and antisocial behavior like extreme aggression. Visual and auditory acuity will be enhanced in some to improve artistic potential. And when our understanding of the genetic input into brain development has advanced, reprogenetics will provide parents with the option of enhancing various cognitive attributes as well." And if we can do all that, we can probably fit pigs with wings, no trouble.

It is a tradition in science books of this sort to go completely bonkers in the last chapter, so one should not judge Silver's book too harshly for it. Those parts that were written before he discovered that all of science fiction is true are very clear, and open giddying perspectives. It was among them, for instance, that I discovered the story of the testicular twosome of Twomeys. Other stories make it clear that much of the future has already happened without anyone noticing; and that the excitement over cloning is simply a way to dramatize other advancements in reprogenetic technology. Almost as revealing, though, are the book's social and political assumptions: The past does not illuminate the present nearly as much as an imagined future can.

If you just want to learn about cloning, Kolata's is the book to buy. For about half her book she describes the research that led up to Dolly's birth with an admirable combination of clarity and detail. (The rest, unfortunately, is a reporter's notebook dump.) This is not a purely scientific story: The reasons that made cloning unfashionable -- so much so that cloning from an adult cell was finally accomplished in the middle of nowhere by a scientist few had heard of -- are social and financial as much as anything else.

"Clone's" incidental details about salary structures and conditions of employment among researchers are fascinating. One of Kolata's heroes, a Dane named Steen Willadsen, who produced the sheep-cow chimera, was paid $150 a month as a research fellow in Cambridge, England, later raised to 150 pounds a month. On that salary, he did ground-breaking research. When he moved to the U.S. to work for a commercial company, he slaughtered a fatted sheep-calf, roasted and ate it in celebration and made a lot of money from stock options in a company that cloned cattle. But he had no time for research there; worse, there was no market for their perfect cattle embryos. The venture capitalists moved out and Willadsen ended up working in a human fertility clinic in Florida. Perhaps he should have tried cloning racehorses instead. But humans are where the money is.

Last week's announcement by Dr. Richard Seed, a Chicago surgeon, that he will clone humans just as soon as he can raise a couple million dollars, and that he already has four couples on his waiting list for treatment, is only the latest in a long line of sensational announcements about cloning. Kolata dissects some notable fakes: In the 1970s, a bestselling book by a fairly reputable science journalist claimed that an eccentric millionaire had already cloned himself on a Pacific island. Even Silver in his most optimistic moods still believes that the cloning of humans will take longer than the two years Dr. Seed is projecting.

N E X T_P A G E | How the religious right helps makes the U.S. safe for cloning