James Watson made his name with the discovery of the double helix in 1953. In his latest book, he draws on personal correspondence to recall what happened next. Jon Turney reports.

How pleasant to be Dr Watson. He had barely started out in science when as a brash 24-year-old intent on fathoming the secrets of the gene he helped tease out the structure of DNA. Almost 50 years on and James Watson has seen our grasp of the molecules of inheritance develop so far so fast that it is not implausible to imagine that we are close to a complete understanding of genetics. Just as Watson was in at the start of gene research, he also played a leading role in the final phase of the project when he was appointed director of the US Human Genome Program. Unfortunately he got fired after falling out with the then director of the US National Institutes of Health, Bernardine Healy. Still, on the whole, not a bad career.

The boy who could not wait to grow up but dreaded getting old is still in pretty good shape as he rolls into his 70s. He has lost his hair, but his mind seems as penetrating as ever. The slight kid who was famously a sartorial disaster has even gained enough weight to look good in a suit befitting one of science's elder statesmen. Not that he talks like one. In the United Kingdom to promote a new book, he is unguarded, mischievous and irreverent.

His next book will probably be better, he says, out of hearing of the publicist - a proper autobiography, with lessons learnt and pointers for how to succeed in science. In the meantime, we have Genes, Girls and Gamow , a sequel to his famous memoir of the DNA story, The Double Helix . Someone suggested he call it "The Morning After". Like its predecessor, it is an artful recreation of an artless young man's experience. Unlike The Double Helix, it is largely a chronicle of failure and confusion - failure in Watson's love life; confusion in the science.

ÖйúAƬ

It concentrates on the fruitless efforts and frustrated speculation that followed Watson and Crick's first paper on DNA structure. The pervading sense of muddle is a nice counter to the triumphal outcome of the first memoir. "Lots of people say they got into science because Double Helix . Now they can tell me this is why they did not go into science," he says.

Part of the muddle is reconstituted from the letters of physicist George Gamow, whose idiosyncratic contributions to what became known as the coding problem run through the book. Gamow was soon joining in with his own gloriously incorrect notions about how a script written in DNA bases might get amino acids to line up in proteins. He appointed himself and his correspondents members of the RNA-tie club, licensed to speculate and criticise. Indeed, the next crucial idea, Crick's so-called adaptor hypothesis, was first aired in a 1955 paper sent to other members of the club - although no one really believed it at the time.

ÖйúAƬ

For Watson, the book began with Gamow's letters. "I just wanted to put the RNA-tie club in the context of my life. So I started off writing about Gamow and then I thought, well, it is best to start right after we got the double helix."

This was also the time he was intermittently courting Christa Mayr, daughter of the great Harvard evolutionist Ernst Mayr. "I burned all her letters the day she got married, which is why it is hard to make her alive in the book," Watson says. Mayr, it turned out, still had all the letters - 68 of them - that Watson wrote her. They were a great aid to accuracy, he says with a grin. "When I got the letters, I'd already written quite a bit of the book and it turned out I'd forgotten all my really bad scientific ideas!" The detail provided by original letters, the candour about people and places and the sexual tension, are all qualities the new book shares with Watson's earlier tome. So is the voice of the narrator, preoccupied with who is really smart, with hard problems, with staving off boredom, with girls and tennis.

Watson the writer was trying again to recreate the outlook of his younger self, as he did nearly 40 years ago when he began The Double Helix . Both books had long gestations, the first because he was diverted by his classic (and lucrative) textbook Molecular Biology of the Gene , the second because of his human-genome job. Now, he says, he does not know if in the follow-up he sounds like a 25 year old or a 60 year old.

An hour's conversation suggests that the two have a lot in common. Aside from the girls - he has been happily married for more than 30 years - the preoccupations endure. He tries "fairly strenuously" to avoid the company of old people, still plays tennis three times a week and still finds new science endlessly interesting.

Boredom is more complicated. "The only good thing about boredom is, if you are bored, you have time to think about science. If you are not bored, science is hard work, so I always think you do the thing that is least hard."

But here there has been a change. "I'm just never bored. That is the bad part of my life. I'm out to dinner four or five nights a week - no good at all for creative thinking."

But he is still excited by the company of young people trying to solve difficult problems. One way to have fun in science today, he says, would be "trying to figure out how the brain stores information. How is a telephone number written in the brain. It clearly has to be represented, so what is the representation. No one has the slightest idea."

ÖйúAƬ

The Cold Spring Harbor Laboratory in upstate New York, where Watson now serves as president, supports a small theory group working on the brain. "There are not many people trying to do it because it is like thinking about the gene before you had the double helix. Before you had the double helix, you could not think about it."

ÖйúAƬ

He notes with approval that the Cold Spring Harbor group has time to be bored. "If you are an experimentalist, you know what you are supposed to do, so you work all the time. If you don't know what you are doing, it is hard to work all the time."

The information storage problem is just one area to work on. More generally, Watson says: "This coming century, we will be trying to understand ourselves at the level of our brains whereas before we were trying to understand ourselves at the level of our genes." He suggests this will involve trying to understand humans as animals, "a repulsive thought to many people: why we get hungry; why boys like girls; why we don't like snakes". It may shed light perhaps on one of his lifelong preoccupations:

"One wonders why there are dumb people. And there are a lot of them. You'd think there'd be continued selection for being brighter."

He can see that universal smartness might have drawbacks. "Could you have a stable society if everyone was like Francis Crick? No. No one would sweep the streets." Or perhaps there are more direct selection pressures. "It's an interesting thought that if you have too much brains people will kill you because you won't be an ordinary member of your tribe."

So there is still plenty of interesting unfinished business in science. And with history? At least a couple of things, it seems. One is clearly visible in the book. "The person who has always fascinated me most is Linus Pauling," Watson says. The great structural chemist tried to solve the DNA structure, and got it spectacularly wrong. "He should have found it." So the book keeps going back to him, and to his son Peter, Watson's close friend, trying to fathom what he was really like. One impression is that he did not invite the stern critics a scientist really needs. Having been right so often, "he believed he was infallible, like the pope. He rejected religion, but gave himself mythic properties."

Another myth that echoes in both books is that of Cambridge as an ideal intellectual community. But it has taken on a more ambivalent cast since the elegiac memoir of an anglophile American in The Double Helix . The new book opens with a visit to a Cambridge that shows little trace of Watson - or even Crick, who stayed there until his retirement prompted a move to California. "They could never recognise Crick for what he was," he says.

As for himself, Watson feels he is a bit of an embarrassment to the place. Until recently he kept a flat in Oxford, where a visiting professorship helped him finish the book. "No one knows me in Oxford. I'm not important to its history. I think they don't want to see me because I'm not dead. And no one in Cambridge is important until they die. When I'm dead they can deal with me."

It seems they will have quite a wait.

Jon Turney teaches science communication at University College London.

ÖйúAƬ