Hunters of the double helix - 40 years on: The story of DNA and the team of scientists that revealed its structure are recalled by Steve Connor and Tom Wilkie

FORTY YEARS ago today, two brash young men announced the greatest scientific discovery since Einstein's theory of relativity. In a brief letter, published in a scientific journal on 25 April 1953, James Watson and Francis Crick revealed that they had unlocked the secret of genetic inheritance and found that DNA, the molecule that carries genes, had the shape of a double helix.

Einstein's theory, coupled with later discoveries in nuclear physics, led to the atomic and hydrogen bombs and the nuclear arms race. It is possible that, in the 21st century, the consequences of Watson's and Crick's discovery will have an even greater effect.

The search for the double helix was a transatlantic race - a story marked by human foibles. There were clashes of personality, fierce competition and interludes of afternoons punting on the river Cam instead of working in the laboratory. In the end, Watson and Crick stole the thunder from the American Linus Pauling.

The 1962 Nobel Prize was shared between Watson, Crick and the British physicist Maurice Wilkins. The woman who had done much of the experimental investigation, Rosalind Franklin, had died in 1958. She did superb work, taking the best X-ray pictures of DNA fibres then available. Without her, the structure would not have been discovered in Britain.

Watson, who become a biologist because of an early interest in birdwatching, was only 23 when he arrived at the Cavendish laboratory in Cambridge. Crick, a physicist, although 12 years older than Watson, had not even got his PhD. They arrived at the structure within a couple of years.

Watson did comparatively little further research thereafter. Instead he displayed a genius as a teacher and leader of research workers. In 1968, he became Director of the Cold Spring Harbor laboratory which he rejuvenated as a front-rank research institution. He was appointed the first director of the US Human Genome Project - a multimillion-dollar research programme to analyse every one of the 50,000 to 100,000 genes within humanity's DNA. However, he fell foul of internal politicking in the US government and returned to Cold Spring Harbor.

Crick stayed on, teasing out the puzzles of genetics. He played a major role in deciphering 'the genetic code' - the precise chemical language by which a gene specifies that a living cell should make a specific protein. In 1976, he went to the Salk Institute in California, and switched from studying genes to studying brains.

Wilkins continued work at King's College London where he became professor of biophysics. He was actively involved in the nuclear disarmament movement, one of the many scientists who ended up fighting toeliminate what they took part in creating. He still lives in London.

(Photographs omitted)