New set of letters in book of life

There are few examples of a great breakthrough in science being described in detail by one of its participants. Maurice Wilkins - who shared the Nobel prize with Francis Crick and James Watson for the discovery in 1953 of the structure of DNA - has done just this in his autobiography, The Third Man of the Double Helix .

Although I was at King's College London from 1946 to 1948, where Wilkins was working at the time, I do not believe I met any of the principal participants in this drama with the exception of J. D. Bernal.

His amazing book The World, The Flesh and The Devil (1929) was one of the first suggestions by a reputable scientist that one day we should not only explore, but even re-make, the universe.

In 1952, as chair of the British Interplanetary Society, I persuaded Bernal to give a lecture. The full report, published in the Journal of the British Interplanetary Society in 1953, still makes interesting reading. "It was Professor Bernal's interest in the chemistry of proteins that led him to speculate about the origin of life. When we look into the structure of a protein, he said, we find it both complicated and peculiar. The 'paper chromatographer' can discover the order in which amino acids occur in proteins; they find that the book of life is written in an alphabet, of which each unit, which is an amino acid, can be regarded as a letter, while the proteins build up the sentences, and organisms are chapters or whole books. Even religion does not claim that the actual letters in the Bible are divine; they have a history of their own."

The report continues: "Similarly, living molecules must have a history too, which, Professor Bernal said, he was trying to write backwards. For instance, we have three or four major types of biological molecules. Sugar, of which glucose is the fundamental form, is one; it is a major fuel for the whole of life, which is carried on by the burning of glucose. Proteins form another type; they are really the jigs on which other molecules are built. The tools which keep things circulating, and make possible the business of getting on with life, are triple combinations of a pyrimidine or purine, a sugar, and phosphoric acid; the last is needed wherever there are energy exchanges. These also make up the nucleic acids, which are always present where reproduction or growth is occurring." An astonishing statement, made more than half a century ago.

Wilkins also mentions his colleagues Harry Boot and John Randall, the inventors of the cavity magnetron. This was the scientific invention that did more to win the second world war than any other (the atom bomb merely finished the job), by generating radio waves of a frequency and power never before possible, making radar much more effective. I can well recall being trusted with one of the first magnetrons, and having to draw a pistol from the guardroom in case German paratroopers tried to relieve me of it.

Wilkins regrets the inability of his colleagues to catch a giant squid to analyse its DNA. Perhaps they were lucky not to get too close to one of these magnificent and terrifying creatures.

No intelligent person who wishes to know how the universe works should fail to read this book. Not only is it completely understandable to the layman, it is also often very amusing and frank. Much of the book's interest lies in the author's understandably self-serving account of his King's colleague Rosalind Franklin, whose X-ray crystallographic studies form a key part in the DNA story. Brenda Maddox's recent biography of Franklin has encouraged many people to wonder whether she was treated unfairly by Wilkins, Crick and Watson, perhaps like too many other female scientists. (How many non-scientists can name any besides Marie Curie?) Wilkins is anxious to prove that Franklin got due credit.

We are lucky to have lived at a time when the secret of life has been uncovered. There may be more exciting developments very shortly. The images from the Mars Orbiter camera make it 90 per cent certain - in my opinion at least - that Mars is infested with life. Will it have the same DNA as ours?

Beagle 2 is due to land on Mars on Christmas Day, and we may then learn that we are all Martians. Indeed, our relationship may be even wider than that. According to the panspermia theory, the seeds of life drift through the universe and fertilise any habitable planet.

Sir Arthur C. Clarke, a fellow of King's College London, has just finished writing a new novel, The Last Theorem .