- The Astounding Hypothesis: The Scientific Search for the Soul by Francis Crick
Simon and Schuster, 317 pp, £16.99, May 1994, ISBN 0 671 71158 X
‘I have never seen Francis Crick in a modest mood.’ Thus James Watson opens his notorious account of the discovery of the structure of DNA which won him, Crick and Maurice Wilkins a Nobel Prize in 1962. Whichever other of Watson’s judgments have been controversial – notably his dismissal of Rosalind Franklin, from whom, courtesy of Wilkins, he and Crick were provided with the crucial X-ray photographs of DNA crystals – his assessment of Crick has scarcely been disputed. The subsequent history of the DNA quartet is instructive in this regard. Franklin, miserable in the unfriendly and sexist environment of King’s College, London, switched research topics from DNA to the structure of coal and moved to Birkbeck and the more welcoming lab of Desmond Bernal. Wilkins has remained at King’s for the subsequent forty years, refining the early DNA measurements, working on the tubule-forming proteins of the cell’s internal skeleton and quietly deploying the prestige of the Prize in his concerns over the social responsibility of science. Watson returned from Cambridge to the US and became director of a major research institute. His gift for the outrageously dismissive mauvais mot has never left him: its most recent manifestation a feud with the then director of the National Institutes of Health, Bernadine Healy, which resulted in his abrupt departure from his position as the head of the Human Genome Project.
Crick was a decade older than Watson, in his mid-thirties at the time of their partnership, and had moved from a wartime background in engineering into slightly desultory studies on protein structure at the Cavendish, from which the DNA work began as a diversion. He was then, and has always remained, that rarest of creatures in biology, a theoretician. Theoreticians are common enough in physics, where the pecking order of mental over manual gives them greater power and prestige than mere experimentalists. But the domain of nature which physics studies is relatively constrained: experiments are hard to design and often very expensive. The terrain of biology is broader, its regularities are often historically contingent rather than apparently lawlike. Our experiments are relatively easy and cheap, but the complexities of the universe we study all too readily slip through the theoretical mesh. Perhaps this is why theoretical biologists are often physicists or engineers manqué and are regarded with suspicion by those who spend their lives in the lab or the field.
That Crick has largely – though never entirely – escaped this suspicion is a tribute both to his undisputed brilliance and to his success in choosing a series of superb experimentalists with whom to work. As he and Watson pointed out in their famous 1953 paper, the double helix with its pairs of matched nucleotides (‘bases’) immediately suggested a copying mechanism by which the molecular sequence of DNA could replicate itself in successive generations of cell division. But the working molecules of the cell are chains of amino-acids – proteins – not DNA, and it was clear that the sequence of amino-acids in proteins was somehow defined by the sequence of bases in the DNA molecule. For the next decade, in a series of superbly conceived experiments with Sydney Brenner, Crick was to concentrate on how this process occurred: on cracking the DNA code. In doing so he provided several of the key metaphors which have dominated – haunted, some would say – biological thinking ever since. DNA became an ‘informational macromolecule’, and its sequence of bases the ‘genetic code’ on which life is based. The irreversible nature of the relationship between DNA and protein Crick christened ‘the Central Dogma’ of the new science of molecular biology: ‘DNA makes RNA makes protein’ and ‘once information has got into the protein it cannot get out again.’ In its more modern version, the Central Dogma reappears as the ‘selfish gene’ and for the thirty years since Crick enunciated it, hard-line molecular biologists have struggled to maintain it against a series of increasingly emphatic challenges.
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[*] Blackwell, 380 pp. £18.95, 5 May, 0 631 03054 2.