The death last week of molecular biologist and Nobel laureate Max Perutz reminds us, writes Michael Ruse, that a chapter in the history of science is nearing its end

The death last week of Max Perutz, aged 87 - refugee from the Nazi horror, long-time Cambridge professor, joint winner in 1962 of the Nobel prize for chemistry - reminds us forcibly that an era, a generation, is coming to an end.

The last century was in many respects a dark and terrible time in human history, but it had its great triumphs, perhaps more than anywhere in science. One thinks of the great advances in physics in the first part of the century. One thinks of the revolution in geology, with continents now moving around the planet like icebergs in the sea. And one thinks above all of the great discoveries in the life sciences, most especially those at the molecular level: Perutz's own brilliant work on deciphering the nature of the haemoglobin molecule; James Watson and Francis Crick's discovery of the double helix, and the consequent discerning of the genetic code; Francois Jacob and Jacques Monod's operon theory of the control of the gene. And since then, the discovery of recombinant methods for studying DNA and, most recently, the triumphant mapping of the human genome and the genomes of several other plants and animals.

One starts to think - if, like me, one is a historian and philosopher of biology - about what precisely it was that led to such a blossoming of talent and achievement. Given the total transformation of our thinking about the nature of organisms, what was it especially about that time and stage in the history of science that led to such magnificent discoveries?

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Most obviously one would say that there were a lot of really brilliant people who came together at the same time and in much the same places. Brain power will out. This is obviously true and it does count. Having Michael Owen on your soccer team really does help, and the same is true in science. Reading biographical accounts of Perutz, about how he thought up the trick of attaching heavy molecules to the haemoglobin so he could use X-ray crystallography to image the molecule, makes you realise that some people really are Premier League material. In addition, one had people with a solid grounding in the physical sciences moving towards the life sciences. Their collective background knowledge made for whole new approaches, both theoretical and experimental.

But there had to be more than this. There were brilliant biologists before the middle of the 20th century. There were also brilliant scientists who had moved in from other areas of science to study biology, so it cannot be simply that biology suddenly got an influx of genius from physics and chemistry. And in any case, one suspects that had any one of the great molecular biologists not existed - or gone into philosophy instead of science - there would have been someone else around to do the job instead.

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What makes Watson's account of the discovery of the structure of the DNA molecule so exciting is precisely that he and Crick knew that their time slot was so small. If they did not get it almost at once, then the folk in London would. Or Linus Pauling in America would realise that he was making simple mistakes that his own textbook could correct, and that, done properly, he had the picture of the molecule as a double helix.

One thing that was necessary for this mid-century success was the right atmosphere. You can do good science in wartime - the Manhattan Project shows that - but it is going to be directed towards the (perceived) immediate needs of the day - the Manhattan Project shows that too. In 1950, although there was a war in Korea, back home there was a renewal of hope and the energy to consider ends not immediately related to the demands of the day. Never forgetful of the old joke that the scientist who discovers a cure for cancer is going to be the most unpopular person in the laboratory, and realising that the prospects of future medical payoffs were never far distant, there was enough money and support available for scientists to follow their own interests and leads. Perhaps it is instructive here to compare the successes of mid-century molecular biologists with the great successes of 17th-century British physicists and chemists under the Restoration. There, too, one had relief from war and tension; there, too, one had some support for science and approval that it should exist; there, too, were vague payoffs down the road for various technological applications - flowering in the next century with the industrial revolution - if one may use so inappropriate a metaphor as "flowering".

Another characteristic of these periods was the sense of community. In the 17th century one sees the interactions that took place through the new Royal Society, and one sees how one scientist can help another. The wealthy Robert Boyle, for instance, employed and supported the less monied Robert Hooke.

Perutz has been characterised as a deeply non-selfish man, wanting the success of others and aiding the young and insecure. Watson (writing in The Independent) says: "From the moment of my arrival, Max made me feel very much wanted, liking the idea of a visitor from the world of genetics who wanted the gene attacked at the molecular level. When I momentarily lost my American fellowship support, Max told me he would find monies to keep me on, despite my still-total ignorance of crystallographic methods."

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As a result of the conflict in Afghanistan, we have been hearing a great deal about how soldiers depend on one another and how, more than ideology or equipment or other issues, success demands a feeling for one's "buddies". The same is true of great science. It is a collaborative enterprise, and when it is directed by people of generosity and spirit it succeeds as it never can when ruled by personal ambition.

But perhaps more than anything, really productive science depends on factors well described by the late Thomas Kuhn in his Structure of Scientific Revolutions. Really good science not only has to be doable but has to keep creating new problems.

One of the biggest fallacies of the American creationists - those folk who believe in the Bible taken literally - is that new problems equal failure. In truth, really good science lets you solve a problem during the day and have two more to solve tomorrow. The mid-century molecularisation of biology did all of this and more. Think, for instance, of the famous passage at the end of the Watson-Crick paper announcing the double helix. Did they say: "That's all folks"? Not a bit. They invited us to think about the implications of their discovery and about how the fact that the DNA molecule carries four bases down its spine in a non-predetermined order could be the key to the information content of the gene. In other words, they hinted at a genetic code and at the need to crack it. Lovely research projects for themselves and for other bright young people coming into the field.

Really good scientists do not spend their lives polishing the theories of others. They are out there, in the messy world of experiment and observation and theorising, trying to come up with models and theories of their own. More than anything else, the generation of Perutz and his fellows found a field that was ripe for the picking. They helped themselves to the fruit, but at the same time they left the plants in such good shape that there were to be many crops for future researchers - indeed, as one looks at the incredibly exciting state of molecular biology today, for scientists well into the 21st century as well as for those from the one that has just passed.

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Those of us who cherish the triumphs of the human spirit salute the achievements of Max Perutz and his colleagues. They were the Mozarts and Kants and Goethes of their age.

Michael Ruse is professor of philosophy at Florida State University.

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