EVER since James Watson and Francis Crick first described the structure of DNA in the 1950s, people have been trying to come up with a metaphor that properly captures what this complex molecule does. There have been no shortage of contenders, from 鈥渄ouble helix鈥� (which describes its shape rather than function) to 鈥渂lueprint鈥�, 鈥渃hemical building block鈥�, 鈥渁lphabet of life鈥�, 鈥渂ook of life鈥�, 鈥渃omputer code of life鈥� and even 鈥渟ymphony of life鈥�. One author even likened DNA to Israeli kibbutzniks getting married and setting up new communes.
Yet we still don鈥檛 have a metaphor that communicates what DNA is all about to those without a background in biology. We need one more than ever. Advances in genetics, in particular in uncovering the links between genes and disease, have thrust the molecule into the public eye as never before. It is important that scientists explain genetics rather than hide behind its complexities, at least if they want the public鈥檚 support for their work. Without a simple way of characterising DNA, it鈥檒l be harder for researchers to make that connection.
It鈥檚 a tall order. The Nobel prizewinning biologist David Baltimore has suggested DNA is 鈥渁 reality beyond metaphor鈥�. 鈥淣o mere tool devised by humans has the complexity of representation found in the genome,鈥� he said in a in 2000. He is right in one respect: nothing humans can make reinvents itself like DNA. Every discovery reveals a new complexity. We now know, for example, that each gene produces not one protein, but an average of 5.7 molecules of various kinds. Still, to claim it is impossible to distil at least something of this into a trill of language suitable for public consumption is defeatist.
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鈥淣o mere tool devised by humans has the complexity of representation found in the genome鈥�
In the early 1990s, when I was a science reporter at newspaper in Toronto, I got fed up with the inexactitude of DNA metaphors and announced a contest. I asked readers to come up with an expression consisting of six words or fewer that captured the molecule鈥檚 ability to replicate itself.
My favourite was by Trevor Spencer Rines: 鈥淒NA: the web which spins the spider鈥�. Rines explained to me this year how he came up with his image: 鈥淚f you look at a DNA molecule down its axis it looks like a spider web; then again, the idea of the molecule that unzips itself and puts itself back together reminded me of spiders consuming their own web and then re-spinning it.鈥�
Every geneticist and non-scientist to whom I have described Rines鈥檚 metaphor has found it enormously evocative. So if it was so good, why didn鈥檛 it catch on? One reason is that nobody but the readers of the 14 April 1990 edition of The Globe and Mail are likely to have seen it. But I think there is another reason. The metaphor was too poetic for its time. It conveyed complexity in too startling a way. As our understanding of DNA has matured, the idea of a molecule that is both the spinner and the spun now seems perfectly apt. If you disagree, I challenge you to improve on it.
