Monday, December 17, 2007

Natural and artificial -- Part 1

Nothing more exacerbates my nature writing colleagues than the mechanical metaphor for life. Think of life as a machine, they say, and you'll treat life as a machine. We will only preserve what we cherish, and no one loves a machine. Life is an organism, irreducible to its component parts.

Well, fine. And certainly we have the pleas of Wordsworth and Goethe ringing in our ears: To dissect is to murder.

But the problem arises when we want to understand exactly what life is, where it came from, and how it works, a goal that even the most ardent romantics can aspire to, unless of course they are willing to forego the benefits of modern medicine. So far, the most fruitful -- the only? -- way of doing biology has been reductionism, pulling the organism apart and inspecting it piece by piece.

These thoughts came to mind as I looked through a recent issue of Nature. Article after article invoked the mechanical metaphor for life. Protein "motors." Intercellular "sensors." "Scaffolds." And so on. One remarkable article, "Determining the architecture of macromolecular assemblies," is devoted entirely to "a mechanistic understanding of the cell." Take a look at the illustration at right from another article, "The molecular architecture of the nuclear pore complex." It will surely look familiar to anyone who has taken a few machines apart.

A distinction between natural and artificial goes back at least to Aristotle and Plato. It is a distinction that is becoming increasingly irrelevant. Living organisms look more and more like machines, and machines look more and more like living organisms. Is a computer-controlled artificial limb fitted on an Iraq war vet natural or artificial? OK, artificial. What if we find a way to regrow limbs, which is very much within the realm of possibility? Is such a limb natural or artificial?

The natural/artificial distinction is subtly at work in our discussions of religion, conservation, genetic engineering, food production, food consumption, virtual realities, computer intelligence, medicine, contraception, and heaven knows what else -- troubling our consciences, complicating analysis. We are deeply ingrained with the notion that "natural" is good, and "artificial" is -- well, artificial, as in "She has an artificial smile." Even the secondary meanings of the words have moral implications.

This is a deep and perplexing subject, to which I shall return all week.