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The molecule, he acknowledges, is not alive. Magical as it seems, it cannot replicate without a steady supply of prefabricated proteins. To qualify as living, a molecule would need to have the ability to reproduce without outside help. An important step in this direction was recently taken by Harvard molecular biologist Jack Szostak and his graduate student David Bartel, who mimicked the prolific chemistry of primitive earth by randomly generating trillions of different strands of RNA. Eventually the scientists came up with a good five dozen that were able to join themselves to other strands suspended in the same test tube. The process of linkage, explains Szostak, is critical to the formation of complex molecules from simple building blocks. What's exciting, he says, is this part of the origin-of-life puzzle does not look quite so daunting as before.
One of these days, both Joyce and Szostak believe, when someone fills a test tube with just the right stuff, a self-replicating molecule will pop up. If that happens, the achievement could be as upsetting as it is amazing. For it would challenge the most fundamental conceptions of what life is all about. Life, to most people, means animals or plants or bacteria. Less clear cut are viruses, because they are nothing more than strands of nucleic acid encased in protein, and they cannot reproduce outside a living cell.
As scientists close in on life's origins, the working definition of life will be pondered, debated and perhaps even expanded. If a sliver of fully functional RNA arises in a test tube and starts building its own proteins, who is to say it is any less alive than the strand of RNA doing the same thing inside a cell?
Some people will always hold to the belief that it is a divine spark, not clever chemistry, that brings matter to life, and for all their fancy equipment, scientists have yet to produce anything in a test tube that would shake a Fundamentalist's faith. The molecule in Joyce's lab, after all, is not as sophisticated as a virus and is still many orders of magnitude less complex than a bacterium. Indeed, the more scientists learn about it, the more extraordinary life seems. Just as the Big Bang theory has not demystified the universe, so progress in understanding the origin of life should ultimately enhance, not diminish, the wonder of it.
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