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Could we have designed such a system ourselves?

From The Medusa and the Snail by Lewis Thomas:

"If our kind of mind had been confronted with the problem of designing a similar replicating molecule, starting from scratch, we'd never have succeeded.  We would have made one fatal mistake:  our molecule would have been perfect.  Given enough time, we would have figured out how to do this, nucleotides, enzymes, and all, to make flawless, exact copies, but it would never have occurred to us, thinking as we do, that the thing had to be able to make errors.

"The capacity to blunder slightly is the real marvel of DNA.   Without this special attribute, we would still be anaerobic bacteria and there would be no music.  Viewed individually, one by one, each of the mutations that have brought us along represents a random, totally spontaneous accident, but it is no accident at all that mutations occur; the molecule of DNA was ordained from the beginning to make small mistakes.

"If we had been doing it, we would have found some way to correct this, and evolution would have been stopped in its tracks."


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