The Blind Watchmaker Richard Dawkins

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checking showed that there was no possibility of chance infection by

RNA molecules. This is a remarkable result when you consider the

statistical improbability of the same large molecule spontaneously

arising twice. It is very much more improbable than the spontaneous

typing of METHINKS IT IS LIKE A WEASEL. Like that phrase in our

computer model, the particular favoured RNA molecule was built up

by gradual, cumulative evolution.

The variety of RNA produced, repeatedly, in these experiments was

of the same size and structure as the molecules that Spiegelman had

produced. But whereas Spiegelman's had evolved by 'degeneration'

from naturally occurring, larger, Q-beta viral RNA, those of the Eigen

group had built themselves up from almost nothing. This particular

formula is well adapted to an environment consisting of test-tubes

provided with ready-made replicase. It therefore is converged upon by

cumulative selection from two very different starting points. The

larger, Q-beta RNA molecules are less well adapted to a test-tube

environment but better adapted to the environment provided by E.coli

cells.

Experiments such as these help us to appreciate the entirely

The Blind Watchmaker

automatic and non-deliberate nature of natural selection. The

'machines' don't 'know' why they make RNA molecules: it is just a

byproduct of their shape that they do. And the RNA molecules themselves

don't work out a strategy for getting themselves duplicated.

Even if they could think, there is no obvious reason why any thinking

entity should be motivated to make copies of itself. If I knew how to

make copies of myself, I'm not sure that I would give the project high

priority in competition with all the other things I want to do: why

should I? But motivation is irrelevant for molecules. It is just that the

structure of the viral RNA happens to be such that it makes cellular

machinery churn out copies of itself. And if any entity, anywhere in

the universe, happens to have the property of being good at making

more copies of itself, then automatically more and more copies of that

entity will obviously come into existence. Not only that but, since

they automatically form lineages and are occasionally miscopied, later

versions tend to be 'better' at making copies of themselves than earlier

versions, because of the powerful processes of cumulative selection. It

is all utterly simple and automatic. It is so predictable as to be almost

inevitable.

A 'successful' RNA molecule in a test-tube is successful because of

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