[10ren]

I think there's an argument that DNA is more likely to lead to life (not intelligence) than an arbitrary coding scheme; that is, that with DNA it's easier to create life than you'd expect for a vanilla encoding scheme.

This assumes that during the billions of years on earth before DNA, lots of different chemicals came together, but if any self-replicating one came together, it would grow and still be around. Exceptions are if it wasn't very good at it and died out, or that DNA-based life attacked it or grew faster, crowding it and starving it (or bad luck wiped it out - but it could arise again.)

The fact that DNA did survive shows that DNA is indeed specially suited to encoding life. One might even try to estimate how specialized it is, by estimating how improbably it is, based on how long it took for a planet of experiments to arrive at it.

The details of how it's special could be in terms of protein folding, eg. that you can specify some really cool and useful folds, crucial for life, in surprisingly short DNA sequences. It's as if the search space of encoding schemes was scoured for schemes that in effect included a handy collection of library functions.

But this lovely (I think) argument doesn't apply to intelligence at all; nor even to mammals, or indeed animals - just for basic life. Once life existed, all the extra features were just hacked on.