"Joost Vrielink"  wrote in message
news:c8fujk$3e$1{at}darwin.ediacara.org...
> As I understand it, DNA is used for development/replication in all life
> forms.

Almost all.  Some viruses use RNA.

> Natural selection would imply that it is the 'best' way to do
> this (not stating all this as fact, just my perception so correct me if
> I'm wrong).

The best that nature has come up with so far.  More on this below.

> Are there any other known frameworks similar to DNA used maybe in the
> earlier stages of evolution or didn't 'life' start until DNA was
> synthesized randomly?

RNA was almost certainly used before DNA.  Search the web for
"RNA world".

> Did DNA evolve from a simpler replication system?

I'll break this into two questions.  (1) Was there a simpler system
before RNA?  (2).  Did RNA "evolve" from that system, or did
it simply "replace" it?  There are a variety of opinions on the
answers to both of these questions.  You should find links to
these opinions from "RNA world".

> Since DNA is basically the same in all life forms and has been for
> millions of years, can it be expected that it will not be replaced by
> something else in the future? In other words, is it perfect for
> sustaining life?

Probably not perfect, but I doubt that it will be replaced.  The reason
is that so much "infrastructure" has grown up around RNA/DNA
that it would take something like a miracle to come up with both
a better basic material plus all of the infrastructure that makes that
material work so effectively.  For similar reasons, you will probably
never see silicon replaced with a better semiconductor (such as
gallium arsenide) for electronics.  Even though there may be better
materials around, there is not better infrastructure, and there is no
incentive to develop that infrastructure since, by the time you develop
it, the silicon infrastructure will have gotten even better and the cost
of your development effort will have been wasted.

However, Tim Tyler is almost certain to provide a different science
fiction answer to this question.   You can ignore that, if you wish,
but don't ignore what he says about clay in his "simpler replication"
answer.  That is real science, though not mainstream science.
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