>> I'm
>> not sure at what point this system would have acquired a "cell
>> membrane", but such as the obvious advantage of concentrating the
>> nucleotides synthesized next to the RNA strands that want to use them.
>
> There's a theory that "cell membranes" would have existed even before
> self-replicating stuff:

That sounds reasonably plausible also.

In fact, the only implausible thing seems to be thinking that we will 
ever truly know what actually happened. ;-)

>> So what roles does RNA play today?
>
> AFAIK viruses, too, commonly use RNA.

Yes.

In fact, human skin produces enzymes that chop up RNA, specifically as a 
defence against RNA viruses.

> Maybe the first life can be thought of as a bunch of different ribozymes
> entering a symbiosis.
>
> In that sense, viruses would be the oldest type of life.

Well, if you think about "life" as originating as a set of 
self-catalysing chemical reactions that eventually evolved into a 
complex system with a genome, then a virus (which is basically a genome 
with no copying machinery) would logically seem to pre-date more complex 
life.

Now discuss plasmids. ;-)

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