I've promoted this just to allow some answers to be posted.
I suggest that you should have read over the Origins Of Life topics. There has been some discussion of this in there.
I'm no expert but quick answer is that researchers don't figure that DNA came first. It is, perhaps, an evolutionary development by earlier evolving replicators.
Thread moved here from the
Proposed New Topics forum.
This message has been edited by AdminNosy, 09-23-2004 01:39 PM