Comment Re:religion (Score 1) 585
The problem here is that you're trying to start with DNA forming a complete organism with 'accurate' self-replication. This is hard, yes.
Start simpler. If you look at the citric acid cycle, it is a self-replicating chemical reaction (in the sense that given the building blocks, the main molecule that goes around the cycle ends up doubling itself after one cycle). So all you really need to do to start things off is to randomly generate the citric acid cycle. The various reactions necessary to form the molecules needed for the cycle are a matter of current study, and there are missing points in the chemical theory there, but resolve those points and its a matter of inevitability, not a matter of probability (i.e. you're no longer trying to figure out the chance of this one very rare combination forming, you're just trying to figure out what environment will guarantee the origin of the citric acid cycle within X amount of time)
Now, lets say you don't buy that (there are still those missing reactions/conditions, after all) and you want to start with DNA or RNA. You still don't need a complete organism to take off - you can make do with any sort of analogue of the PCR reaction which amplifies strings currently found in solution. A (very) slow version of this has been observed in water in arctic regions, where the high salinity, low temperature water trapped between a lattice of ice allows the replication to occur without the strands breaking apart over time - this is without the usual PCR enzymes, mind you. You can read that paper at http://www.et1.tu-harburg.de/downloads_et1/ep/publikationen/trinks_ea85.pdf
Additionally, hydrothermal vents could provide an environment perfect for that, since a chamber cycling via thermal convection has been found to be quite good for PCR reactions [Braum, Goddard, and Libchaber "Exponential DNA Replication by Laminar Convection" PRL 91, 2003).
So, while the exact pathway is still a matter of research, I think that this at least shows that the 'critical initial chain' thing may be quite a bit softer of a constraint than you expect.
Start simpler. If you look at the citric acid cycle, it is a self-replicating chemical reaction (in the sense that given the building blocks, the main molecule that goes around the cycle ends up doubling itself after one cycle). So all you really need to do to start things off is to randomly generate the citric acid cycle. The various reactions necessary to form the molecules needed for the cycle are a matter of current study, and there are missing points in the chemical theory there, but resolve those points and its a matter of inevitability, not a matter of probability (i.e. you're no longer trying to figure out the chance of this one very rare combination forming, you're just trying to figure out what environment will guarantee the origin of the citric acid cycle within X amount of time)
Now, lets say you don't buy that (there are still those missing reactions/conditions, after all) and you want to start with DNA or RNA. You still don't need a complete organism to take off - you can make do with any sort of analogue of the PCR reaction which amplifies strings currently found in solution. A (very) slow version of this has been observed in water in arctic regions, where the high salinity, low temperature water trapped between a lattice of ice allows the replication to occur without the strands breaking apart over time - this is without the usual PCR enzymes, mind you. You can read that paper at http://www.et1.tu-harburg.de/downloads_et1/ep/publikationen/trinks_ea85.pdf
Additionally, hydrothermal vents could provide an environment perfect for that, since a chamber cycling via thermal convection has been found to be quite good for PCR reactions [Braum, Goddard, and Libchaber "Exponential DNA Replication by Laminar Convection" PRL 91, 2003).
So, while the exact pathway is still a matter of research, I think that this at least shows that the 'critical initial chain' thing may be quite a bit softer of a constraint than you expect.
