Monday, July 14, 2008

Abiogenesis and Evolution

Contrary to what some evolutionists have said, abiogenesis and evolution actually are the same thing.

Or at least, evolution is key to explaining how simple self replicating systems eventually became living cells. Let me explain how: Evolution is a change in the gene pool over time. Anything with a genetic medium, which reproduces, and of course experiences changes in that genetic medium, evolves. Nearly every hypothesis about the origin of life begins with something which replicates itself (Dawkins, 1976). This replicator reproduces itself into a population, and suble changes sneak in. Changes which allow the replicator to reproduce more quickly, for instnce, may make it more common. What I have just described (replication, mutation, natural selection) is evolution. So while technically chemistry may have to supply the answers to how the replicator originated, the transition from replicating RNA strand/peptide to primitive cell is within the theory of evolution. Plenty of research exists in this area:

One more thing: I did not think about this until Matzke mentioned it, but the fact that biological molecules form so easily in early earth simulating conditions is a good indication that the notion of life coming from inanimate matter is on the right path.


Jon Voisey said...

I have to disagree. While I think there is certainly some overlap, the two are not identical. Evolution really only deals with what happens after you have things that can replicate. As I've seen it, this is generally termed "life", but as far as I've seen, that definition is about as vague and useless as the term "planet".

So while evolutionary principles (RM+NS) do explain some of what's rapped up in abiogenesis (the development of self replicating non-"life" molecules to form life), there is still a component that is strictly non-evolutionary: The development of the first self replicator.

Efrique said...

If we don't call the earliest replicators alive, yet they were able to replicate and were subject to selection, then I think that argument can be made, but I think it just shifts the argument.

At some point you have a switch to replication with modification** from something that wasn't that; immediately before that point it's not evolution in the sense we're discussing, we still need to discuss "origins", even though it's pre-life ("how did we get to the point that stuff could begin to be subject to selection?"). It seems like that might just be "well, the physical and chemical conditions were all that was needed, with no intermediate stages", but who knows for sure.

**(though maybe it's not clearly identifiable as a single point - there may be a greyish region where you'd say "well on this side it's not replication, on that side it is, and in the middle it's kind of hard to be sure)

I kind of suspect that replication long precedes anything we'd call "life", and "life" has no clearly defined beginning. We probably go through a longish period of increasingly-life-like replicators that eventually acquire all of the characteristics we associate with life. In that case, where replication and modification far precede life, yes, abiogenesis and evolution go hand in hand.

I'm not certain that's been established yet, however.