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It makes perfect sense to me. There is indeed a division between the metabolic first hypothesis, which posits the spontaneous assembly of autocatalytic metaboli
by Cybiote 10y ago
It makes perfect sense to me. There is indeed a division between the metabolic first hypothesis, which posits the spontaneous assembly of autocatalytic metabolic networks under the correct conditions (lots of incoming useful energy + abundant simple molecules for autocatalysis). The problem with this view is it doesn't realistically allow for natural selection (even putting aside the difficulty of achieving a biochemically plausible cycle in early earth conditions). The replication first hypothesis allows for natural selection but in turn faces the problem of how the raw material of sufficient complexity (nucleotides) to allow reliable template based synthesis could have plausibly come about. The linked to article addresses one hypothesis for one possible path for arriving at the building blocks of RNA given that early conditions were close enough to its assumptions.
I enjoy works which look for scenarios where both could have emerged simultaneously. Reading the introduction of this paper/article provides an accessible exposition to the topic: http://www.mdpi.com/1422-0067/10/4/1838/htm http://www.mdpi.com/1422-0067/10/4/1838/htm
If you are curious about under what conditions self-organization might more effectively dissipate entropy I suggest reading anything by Ilya Prigorine. But this short minute physics video narrated by Sean Carroll is good for a start: https://youtu.be/HxTnqKuNygE?t=2m07s https://youtu.be/HxTnqKuNygE?t=2m07s
- mtdewcmu 10y agoI don't see self-replication as being the hard part. Once you have enough complex chemistry going on, self-replicating processes will appear spontaneously like contagious diseases. I'm thinking of, e.g., prions, which self-replicate, but they are not life -- they're just screwed-up proteins that happen to screw up other proteins in exactly the same way they themselves are screwed up, thus making more of themselves. There are also plasmids, which don't really resemble anything like life, yet they self-replicate. Self-replicating things pop up randomly in strange places and they are amplified through positive feedback. The hard part seems to be getting to the point where the chemistry is so complex that self-replicating things are even possible.