Saturday 13 September 2014

The Origins of Life problem reconceptualized - implications of the new replication-entropy-natural selection idea

Continuing from:

The origin of life is not a problem!

Since replication is built into things, and can be 'taken for granted' (many inorganic molecules and other structures with propagate and make copies of themselves, in the right environment)

- then if we define 'life' in terms of replicating entities subject to natural selection (which is the usual modern concept of life, that embraces viruses and other things that lack a 'metabolism') it can be seen that life is something that can be taken for granted.

Life is something that happens whenever there is propagation or copying of any structured entity (such as a molecule or a process).

So, life will be starting all the time and all over the place; but the big problem for any replicating entity is that entropic damage with rapidly accumulate, generation upon generation and most lineages will rapidly become extinct after just a few generations.

So, we can envisage a world in which life is not a problem, life is starting out again and again and all over the place; but almost all instances of life very rapidly become extinct.

The primary function of natural selection is therefore to combat entropic damage, and to enable life lineages to survive.

Natural selection would be most likely to kick in where there is massive overproduction of 'offspring', that is to say overproduction of replicates and propagated copies of all types. In such a situation, a large population and more time make it possible that some variants will be sufficiently stable as to maintain themselves against entropy (e.g. actual crystalline structures such as we observe in the world are examples of successful variants of sufficient stability or accuracy or repair as to combat entropy).

So the proper way to consider natural selection in relation to the origins of life is not to think about how replication began in terms of replicators developing adaptations to enhance the survival of their information, but to consider how entropic accumulation and extinction was avoided.

It is the difference between explaining life as something which originates in adaptation, and explaining how life is spontaneous but with an intrinsic tendency to die (death being entropic loss of structure and organization).

So the focus shifts from explaining the origins of life to explaining the continuation of life; from explaining how life is formed to explaining how the extinction of formed-life is prevented.


(Note - in a phrase, I am suggesting that the Origins of Life is primarily a Red Queen phenomenon; 'running to stay in the same place' - i.e. there must be an active process in order to sustain life as it is.)


Bruce B. said...

I read Thomas Gold’s book about 10-12 years ago. It seems, he imagined life as originating as auto-replicating hydrocarbon-“consuming” molecules located in the Deep, Hot Biosphere.

Bruce Charlton said...

@BB - I haven't read that but it sounds to follow up Cairn's Smith's insight that there must have been a bridge class of simple non-organic replicators from which organic replicators (nucleic acid, protein etc) evolved. The molecules need to have been simple enough to have arisen by random chance - which organic molecules are not.