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Clive Tester
2011-Nov-18, 10:26 PM
Could abiotic self-replicating molecules, or their precursors be forming in the earth’s waters today? I am aware of experiments, which have been conduced in laboratories to try to replicate the very early processes that are thought to have brought forth life. Have there been any substantive studies directed at the earth, to try to find this process still at work? If this process were taking place, could its products be discerned from the products of the earth’s biota?

Strange
2011-Nov-18, 11:04 PM
I suspect that any complex molecules that formed in that way would rapidly be digested by one form of life or another.

Clive Tester
2011-Nov-19, 12:14 AM
I suspect that any complex molecules that formed in that way would rapidly be digested by one form of life or another.

This would be the major problem in this type of research. Perhaps it could be addressed in two ways.

If the abiotic process yields both chiral forms, then would organisms assimilate only one chiral form?

The search could be directed to naturally sterile environments.

Grashtel
2011-Nov-19, 02:24 AM
This would be the major problem in this type of research. Perhaps it could be addressed in two ways.

If the abiotic process yields both chiral forms, then would organisms assimilate only one chiral form?
Bacteria are sufficiently adaptable to evolve the ability to break down molecules of different chirality so the proto-organisms would still get eaten before the had the chance to make it to being actual life.

The search could be directed to naturally sterile environments.
The trick is finding a naturally sterile environment that supports the existence of complex organic molecules, pretty much everywhere that its possible for life to survive (and in more than a few places that it was though to be impossible, eg the innards of nuclear reactors) its found and it all seems to be from the same common origin.

eburacum45
2011-Nov-19, 10:23 AM
I think the presence of free oxygen probably prevents any process of new abiogenesis from getting very far. That wouldn't mean it is impossible, though; there are plenty of anoxic environments on Earth. Whether there is any abiogeneis occurring in the sea-ooze and peatbogs of this world is another matter- it seems unlikely to me. The absence of oxygen is usually accompanied by a deficit of most other gases as well.

Paul Wally
2011-Nov-19, 11:44 AM
Is it not possible to build something like a large sterile lake, and close it off completely? What shall we call it, an abiosphere. I suppose it must be very difficult to practically impossible to sterilise such an environment completely. But suppose we construct such a large abiosphere, and add some chemicals and what have you, and then we wait and see what happens. I wonder how long we will have to wait for anything resembling self-replication to emerge.

Noclevername
2011-Nov-19, 05:43 PM
I wonder how long we will have to wait for anything resembling self-replication to emerge.
Well, on early Earth with a whole ocean to work with, it only took a hundred million years or so. Since our tiny pool won't have as much variety as the early seas, it might take longer.

Paul Wally
2011-Nov-19, 06:46 PM
Well, on early Earth with a whole ocean to work with, it only took a hundred million years or so. Since our tiny pool won't have as much variety as the early seas, it might take longer.

Sarcasm noted. :) Anyway, since it takes millions of years, let's just make it a thought experiment then.

Clive Tester
2011-Nov-19, 09:53 PM
With biological or chemical factors at work, the molecules would however have a residence time in the environment: Maybe there would be a low background level in a dynamic equilibrium.

Noclevername
2011-Nov-20, 01:09 PM
With biological or chemical factors at work, the molecules would however have a residence time in the environment: Maybe there would be a low background level in a dynamic equilibrium.

But as soon as the molecules began to self-replicate, they would be subject to mutation and evolution, and that equilibrium would become unstable.

Clive Tester
2011-Nov-20, 03:52 PM
But as soon as the molecules began to self-replicate, they would be subject to mutation and evolution, and that equilibrium would become unstable.

Such a process would indeed be part of the system, and a factor in determining the mean residence time of a particular molecule.

Paul Wally
2011-Nov-20, 07:25 PM
With biological or chemical factors at work, the molecules would however have a residence time in the environment: Maybe there would be a low background level in a dynamic equilibrium.

Then there are also other physical factors, especially energy and continuously entering and exiting the system. We have day-night, seasonal, climatic cycles, geological events etc. So the environment itself is highly dynamic. Within this dynamic environment we have a rich chemical soup and here we have chemical reactions continuously taking place. My question: how does the molecules become more complex over geological timescales? There is a change in the chemical composition of the ocean over millions of years but why does it not stabilize like a reaction in a test tube or enter a limit cycle? Is it perhaps because it is an open system and is continually disturbed by physical processes?

I'm trying to understand this geochemical process. It must be explained without recourse to selection mechanisms because we don't yet have self-replication at this early stage. Carbon, I would say, is a key element in all this.

PraedSt
2011-Nov-20, 07:38 PM
Sarcasm noted. :) Anyway, since it takes millions of years, let's just make it a thought experiment then.It's not as bad as you think. Given a starting soup and a source of energy, molecular concentration is the next important thing. So you'd be better off doing your experiment in a flask, rather than a lake (e.g the Miller-Urey experiment (http://en.wikipedia.org/wiki/Miller-Urey_experiment)). If you ran that for a century or two, who knows?

Clive Tester
2011-Nov-20, 08:30 PM
I'm trying to understand this geochemical process.

Me too.

It is intriguing how life has developed from non-living minerals. It may be the most important scientific reason for our exploration of space.

Paul Wally
2011-Nov-20, 10:55 PM
It's not as bad as you think. Given a starting soup and a source of energy, molecular concentration is the next important thing. So you'd be better off doing your experiment in a flask, rather than a lake (e.g the Miller-Urey experiment (http://en.wikipedia.org/wiki/Miller-Urey_experiment)). If you ran that for a century or two, who knows?

I take it then that Amino acids formed very early and rapidly here on Earth. Now if we manufacture a lot of this Miller-Urey amino acid mixtures and then do a different experiment to see if we can make the amino acids combine? I guess this will then be a different more subtle process; no more electric arcs. I think experiments must be done with different kinds of possible catalysts or material substrates like clay minerals.

PraedSt
2011-Nov-21, 08:14 PM
I take it then that Amino acids formed very early and rapidly here on Earth. Now if we manufacture a lot of this Miller-Urey amino acid mixtures and then do a different experiment to see if we can make the amino acids combine? I guess this will then be a different more subtle process; no more electric arcs. I think experiments must be done with different kinds of possible catalysts or material substrates like clay minerals.I'd love to do all those experiments. The exciting thing is that we keep finding more and more complex organic chemicals being produced by abiogenic processes out in the galaxy. So the gap that "randomness" has to fill is growing smaller by the day.

Noclevername
2011-Nov-24, 03:24 PM
Should this thread be merged with the Abiogenesis Discussion theread?