Mageth

I know that the abiogenesis 'thing' must be
1) simple enough to have occurred randomly

Some (e.g. Stuart Kaufman) propose that laws of complexity and self-organization may explain the emergence of order in complex systems, including life. If true, then life's emergence under the right conditions may be as inevitable as snowflakes forming under the right conditions.

Starboy

There is not much to go on. As far as I know there are two main sources of evidence that can be drawn on:

1. The fossil record.
2. All living things and specimens on the planet.

There are two major classifications of possibilities:

1. Occurred naturally on Earth
2. Introduced from an external source

What we know:

-1. If it occurred naturally on earth
--a. It probably did not occur under conditions that are now present. My understanding that as soon as the earth cooled enough to support liquid water, BAM!
-2. There are several possible external source scenarios that I have heard of over the years:
--a. The broken record � Some God or gods created life on the earth while creating everything else.
--b. Life started on Mars and was transported here by way of debris from large Martian meteorite impacts.
--c. Life started somewhere else and is present in interstellar dust and debris, which is constantly raining down onto the earth.
--d. Life started somewhere else and was introduced here by some sort of intelligent being.
---i. This could have been deliberate
---ii. This could have been accidental

Can anyone think of any others?

Lets look at the possible research avenues:
-1. If we understood the initial conditions that created it, we should be able to recreate them in a laboratory (with some possible modifications to speed things up if needed). As far as I know this has not happened yet. This could be because:
--a. It is impossible to recreate in a laboratory
---i. There is research to look for other places in the solar system that might also have the correct conditions and have produced life in a way that we could detect it.
--b. Insufficient clues in the geologic and fossil record to determine the correct initial conditions
--c. Not enough interest in the scientific community to try to nail the experiment
-2. Here are the possible research avenues for this approach:
--a. Examine all the creation myths of all the religions that can be examined and see if there is any interpretation of these myths that can be made that is consistent with what we know that might lead to some test of this explanation. Because of the history of mankind, I suspect this avenue has been picked over extensively, so there may not be much here, but it is always possible that the discussion has been so blindsided by the influence of a handful of religious myths that other myths that may contain a germ of information have been completely ignored (Christians you know who I am talking about).
--b. I think everyone of this board should be familiar with this line of research. Last I heard it was still controversial and far from conclusive.
--c. I have heard of people looking into this, and of course there are large clouds of interstellar gasses that are rich in organic compounds. I also read someplace that complex organic molecules have been found in dust floating to earth. However, it is also possible that the compounds detected could have come from earth and are just falling back into our gravity well. In any case it would take a serious commitment from NASA to pursue this in any kind of rigorous fashion since we would need a probe to be launched that would return to earth that could get far enough away from earth to eliminate the possibility that it originated on the earth.
--d. This may be impossible to do anything with, unless they left unequivocal artifacts behind. In that case we just keep going on as we are and hope something turns up.


I suspect that a great deal has already been done in some of the areas I mention, but since it is not my specialty I know little about it.

Starboy

[ July 19, 2002: Message edited by: Starboy ]</p>

pseudobug

This is an intereesting question which I wish I had time to read about.

There is quite a bit published about self-replicating molecules. Just as important, and often neglected, is the enclosure of these molecules in precursor envelopes or cells.

<a href="http://www.astrobiology.com/asc2002/abstract.html?ascid=21" target="_blank">This link</a>, is a short reader friendly blurb of a recent meeting of the subject.

If you really want to dig a little deeper, check the refs at the bottom of the link. Then visit your favorite journal database and dig some more.

It's not to hard to imagine the formation of micelles/lipid bilayers. Throw a little cooking oil into water and there you have it. Most cells are just souped up versions of those. The hard part--at least for me--is to imagine/model primitive conditions that would coordinate replication of primitive macromolecules with maintenance of the primitive envelope/cellwall/cell membrane.

Wish I got paid for thinking about such esoteric topics.

Theophage

Perhaps I missed it, but I don't think this point was addressed sufficiently:

Water forms due to natural law: Take hydrogen, mix oxygen, add spark... BAM! Water. In my book, there is nothing random about that; it is quite deterministic.

It seemed to me that in the quote above, Didymus was implying a false dichotomy that either things are intelligently designed or they happen randomly. That (due to the existance of deterministic laws) is false.

Just wanted to point that out...please carry on.

[ July 20, 2002: Message edited by: Theophage ]</p>

WWSD

Hi Doubting Didymus,

Can you provide some links to the theories you speak of as I'd love to check them out.

As for WWSD, What Would insert somehting that starts with an S Do? A nice contrast to the annoying WWJDers.

Today it is What Would Sterilization Do?

The answer is: stop me from accidently having a child.

Starboy

Hi pseudobug,

I was thinking the same thing. Are there any non-organic catalysts for combining amino acids? The other thing I didn�t understand is the source of the lipids, even though they are found in extraterrestrial material, how would enough of it get to earth? Maybe there are clues in the Oort cloud.

I really don't know what I am talking about but this is a very interesting problem.

Starboy

Mike H

As for the preparation of amino acids from basic components using inorganic catalysts, you may be interested in the work of a German scientist named G�nter W�chtersh�user. He espouses a concept that might be called "the iron-sulfur world." Still a topic of debate, but it's certainly interesting to think about nonetheless. Wachtershauser has noted that the individual reaction steps of peptides from carbon monoxide have been demonstrated (for reference see Gunter Wachtershauser's review article, "Life as We Don't Know It" Science 2000 August 25; 289: 1307-1308). Still plenty of work to be done and things cleared up, but one of the slightly more interesting hypotheses out there.

beausoleil

Amino acids with enantiomeric excesses have been identified in meteorites. They aren't terrestrial contamination because the amino acids in question aren't part of terrestrial bioloogy. You can also use isotopic measurements (especially D/H) to determine whether the molecules are extraterrestrial - that ratio varies by orders of magnitud between the Earth and molecular clouds, though there's so much organic material in some meteorites you really don't need to worry that it's all contamination. In fact, both Genesis and the cosmic dust mission (I can't remember its name this instant) will be able to eliminate the Earth as the source of returned material.

beausoleil

Leaves open the question of what establishes the natural law in the first place, of course. Are they random or by design - personally I have trouble with 'they couldn't be otherwise' since 'the invariability of natural laws' looks like a natural law to me.

KeithHarwood

Didymus is supposed to mean twin; that is, doubting Thomas was one of a pair. However, my Latin dictionary doesn't give didymus and has geminus for twin. OTOH, it is a small dictionary.