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Life's Chemical Origins - Not About Information


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#1 Guest_George R_*

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Posted 09 February 2006 - 07:26 AM

The current issue of American Scientist (Jan-Feb 2006 vol 94 no 1) has an article by Michael Russell called: First Life.

It depicts one multi-stage scenario of chemical origins of first life - from soup to RNA - stopping short of the information issues once RNA/DNA are first formed.

It even has a generalized "chemical formula" for "proto-life" creation from ocean & hot spring chemicals.

I think it is worth exploring because we will not get hung up in the information content issues and deal with how far you can get with chemicals.

Each step in the first Life scenario is supported by known chemical reactions, although the plausibility of conditions for some steps is debatable.

NOTE: I am only briefly recapping the article - it is more technical and fills in detain what I have briefly summarized here.

The interesting advances in this suggested scenario are:

1. COOLER VENTS: Mid-ocean hot vents that are cooler than the previously considered black smokers.

Why useful? There is less likelihood of organic chemical breakdown in the cooler vents.

2. MINERAL MEMBRANE BUBBLES: Inorganic semi-permeable "membranes" from hollow mineral bubbles at vent sites.

Why useful? They are depicted here as a necessary precursor for isolating products of chemical reactions that otherwise would break down - like an inorganic cellular membrane

3. MEMBRANE REPLACEMENT: As the bubble-protected "proto life" reactions build, the bubble is eventually filled with material that can make a real organic membrane (here I use the term organic in a strict chemical sense, as carbon based, not really implying an organic life form - we are still at a purely chemical stage)

The articles states that

(p34, bottom right) Laboratory experiments have demonstrated such iron-sulphide membranes to be semi-permeable. Any larger "sticky" organic products (amino, fatty and nucleic acids, sugars) were trapped in the bubbles and pores, but small unreactive organic molecules (acetic acid, methane) escaped.


and

 

Amino acid polymers not only had the propensity to co-opt catalysts from their surroundings, but in bulk, they could also have lined the inorganic bubbles that enclosed them.


4. SPECIFIC CATALYSTS: The energy for each these reactions is stepped up through catalysts.

For example, Russell suggests that greigite [Fe5 Ni S8], a nickel sulphide that co-precipitated in the membrane experiments in Russells's lab.

5. RNA AS A CHEMICAL PRODUCT ALONE: a) Russell suggest that the basics for RNA (phosphate from hydrothermal vents, sugar ribose and adenine from "primitive materials". When linked together "adenine, ribose and phosphate are known as adenosine monophosphate, one of the building blocks of RNA"

5 B) Citing Mellerish, Russell suggests that "a bound chain or RNA would have gripped amino acids and effected the formation of peptide bonds"

Citing models developed by Copley & Morowitz, Russell then suggests that RNA captured on a mineral is a template to generate amino acids without transfer RNA.


6. FROM ACETATE GENERATION TO 2 FORMS OF PROTOLIFE

a) I will just quote the article here:

As productive as acetate generation must have been for the first organisms, some other means of combining CO2 and H2 - to synthesize methane for example, are even more advantageous in term of energy release

4H2 + CO2 - - > CH4 + 2H2O

But achieving this reaction is not so easy: Substantial barriers exist, although they can be side-stepped by catalysis and jumped with a bit more thermal energy.

William Martin and I posit that the organisms that achieved this feat, the proto-methanogens, marked the first and most significant fork in the evolutionary tree. In our view, these two different carbon dioxide assimilators, the proto-acetogens and the proto-methanogens quickly specialized and fledged, evolving over time into bacteria and archaea (primitive microbes that are neither bacteria nor eukaryotes).  But how did they escape the hydrothermal hatchery?



7. EARTH's MOTION MOVES IT FROM VENT TO IDEAL LOCATION:

Convection of the earth's mantle, and a tendency for chemical proto-life "cells" to gravitate downward (where surface-based harm would not destroy the "cell"), after a thrust up from a tectonic junction, releases the "colonies of bacteria" and places some at an ideal depth for further life to form.

8. PHOTOSYNTHESIS More good stuff here - read the article.

I won't repeat the article here, and it is not yet on their web site, so a library or a magazine stand is the next best thing.

The article goes on to suggest with some specificity and laboratory backing, that:

- Short pieces of RNA (such as might be form on a mineralized iron sulphide surface) can act as templates for the formation of peptides.

- primitive photosynthesis

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

That ends my review. I will make my views known in an opinion piece later in the thread.

This article is about chemistry.

I beg you ... Please do not distract from chemistry to information theory in this thread. I am well aware of the endless "abiogenesis" threads that get stalled in assumptions about the information content issues.

#2 Guest_Admin3_*

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Posted 09 February 2006 - 08:55 AM

I beg you ... Please do not distract from chemistry to information theory in this thread. I am well aware of the endless "abiogenesis" threads that get stalled in assumptions about the information content issues.


It's probably to tempting. But we'll see.

#3 Guest_92g_*

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Posted 09 February 2006 - 02:23 PM

How do they overcome chirality issues?

Terry

#4 chance

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Posted 09 February 2006 - 02:44 PM

Sounds fascinating George R please post a link if and when becomes available.

#5 Guest_George R_*

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Posted 09 February 2006 - 04:16 PM

Chance -

Re: American Scientist magazine Online:

Usually only some articles of the American Scientist archive are available free on the web after a few weeks. Most articles are subscription-only.

I recommend ... Get a copy from the local library or read it at a Book chain store magazine stand. Or buy one.

You can browse the "classics" and "archives" for some very good free articles of interest There are many others for free that are relevant to evolutionary biology.


Re: The author's technical works

Michael Russell contributes to a web site devoted to the origin of life project.

http://www.gla.ac.uk...df_articles.htm

American Scientist does not introduce him in a way that conveys his bias or at least strong predisposition to commit / believe in the chemical origin of life theory without proof - yet.

If you get beyond his too-free use of misleading words (like sometimes calling a simple chemical reaction "evolution") he is quite readable.

Of course, chance, you and I may give different very weights to the likelihood that Russell has mastered the "formula for life".

I am encouraged that his current views respond well to some of the challenges that creation scientists have raised, proving once again that creation science advances the total cause of mankind's scientific knowledge and certainly prods evo-concluders to rethink some implausible assumptions that they previously held.

I am glad that you found this useful.

#6 Guest_George R_*

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Posted 09 February 2006 - 04:53 PM

92g

As a wide-ranging piece, this article is short on many specifics. But then, it is one of the "grand plan" schemes and seen from that context, it is an accomplishment in that it presents such a sequence of steps ... drawn from many fields within geology, biology, chemistry, geography, and astronomy.

One such specific you mention: chirality .

I assume you are referring to left and right handedness as in the following link:

http://www.icr.org/i...ion=view&ID=105

The probabilistic challenge of chirality is not dealt with... it is one of the many issues not doubt "to be addressed at a future time"...

#7 Guest_George R_*

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Posted 09 February 2006 - 04:55 PM

In don't want to spoil the article for you. But I will give my views now anyway.

The article moves the debate forward ...

(1) it provides a framework for a sequence of chemical and mechanical possibilities that could "lead to life" ... by updating the old thermal vent theory and adding on steps that encompass recent speculation and discoveries in "post-vent chemistry".

Many challenges are removed from the absolutely off-the-map idea of life forming gently in thermal vents so hot they can melt lead.

However, many challenges remain ... Michael Russell is not about to produce life in a bathtub this week-end.


(2) if science buys this ... and if they stick with this sequence of life-building ... I predict that creationist are going to have a field day.

On deeper analysis it all amounts to speculation and hopeful saltations between steps ... and that chemists are going to do the spade work of challenging these assumptions

(a) The logistics for the chemical reactions listed in the article (actually they are at a high level and clump many parallel and serial reactions into a single formula) together are not really a likely chain of events ...

On sober reflection (without the cheer-leading words in the article) they will be rejected as impossible by other chemists who are not predisposed to see them as part of a grand scheme for life, but just as a near-impossible chain of chemical events.

(B) No real recipie for life here... just scenarios at a high level

They are in a form that nobody can do ... or ever will. Not just because they need more specifics, but because they assume no countervailing feedback from parallel reactions, and assume chance arrival of inexhaustible inputs that Russel sometimes calls "nutrients".

Maybe more homework will overcome these challenges. Who knows?

© The convenient access to catalysts at the right moments seems to me at least to be as faith-based as believing that angels will appear at the right moment to cure baldness.

(d) The convenient access to "just so" temperatures and other conditions for these reactions also seems more than a small stretch.

(e) The real stretch is the mechanical movement of the earth that places the bacteria in "just right" sea depths.

If creationists demanded such far-flung preconditions for Eden ... nobody would buy it.

#8 chance

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Posted 09 February 2006 - 06:57 PM

George R I read (ok skimmed) “The emergence of life from iron monosulphate bubbles at a submarine hydrothermal redox and pH front” at the site you posted.

It must be understood that M. J. Russell and A. J. Hall are hypothesising

”Our hypothesis is that the FeS membrane, laced with Nickel, acted as a semipermeable catalytic boundary between two fluids………

to which they write up their paper. It’s a legitimate step in the scientific process, and it is distinct from what some may call guesswork of wishful thinking. If nothing comes of it, it merely represents a failed hypothesis.

What is interesting however is the change in thinking, as previous to discoveries of thermal vents under the ocean, abiogenesis was of the “warm pool zapped by lightning variety”™.

#9 Guest_George R_*

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Posted 10 February 2006 - 03:26 PM

chance

It is indeed legitimate to speculate and hypothesize and feel confident to assume etc in the process of seeking the truth.

In fact... ... okay to bypass gaps, and bypass empirical tests etc. at a speculative stage of seeking the truth. It's just brainstorming and spitballing.

My only concern would be if the same technique sufficed to announce (without further appropraie rigor) that they have found a possible way for life to spontaneously generate.

Before stating that it is likely or even possible ... The hypothesis must be rigorously tested ... It must be tied to a tied sequence of repeatible empirical tests ... not a computer simulation ... not a sequence with gaps,... and also stating premises and assumptions about past conditions ... not assuming "just so" conditions because they are ideal for the hypothesis being proposed ... and all these must be subject to challenge.

#10 chance

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Posted 12 February 2006 - 02:44 PM

It is indeed legitimate to speculate and hypothesize and feel confident to assume etc in the process of seeking the truth.

In fact... ... okay to bypass gaps, and bypass empirical tests etc. at a speculative stage of seeking the truth. It's just brainstorming and spitballing.

My only concern would be if the same technique sufficed to announce (without further appropraie rigor) that they have found a possible way for life to spontaneously generate.


Agreed.

Before stating that it is likely or even possible ... The hypothesis must be rigorously tested ... It must be tied to a tied sequence of repeatible empirical tests ... not a computer simulation ... not a sequence with gaps,... and also stating premises and assumptions about past conditions ... not assuming "just so" conditions because they are ideal for the hypothesis being proposed ... and all these must be subject to challenge.


I looked up the word hypothesis in the Wiki, there is some amount of give and take as to it meaning, as you can see from the extract below, the amount of testing that you have described is perhaps too demanding. But I am willing to accept that it could be called a conjecture or a hypothisis.

From the Wiki:

In early usage, a hypothesis was usually a clever idea or convenient mathematical approach that simplified cumbersome calculations; it did not necessarily have any real meaning. A famous example of the older sense is the warning which Cardinal Bellarmine issued to Galileo, that he must not treat the motion of the Earth as a reality, but merely as a hypothesis.

In common usage at present, a hypothesis is a provisional idea whose merit is to be evaluated. A hypothesis requires more work by the researcher in order to either confirm or disprove it. In the hypothetico-deductive method, a hypothesis should be falsifiable, meaning that it is possible that it be shown false, usually by observation. Note that, if confirmed, the hypothesis is not necessarily proven, but remains provisional.

The term hypothesis was misused in the Riemann hypothesis, which should be properly called a conjecture. As an example, someone who enters a new country and observes only white sheep, might form the hypothesis that all sheep in that country are white. It can be considered a hypothesis, as it is falsifiable. It can be falsified by observing a single black sheep. Provided that the experimental uncertainties are small (for example that it is a sheep, instead of a goat) and that the experimenter has correctly interpreted the statement of the hypothesis (for example, does the meaning of "sheep" include rams?), the hypothesis is falsified. IT is an If/then statement


IMO the papers produced by Russell and Hall are detailed enough for some future research to test various aspects.




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