At 06:20 AM 08/17/2000, you wrote:
>Reflectories
>
>On Mon, 14 Aug 2000 12:09:26 -0700, Tedd Hadley wrote:
>
>[...]
>
> >SJ>But I wonder how true that assumption is? Even if it was granted
> >>(arguendo) that the earliest bacteria consumed "prebiotic elements" (i.e.
> >>raw amino or nucleic acids or their chemical building blocks), what
> >>evidence is there that *modern day* bacteria consume such "prebiotic
> >>elements" today? Most bacteria today consume the products of existing
> >>biological activity.
> >>
> >>There are some highly specialised bacteria which consume some inorganic
> >>products, but none, AFAIK, that consume raw amino or nucleic acids.
>
>TH>You're apparently not aware that the putrefactive bacteria break
> >down amino and nucleic acids. In the large instine, for example,
> >these bacteria convert amino acids into toxic amines or ptomaines
> >by decarboxylation (lysine -> cadaverine, arginine -> agmatine,
> >tyroseine -> tyramine, orithine -> putrescine, histidine ->
> >histamine.) The same or similar bacteria make short work of
> >the veritable mountains of proteins left over when we "pass on".
> >Putrefactive bacteria are found anywhere decaying plant or
> >animal matter is found.
>
>OK. Thanks to Tedd for furthering my education! :-) This was not my
>major point, but nevertheless:
>
>1) do we know that these "putrefactive bacteria" have always been around
>from the beginning cleaning up any "amino and nucleic acids" produced?
>
>2) are they anerobic, since there was presumably little or no oxygen around
>for the first billion years? and
>
>3) since there were no "intestines" around for the first billion years or so,
>do these "putrefactive bacteria break down amino and nucleic acids" out in
>the *outside world* in a completely abiotic setting?
>
>[...]
>
> >>TH>Where can you go on Earth today
> >>>to escape life and still have the conditions for life? No where,
> >>>it would seem.
>
> >SJ>That might be true in nature but it is not necessarily true in a
> controlled
> >>artificial setting, like a laboratory.
>
>TH>Nature seems pretty much out of the question as a fruitful laboratory
> >for abiogenetic expirements.
>
>Even here I am not convinced. A complete mirror image D-amino acid life
>form could emerge and existing bacteria might not be able to eat it?
>
>TH>However, an artificial setting is a different story, yes. And,
> >strangely enough, that's where abiogenesis research is taking
> >place today :)
>
>Tedd makes it sound like it is new. In fact a "abiogenesis research" has
>been "taking place" in laboratories since at least *1953*, i.e. 47 years
>(!) and no life has yet emerged spontaneously.
>
>For a fraction of the cost of sending a mission to Mars to see if life
>spontaneously generated there when conditions were once right, every
>conceivable set of such condition could be repeated on Earth in a laboratory
>and hey presto! life should emerge.
>
>Yet if this has been tried it must have failed (otherwise we would know all
>about it). And if it hasn't been tried, then why hasn't it?
>
>Total failure of undirected abiogenesis is of course what ID would predict
>and *not* what naturalistic prebiotic evolution would predict.
>
>So if 47 years of failure is not a falsification of naturalistic prebiotic
>evolution, how could it ever be falsified?
Chris
In such a general form, it might not be falsifiable. But any *specific*
theory of abiogenesis might be falsified that way. For example, if someone
claimed that life should arise in an empty vacuum of one cubic foot on an
average of once every ten minutes, it would not take many hours of failure
of such life to arise to falsify *that* particular theory.
>[...]
>
>Steve
>
>--------------------------------------------------------------------------
>"The firm step toward explaining the appearance of living things had been
>taken. The elementary organic constituents required for the construction of
>the big molecules, from which life subsequently developed, may be formed
>spontaneously and easily. It seemed that once the first steps had been
>taken, the others would have followed easily. Research scientists threw
>themselves unhesitatingly into the frenetic race to be the first to
>synthesize
>living matter in the laboratory; but so far no one has succeeded. There are,
>in fact, many thresholds to be crossed. Life is based upon two mutually
>interactive systems, one of which makes provision for growth and the other
>for reproduction. The systems are also interdependent, and neither may
>exist without the other.
This last is simply false. Growth is only necessary if there is a
phenotype, a body of some sort beyond the initial replicating molecules (or
whatever). Bacteria *do* grow, but growth is not a defining or necessary
characteristic of life as such or of evolution. In fact, *replication*
(with variations being introduced somehow) is all that is necessary for
evolution, for the development of new structures. Growth comes later, as
"genomes" begin to develop bodies to help them in their "quest" for further
replication (I put "genomes" in quotes here because I am by no means
convinced that anything much like DNA was the original evolving "thingy";
RNA and DNA may have come about even *after* the first life forms evolved
out of some other type of molecule -- which may be another reason that
abiogenesis research for 47 years has not yet led to the development of
"original" life. If you consider the number of possibilities that would
need to be tested, and the amount of work that would go into testing each
one, it doesn't seem surprising at all that 47 years of such research has
not yet succeeded. 47 years ago, we did not even have the theoretical
underpinning that we have now as a basis for doing research (much of which
has been developed only in the past ten years).
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