On Tue, 25 Aug 1998 08:23:01 -0700, Pim van Meurs wrote:
>SJ>1) L-amino acids were generated in outer space, travelled millions of
>>kilometres to Earth, and then fell into a volcano or hydrothermal vent
>>(all the while preserving their left-handedness), where
>PM>Why not ? Please explain why these amino acids would change their
>>left handedness ?
>SJ>The burden of proof is on those who claim it. The facts are:
PM>And those who claim it, mentioned how left-handedness could have
started.
It has been well-known for some time that L- (or R-) handedness can be
generated by polarised radiation or light:
"Preferential interaction with radiation. A number of researchers have
pursued the idea that certain types of radiation are able to destroy one of a
pair of enaniomers. This preferential destruction could lead to an
accumulation of one enantiomer in the primeval soup. Circularly polarized
sunlight, for example, leads to a selective photochemical decomposition of
chiral molecules. The effect is rather weak and it is doubtful whether it
could have affected the composition of a primeval soup." (Croft L.R.,
"How Life Began," 1988, p62)
"Suggestions have been made over the years that circularly polarised light
may direct the synthesis of optically active compounds; that one optical
isomer may spontaneously crystallise from a racemic mixture, or be
selectively absorbed on asymmetric crystals; and that L and D monomers of
amino acids may exert some stereoselective action during peptide bond
formations. Most of these suggestions, and others of a similar kind, have
not been confirmed experimentally." (Aw S.E., "Chemical Evolution," 1982, p99)
But this finding did not even do that, despite all the hype. What they found
was circularly polarised *infrared* light, which is too weak to selectively
destroy R- or L- amino acids to generate homochirality:
"A team led by Jeremy Bailey of the Anglo-Australian Observatory near
Sydney has spotted circularly polarized INFRARED LIGHT-in which the
electromagnetic wave rotates steadily-streaming from a region of intense
star birth in the Orion Nebula. ULTRAVIOLET (UV) LIGHT polarized
this way can selectively destroy either lefts or right-handed (D) amino
acids, depending on the direction of spin...INFRARED LIGHT, however,
DOES NOT PACK THE ENERGY NEEDED TO DESTROY ORGANIC
MOLECULES. THAT WOULD TAKE UV LIGHT." (Irion R., "Did Twisty
Starlight Set Stage for Life?" Science, Vol. 281, 31 July 1998, pp626-627.
My emphasis.)
What they needed to find was circularly polarise *ultraviolet* light,
which they didn't see, but calculated *should* be there:
"Although Bailey's colleagues COULD NOT SEE UV LIGHT from Orion
because of obscuring dust, they calculate that a similar percentage of UV
light SHOULD also be circularly polarized." (Irion R., "Did Twisty Starlight
Set Stage for Life?" Science, Vol. 281, 31 July 1998, p627. My emphasis)
PM>Why would the amino acids revert to an even-handed distribution ?
The summary article points this out:
"Origin-of-life experts have a different spin. "There are so many problems"
with the scenario, says biogeochemist Jeffrey Bada of The Scripps
Institution of Oceanography in La Jolla, California.), who doubts that large
quantities of amino acids from space would have survived the journey to
Earth or hung around long enough to influence early biology. "I doubt this
will settle the issue of how homochirality arose." (Irion R., "Did Twisty
Starlight Set Stage for Life?" Science, Vol. 281, 31 July 1998, p627)
"Even so, Bailey and Hough acknowledge, many events must fall into place
to render their scenario plausible. Those steps include making huge
amounts of amino acids in space and delivering them to Earth WITHOUT
LOSING THE SURPLUS TO "RACEMIZATION"-THE
SPONTANEOUS TRANSFORMATION OF HOMOCHIRAL
MOLECULES TO AN EVEN-HANDEDNESS that happens quickly at
high temperatures and in water...."The open question is, would such an
excess be important to the origin of life?" Bada and his colleague at the
University of California, San Diego, chemist Stanley Miller thinks not.
"Once the amino acids get to Earth THEY WOULD RACEMIZE IN
VERY SHORT ORDER,' Miller says." (Irion R., "Did Twisty Starlight Set
Stage for Life?" Science, Vol. 281, 31 July 1998, p626. My emphasis.)
>SJ>1. No extra-terrestrial non-racemic (ie pure L- or R-handed ) amino
>acids have ever been found. There has been claims of 90% L-amino acids
>found but these were non-biological amino acids.>>
PM>No one is talking about pure L or R handed amino acids.
But "pure L or R handed amino acids" are the *only* ones that work,
because a protein will not fold if even *one* wrong optical isomer is
present:
"Furthermore, the activity is destroyed by the incorporation of one
analogue or one wrong optical isomer because that prevents the folding of
the protein chain." (Yockey H.P., "Information Theory and Molecular
Biology," 1992, p254)
"From the above it is obvious that amino acids which are to act as the
building blocks of life at biogenesis must exhibit the correct chirality. For
biogenesis to take place, all building blocks (amino acids) of living
protoplasm must be laevorotary. It is very important to stress this point- all
building block molecules involved in the synthesis of vital proteins must be
"optically pure" and "left"-that is, they must be laevorotary without any
traces of dextrorotary isomers. In this respect living protoplasm is very
fussy: it demands absolutely pure "fare." If even very small amounts of
amino acid molecules of the dextrorotary type are present, proteins of a
different three- dimensional structures are formed, which are unsuitable for
life's metabolism." (Wilder-Smith A.E., "The Natural Sciences Know
Nothing of Evolution," 1981, p21)
>SJ>2. All terestrial amino acids that are not part of a living organism are
>racemic (ie. a mixture of L- and R- handed).>>
PM>Hence the hypothesized origin among the stars.
Yes. But there is no evidence that those are not racemic also.
>SJ>3. All non-racemic amino acids become racemic over time after the
>organism dies. There is even a test of which uses this to measure how
>long ago the organism died.
PM>And the mechanisms underlying this are ?
The article mentions "high temperatures and...water" as well as "UV light".
I presume it is just by the normal breaking of molecular bonds as in other
chemical reactions.
>PM>You must surely aware of some of the excellent work which has
>shown that such is hardly as far fetched as you sound it to be. Fox and
>others have gone through many of the steps required.
>SJ>Please give *details* with *references*. If you are referring to
>Sidney's Fox's so-called "proteinoids" theory, origin-of-life specialist
>Robert Shapiro observed that Fox's it has the unique distinction of being
>criticised for its lack of "relevance" by both evolutionists and
>creationists:
PM>Irrelevant you are now arguing from authority not from fact.
It is superficial and fallacious to dismiss a reference as "arguing from
authority not from fact." Both laymen and all scientists outside their own
field of expertise, *must* rely on the "authority" of other scientists who are
experts in their respective fields:
"But when scientists transgress the bounds of their own specialty they have
no choice but to accept the claims of authority, even though they do not
know how solid the grounds of those claims may be. Who am I to believe
that quantum physics if not Steven Weinberg, or about the solar system if
not Carl Sagan?" (Lewontin R., "Billions and Billions of Demons", review
of "The Demon-Haunted World: Science as a Candle in the Dark" by Carl
Sagan, New York Review, January 9, 1997, pp30-31)
PM>What is much harder is dealing with the findings of Fox
First, how do you *know*, since you are an oceanographer? You *must*
be relying on the *authority* of "Fox" or someone else relying on "Fox".
Second, unless you post exactly what are "the findings of Fox", with
references (as previously requested), you are here using your *authority*
as an argument that "much harder is dealing with the findings of Fox".
>SJ>For example, if each step in the chain had an average probability of
>10^-6 (ie. 1 in a million), for all five to happen in a series is the product of
>all five multiplied together, ie:
>
>10^(-6*5) = 10^-30. That is 1 chance in:>>
PM>Of course you are quite aware of the many fallacies in these
>calculations ?
The above was just an "example". The values were hypothetical: I prefaced
them with "if". So, with those provisos in mind, how about you posting
what the alleged "the many fallacies in these calculations" are?
>PM>Unlikely since Darwin's theory of evolution is not about 'warm little
>>ponds' but about observations and data. The warm little pond hypothesis
>>is about abiogenesis, the possible origins of life as we know it. Darwin
>>envisioned the 'warm little ponds' others have found 'black smokers'
>>which show a remarkable little biosphere.
>SJ>The fact is that a million people in Western Australian read on the
>front page of their major newspaper that doubt was thrown on Darwin's
>origin of life theory. I doubt that the layman would know the difference
>between Darwin's origin of life theory and his evolution theory. That's
>why I said it was "ironic".
PM>You are presuming that the average Australian would see this as
'doubt of Darwin's origin of life theory'. And even more, that this would
affect how they perceive Darwin's evolution of life theory.
Yes. That's what I said.
>SJ>BTW I am not aware of any evidence that "smokers" even existed 3.5
>billion years ago when life first appears in the rocks. Another article I
>posted pointed out that the oldest "smokers" on Earth are only 27,000
>years old and they are only active for 2,000 years at a time.>>
PM>Yep, some volcanoes of the past have since long gone dormant,
>haven't they.
Yes. "Volcanoes" can lie "dormant" and then come to `life' again. But the
problem for living things depending on smokers, is that if the smokers went
dormant every "2,000 years" then that life would die, unless it could
migrate to another "smoker". If it could migrate to something other than a
smoker then the smoker theory is superfluous.
For the smokers theory to be viable, its proponents would have to show: 1)
that smokers existed "3.5 billion years ago when life first appears in the
rocks"; 2) there has been a unbroken series of contiguous smokers for the
last "3.5 billion years"; and 3) that those life forms can migrate to other
smokers.
Steve
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Stephen E (Steve) Jones ,--_|\ sejones@ibm.net
3 Hawker Avenue / Oz \ senojes@hotmail.com
Warwick 6024 ->*_,--\_/ Phone +61 8 9448 7439
Perth, West Australia v "Test everything." (1Thess 5:21)
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