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22 August 2009

Much Ado About Nothing

The latest evo post over at Little Green Footballs is even more clueless about actual science than usual. In this one, Charles Johnson links a hyperventilating screed from the Reuters "science" section about the presence of an amino acid in the tail of a comet,

The amino acid glycine, a fundamental building block of proteins, has been found in a comet for the first time, bolstering the theory that raw ingredients of life arrived on Earth from outer space, scientists said on Monday.

Microscopic traces of glycine were discovered in a sample of particles retrieved from the tail of comet Wild 2 by the NASA spacecraft Stardust deep in the solar system some 242 million miles (390 million km) from Earth, in January 2004....


....The latest findings add credence to the notion that extraterrestrial objects such as meteorites and comets may have seeded ancient Earth, and other planets, with the raw materials of life that formed elsewhere in the cosmos.

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare," said Carl Pilcher, the director of the NASA Astrobiology Institute in California, which co-funded the research.

Glycine and other amino acids have been found in a number of meteorites before, most notably one that landed near the town of Murchison, Australia in 1969, Elsila said.

Even for a mainstream media science article, this one is remarkably clueless about the basic science surrounding this issue. The way the article reads, they found glycine - GLYCINE!!!!! - in the tail of a comet, and poof, this practically proves that earth was seeded by extraterrestrial amino acids and *poof* life appeared!

Frankly, they're just lucky it was glycine they found, and not any other amino acid.

The reason is that glycine - which the article correctly notes is the "simplest" amino acid - is also the only amino acid which does not contain a chiral centre. Now, glycine is relatively simple to produce in nature - Miller-Urey produced it primarily when they did their little "lightning in a bottle of ammonia and methane" trick that the evos usually hold up as evidence that early earth conditions could have produced amino acids, which formed proteins, which formed everything else! (I'm simplifying, of course) There's no reason to think that the input of a little solar energy couldn't have done the same thing with ammonia and methane in the tail of a comet, at least enough to produce the "microscopic traces" of glycine the article mentions.

In fact, as the article also mentions, the Murchison strike in Australia yielded evidence for extraterrestrially-produced amino acid production.

But, the problem with using that as evidence is that a number of amino acids from the Murchison strike were non-biological, and all of them, biological and non-biological alike, were present as racemates - meaning that they were present in both left-handed and right-handed chiralities. Problem is, biologically active proteins incorporate left-handed amino acids exclusively. Yet, there is no chemical reason why a protein would selectively incorporate only one handedness of amino acid into a growing polymer chain. What this means is that any proteins that did somehow manage to overcome all the other things that basically rule out the naturalistic arguments for abiogenesis, like ionising radiation in an "oxygenless early earth atmosphere" (think, no ozone layer) and the Le Chatelier impossibility of performing a condensation reaction with water as a product (such as, you know, amino acid polymerisation to form proteins) in an ocean, would still have incorporated both handedness of amino acids, and have been completely useless as evolution-bearing precursors to life on this earth.

This is why I said that the evos got lucky that only glycine was found in the comet's tail, because any more complex amino acids would - if the evidence from every other extraterrestrial source of amino acids we've found to date is any indication - have been enantiomerically mixed, and would have been useless from an origins-of-life perspective. Being achiral, glycine does not have "handedness", and hence does not present the problem for the requirement of enantiopurity that any other amino acid would.

And let's note - merely finding glycine (ONE amino acid) does not prove anything about any evolutionarily-demanded "seeding" of life on earth. You don't build proteins out of just glycine. You need other amino acids as well - and to date, the scattered few that we're found from off-planet would be useless.

Not only is the science underlying the suppositions of the article faulty, but the article itself is written somewhat deceptive, like they're trying to slip stuff past the undiscerning reader. For instance, having admitted early on that "microscopic traces" of glycine were found in Wolf 1's tail, we are later told,

"The discovery of glycine in a comet supports the idea that the fundamental building blocks of life are prevalent in space, and strengthens the argument that life in the universe may be common rather than rare."

So, they're "microscopic traces", but they're "prevalent in space" and show that life in the universe "may be common." Friends, that's not science, that's wishful thinking. And it's not even supported by scientifically-valid evidence. Find trace amounts of glycine in a comet's tail and assuming from this that life may well be common all across this universe is simply non-sequitur.

Articles like this do nothing to actually "prove" the truth of evolution, or even its likelihood. They only demonstrate the scientific illiteracy of so many of the MSM's "science writers" and those who repeat them ignorant, like Charles Johnson at LGF 1.0.

1 comentários:

One word comes to mind: despair!

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