Uncommon Descent Serving The Intelligent Design Community

Homochirality and Darwin: Part 2


Judging from the comments to the homochirality post, Darwin (aka evolution) still gets support and Pasteur still endures ridicule. Some suggested that I had misread the meteorite data, others suggested that homochirality is easily obtained in the laboratory, while still others proposed circularly polarized light. So it is with a certain sense of vindication that I read the New Scientist article, Did exploding stars shatter life’s mirror?

The article begins by saying all life is L-amino, and then admits that all amino acids found on meteorites has an excess of L-amino.

“For every type of amino acid found in meteorites there is an excess of the left-handed form over the right-handed of between 2 and 18 per cent,” says Uwe Meierhenrich of the Nice Sophia Antipolis University in France. “An excess of the right-handed form has never been found.”

This amazing admission is then qualified with a “well it might be Earth contamination”, but for unspecified reasons this excuse is not followed up. The reason is simple, it can’t be Earth contamination, at least not recently, as in the last 400 million years. So if Earth can contaminate comets in the Oort Cloud 400 million years ago, then there is no reason to believe the opposite is impossible either. Hence the quick change in argument.

So how do we explain this (presumed abiotic) production of amino acids? The article goes on to shoot down the circularly polarized light argument, which is what I alluded to in the comments.

Circularly polarised light interferes with the arrangement of electrons that bind atoms together in such a way that it can selectively break up molecules of one or other chiral form, depending on which way it is rotating. …It is a seductive possibility, but it has its problems. The selective destruction of amino acids only kicks in if the light has enough energy to trigger the necessary chemical reactions – in practice requiring the presence of ultraviolet light, rather than the less energetic infrared light seen in the Orion nebula. “No one has detected any of this light yet,” says Meierhenrich…

As an aside, you never hear the caveats until a new new theory is advanced, and suddenly all the problems with the old theory are freely admitted. The Darwin-defenders at Wikipedia, for example, happily talked about circularly-polarized light producing homochirality, without actually discussing whether visible and IR light actually destroyed any amino acids. Like Darwin himself, theoretical possibilities that advance the cause will trump reactionary experimental observations every time. This is why Pasteur never gets the respect he deserves.

read more…

I like your last sentence Dr. Sheldon: With regard to the deniers who think homochirality is not much of a problem, I only ask whether a solution requiring multiple massive magnetized black-hole supernovae doesn't imply there is at least a small difficulty to overcome? A difficulty, perhaps, that points to the non-random nature of life in the cosmos?bornagain77
May 22, 2010
07:28 PM

Leave a Reply