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Meteorites May Have Delivered Seeds of Life On Earth
esocid writes "At the national meeting of the American Chemical Society, scientists presented evidence today that desert heat, a little water, and meteorite impacts may have been enough to cook up one of the first prerequisites for life. The result of that brew could be the dominance of "left-handed" amino acids, the building blocks of life on this planet. Chains of amino acids make up the protein found in people, plants, and all other forms of life on Earth. There are two orientations of amino acids, left and right, which mirror each other in the same way your hands do. These amino acids "seeds" formed in interstellar space, possibly on asteroids as they careened through space. At the outset, they have equal amounts of left and right-handed amino acids. But as these rocks soar past neutron stars, their light rays trigger the selective destruction of one form of amino acid."
Interesting read. It has been one of the more pressing questions of the theory of biogenesis: where did the first organic matter come from? I have always found chirality and the left-handed nature of Earth's proteins to be more than mere coincidence.
It is strange that our location in the galaxy led to a slight imbalance in the amount of gravitationally polarized light striking chunks of rock and metal floating in a cosmic dance 4 billion years before I was born....yet that combination of factors resulted in the alanine in my body to contain only the left-handed chiral.
Studies like this are the cause of my personal religious dilemma. Most of the major religions came about 1500-5000 years ago...and at the time they were conceived, they convincingly explained every natural occurrence well enough to placate the masses. I wonder what the Pope would have to say about this study...was God a southpaw??
khasim (12/9/06): In a blind taste test, more people preferred Coke over the Pepsi that I had previously pissed in.
"what are the odds that we'd all have left-handed amino acids..."
In econometrics, I learned this to be "Sample Selection Bias". The odds that we'd all have left-handed amino acids might be nill. However, the odds that we'd all have left-handed amino acids GIVEN that we've become conscious beings able to analyze such a thing?
I mean, maybe there WERE a lot of failures. But somewhere in the universe, ONE worked. And BECAUSE we worked, we're able to wonder about it.
Well, proteins are simply chains of amino acids. It's really cool if you think about it; amino acids have amino and carboxy terminuses. The carbon in between these 2 are hooked up to a variable side chain with varying chemical structure/properties depending on the amino acid.
But, moving along, the carboxy and amino terminuses are perfectly capable of linking up via chemical reactions. It wouldn't be a stretch, taking into account the conditions of ancient Earth, that amino acids in the "primordial soup" just kept linking up and polymerized under favorable conditions, generating complex proteins.
Personally, this is why the evolution of early life is so interesting to me. The modular structure of DNA, RNA, and proteins, coupled with phospholipids (which spontaneously form cell like compartments in water), if all these are thrown into early earth conditions, spontaneous creation of life seems very, very possible.
Maybe complex organic molecules form into self-organising self replicating structures BECAUSE they were delivered from elsewhere. The two need not be mutually exclusive.
What if the "seeds" of life require foreign interference to mutate into life. I don't understand how we can evaluate a missing link if we don't know where all the components came from. The Earth could have been an unfertilized egg waiting to be inseminated. For that reason how they came to be is just as interesting as where they came from especially if they are intertwined.
Imagine the odds that would have to be overcome if it takes a specific type of meteor to react with a specific type of dead planet to make life. If that is true the odds of the right elements being present in both cases could be so high that they could be conceivably called divine. It would be pretty funny as well if the chain reaction took 7 days.
I view the the creation story in Genesis as a literary fable, but believe that the creation and evolution of life is the result of an "intelligent design". Yes, parts of it appear to behave randomly, but all life is "derived" (using a software design metaphore) from abstract "foundation classes" i.e. sets of universal templates and behavioral principles, that permit life to be instantianted and elaborated with form to match needed functionality.
So, for example, I would not be surprised to travel to another planet and find creatures with teeth, arms, legs and brains similar to those found in terrestial creatures. I would not be surprised to find creatures swimming in extra-terrestial oceans with fins and shaped like our fish. etc.
Also, I don't think this idea conflicts with the teachings of Jesus at all. It is well-known that the "genetic code" is a kind of language where triplets of nucleotides ("codons" => words) denote individual amino acids and sequences of codons (=> sentences) are interpreted by RNA to produce proteins. It seems to me that you could interpret these "sentences" as the very Word of God.
In fact, that's exactly how one could interpret Jesus' Parable of the Seed (Luke 8:5-8:16)
According to your link "The parity violating energy differences between enantiomers are small, of the order 10[^]-14 J [per] mol". If I have my information right the thermal energy of one mole at room temperature is something like 2.4*10^3 J per mole. So random thermal jostling will swamp the cited effect by a factor of around 100,000,000,000,000,000. It's kinda like dropping ping pong balls from the space shuttle during a hurricane, and saying more ping pong balls will land in North Carolina than South Carolina because the ground in North Carolina is on average one billionth of an inch lower than the ground in South Carolina. Technically true, but the bouncing and winds are so much more powerful than a billionth of an inch average altitude difference that you still have nearly a 50-50 chance of finding more ping pong balls in South Carolina at any particular moment.
Unfortunately the linked paper costs $35 so i didn't get to read it, but I'd be somewhat surprised if they claim it has any solid role in the startup of life. On the other hand this meteor story shows far more potential. If a meteor can create a crater-pool with 45%-right amino acids and 55% left amino acids, and the 45% rights can pair up with 45% lefts to crystallize out, then you can end up with only the last 10% lefts still in a rather substantial all-lefts solution.
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I don't think that it's true that you cannot reason someone out of something they were not reasoned into. I was raised to believe in a certain religion but I was talked out of it (not all at once, mind you). I guess a more accurate thing would be to say that the problem is that these people aren't susceptible to reason in the first place...
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I disagree, I find it very interesting. The visual analogy of a sperm fertilizing an egg replicated in life being fertilized on a planet? Beautiful.