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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."
We discussed something similar to this here where they found organic molecules in a Canadian meteor.
My work here is dung.
It means that there is only a 50% chance we are edible for aliens!
I have a feeling a creation vs. evolution flamewar is about to start. Creationists will be creationists, but everyone else just think for a second:
If you were an average joe, not even a stupid joe but an average joe, which honestly sounds more convincing: 1) A supreme being did it, or 2) blah blah amino acids blah blah meteorites blah blah neutron star light rays blah blah?
So y'know, take it easy on the creationists. They may not understand how science works, but when faced with an article like this, can you really blame them?
The United States of America: We do what we must because we can.
Makes sense in a way: the meteors are sperm, the Earth the egg, the orbital bombardment the BDSM.
Hail Eris, full of mischief...
E pluribus sanguinem
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.
The fact that meterorite showers brought life to our planet is no mystery to me. See, I lived in Smallville for a while and I've seen things you wouldn't believe.
- Chloe Sullivan
"All earthbound meteors catch an excess of one of the two polarized rays." [which are generated by neutron stars]
Doesn't this imply that there is a neutron star somewhere in the immediate vicinity of Earth that's zapping all our incoming meteors? Wouldn't we, um, notice?
I mean, neutron stars are pretty rare things (~2000 known in our galaxy, nearest known is 280 lt/yrs away). I find it improbable that a significant majority of the incoming material has passed by one at some point in its life.
Now that we know that life as we know it sprang from meteorite-sperm, we owe it to the rest of the Universe to immediately deploy Dyson condoms.
Someone correct me if I'm wrong, but I was under the impression that the left-handed chirality bias had already been explained by the non-conservation of parity in the electroweak force. The L enantiomers have a slightly lower binding energy, so in any mole of racemic amino acids you'll have about a million excess on the L side, which is enough to tip the balance.
-- Insert witty one-liner here. --
Ned Flanders for one welcomes our new left handed amino overlords.
Science advances one funeral at a time- Max Planck
Where did those amino acids come from?
Engineering is the art of compromise.
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.
I'm not sure left handedness needs such a far fetched explanation. It makes sense for cells to pick one handedness or another, otherwise they need twice the machinery. And there are plenty of pathways that connect different amino acids and other compounds, so if one of them is left handed, chances are most of the rest are as well. And which handedness it ended up being may just have been chance.
I don't see much discourse on that subject in the scientific media.
You mean in popular scientific media. The origin of the first life is a very hot topic amongst those in biological disciplines, and there are several competing theories. I suggest you start with a bit of reading on Abiogenesis on Wikipedia. You'll find quite a few relevant citations as well as a discussion of past and current models.