Posted on 04/06/2008 7:15:15 AM PDT by decimon
NEW ORLEANS, April 6, 2008—Flash back three or four billion years — Earth is a hot, dry and lifeless place. All is still. Without warning, a meteor slams into the desert plains at over ten thousand miles per hour. With it, this violent collision may have planted the chemical seeds of life on Earth.
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 dominance of “left-handed” amino acids, the building blocks of life on this planet.
In a report at the 235th national meeting of the American Chemical Society, Ronald Breslow, Ph.D., University Professor, Columbia University, and former ACS President, described how our amino acid signature came from outer space.
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. This is known as “chirality.” In order for life to arise, proteins must contain only one chiral form of amino acids, left or right, Breslow noted.
“If you mix up chirality, a protein’s properties change enormously. Life couldn’t operate with just random mixtures of stuff,” he said.
With the exception of a few right-handed amino acid-based bacteria, left-handed “L-amino acids” dominate on earth. The Columbia University chemistry professor said that amino acids delivered to Earth by meteorite bombardments left us with those left-handed protein units.
“These meteorites were bringing in what I call the ‘seeds of chirality,’” stated Breslow. “If you have a universe that was just the mirror image of the one we know about, then in fact, presumably it would have right-handed amino acids. That’s why I’m only half kidding when I say there is a guy on the other side of the universe with his heart on the right hand side.”
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. The stars emit circularly polarized light—in one direction, its rays are polarized to the right. 180 degrees in the other direction, the star emits left-polarized light.
All earthbound meteors catch an excess of one of the two polarized rays. Breslow said that previous experiments confirmed that circularly polarized light selectively destroys one chiral form of amino acids over the other. The end result is a five to ten percent excess of one form, in this case, L-amino acids. Evidence of this left-handed excess was found on the surfaces of these meteorites, which have crashed into Earth even within the last hundred years, landing in Australia and Tennessee.
Breslow simulated what occurred after the dust settled following a meteor bombardment, when the amino acids on the meteor mixed with the primordial soup. Under “credible prebiotic conditions”— desert-like temperatures and a little bit of water — he exposed amino acid chemical precursors to those amino acids found on meteorites.
Breslow and Columbia chemistry grad student Mindy Levine found that these cosmic amino acids could directly transfer their chirality to simple amino acids found in living things. Thus far, Breslow’s team is the first to demonstrate that this kind of handedness transfer is possible under these conditions.
On the prebiotic Earth, this transfer left a slight excess of left-handed amino acids, Breslow said. His next experiment replicated the chemistry that led to the amplification and eventual dominance of left-handed amino acids. He started with a five percent excess of one form of amino acid in water and dissolved it.
Breslow found that the left and right-handed amino acids would bind together as they crystallized from water. The left-right bound amino acids left the solution as water evaporated, leaving behind increasing amounts of the left-amino acid in solution. Eventually, the amino acid in excess became ubiquitous as it was used selectively by living organisms.
Other theories have been put forth to explain the dominance of L-amino acids. One, for instance, suggests polarized light from neutron stars traveled all the way to earth to “zap” right-handed amino acids directly. “But the evidence that these materials are being formed out there and brought to us on meteorites is overwhelming,” said Breslow.
The steps afterward that led towards the genesis of life are shrouded in mystery. Breslow hopes to shine more light on prebiotic Earth as he turns his attention to nucleic acids, the chemical units of DNA and its more primitive cousin RNA.
“This work is related to the probability that there is life somewhere else,” said Breslow. “Everything that is going on on Earth occurred because the meteorites happened to land here. But they are obviously landing in other places. If there is another planet that has the water and all of the things that are needed for life, you should be able to get the same process rolling.”
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The American Chemical Society — the world’s largest scientific society — is a nonprofit organization chartered by the U.S. Congress and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio.
I’m still going with the Marooned Space Alien theory.
It’s more colorful.
Let’s proceed that you are correct. If “scientists” are going to push their theories into the realm of faith (because it can’t be proved or reproduced) well that’s just religion, too. The Bible doesn’t say that’s how it happened. Whatever happened, happened here. If that’s my choice, I’ll simply go with God.
Well that was several years later. Before the meteorite hit in the dry still desert all my friends and I were just free floating subatomic particles. Suddenly we began to develop molecular structure and we were thankful for that. First we ate dust but in time we had dirt to eat. Mud followed and that was a real treat.
We didn’t have much but we were thankful for what we had. We knew many who had less and we shared as much as we could. In time we all were able to divide our cells and prosper.
The concept of building blocks of life, or even of life itself (panspermia) coming to earth from meteorites is not inconsistent with God creating life.
It is one of many possible mechanisms God could have used.
By U/Pb-Th/Pb isotope ratios it seems that meteors originiated concomitant with the Sun. Thus those scientists who will, are left with still having to thrash about to discern what God wrought. Though I doubt they ever will, since discovering life’s beginnings necessarily also means discovering its end.
Interesting hypothesis. The fact that the preponderance of amino acids found in those meteorites were of the left-sided type certainly suggests its a possibility. But, lets see where it goes from here.
These scientists are coming up with hypotheses based on evidence that they’re finding on meteorites or in the lab. Whether those hypotheses stand in the long run remains to be seen, as further experiments are carried out and new data is considered. That is how science works. Religion has nothing to do with it except that it seems to upset some people’s religious sensibilities that scientists have the audacity to actually tackle questions such as these in the first place.
'Splain me sometin':
Why would it be easier for amino acids to form on lifeless asteroids than on lifeless earth?
Is that what they are saying?
I thought they were pointing to the fact that left-handed amino acids dominate on the meteorites after their journey through space suggests that they may be responsible for the fact that they also dominate on earth, not necessarily that amino acids are more likely to form in space.
But I am not a biochemist and I only quickly read the article, so I will bow to anyone else’s superior knowledge!
Or the Adam and Eve story as literal history?
Question: What goes clip-clop, clip-clop, BANG clip-clop, clip-clop.
Answer: An Amish meteorite.
Fewer distractions?
I don't know but according to the article the amino acids were there but...well, here is from the article:
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. The stars emit circularly polarized light—in one direction, its rays are polarized to the right. 180 degrees in the other direction, the star emits left-polarized light.
Probably to lead people away from the truth.
What is the truth?
Genesis, chapters 1 and 2, mostly. This author has never lied.
It’s not a stupid postulation, just far fetched.
Saying God created life is not a process. Scientists are concerned with the chemical compounds and how they might have occurred in nature. BTW- Maybe God made the comet hit the Earth and a bolt of lighteneing....
The big bang can’t be proven either. If scientists trying to expalin life in chemical and mechanical terms, just add “God caused” to every scientific hypothesis you read. Truth is we don’t know why opposite charges attract or what causes gravity. We just witness and measure the pheneomena.
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