Slashdot Mirror
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."
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.
Where did those amino acids come from?
Engineering is the art of compromise.
The idea that nucleic acids and other organic building blocks were delivered to Earth from a meteor is not new. In fact, I remember reading about that in a space book when I was 5.
Personally, I think that whether or not the "seeds of life" originated here or came here on a meteor is a stupid idea, as it's not where they came from that is even remotely interesting, but how they came to be in the first place. If they originated here, then an asteroid impact may have scattered them elsewhere, and there may be other bewildered life forms on other planets wondering where they came from, or vice versa. What difference does it make?
What I want to know is how complex organic molecules were formed into self-organising, self-replicating structures. Bigfoot is not the missing link. How we got to elemental material spewed out from a supernova to DNA, *that's* the missing link.
I hate printers.
No, that book is an evolution (pardon the pun) of the theory of evolution. It deals with what happened (in RD's view) *after* the avalanche of life had been triggered.
What I was asking was, what was the first snowflake that started that avalanche. Wake me up when people have started caring about that, coz I don't see much discourse on that subject in the scientific media.
I hate printers.
I at least can recall the following. We have plenty of stereospecific molecules to the extent that sometimes the lefthanded molecule of something is good for us while the righthanded variant is poisonous. It doesn't mean that for every molecule in nature only one handedness will occur. Amino acids are nearly always lefthanded. Google for "homochirality".
If we create a mirror case for the current biological condition where all lefthanded molecules are replaced by righthanded and vice versa, this condition would be equally plausible.
The idea of symmetry breaking is that each of the conditions is equally plausible but mutually exclusive, and that a small perturbation early on would magnify to result in complete dominance of one variant. The origin of this perturbation is trivial, a butterfly flapping its wings if you wish, the important thing is the magnifying effect.
Parent post refers to a modification of that idea, where the two conditions are not exactly similar but there is actually a slight preference for one of the conditions. In the first case on half of the planets with life will have lefthanded life, the other half will have righthanded life. In the second case, all life is lefthanded.