So you are talking about the environment. You're basically saying A can not eat B's food and there was more B-food than there was A-food?
Something like that.
Man, those meteorites must have been raining like crazy if they managed to offset the balance. If they were able to do it, then Earth turbulent childhood could have done it too, much more likely and on a grater scale. And we do see life even in the most inhospitable places we can find.
Do you understand yet why this is even considered a posibility? Or are you still trying to understand why it is thought that these meteorites bought earth its water?
Their world is our world, the right-handed amino acid based "aliens" live among us.
-"Over 90% of gastropod species have dextral (right-handed) shells in their coiling, but a small minority of species and genera are virtually always sinistral (left-handed). A very few species show an equal mixture of dextral and sinistral individuals."
http://en.wikipedia.org/wiki/Chirality
This. Is not. The same thing.
Species with left handed shells share the same chirality of proteins as we do, it is only their shells that are special. Even there, within species that have predominantly right handed shells there are indviduals with left handed shells.
This is no more evidence than pointing out that left handed people exist.
So it's not impossible, the ratio can go up to 50-50%, and even more in favor of "evil-twin alien gene".
Yes, it is impossible. An enzyme that has evolved to couple to a left handed protein can not couple to a right handed protein.
But can they all eat the same food?
No.
It's enough their enzymes can break down chiral molecules to the point they loose chirality, and then they can be "consumed" regardless of what chiral form they originally came with.
No.
And I also must ask, can they have babies? Can they share their blood?
No.
Could it be possible there are some humans based on right-handed chirality, or why not?
Definitely not. Because, for the most part, our bodies interact poorly or do not interact at all with the wrong handedness - I mentioned drugs earlier. I mentioned Carvone, carvone isn't the only one. Ibuprofen tablets are a racemic mixture, they don't even try to make them enantiopure because it would just racemise in vivo anyway.
Levoamphetamine and
Detroamphetamine are both active, but have different effects, and affect different parts of the body.
Thlidomide One enantiomer is effective against morning sickness, the other is teratogenic - it was taken off the market not because enantiopure tablets could not be made, but rather because it behaves in the same way as ibuprofen and racemises in vivo.
Ethambutol One enantiomer is an effective tuberculosis treatment, the other causes blindness.
Naproxen One enantiomer is an effective analgesic, the other causes liver poisoning with no analgesic effect.
Penicillin Only one enantiomer works because it works by mimicing d-alanine.
Propranalol One enantiomer has a calming effect, interacting with the fight or flight system, the other does not.
Do you need me to go on? Or have I made my point. If you ate food that had the wrong chirality of proteins and amino acids, your body would not be able to process it, or would potentially poison itself in trying to do so. If the poison didn't kill you, the starvation probably would.
