Thursday, May 12, 2005
Talk.Origins "Index to Creationist Claims" pt1
Claim: life uses only left-handed amino acids, which couldn't have arisen naturally.
T.O's talking points are mainly hand-waving:
"The amino acids that are used in life, like most other aspects of living things, are very likely not the product of chance. Instead, they likely resulted from a selection process."
Oh, the unobserved _chemical_ selection process. I hate to break it to you, but natural selection requires life, and chemical selection is a contradiction in terms. Chemical reactions move TOWARD equilibrium, not away from it.
"A simple peptide replicator can amplify the proportion of a single handedness in an initially random mixture of left- and right-handed fragments"
Amplification isn't good enough. We need 100%.
"Serine forms stable clusters of a single handedness which can select other amino acids of like handedness by subtituting them for serine; these clusters also incorporate other biologically important molecules such as glyceraldehyde, glucose, and phosphoric acid"
From Creation Safaris:
"The serine cluster is not a chain, but a ring. Further, it does not attract other amino acids to form peptide-bonded chains. The Cooks crew only tested eight amino acids for like-handedness joining the serine clusters."
So, not much help there.
"An excess of handedness in one kind of amino acid catalyzes the handedness of other organic products, such as threose, which may have figured prominently in proto-life"
Wild speculation doesn't count as evidence.
"Amino acids found in meteorites from space, which must have formed abiotically, also show significantly more of the left-handed variety, perhaps from circularly polarized UV light in the early solar system"
We're looking for 100% here.
"The first self-replicator may have had eight or fewer types of amino acids"
Speculation unless we can actually build a self-replicator.
"It is not all that unlikely that the same handedness might occur so few times by chance, especially if one of the amino acids was glycine, which has no handedness."
It depends on the length, and we've tried thousands of different combinations and have not been able to even force one in the lab.
"Some bacteria use right-handed amino acids, too"
This sounds like a big claim, but really is a bunch of crap. It's a bluff that you won't do the research yourself. Do you know WHY some bacteria use right-handed amino acids? They use it as a COATING to DEFEND THEMSELVES (i.e. screw up the functioning of would-be predators). It is not just a "plug-n-play" system. I'm not 100% sure, but I think that the cases where right-handers are used, again, it's 100% right-handers.
For all known enzymes, if you have EVEN ONE amino acid of the wrong hand, the entire enzyme will be rendered useless.
Here's a good AiG article on the subject.
Also, other molecules (like DNA) are all right-handed.
CB015 : DNA needs certain proteins in order to replicate. Proteins need DNA to form. Neither could have formed naturally without the other already in existence.
"DNA could have evolved gradually from a simpler replicator;"
Complete bluff. We have no idea if this could have happened.
"RNA is a likely candidate, since it can catalyze its own duplication"
Another bluff. While RNA has enzymatic properties, we have never found an RNA molecule that could self-sufficiently catalyze its own duplication. We've tried thousands of combinations and haven't gotten it to work. We still need those enzymes to do the very tricky copying procedures for us.
"The RNA itself could have had simpler precursors, such as peptide nucleic acids (Böhler et al. 1995). A deoxyribozyme can both catalyze its own replication and function to cleave RNA -- all without any protein enzymes (Levy and Ellington 2003)."
I have not looked into this work, but my guess is that this is more bluffing. I know that other works (Huber et al., A Possible Primordial Peptide Cycle, Science 2003) contain nearly all bluffs and no real data. Just a lot of suppositions, what ifs, and maybes. For a full response, see this.
There's not a whole lot wrong with their criticisms of creationist criticisms, except that they leave out a REAL BIG CLAIM -- it doesn't matter. Edward Peltzer first noticed this years ago. The Miller-Urey experiment was thought to be useful because it matched the examination of a meteorite believed to be billions of years old. Here's what Peltzer had to say:
I asked myself, "Why is a meteorite that is 4.5 billion years old, with processes that went on for perhaps millions, if not billions, of years, so similar to an experiment that a graduate student can do over the weekend?" Something else is happening here, and we are missing it.
Sure, in Miller's experiment we make that first step. But in the meteorite, there's so much more time there. Shouldn't there be some evidence of going the second step, or the third step? And it suddenly hit me. Why should the two look anything alike at all? The Miller experiment was stopped after a week or ten days. Nobody stopped the meteorite. It had ample opportunity to go much further. Yet the two are virtually the same.
CB010.1: Even the simplest, most primitive forms of life -- bacteria -- are incredibly complex, much too complex to have arisen by chance.
Here is their response:
"There is no reason to think that the life around today is comparable in complexity to the earliest life. All of the simplest life would almost certainly be extinct by now, outcompeted by more complex forms."
Eukaryotes ate my evidence. But you have to take my word for it anyway.
"Self-replicators can be incredibly simple, as simple as a strand of six DNA nucleotides (Sievers and von Kiedrowski 1994). This is simple enough to form via prebiotic chemistry. Self-replication sets the stage for evolution to begin, whether or not you call the molecules "life.""
This one is new to me, but I'm going to call a pre-emptive BS. DNA doesn't self-replicate -- that's the whole reason for proposing RNA world, which still hasn't found a self-replicating RNA strand.
"Nobody claims the first life arose by chance. To jump from the fact that the origin is unknown to the conclusion that it could not have happened naturally is the argument from incredulity."
To say that it did happen naturally is not shown by ANY EVIDENCE WHATSOEVER, but instead by a whole lot of bluffing about might-have's and could-have's, when we still haven't gotten chirality figured out.
We still don't have evidence that the fountain of youth doesn't exist, but most of us have grown up and stopped searching for it. The argument against the fountain of youth is likewise an argument from incredulity.
If you have no weapon, no motive, no body, and no circumstantial evidence, you can't make a case at trial. Likewise with the origin of life. All indications is that life comes from life, and information from intelligent beings. If someone has another mechanism, that's great. But so far it's just a lot of hand-waving.
Notice how much T.O assumes that you aren't going to look into their claims and just assume that they've done proper research, and that claims from evolutionary scientists don't need to be checked and validated against a BS detector. It's a giant confidence game.
Anyway, that was fun, though it took more time than I wanted. Hopefully I'll have time to do it again soon.