dabmdell:

I don't really care to discuss this further with you, but this link also makes the point (a lot better, too, I should have linked to it first, but didn't think of it) if you didn't understand the first one.

http://lesswrong.com/lw/aq2/fallacies_as_weak_bayesian_evidence/

I'll tell you the reason behind homochirality.
If some cellular molecules were of different chiralities, then they wouldn't fit together. duh.

@rlumley, I hope you will indulge me just a little further. I read through your new link, and I have a question for you.

Is there any evidence for creation, aliens, ghosts, etc, /besides/ Bayesian evidence? For every theory currently taught in primary and secondary schools, there is non-Bayesian evidence to support it. This is why I ask.

How does someone who goes to a very prestigious technical school not know what a scientific theory is.

"You really need to study history of science and its development."

And its meteoric rise in the age of 19th century secularism? Oh and the longstanding hostility of religion to virtually every scientific advance? Noted.

@dubmdell:

Well there isn't really "Bayesian evidence" and "non Bayesian evidence". Much better phraseology is "strong Bayesian evidence", ie. something that makes you change your probability estimate very significantly, and "weak Bayesian evidence" which doesn't really change it at all. So to your point, there is absolutely no "strong Bayesian evidence" for religion and the ilk, which I never meant to claim. (Perhaps you misunderstood) There is just some incredibly minor weak evidence for it, which is why I said it's really an academic point that it's not necessarily true that there "is no evidence" like you said.

I think the schools should teach reading, writing and arithmetic. Silly HC science is for adults.

@rlumley,

Okay, I think I understand the point and position you take. And at this point we will have to agree to disagree, but I thank you for the further clarification.

"Silly HC science is for adults."

But yet you religious freaks teach your silly religion to your 4 year olds.

I think fulhamish should realise that natural selection and 'evolution' applies to non-living things as well. Surely a substance that self-replicates and converts other substances into it is more likely to last a long standing time. Surely a substance that does this better than others will be more likely to exist at a later time in larger amounts. So there, that's what crystallization has to do with evolution and natural selection.

Then if you continue on that basis, and study where the barrier between what lives and doesn't live, you'll find that it is hard to draw a finite line. The barrier between extremely basic lifeforms and complex non-living things is extremely difficult to define. They are extremely similar, which would suggest that the complex non-living things (which 'evolved' from the simpler substances) must have evolved into these simple lifeforms (bacteria), which were more successful at reproducing themselves than the original non-living things, and as such became more common, and then you can apply proven science to get the rest of the lifeforms that exist.

This post is just a hypothesis derived from the logical conclusion in the last post I made. It probably oversimplifies things, but a "hand of god" action does not appear to be necessary to create life from non-life. (Note that I said "life from non-life", you could argue that the non-life would not exist without god, and I probably wouldn't have anything to disagree with that point.)

"you could argue that the non-life would not exist without god, and I probably wouldn't have anything to disagree with that point."

I was told long ago, as a child, that: the only people who should roll dice are those who are prepared to roll a 1.

This correlates also, obviously, to deities who choose to use quantum mechanics.

Perhaps this deity IS prepared to roll a 1. You have a reason to not believe it, but it isn't conclusive proof of its non-existence. Also, you assume that the deity has no influence on the outcome of the dice, that they didn't load it for a 6 before they rolled.

"Surely a substance that does this[grow] better than others will be more likely to exist at a later time in larger amounts."

That was the thrust of my arguement, but i think you take it too far, at least from what we know.

The position i'm trying to make is that some chemcials(systems) do indeed exhibit 'life-like' qualities, while not being life, and thus similar systems are capable of exhibiting the same - though this does not demonstrate some kind of evolution in systems which are on the life/non-life divide, it does demonstrate that the same properties are possible.

As for the divide, i'd imagine that we're great at understanding simple systems, and it takes a lot more work to figure out what's going on when they become complex - thus I would propose that 'chemistry' is a study of simple 'chemical' systems, which we can understand, but complex chemical systems become much harder to intuitively understand -> up until the point where we can simplify our understanding again and refer to them as 'biological' systems.... with simple cells which we identify as the basic unit, and cell functions understood from a marco-scopic perspective rather than a basic chemical one...

I'd guess there are a few people in the world who do have a decent understanding of molecular cell biology, as a static discipline (ie how cells which exist today actually manage to function) but not as these systems change over time, or how to invent such systems from scratch, or what other kinds of systems might have similar qualities.... because it's way too complex.

oh, and homochirality doesn't figure into my conversation. Great - some molecules are single-handed, there may even be chemicals like 'prions' which convert left-handed chemicals into right-handed ones... there is tonnes of room for that within chemistry.

Long way to go yet guys. Can you really extrapolate from your simple systems to to explanations for the origins of movement, respiration, sensitivity, growth, reproduction, excretion and nutrition? That is actually where you need to go. Oh yes and we have rather forgotten my first point: ''evolution by natural selection has nothing to offer on the origin of life''. Do you remember?

On chirality why not a racemic mixture of aminjo acids in your soup, and hence no life at all? That has got to be the Occam position.

@fullham:

I used to believe very similarly to you, ie. that microevolution was possible and macroevolution is impossible - I always asked people how you explain the evolution of gender.

But the more genetics I learned, the more I realized how ridiculously complicted life is. For example, did you know that bacteria have what essentially amounts to a sex organ? It's called the sex pilus, and it transfers a plasmid (mini-chromosome) from one bacteria to another. Learning that was the first time I ever began to think macroevolution might be possible.

So to answer your question more directly, yes, I can. The evolutionary selection pressure for movement seems obvious - escape predators and find food. Respiratory systems allow you to grow bigger organisms with bigger brains that allow you to do more complex tasks. Sensitivity to ones environment allows for more precision of motion instead of the random tumbling exhibited in e coli. Etc.

And as to chirality, it might interest you to know that there are strains of bacteria which use both the L and D enantiomers of amino acids. And homochriality, which does largely exist, is probably an accident of evolution and astonishingly further evidence of it. It's not that L provided any evolutionary benefit, but rather that the first organism to use amino acids could only make L ones - if it wanted to make R ones, it would have to evolve ANOTHER mechanism, which wouldn't really be very useful, since that would take time, energy, and genetic space, all of which are at a premium in the evolutionary world.

@ smiley face this debate is not about evolution by natural selection, but rather whether it has a role in abiogenesis.

On chirality the first organism you propose must also be completely homo-chiral too. That would be rather remarkable I think, almost literally miraculous I think.

The organism wouldn't necessarily be homo-chiral; why would it? All it needs to do is have a way of making one and just one of the enantiomers, and then be able to pass that way onto its progeny.

So each of the amino acids that formed each of the essential peptide chains, both in terms of number and variety, were miraculously produced in a homo-chiral form in your original organism? What do you think that the odds might be against this, particularly given the requirement for original movement, respiration, sensitivity, growth, reproduction, excretion and nutrition?

"So each of the amino acids that formed each of the essential peptide chains, both in terms of number and variety, were miraculously produced in a homo-chiral form in your original organism?"

Not necessarily. There's a term for the world of early life called the RNA world. It refers to the fact that RNA is capable of being both an enzyme AND a unit of information storage. They think that RNA originally did the majority of the catalytic work in the evolutionary world, not amino acids. So you have RNA, and then you evolve a way to make a single amino acid - that's your L enantiomer. Then you start using that in things, and everything is dependent on using the L enantiomer. Soon you evolve the ability to make polypeptides, which can do even more things, and then finally (or maybe not finally) proteins.

"What do you think that the odds might be against this, particularly given the requirement for original movement, respiration, sensitivity, growth, reproduction, excretion and nutrition? "

You're asking the wrong question. The original odds aren't really relevant here. Well they are. But not in the way you're asking it. The odds are undoubtedly miniscule, regardless of the theory. But the question is given that life exists how it does, what are the odds that we evolved this way? And I think those odds are pretty damn high. We have an inherent selection bias. Our time-cone in the universe is not randomly selected. By virtue of our existence, it's selected for the presence of sentient organisms.

RNA has homo-chiral ribose.

Next step........the extra-terrestrial explanation!

''The odds are undoubtedly miniscule, regardless of the theory.''

Well I can think of one old well-established theory where the odds are actually 100 %. I can't prove it to you, but I can say that it is a lot more likely than the miniscule likely mechanism which you propose.

No, you definitely can't. Either you take that theory of yours literally and at face value, in which case your theory is ostentatively wrong, or you can take it figuratively, in which case it isn't well-established at all since there exists million different interpretations of it and you don't have any measure to say which one is better than the other – about as well-established as a theory explaining the meaning of life.