Yeah, I'd say that a requirement for "life" coming from previously "non-living" things is impossible without those "non-living" things evolving.
Of course we can't go back in time to find out how it actually happened, but chemical and molecular evolution happens all the time. There are selection pressures on "non-living" systems too.
One thing to consider is that there is no clearly defined line between what constitues life and non-life.
I mean just some simple protocells can sit and replicate as long as there is a steady supply of fatty acids or phospholipids. If they were sitting on some montmorillonite (a clay found in scoopable kitty litter) with some nucleic acids and some ribose and you have RNA sitting in a vesicle. This isn't alive but the vesicles can reproduce by simply growing and dividing, which all rely on diffusion rates and surface area to volume. Throw in a supply of molecules that can enter the vesicle undergo hydrolysis and you just might have the beginnings of vesicles that can both reproduce AND evolve. Are they alive yet? I guess that would make them alive.
quote:The bilayer membrane that surrounds all present-day cells is thought to have spontaneously assembled from amphiphilic molecules (i.e., fatty acids). It has been demonstrated that fatty acid mixtures can form membranes and that these simple amphiphilic molecules could have existed in the prebiotic conditions of the early Earth. But primordial life also requires other ingredients, such nucleic acids. Mineral surfaces can catalyze the assembly of nucleic acids into RNA, but how these molecules became encapsulated in a vesicle membrane has been unclear. In the October 24 Science, Martin Hanczyc and colleagues at Massachusetts General Hospital report that clays can catalyze the formation of vesicles and that simple physicochemical forces can drive their growth and division (Science, 302:618-622, October 24, 2003).
Hi Gnojek. There's one problematic little phrase in your post which allows your majority opinion here on this board no more clout than the minority view. Here it is:
could have existed
Hi back, buzsaw!
Ok, I don't see the problem. Could have existed is the only way to put it. That's what science tries to figure out with regard to the inaccesible past, what could have been. Unless we have some kind of time machine, that's as good as it gets, the most plausible scenario.
That's what differentiates science from religion. Science says maybe, could have, and even most likely, while religion says most definitely based on an equal or lesser amount of evidence.
If you think you are in the minority and would like to be in a majority, there is another board here that's on your side. It didn't take me long to get banned from this one. If you are in the minority and you let the least bit of sarcasm or condescension in your posts, and you will be banned immediately with no warning. If you are a creationist, you can be as flippant as you want to be.
yes. you piqued my interest in seeing what the final result was for strict comparison to develop a preselected formation. if you do open it up to the probabilities of creating a soup with varieties of amino acid building blocks then each addition can be thought to have the same probability of bonding to any previous location, thus the fifth and last of a 5 bond molecule would have a 1 in 1000 probability with each of the previous 4, or a total 1 in 250 chance.
Hi RAZD, I'd just like to point out that the products of typical chemical reactions aren't nearly as random as that. Firstly, molecules are not normally built up bare atom by bare atom as the mental model here would imply. I could be totally mistaken about reactions in interstellar space. There is plenty of atomic hydrogen, but I'm not sure about oxygen, carbon, and nitrogen. I would think that carbon would be mostly in the form of methane, oxygen as water, and nitrogen as ammonia. So you usually start out with molecules that have to overcome an energy barrier to react with each other, and on the other side of that hill there is a distribution of thermodynamic states that the products can fall into. This severly limits the products of the reaction to one or two major products in most cases (especially for simple molecules of only a few atoms).
I'm sure I'm just misunderstanding Jacinto's probability exercise, though and I'm not too versed on space chemistry.