[Poultricidal]

I have recently been wondering about the first steps of how life began from nothing. I know this is an impossible question to ask, but im just asking for theories, how can 'life' just exist (chemical reactions, geological mutations, creationsm(i dont care, i havent any clue))

[Iain]

The one thing everyone can agree on, I think, is that life didn't begin from nothing. I guess the creationists would say that life began with God. I'd say that life is a particular arrangement of chemicals which has particular properties (e.g self-replication) which emerged from non-living arrangements of chemicals through particular sets of events.

As for how exactly it happened, we don't know; but there are lots of theories. These include life emerging in a primordial "soup" of chemicals, around hot vents on the ocean floor, or even being carried to Earth from elsewhere (though that just passes the question onto somewhere else).

[bradley]

i find abiogenesis to be the one of the most fascinating mysteries of all, and one I would dearly love to help elucidate once I get my Biochemistry degree (and if i decide that i actually like research, and to focus on more esoteric pursuits in science than helping the fight against AIDS or something).

I wrote a brief article for my old school's newspaper a few years ago (excuse the ramblings of a 16-year old) but by all means read into abiogenesis. Because pretty much nothing is known about it, you should have no difficulty coping with the science involved - all the experiments that have been done are fairly straightforward, and quite nice; I'll copy-paste the article at the end.

I think the man/woman that proposes a watertight and plausible theory for how life arose from 'chicken soup' is going to be the next Darwin, in terms of fame at least, if not imagination. It is a massive question, and I look forward to the time when someone provides a concrete answer that i can believe in - we won't know if it is the absolute truth, but like evolution, we can accept it as such. Telling the world where Life comes from will be another nail in the coffin of organised religion. Furthermore, abiogenesis represents for me the very point where physics, chemistry and biology (or rather, biochemistry) all come together.

The Origin of Life


It wasn’t until 1859 that the accepted idea that life, in the form of animals, could spontaneously arise from a pile of organic matter, was rejected, by none other than Louis Pasteur. He showed that new organisms could not just appear magically out of nowhere – thus asking for the first time the question “How did life originate on this planet?”, and setting the ball rolling for a field so dense in theories that it has become a subject in its’ own right - exobiology. Before we can begin to answer that question, we first have to define ‘life’. Once we know what it is, we can then put forward theories as to how it arose on this planet.

My definition of life is an organic, localised habitat which has achieved a certain degree of homeostasis and can replicate. The habitat might be a cell or a multicellular organism. Within that habitat several interlinking chemical reactions and cycles take place, however overall there is a net - but dynamic - equilibrium in the concentrations of the various chemicals present (in other words, homeostasis). Obviously in the real world the equilibrium fluctuates as conditions change. But the point of homeostasis is that to a certain extent these fluctuations are ironed out, compensated for by the metabolisms. For example, if a particular substrate were to enter the habitat, a reaction it is involved in would speed up to reduce the concentration.

The replication involved doesn’t have to be perfect. As long as the original habitat can spawn a separate entity that resembles it, even though it might be slightly mutated, I still count that as replication. Even today our highly evolved form of life still is somewhat inaccurate when it replicates (though we usually repair the mutations so we don’t get to see their effects). That implies that the error percentage must have been much higher millions of years ago. Basically, the first life form must be able to pass on genetic information to another generation.

There exist many theories of how life arose on this planet, but they can nonetheless be placed in two general categories. There are some scientists who believe the homeostatic habitat and the replication machinery arose separately and then merged together because the system formed was symbiotic, i.e. the merged form had greater chances of survival than the two separate entities. By natural selection, the merged form would have become the dominant species.

The other category of scientists think life arose when a molecule formed that could catalyse reactions to create homeostasis around it, and could also act as a template for the formation of molecules identical to itself. Each one of these properties, observed on its’ own merits, is possible. However it is pretty much unheard of – and relatively improbable – that such a molecule could arise by chance.
Let’s first look at a dual-origin theory. It has been mathematically modelled that in a closed environment, homeostasis can spontaneously occur. The presence of enzymes would make this even more likely because they can be inhibited and promoted, setting up negative feedback loops. Because the ‘cell’ cannot reproduce, it cannot evolve. In parallel, a molecule formed that could act as a template for copies of itself to be made. If, again by chance - for that is what all these theories revolve upon – the molecule, like a virus, got into the ‘cell’ and the enzymes there could make copies of it, then it could have evolved. In this situation, it would be acting as a parasite. This is not unheard of – today we all carry mitochondria, which look more and more like they did exactly that – infect and parasite a cell, leading to a symbiosis of the two. Lynn Margulis and Andrei Oparin are the main proponents of this theory.

Natural selection would of course favour mutants of the replicative molecule that could catalyse the formation of the enzymes that copy it, or that had some other chemical behaviour that protected the enzymes that copy it. This is perfectly possible. Gerald Joyce, amongst others, showed that DNA can cleave proteins, whilst other experiments suggest it is the RNA in ribosomes that forms the peptide bonds between proteins. The genetic-information carrying molecule could well have had primitive secondary activities that would be beneficial to a cell. A symbiosis would ensue which would help the survival of the cell structure and the replicating molecule, together. Which is exactly what we have today, in a far more advanced form – our society, our family, our body, and our cells are extremely complicated – but they all serve the same purpose: they make it easier for us to survive and to pass on our genetic material.

Of course, you could use the conclusions of the various experiments that I mentioned above to support the single origin theories. Let me explain: a nucleic acid polymer like RNA, or TNA (which is easier to synthesise so is more likely to have formed) could have spontaneously arisen – this is highly unlikely, especially compared to the relative ease with which we can synthesise amino acids (the components that make up enzymes), but theoretically possible. Some RNAs, like the ones I described above, can be bred so that they can both cleave themselves AND polymerase themselves. This, supporters say, is the solution to the chicken versus egg problem – you don’t in this case actually need proteins to explain the origins of life, since RNA can act as an enzyme and genomic molecule. This is improbable, but experimentally possible given the right conditions, especially given the billions of years that elapsed between the formation of the Earth and the creation of life. What I find too far fetched to believe is that these molecules could ALSO catalyse the formation of a cell around itself!

In either case, a molecule capable of replicating would have had to come about. Although it is very improbable, a molecule resembling RNA could have formed from base units floating around (nucleotides or similar molecules), who themselves would have formed from raw materials (carbon dioxide, nitrogen, etc) taken from the environment. This is possible - each step I have just described has been more or less replicated under lab conditions in many experiments, notably those of Stanley Miller, Manfred Eigen and Leslie Orgel. If we are to believe this theory, we have to assume hundreds of similar units formed, and then polymerised, and that more and more of these units formed to allow replication.

The sheer implausibility of this suggests that enzymes, or some other catalyst first came into existence that could build nucleotides. One theory I came across, the Cairns-Smith theory, suggested that the original replicating molecules were not organic molecules. Clay, when it dries, forms crystals, and these crystals can be flawed, like an imperfect diamond. Crystals grow, and as they do, the flaws in the original ‘seed’ are reproduced throughout the ever-growing crystal. If bits of the crystal were to flake off, they would carry the flaw pattern of the original seed to another location where, if conditions were favourable, the flake would seed the growth of a new crystal, which had the same flaw pattern… etc.
Clays contain transition metals regularly interspersed in their structure. In fact, a common clay, montmorillonite, catalyzes the synthesis of RNA oligonucleotides. Leslie Orgel demonstrated that zinc was a particularly good catalyst for the synthesis of nucleic acids. Through natural selection nucleic acids thrived because they was better at surviving in harsh conditions or replicated faster than the clays that had given rise to them. This theory is compelling because the clays could evolve through natural selection, making the development of a specific catalytic behaviour less improbable than just assuming things can auto-assemble and have advanced properties at the same time.

I personally prefer the dual-origin hypothesis. The odds that a complex nucleic acid molecule formed that could replicate and create a specific environment around it to protect itself are unacceptably small. On the other hand, the presence of enzymes would remove one of these demands, and reduce the odds – it would just have to be a template. Or, a protocell formed (a membrane-bound, homeostatic ‘organelle’, as well as a semi-replicative molecule, and that these merged and symbiosed, becoming inseparable. It’s up to you to decide whether the informational molecule (nucleic acid) or the catalyst (protein enzyme) came first, or if they both arose at the same time, in the same molecule. I have only scratched at the surface of the various theories – there are so many you can undoubtedly find one you will be comfortable with.

Philippe Bradley

Further reading:
The Origin of Life – Freeman Dyson
The Chemistry of Life – Stephen Rose
The Origins of Life on the Earth; Miller, S. and Orgel, L.E.

[Adam_Smith]

I do not wish to violate PoFo rules against touting another message board so I will not name the message board or provide a link but honesty compels to inform you that what follows is copied from another message board and is not of my own authorship but of someone going by the login of "Oxy-moron".

Here's what Richard Dawkins the worlds premier authority on the subject has to say about Evolution:

"... it was Darwin who first put together a coherent and tenable account of why we exist." [p1. The Selfish Gene]

The scope of the theory of evolution.

"Evolution works by natural selection, and natural selection means the differential survival of the 'fittest'." [p7 TSG]

"... but evolution is blind to the future." [p8 TSG]

Evolution is a blind process with no foresight about what mutations will and will not work.

"Darwin's theory of evolution by natural selection is satisfying because it shows us a way in which simplicity could change into complexity, how unordered atoms could group themselves into ever more complex patterns until they ended up manufacturing people. Darwin provides a solution, the only feasible one so far suggested, to the deep problem of our existence." [p12 TSG]

Shows that Dawkins presupposes that evolution is the only possible solution to the deep problem of our existence. It is this presupposition which allows him and others to believe the astrnomically improbable.

"Darwin's 'survival of the fittest' is really a special case of a more general law of 'survival of the stable'. The universe is populated by stable things. A stable thing is a collection of atoms that is permanent enough or common enough to deserve a name ... The things that we see around us, and which we think of as needing explanation -
rocks, galaxies, ocean waves - are all, to a greater or lesser extent, stable patterns of atoms. Soap bubbles tend be spherical because this is a stable configuration for thin films filled with gas. In a spacecraft, water is also stable in spherical globules, but on earth, where there is gravity, the stable surface for standing water is flat and horizontal. Salt chrystals tend to be cubes because this is a stable way of packing sodium and chloride ions together. In the sun the simplest atoms of all, hydrogen atoms, are fusing to form helium atoms, because in the conditions that prevail there the helium configuration is more stable." [p12 TSG]

Shows that the theory of evolution as it stands is not particular to biological systems and does not rely on any special biological laws. Biological processes could not predate biology organisms anyway.

"Before the coming of life on earth, some rudimentary evolution of molecules could have occurred by ordinary processes of physics and chemistry. There is no need to think of design or purpose or directedness. If a group of atoms in the presence of energy falls into a stable pattern it will tend to stay that way. The earliest form of natural selection was simply a selection of stable forms and a rejection of unstable ones. There is no mystery about this. It had to happen by definition." [p13 TSG]

Evolution before life, before DNA, on molecules. Only driving force being physics/chemistry. His circular reasoning that since evolution is the only possible explanation of life, therefore pre-life evolution
must have occured by logical necessity.

"The account of the origin of life that I shall give is necessarily speculative; by definition, nobody was around to see what happened. There are a number of rival theories, but they all have certain features in common." [p14 TSG]

Admits the wholly speculative nature of the theory of
evolution. Dawkins account is the standard one, common to all variations.

"At some point a particularly remarkable molecule was formed by accident. We will call it the Replicator. It may not necessarily have been the biggest or the most complex molecule around, but it had the extraordinary property of being able to create copies of itself. This may seem a very unlikelly sort of accident to happen. So it was. It was exceedingly improbable." [p15 TSG]

Dawkins concedes that the likelihood of even the first step happening in the evolutionary chain was exceedingly improbable. But by taking evolution as a given he is willing to believe in the exceedingly improbable.

"... erratic copying in biological replicators can in a real sense give rise to improvement, and it was essential for the progressive evolution of life that some errors were made. We do not know how accurately the original replicator molecules made their copies. Their modern descendants, the DNA molecules, are astonishingly faithful compared with the most high-fidelity human copying process, but even they occassionally make mistakes, and it is ultimately these mistakes which make evolution possible." [p16-17 TSG]

Evolution fundamentally relies on random genetic mutation. As Richard Dawkins himself points out it is the mistakes in copying of DNA which makes evolution possible, otherwise known as random genetic mutation.

To summarize, according to Professor Richard Dawkins of Oxford University, the most famous and emminent evolutionary biologist alive today, who also holds the university chair in the Public understanding of science and has written several best selling books on the subject
(The Selfish Gene, The Extended Phenotype, The Blind Watchmaker, River out of Eden, Climbing Mount Improbable and Unweaving the Rainbow):

1. Evolution explains why(how) man exists.

2. Evolution is blind to the future.

3. Darwin's theory of evolution by natural selection shows how unordered atoms could group themselves into ever more complex patterns until they ended up manufacturing people.

4. Darwins' theory provides the only possible solution to our existence.

5. Evolution is not particular to biological systems. Indeed as it stands evolution must have predated biology in order to create biological systems in the first place. This pre-biological evolution relies on random chance and only the basic laws of chemistry/physics.

6. Evolution necessarily relies on the existance of non-biological "replicators" simple enough to be formed by chance, but complex enough to produce life. No one has ever seen or stated the form of these replicators.

7. Admits the necessarily speculative nature of the theory of evolution i.e. it is without direct evidence.

8. Evolution fundamentally relies on mistakes in the copying
procedures of replicators. In genetic terms this corresponds to random mutation. Biological evolution is therefore necessarily and fundamentally driven by random genetic mutation.

9. Evolution relies on the astronomically improbable, but what allows us to believe in the overwhelmingly unlikely is the pre-existing belief that evolution is correct. A circular justification if ever there was one.

I have not read The Selfish Gene, but I have read some short essays by Dawkins and some discussion of his theories. I think his is probably the best explanation of evolution currently available.

[bradley]

i agree with most of that article; it is stating the obvious in any case. It is not til the very last line that i think whoever wrote that is talking bollocks

9. Evolution relies on the astronomically improbable, but what allows us to believe in the overwhelmingly unlikely is the pre-existing belief that evolution is correct. A circular justification if ever there was one.

this comes from the analysis that

Dawkins concedes that the likelihood of even the first step happening in the evolutionary chain was exceedingly improbable. But by taking evolution as a given he is willing to believe in the exceedingly improbable.

this analysis is false and demonstrates a very poor understanding of the actual science involved. The Replicator did not evolve. It is the Adam and Eve molecule. Just as Adam had no belly-button, having had no mother, this Replicator did not evolve. It formed. That is the whole point of abiogenesis - somewhere along te line there is an origin; origins don't evolve. I have explained some of the theories of how such a molecule could have come to bear, for example Cairns-Smith's theory involving clays and transition metal ions.

As for this formation being astronomically improbable: I agree it is improbable at any given instant. But over billions of years it becomes a lot more believable. perhaps if the Replicator came to us from a different planet, not only would life have had even longer to arise, but that planet might have had much more favourable conditions in which the Replicator could form.

[Iain]

It really does show how feeble Creationist arguments are when they have to twist the words of others to such extremes to support their case. Oxy-moron obviously hasn't read anything by Dawkins - he/she could not have done so and believed that these points were an accurate reflection of his views.

This tactic of taking fragments of different works, or different parts of works, out of context and stringing them together to form a narrative is dishonest and I find it difficult to believe that those who do it do not set out to deceive.

I imagine that people like oxy-moron simply believe what they are told, rather than actively trying to deceive, but I could be wrong.

1. Evolution explains why(how) man exists.

Yes to the extent that it explains how we evolved; no, it does not explain the origins of life, or of the universe.

2. Evolution is blind to the future.

Yes. True - full marks.

3. Darwin's theory of evolution by natural selection shows how unordered atoms could group themselves into ever more complex patterns until they ended up manufacturing people.

Roughly true.

4. Darwins' theory provides the only possible solution to our existence.

The only solution that is supported by the evidence we have. Of course there are other possible solutions, but the evidence doesn't support them.

5. Evolution is not particular to biological systems. Indeed as it stands evolution must have predated biology in order to create biological systems in the first place. This pre-biological evolution relies on random chance and only the basic laws of chemistry/physics.

In a sense, yes, but an understanding of what is meant by evolution in the different contexts is important.

6. Evolution necessarily relies on the existance of non-biological "replicators" simple enough to be formed by chance, but complex enough to produce life. No one has ever seen or stated the form of these replicators.

Not true (confusing evolution with the origins of life; this is the classic error of using a word with two different meanings and switching between them).

7. Admits the necessarily speculative nature of the theory of evolution i.e. it is without direct evidence.

Not true, see 6.

8. Evolution fundamentally relies on mistakes in the copying
procedures of replicators. In genetic terms this corresponds to random mutation. Biological evolution is therefore necessarily and fundamentally driven by random genetic mutation.

True.

9. Evolution relies on the astronomically improbable, but what allows us to believe in the overwhelmingly unlikely is the pre-existing belief that evolution is correct.

Not true; there is nothing improbable about evolution.