Since this topic keeps coming up, and is often confused with evolution... I figured I'd start a thread on it...

First, I want to start by defining Abiogenesis and Evolution.. to clearly define what we are discussing here:

Abiogenesis: The study of how life on Earth emerged from inanimate organic and inorganic molecules.

Evolution: Change in the genetic composition of a population during successive generations, as a result of natural selection acting on the genetic variation among individuals, and resulting in the development of new species.

Our discussion on Abiogenesis will end up blurring the line between living, and nonliving... so please, if anyone can come up with a suitable definition to use, please let me know, and we'll add it here... (viruses are not "alive", yet they are... life is a tough term to define...)

Here are some of the more popular theories and supporting theories/hypotheses:

First, we have proven that in the conditions here on earth billions of years go, that Organic Monomers and polymers can form... assuming this... here go some of the more popular theories...

Here's where it gets tricky... try and bear with me

Deep Sea Vent Theory
Hydrothermal vents, deep under the ocean surface constantly "bubble" hydrogen saturated fluids, which react chemically with Carbon Dioxide in solution with Water. Providing sustained energy for chemical reactions with organic molecules to take place.. eventually leading to the development of a protocell.

Metabolism First
Iron-Sulfur World Theory:
Sustained chemical reactions create a primitive "metabolism" by producing energy that can be harnessed by nearby compounds. This Metabolism is hypothesized to be a reaction involving acetic acid (A very basic Carbon, Hydrogen and Oxygen compound). Once this sustained chemical reaction is established, even more complex compounds develope, eventually forming the protocell. Acetic acid is still an important part of the citric acid cycle in cell metabolism.

Self- Replicators First:

Clay Theory:
Complex organic molecules form around pre-existing non-organic replicators. Crystals are the best example of this. Crystal molecules contain all the information needed to create a near identical crystal molecule, thus, crystals are non-organic replicators.

RNA World Hypothesis:
Of the polymers that formed, short RNA molecules form... these chemicals replicate themselves when in the presence of the amino acids (monomers). RNA replication "errors" lead to different RNA "families" existing simultainiously. Eventually, RNA molecules with the arrangements most conducive to allow the molecule to replicate most prolifically... Cell membranes form from proteinoids, which are produced when amino acid solutions are exposed to heat... the combination of RNA and the proteinoid cell wall form the first protocell.

Lipid Rings and Amphiliphiles:
Lipids and amphiphiles naturally form membrane like surfaces on top of water. waves cause these membranes to form bubbles. These bubbles contain water as well as monomers/polymers that would have been present in the oceans. Some of these proteins/amino acids may have strenghtened the surface of these sphyrical membranes... the concentration of the organic compounds within the structure gain concentration as water evaporates. These bubbles in the long run, end up bursting, releasing their organic compounds in stronger solution than the surrounding area... effectively "seeding" other bubbles, and forming the first replicating protocell.

Even though this isn't abiogenesis, I feel it should deserve a mention:

Panspermia/Exogenesis:
the hypothesis that life did not start on Earth, but instead started elsewhere in the universe. There are various ideas about how life may have made it to earth under this hypothesis. Some of these ideas include meteorites/comets, intelligent life, "seeds" being present when the earth was nothing more than a debris cloud.

There are many other ideas as to how abiogenesis may have happened, I only mentioned a few... It is probably important to note that I am nowhere near an organic chemist, I'm a History Major with only the basic college courses in chemestry and biology...

I would like to see other people's favorite theories on this topic, and perhaps discuss evidence for and against each theory/hypothesis that's out there...

As this is a thread on abiogenesis, the idea that a "magic man done it" won't fly...

thoughts anyone?

Mate have you looked at the sheer likelihood of the formation of nucleotides or complex polypeptides where a complex 3D structure can be formed from amino acids quite far away from a functional centre, e.g. an enzyme active site. When you do, the chances of such molecules forming, even under extreme physical and chemical conditions are seen, even by researchers in the field, as mysteries.

Most scientific research has huge question marks in it - I just substitute the word God for the question marks and it satisfies me. Whether He achieves this monumental act of Creation through a limited action or through a bit of evolution does not alter my faith in the least. I remain open minded about the origin of Man. The only thing I cannot accept is that current evolutionary theory denies the concept of a soul to Man. So according to the erudite and brilliant Professor Dawkins, we are soulless robots. What a sad comment on humanity...

Personally, I'm more apt to accept the RNA world hypothesis based on the recent work by Dr. Szostak. However, I'm not really qualified to get into the nitty gritty of debate between RNAworld and other hypothesis - even if I understand their basic precepts.

I will say, however, that I don't particularly like the concept of Panspermia. This isn't because I don't think the theory is valid, or plausable, but only because it really doesn't explain anything. If life originated on Mars (for example) and was somehow transferred to Earth by a meteorite impact or some-such - we would still be left with the question of: "How did life first originate on Mars"?

Even if life didn't originate on Earth, we still need to figure out how life did first originate.

Originally posted by Heronumber0
The only thing I cannot accept is that current evolutionary theory denies the concept of a soul to Man. So according to the erudite and brilliant Professor Dawkins, we are soulless robots. What a sad comment on humanity...

Well what are souls? We have no evidence of them. Are we soulless? yes. But robots? I don't know why anyone would say that.
Either way, the soul is not necessary in science, and is a different subject all together.

Originally posted by Heronumber0
Mate have you looked at the sheer likelihood of the formation of nucleotides or complex polypeptides where a complex 3D structure can be formed from amino acids quite far away from a functional centre, e.g. an enzyme active site. When you do, the chances of such molecules forming, even under extreme physical and chemical conditions are seen, even by researchers in the field, as mysteries.

They have shown (and reproduced in a lab) that Monomers and Polymers are fully capable of coming into existence given the conditions on earth at the time... once you have complex organic compounds, it would be only a matter of time until one came together as a very very basic RNA strand... Doesn't even have to be RNA, all thats required is a self replicating molecule...

The only thing I cannot accept is that current evolutionary theory denies the concept of a soul to Man. So according to the erudite and brilliant Professor Dawkins, we are soulless robots. What a sad comment on humanity...

The idea doesn't have to be "comfortable"... It really sucks that when we die we're worm food...

That doesn't mean I'm willing to live a comfortable lie over an uncomfortable truth...

Why complicate?
Use the Occam's razor.
Where there is exchange there is life.
Replication is not necessarily quality of life.
There are a one time living beings.

Exchange implicates repeating process with some purpose, that alone would encompass reproducing. But if some "being" doesn't reproduce, it doesn't mean it is dead.

Many people don't have offspring, drones do not reproduce...
Now in order to "make them alive" you need the idea of a species.
That complicates things.

Originally posted by DangerDeath
Exchange implicates repeating process with some purpose, that alone would encompass reproducing. But if some "being" doesn't reproduce, it doesn't mean it is dead.

Hrm... That is true, it does not... however from an evolutionary standpoint, the biological goal of life is to reproduce.

Many people don't have offspring, drones do not reproduce...
Now in order to "make them alive" you need the idea of a species.
That complicates things.

Stop me if I'm wrong, but I think you're referring to something like bees? Where most bees do not reproduce, instead leaving it to the queen?

This is a more complicated type of "life"... and is akin to a multicellular organism... each cell (or drone) is furthering the existence of the whole.

I haven't defined "Life" and "Alive" in my OP because of the fact that its a pretty difficult thing to define to begin with... That, and the fact that a discussion on abiogenesis would blur those lines...

at what point do we consider something alive?

I'll happily edit my OP if someone can present me a suitable definition to use for the purpose of discussing abiogenesis.

Evolutionary standpoint is mutation. Evolution is not an ideology. Evolution has no purpose. It is a chance mutation.

Bees, ants, termites, many others. That's why I call for Occam's razor. I am only looking for a basic definition of life.

I am not criticizing your OP. I have been thinking about this before and I concluded that "exchange" most certainly exists in life, so I decided to look right there, before we can even distinguish genre or species. And you can say, there is no life without exchange.

Crystals? They do "reproduce" or "replicate", but is it life?

Maybe the idea of life is similar to the idea of "isolated system", but since isolated system is a consensual idea, which determines "limits" and there actually is exchange of energy and matter between this "isolated system" with the environment, I think that this could be close to definition of life.

An isolated system which establishes a flow, an exchange of matter and energy.

Introduction of idea is necessary, because it is consciousness.

So: Conscious exchange could be the definition of life.

Originally posted by Rren
which tops the list on an ATS search for "abiogenesis," has some good info if you're interested.

Yah, I did a search and read through some of those threads... none of them were quite what I was looking for... but yes, lots of decent info.

Perhaps all this explains why origin of life theorists are so excited about these new reports of more amino acids from Miller’s outdated and highly implausible experiment: they’re a bit over-eager for some good news.

Miller's experement has been updated though... and results published just this year... (Miller's original setup was flawed, in that the atomsphere he created was not accurate...)

Also, if memory serves, Heronumber0 is a scientist (biology) and/or a science teacher.... perhaps he can chime in.

I would love for someone more qualified to chime in Hopefully he's as unbiased as possible!

Right. Easy. Any day now. Organics + deep time + energy = *poof* life. Magic sky guys need not apply. The last fifty or so years of research were just a fluke. Really, it's easy. (just kidding around, stay calm )

LOL i'm calm, dun worry

I don't thing you're appreciating the enormity of the problem

Oh I get the enormity, and the probabilities involved... However, think of the sheer amount of organic molecules that would have been present... then think of the amount of time involved...

Probability might be low, but this is why its not happening everyday all day...

An event such as this, only needs to happen once.

There's also the fact that self replicating non-organic compounds appear here naturally on earth... This could potentially be the beginnings of another process of abiogenesis happening right under our noses...

The ability to self-replicate is the key... once something starts self-replicating, all sorts of possibilities open...


[edit on 15-12-2008 by nj2day]

Originally posted by nj2day
Deep Sea Vent Theory
Hydrothermal vents, deep under the ocean surface constantly "bubble" hydrogen saturated fluids, which react chemically with Carbon Dioxide in solution with Water. Providing sustained energy for chemical reactions with organic molecules to take place.. eventually leading to the development of a protocell.

Metabolism First
Iron-Sulfur World Theory:
Sustained chemical reactions create a primitive "metabolism" by producing energy that can be harnessed by nearby compounds. This Metabolism is hypothesized to be a reaction involving acetic acid (A very basic Carbon, Hydrogen and Oxygen compound). Once this sustained chemical reaction is established, even more complex compounds develope, eventually forming the protocell. Acetic acid is still an important part of the citric acid cycle in cell metabolism.

Self- Replicators First:

Clay Theory:
Complex organic molecules form around pre-existing non-organic replicators. Crystals are the best example of this. Crystal molecules contain all the information needed to create a near identical crystal molecule, thus, crystals are non-organic replicators.

RNA World Hypothesis:
Of the polymers that formed, short RNA molecules form... these chemicals replicate themselves when in the presence of the amino acids (monomers). RNA replication "errors" lead to different RNA "families" existing simultainiously. Eventually, RNA molecules with the arrangements most conducive to allow the molecule to replicate most prolifically... Cell membranes form from proteinoids, which are produced when amino acid solutions are exposed to heat... the combination of RNA and the proteinoid cell wall form the first protocell.

Lipid Rings and Amphiliphiles:
Lipids and amphiphiles naturally form membrane like surfaces on top of water. waves cause these membranes to form bubbles. These bubbles contain water as well as monomers/polymers that would have been present in the oceans. Some of these proteins/amino acids may have strenghtened the surface of these sphyrical membranes... the concentration of the organic compounds within the structure gain concentration as water evaporates. These bubbles in the long run, end up bursting, releasing their organic compounds in stronger solution than the surrounding area... effectively "seeding" other bubbles, and forming the first replicating protocell.

I don't normally participate in this forum since there is so much confusion over the basic tenets of evolution but I will make an exception in this case. I've come across a few supporters of the RNA World. As someone who's been active in the field for several years, I'm going to challenge your thinking on this model. Here's a list of my issues with RNA:
1) RNA nucleotides have NEVER been synthesized under viable prebiotic conditions. Nucleobases have been found in meteorites but the bases themselves (minus the phosphate and ribose) are not RNA.
2) The phosphodiester backbone of RNA is swiftly hydrolyzed by iron sulfides (pyrite; VERY common). Even if we did have a pathway for synthesizing RNA, it wouldn't last long enough to be useful.
3) RNA is extremely fragile (even in the absence of pyrite). Extreme temperatures and pH would confine RNA to very narrow ranges that were unlikely to exist during the Late Hadean when life was thought to have originated. The same flexibility which is responsible for RNA's catalytic capacity also decreases it's stability. While the addition of lipids have been shown to shield RNA from hydrolysis (by pyrite) to varying degrees, liposomes are not without faults of their own. Myrstoleic and oleic acid liposomes commonly employed in laboratory studies have very narrow pH ranges (~7-8.5) which again, would not have been viable.

Might I suggest reading the work of Michael Russell (NASA-JPL)? His work takes these factors into consideration (unlike research produced by the Szostak lab). If you'd like me to dig up some of his more interesting papers, I'd be happy to oblige.

[edit on 15-12-2008 by X-tal_Phusion]