Abiogenesis, origin of life still happening today?

[evolutionquestion]

Is anyone in biology looking into Abiogenesis (origin of life events) still taking place today on Earth? I mean, why would something that happened in the past not still be taking place on Earth today within areas of the Earth that still have similar conditions to pre-life Earth. Places with volcanic activity perhaps?

 

I've looked online for this type of research but have yet to find it. However, I find it hard to believe no one is exploring that the creation of life isn't still taking place on Earth today.

[CharonY]

Research in abiogenesis is most likely to focus on reproducing the conditions in laboratory conditions rather than looking for it in nature. Even if there were organic molecules that may have been precursors of life, they would be rapidly utilized by the lifeforms that exist now. Thus, the likelihood of abiogenesis still to occur is extremely low.

[questionposter]

Is anyone in biology looking into Abiogenesis (origin of life events) still taking place today on Earth? I mean, why would something that happened in the past not still be taking place on Earth today within areas of the Earth that still have similar conditions to pre-life Earth. Places with volcanic activity perhaps?

 

I've looked online for this type of research but have yet to find it. However, I find it hard to believe no one is exploring that the creation of life isn't still taking place on Earth today.

 

Ya know, it honestly takes a billion years for a pool of just the right chemicals to get tampered with just the right amount of heat as to cause life. I doubt scientists can prove it in a single lifetime.

[JorgeLobo]

It is highly unlikely that the origin of life can be "proven" even if imagined conditions can be reproduced and viability elicited. In fact, biology has few if any "proofs. We have theories such as evolution based on and ther interpretation.

[rktpro]

The atmosphere at that time was reducing. A reducing environment can be obtained only in a lab; not at some place full of oxygen.

[Sorcerer]

Is anyone in biology looking into Abiogenesis (origin of life events) still taking place today on Earth? I mean, why would something that happened in the past not still be taking place on Earth today within areas of the Earth that still have similar conditions to pre-life Earth. Places with volcanic activity perhaps?

 

I've looked online for this type of research but have yet to find it. However, I find it hard to believe no one is exploring that the creation of life isn't still taking place on Earth today.

 

Personally I see the presence of plasmids, viruses and transposons (horizontal transfer) as evidence of early life still occurring today. These would have been very helpful at shuttling around RNA/DNA before there was full blown abiogenesis (IE cell replication/mitosis).

 

As for it still happening, all the niches have been filled and adapted to, outcompeting life with protolife doesn't fit evolution.

 

However it is possible there may have been several competing 'protolifes' during abiogenesis, after all competition can accelerate evolution and the emergence of life did happen fast on earth. Perhaps even archea and bacteria are 2 seperate abiogenesis events (but I doubt it).

Edited December 29, 2011 by Sorcerer

[CharonY]

The evidence (e.g. DNA codons) strongly suggests that all known organisms (i.e. including archea and bacteria) share a common ancestor. It is of course possible that several proto-life forms evolved but only one group survived. Current mobile genetic elements depend on relatively highly complex protein systems to facilitate their spread. Early mechanisms were likely much simpler (more in the form of ribozymes, for instance).

[Sorcerer]

Ribosomes are not THAT simple. I know plasmids/transposons/viruses need enzymes to facilitate their spread efficiently into other genomes, but whats efficient now would have been SUPER efficient then. DNA/RNA in close proximity and in the right environment will combine sometimes.

 

Yes I have heard the simple explanation of abiogenesis and it's not sufficient for me, very lacking. Sorry if I'm imposing my pseudo-hypothesis on u because what I was taught doesn't measure up to my expectations.

 

Edit: sorry with ribosomes and RNA we are reducing ourselves to a chicken or the egg argument. Proteins help multiply RNA and proudces proteins (ribosomes) with aid of tRNA. How did the RNA gain the complexity to produce the protiens? IMO through horizontal transfer - in a pre-biotic sense.

Edited December 31, 2011 by Sorcerer

[CharonY]

Ribozymes, not ribosomes. Ribozymes are essentially RNA molecules with catalytic properties (i.e. independent of proteins). Also you got it backwards in terms of efficiency. Now, due to complex cellular systems the required mechanisms are in close proximity (including specialized compartments, when thinking about eukaryotes and to a certain extent prokaryotes, too). Just putting everything into a big pot would dilute everything.

 

There is no strong consensus how early proto life could have been. Many favor a nucleic acid system, though there are proponents that postulate peptides as early replicating units. The mix of the two is almost certainly something that evolved later.

Edited December 31, 2011 by CharonY

[zapatos]

Personally I see the presence of plasmids, viruses and transposons (horizontal transfer) as evidence of early life still occurring today. These would have been very helpful at shuttling around RNA/DNA before there was full blown abiogenesis (IE cell replication/mitosis).

 

As for it still happening, all the niches have been filled and adapted to, outcompeting life with protolife doesn't fit evolution.

 

However it is possible there may have been several competing 'protolifes' during abiogenesis, after all competition can accelerate evolution and the emergence of life did happen fast on earth. Perhaps even archea and bacteria are 2 seperate abiogenesis events (but I doubt it).

That doesn't seem possible. There must be a huge number of resources, or combinations of resources, that a form of life could take advantage of. When a new form of a bacteria shows up that can cause illness, isn't a new niche being utilized?

[Sorcerer]

True zapatos I should've said all the simple niches, i.e. the ones that would be easy for a new abiogenesis to exploit. I don't really see an abiogenesis event going straight to a highly evolved (niche specialised) pathogen.

[LogicGates]

Hello all, I just registered here at Science Forums. I've read (actually listened to) Darwin's "Origin of Species" and am reading Dawkin's "The Ancestor's Tale", and have read a number of other articles on evolution, and seem some mention of speculations on the origin of life on earth. It seems that, like Dawkins, almost all professionals and students of biology take the view that all living things must have a single common ancestor, because Abiogenises is "extremely unlikely" to occur more than once within an extraordinarily long time span; and furthermore, that since all known life shares the same kind of DNA molecule, it would be "extremely unlikely" for such DNA to again form spontaneously from non-living chemicals. Repeatedly I read such verbal arguments. But isn't it fair to ask, how everyone can claim that it's "extremely unlikely" without at least showing some kind of calculation to derive a numerical estimate of this supposed "extremely unlikely" probability? I appeal to Lord Kelvin's famous statement, "when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be". No insult to biological science intended here, because I know it has advanced mathematically to a tremendous degree. But until such time as biological science, coupled with chemical science perhaps, can come up with some quantum-chemical calculation that provides a numerical estimate of the probability that Abiogenesis is indeed "extremely unlikely", is it unfair to ask everyone to quit making this claim, at least for the time being?

[CharonY]

I do not think that we know the parameters necessary to actually calculate probabilities. The current assumptions are based on the data that we have. I.e. the fact that all organisms ever found clearly share the same ancestors and that so far no exceptions have been found. It is for instance possible that early on life arose several times, however all but what we know today got eliminated.

The main argument is therefore less one of likelihood, but rather one of available data. And considering that all biological effects are well accounted for by known organisms, we do not have evidence that any kind of "hidden" alternative organisms exist on earth.

[Jens]

To LogicGates (as addition to all what CharonY already stated):

DNA is not the origin of life. It simple words it is something like a passive, stable and precise data store which evolved later.

Most scientists think that RNA is in the beginning, even though there are other theories also (but no ones assuming DNA as the beginning).

The main reason for this is that RNA can act as a template to copy itself and is capable of catalyzing chemical reactions, while DNA can not catalyze and protein can not act as a template.

 

To understand better have a look at this good web page (I am not promoting any of my work here, I have nothing to do with this page ): http://exploringorigins.org/

 

Yes, calculation of abiogenesis is impossible, because we do not know how the first living structure actually looked like. In this repect "living" is meant to be something which is able to reproduce itself and can undergo evolution to gain additional properties.

 

Taking the minimum set of current living organisms to think of a life form which can reproduce itself leads to a still incredibly complex structure: A long RNA to encode all of the RNA and proteins needed, a copy enzyme (including proofreading), a translation enzyme set, all the enzymes needed to produce the ribose in RNA, the 4 bases in RNA, the 20 amino acids in protein, the membrane molecules, some transporter proteins in the membrane, the enzymes for the energy metabolism to create the polymers (RNA and protein) out of the precursor molecules, some enzymes to overcome the detailed issues of linear or circular RNA replication, and much more. Just a primitive piece of RNA with 1000 bases (which is actually nothing) gives you 4¹⁰⁰⁰ combinations and a probality of 1 / 4¹⁰⁰⁰ for a random abiogenesis (Of course only, if you assume that there are no other sugars present and no other bases, which is a completely wrong assumption. So actually it is even much less probable.). But the RNA mentioned above is much longer and this is still not enough, since it all needs to come together with the other pieces mentioned above and nicely put into one cell membrane. So this means, from what we can deduct out the biochemistry of living cells, this can never occur whatever timescale you take (including the complete earth as laboratory).

 

This means we have to think about what this first living structure actually looked like. And of course the more you know about the biochemical details, the more you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look like (but maybe somebody will find it one day). This is why you see a trend in the discussions, that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details).

[ewmon]

I agree that nowadays,

...if there were organic molecules that may have been precursors of life, they would be rapidly utilized by the lifeforms that exist now. Thus, the likelihood of abiogenesis still to occur is extremely low.

Thank you LogicGates for the Lord Kelvin quote.

 

As to "what this first living structure actually looked like", I lean toward First Life consisting of the combined oceans (ie, the entirety of the Earth) as a single organism, without any need for a cell wall (to isolate or protect it from what?), obtaining energy through photosynthesis from the Sun, etc (or perhaps geothermal or something similar).

 

So, if abiogenesis is happening today, it would not succeed where life already exists (ie, it would not succeed here on Earth).

[Essay]

This means we have to think about what this first living structure actually looked like. And of course the more you know about the biochemical details, the more you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look like (but maybe somebody will find it one day). This is why you see a trend in the discussions, that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details).

 

Check out this May 2003(?) article from the American Society for Microbiology:

http://forms.asm.org...x.asp?bid=16349

Bacteria became a distinctive domain when its first member developed a cell wall to protect itself against internally generated osmotic pressure

 

"Three attributes seem essential for life and evolution: a source of energy; a capacity for making specific, even if imprecise, informational macromolecules; and a capacity for replicating. Although other properties would be useful and valuable for success and gradually emerged, seemingly a strong, stress-resistant wall was not initially required. However, as metabolic capabilities grew, the primordial organism's cytoplasm likely became increasingly crowded with an assortment of biochemical ingredients and salts, leading to an ever-higher osmotic pressure and making that crowded cell's ability to withstand turgor pressure valuable, if not essential."

 

I currently have his 2001 book, Bacterial Growth & Form (cited in link above), checked out from a local library.

 

~

Edited September 2, 2012 by Essay

[Bill Angel]

It's interesting to note that the first life forms on earth quite likely utilized sulfur rather than oxygen in its metabolic processes. Also such life forms still exist on Earth.

See http://m.popsci.com/science/article/2011-08/oldest-fossils-ever-found-could-present-new-target-search-extraterrestrial-life

 

So it could be possible hypothetically for life based on alternative chemistries to emerge on Earth in an environment that was inhospitable to DNA RNA based organisms. But I am unable to suggest what kind of environments that might be.

[Jens]

Check out this May 2003(?) article from the American Society for Microbiology:

http://forms.asm.org...x.asp?bid=16349

Bacteria became a distinctive domain when its first member developed a cell wall to protect itself against internally generated osmotic pressure

 

"Three attributes seem essential for life and evolution: a source of energy; a capacity for making specific, even if imprecise, informational macromolecules; and a capacity for replicating. Although other properties would be useful and valuable for success and gradually emerged, seemingly a strong, stress-resistant wall was not initially required. However, as metabolic capabilities grew, the primordial organism's cytoplasm likely became increasingly crowded with an assortment of biochemical ingredients and salts, leading to an ever-higher osmotic pressure and making that crowded cell's ability to withstand turgor pressure valuable, if not essential."

 

I currently have his 2001 book, Bacterial Growth & Form (cited in link above), checked out from a local library.

 

~

 

Thanks for the interesting link.

I agree to the statement you quoted.

My favorite book which focusses more on the even earlier stages of abiogenesis is RNA worlds. This collection is also available online (so its free):

http://cshperspectives.cshlp.org/site/misc/rna_worlds.xhtml

[dmaiski]

i would scram in anguish at the closed mindedness of this

DNA, RNA, peptide, complexes are not the only possible forms of life, they aren’t even the only probable ones, they are just the ones that exist at the moment on earth

 

if a second genesis event happened scientists would not notice it other then by absolute dumb luck, it would also be in an environment so hostile to biological life that it would be isolated (to prevent some rouge bacterium running in and ruining everything)

 

this limits the locations for a second genesis to: the centre of the earth (magma men from Mars...), deep oceanic trenches, and probably large geodes (complex quartz crystal resonance, its a form of life, just not one you are used too), and possibly the whole planet(anyone who has read Terry Pratchett, were the ants in the tubes of hex)

 

a second genesis of biological life could happen but it would be lost in the results of the first genesis, or used up immediately

lab grown conditions have only two problems, the lab that made the first genesis consisted of the whole surface of the planet earth, and was working on it for at least 1 billion years before it got any results

 

 

 

to solve a problem; you first break it down into its components, work out what they do, and then use them to build a solution.

[LogicGates]

Thank you all for your thoughtful and illuminating replies. I have gained insight from them, but I must say, respectfully, that most of you have (no doubt unintentionally) skirted my question. You have skirted it by reiterating/rephrasing/amplifying the very same standard argument presented by Biologists to which I am objecting in the first place: That is, you have once again spoken some *words* about how improbable Abiogenisis "seems", based, once again, on your *intuitive* arguments to support your views. Jens, you say "that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details)", but shortly before that you say "you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look".

 

It sounds almost as if you're saying that Biologists assume it's *complicated* because they don't know the details, while Physicists assume it's *simple* because they don't know the details. But I would like to point out that Physicists do not assume that something is simple because they don't know the details. Physicists do look for the simplest form of the underlying fundamental laws that will successfully explain the thing they are studying. But that is far from assuming that the solution to something complex, will be simple if you don't know the details!

 

We do have confidence, in Science, that Biology is based upon Chemistry, which is turn is based upon more fundamental physical laws at the smallest level. The fact that mind-bogglingly complex chemical reactions occur in nature, does not change the fact that, given a certain range of conditions, with a certain set of chemical ingredients, we can expect an ensemble of such systems to evolve in a way which is, in principle, predictable.

 

Thus, based upon these "word" arguments that we all seem to be using since we don't in fact know the complex details well enough to calculate our probabilites, it seems completely logical that, given the right conditions in nature, Abiogenisis could indeed take place multiple times independently, and produce the same arrangement of chemical elements and compounds required to become self-replicating.

 

My original question, was simply, that unless and until we gain enough knowledge to really be able to make probability calculations, at least with some statistical degree of confidence, are we not completely unjustified in continuing to insist that Abiogenises is "extremely unlikely" to happen more than once? I firmly believe that we *are* completely unjustified in proclaiming that. Note that I'm also not proclaiming it to be "extremely likely" either. I'm simply saying, I don't know. And I think, neither does anyone else. I propose that we wait until we can say, for example, "The probability of Abiogenisis under set x of conditions, is 52.2 percent, +/- 7 percent" (for example). Until then, let's quit using phrases such as "extremely unlikely".

 

Finally, let me ask you all to consider the following two well known facts, in helping to think about whether you have the right to proclaim Abiogenisis "extremely unlikely" simply because you don't understand the complexity of how it happened.

 

(1) It's well known that complex fractals are generated from very simple laws, in a predictable manner.

 

(2) It is recently confirmed by Astronomers that many planets in far-flung galaxies, exhibit spectra that indicate Methane, which implies life. If the chemical properties of methane are the same in all those far flung galaxies as here, then why would you reject the notion that the chemical characteristics of Abiogenisis might be the same out there in all those places?

[CharonY]

My original question, was simply, that unless and until we gain enough knowledge to really be able to make probability calculations, at least with some statistical degree of confidence, are we not completely unjustified in continuing to insist that Abiogenises is "extremely unlikely" to happen more than once?

 

What is being stated is that under current conditions, it is unlikely to happen (or at least not at any significant scale). For this, we do have quite a bit of evidence. First, we can assume, as already mentioned, that existing organisms would readily cannibalize simple organic molecules that may be created via abiogenesis. Second, we do not have evidence of metabolic activities (or any other evidence for that matter) that hints at novel organism that may have arisen due to abiogenesis. I.e. all detected organisms and their activities show a common lineage. Calculations are not all based on first principles. We can use existing data and model it (which is common for complex questions). If there was large scale abiogenesis of novel organisms, evidence of them must exist somewhere. As of yet, there is no real need to add novel chemistry to understand nutrient cycles, for example.

 

Based on that we can assume that if it happens, it must be highly limited and highly isolated (the latter due to our knowledge on how effective organisms are at sequestering biomolecules). In other words, if we speculate about abiogenesis under conditions other than current Earth conditions, you are right, we do not know. But for what we can observe now, the evidence indicate low probabilities. Regarding methane, while it is not my field, I assume that methane was used as an indicator for life because the assumption was that without a biological source it would dissipate rapidly from the atmosphere. The path to methanogenesis could potentially be diverse, depending on the chemical environment. And obviously life could arise without the development of methanogenesis at all.

Edited November 7, 2012 by CharonY

[Ronald Hyde]

Consider that for life to exist in advanced forms, as it does today, one of the capabilities it had to have was the ability to evolve.

Life may have started may times before but until it had that precious ability to evolve, it could only have had a very primitive form.

[Ophiolite]

@Logic Gates You seem (no doubt unintentionally) to have erected one or more strawmen (which some posters have been tempted to support) against which you are then arguing. Opinions, based upon careful consideration of the available facts, not upon assumptions, lead to a range of assessments as to the probability of abiogenesis. On the one hand we have the optimistic view of Christian de Duve, Nobel laureate, whose book The Cosmic Imperative explains why he sees life as inevitable and abundant. On the other hand is the pessimism of Jacques Monod, another Nobel laureate, who believed life was a freak accident, unique to Earth. And we have every view in between. Study any of these views carefully, when expressed by a qualified commentator, and you will find the which observations they have given weight to and what caveats they are applying to their (highly) provisional conclusions.

 

Why the range in views? Because, as I am fond of remarking, to extrapolate from a sample size of one is a questionable practice.

 

 

(2) It is recently confirmed by Astronomers that many planets in far-flung galaxies, exhibit spectra that indicate Methane, which implies life. If the chemical properties of methane are the same in all those far flung galaxies as here, then why would you reject the notion that the chemical characteristics of Abiogenisis might be the same out there in all those places?

You have a number of errors of thought here.

1) We have not detected any planets in far-flung galaxies. The most distant exoplanet yet identified is around 22,000 light years distant, well within our own galaxy. (There is some highly questionable suggestion of two planets in other galaxies, but confirmation is - as I understand it - currently lacking.)

2) Only two exoplanets have had methane identified in their atmospheres: HD189733b and WASP12b. These are, I think, Jupiter size gas giants, in which methane is expected to be found.

3) Methane is a commonplace organic molecule, but not necessarily a biological one. There are methane rains on Titan; a thin atmosphere of nitrogen and methane on Pluto; Uranus has a high altitude methane haze, while at lower levels it and Neptune harbour methane ices; traces are to be found in Saturn and Jupiter; comets contain methane ices. The list goes on. The evidence for life doesn't.

[Jens]

Thank you all for your thoughtful and illuminating replies. I have gained insight from them, but I must say, respectfully, that most of you have (no doubt unintentionally) skirted my question. You have skirted it by reiterating/rephrasing/amplifying the very same standard argument presented by Biologists to which I am objecting in the first place: That is, you have once again spoken some *words* about how improbable Abiogenisis "seems", based, once again, on your *intuitive* arguments to support your views. Jens, you say "that biochemists and microbiologists tend to assume that abiogenisis is highly improbable and physicists tend to assume that it is simple (since they typically do not know the details)", but shortly before that you say "you tend to think that abiogenesis is a highly improbable event, because there is no simple solution of how a primitive self replicating and evolving molecule (or molecule system) could look".

 

(You have not used the "reply" to another statement function, so that is why I have not received an email that you are actually adressing me. This is why I only answer now and not earlier.)

 

I do not try to skirt anything. I just did not want to repeat what has already been said (e.g. by CharonY).

So back to your original question.

 

The answer is: No. (since you asked, if origin of life is still happening on Earth today and not anywhere in the universe. I hope this is a clear answer )

 

• (As already mentioned:) The existing life makes it impossible for life to start again (because it is using the same resources and already optimized for several billions (in the american english meaning) of years.
• If the reasoning above would be wrong, we would be able to find life forms with a fundamentally different genetic code (in its scientific sense), or life forms using another set of amino acids (or L-sugars, or ....). So as CharonY has already mentioned: All exisiting life is coming from one source.

About you claiming that I am using "intuitive" arguments:

The current understanding of how life can start gives a probality of life to start, which is to low to happen even once in our galaxy (see my tiny stupid calculation) not talking about happening again on Earth today. So only because we exist, we know something is obviously wrong with this understanding. That is not going to "intuitive" arguments, that is using the current status of science. So calculation is pointless at the moment.

(The same way I could ask to you: Can you give an exact calculation of how probable it is that the theory of dark energy is right? And if you answer "no", I will assume the theory of dark energy is wrong, because that is my gut feeling , despite what the experts say.)

 

But most important: Your question is about, if something is happening today (so historical events) and not about a natural law. So the approach to answer this question is not calculation but detective work. (see the second bullet point in this text above).

By the way, how do you expect to calculate this, if we cannot even calculate all the properties of one amino acid out of the laws of physics (quantum mechanics) ab initio today? Not talking about protein folding....

 

Sorry, I did not want to be negative about physicists in my statements and I agree one should try to quantify things, if possible (of course). However, I think it is fair to state that the origin of life is a historical event and a biochemical event. Research in history and biochemstry is often using other tools than calculations (because often science has not the means yet to calculate). This does not mean it is no science.

 

what do you think? (actually I appreciate the discussion )

 

Finally, let me ask you all to consider the following two well known facts, in helping to think about whether you have the right to proclaim Abiogenisis "extremely unlikely" simply because you don't understand the complexity of how it happened.

 

(1) It's well known that complex fractals are generated from very simple laws, in a predictable manner.

 

The issue is more that we understand a lot and it still looks impossbile. So obviously we are missing something .

 

To the fractals: Yes that can be seen as analogous to evolution. So once life started, there is a convincing explanation of how it gains more and more complexity. And the rules of evolution are simple compared to the complexity of the life forms. However, we are talking about abiogenesis, exactly the steps you need for evolution to start. So the simple rule is still missing here despite all the knowledge we have. We are all humans and our brain is optimized by evolution to search for rules and causes everywhere (so by default we all believe that there is such a rule), this does not mean nature is working like this (see the statistical behaviour of quantum mechanics for example, ... if even the Nobel laureate Feynman states, that he does not like it ).

Edited November 18, 2012 by Jens

[LogicGates]

Perhaps I did not state my original question clearly enough. Sorry if that's the case. It seems that my question was interpreted as "Couldn't Abiogenesis still be happening today?" What I meant, was "Couldn't Abiogenesis have happened multiple times (and in multiple places, for that matter) way back during the epoch when it first started happening?" And these independent occurrences of the chemical precursors to life could look just like each other because they spontaneously arose in the same conditions. If the conditions were right for it to happen once, then perhaps they were right for it to happen twice, three times... N times. Then, if they all "looked alike", they could combine and evolve from there.. and what now may appear to be a single common ancestor could really be multiple common ancestors.