Thoughts on Abiogenesis

[AV1611VET]

I just invented it an hour ago.

Maybe that's why you're not willing to apply it to children in the womb?

 

[Occams Barber]

Maybe that's why you're not willing to apply it to children in the womb?

Perhaps because I recognise your comment as way off-topic and a deliberate attempt to further a personal agenda at the cost of derailing the conversation.

OB

 

[AV1611VET]

Perhaps because I recognise your comment as way off-topic and a deliberate attempt to further a personal agenda at the cost of derailing the conversation.

You mean derailing a conversation between you and Subduction Zone?

In Post 45, you said this:

I imagine they could invent an undefined word, similar to 'kinds', to confuse the issue. I am going to recommend 'splurgle' as an overarching creationist term for life including all cases which are scientifically fuzzy.

I've given a clear-cut definition (or synonym, if you prefer) for what "kind" is; even using the online etymology dictionary to back it up.

And for you to say it is an "undefined word" is wrong.

Then you go on and make up a word (which backfires on you, since that word already exists), and I'm asking you if you're willing to apply that word to a "child in the womb".

I would assume you are and, if so, I can take this further and ask you if you're willing to call a generation of Thalidomide children "splurgles" as well?

Maybe you'd better rethink your remarks?

 

[SelfSim]

The characteristics are not environment dependent.

If you mean the characteristics you gave (ie: grow and change, react to the environment, reproduce, have a metabolism etc), all of those are known to depend on the physio-chemical properties of the environment in which they are measured. For example solubility, in an earthly context, is dependent on liquid water being present for use as a solvent in earth-life's biochemistry. The surface temperature of Titan however, is not conducive to the presence of liquid water. DNA/RNA cannot dissolve in the liquid hydrocarbons present on Titan. DNA/RNA therefore could also not interact with other biomolecules at these temperatures .. which is a fundamental necessity for leading towards complexity in known biological systems. Titan's liquid methane solubility range is also too narrow for it to act as a solvent for any other known repeating sequence, longer chain genetic biopolymer candidates. Therefore any of life's known measurables, which depend on solubility in liquid water, would not be evident on Titan's surface.

But I'll be quite happy to agree with you if you can come up with a different set of characteristics we could use for life in an alien environment.

Two of the main suggested base 'metabolic' reactions catalysed by Titan's so-called (and mis-named) 'methanogens' are:

i) C2H2 + 3H2 = 2CH4;
ii) C2H6 + H2 = 2CH4

If so-called hypothetical Titan 'methanogens' are consuming atmospheric hydrogen, it would have a measurable effect on the hydrogen mixing ratio in the troposphere, at a certain levels of consumption. Anomalous depletions of acetylene and ethane, as well as hydrogen at the surface, would find some consistency with this hypothesis.

 

[Bradskii]

If you mean the characteristics you gave (ie: grow and change, react to the environment, reproduce, have a metabolism etc), all of those are known to depend on the physio-chemical properties of the environment in which they are measured. For example solubility, in an earthly context, is dependent on liquid water being present for use as a solvent in earth-life's biochemistry. The surface temperature of Titan however, is not conducive to the presence of liquid water.

How does a lack of water prevent growth and change? Or prevent some life form reacting to the environment? Or reproduce? Is it possible to class something as alive if it doesn't grow? Or cannot react to it's environment (how would it feed?).

If you like you can give me some other characteristics of life other than those we use for terrestrial life that might be considered for alien life.

 

[Quid est Veritas?]

(Interesting side issue - if trees lack souls do they have some kind of 'life force' to differentiate a tree from a piece of wood? This is a concept associated with animism. Is there a Christian equivalent?)

Traditionally Western Civilisation until the mid 17th to 18th centuries (which can equally be called Christendom) had a concept of graded souls. There was the Nutritive soul in plants, then the Animal soul, going up to the Rational soul in humans. Thereafter with the breakdown of old-style Scholastic Aristotleanism and the increasing adoption of the mechanical metaphor (of the soul in some sense 'driving' the body) perhaps from Descartes' influence, the idea of animals and plants being 'soulless' arose (or some idea of Transcendentalism or panpsychism based on classical philosophy). The concept of Life itself was also much looser before, as mediaevals were happy to ascribe life to the stars for instance, and debates on whether rivers were not in a sense 'alive' not unheard of. It is more the rigid post-Baconian and Linnaean nature that is at play today, creating our classifications that always has exceptions somewhere.

The old idea was that there were body, spirit and soul - a dead thing having body, but its soul had fled. It has biblical antecedents in the OT concept of living and dead nephesh. Similarly men had a rational soul, but it was the spirit (which was God-breathed) in combination with the rational soul that was important. The body too was required, hence we got new bodies at the Parousia and that the dead were in-Christ, as the form of soul had to be embodied somehow to continue to be meaningful categories. Old concepts of Heaven and Hell were still in some sense corporeal often, as the impulse to clearly delineate was not yet as strong as today. In fact, it was deemed Manichean or Gnostic heresy often, to think of humans as 'souls' separate from the body, as is often conceived today.

 

[SelfSim]

How does a lack of water prevent growth and change? Or prevent some life form reacting to the environment? Or reproduce? Is it possible to class something as alive if it doesn't grow? Or cannot react to it's environment (how would it feed?).

Re: my underline - That’s not exactly what I was saying there .. Let me go a little deeper (to clarify):

Solubility is a function of attraction and association between solute and solvent ionic molecules. Dissolution is dependent on the degree of the relative polar or non polar natures of the solute and solvent molecules respectively, and is thus a property of the compounds involved .

Methane, (for eg), lacks the polarity of water, and thus would not be a good transporter of polar molecules within a cell.

Life is critically dependent on transport of polar molecules within and between cells. I can't see any life processes functioning without a physical inter or intra-cell transport mechanism.

There’s a good, (yet rather lengthy), video on water’s lesser known electrostatic properties which, at the end, (try around the 49:27 mark), the lecturer explains what he argues would be the very first minimal physical starting conditions for Earth-life (ie: Abiogenesis). All it requires, (he says), is: water, molecules and the Sun’s energy.

Generalising from the overall theme of his lecture/book, the solubility/dissolution properties I mention above, are the same key physical properties he's arguing for in his Abiogenesis hypothesis.

If you like you can give me some other characteristics of life other than those we use for terrestrial life that might be considered for alien life.

I thought I just did in my last post(?), as follows:

A measurable effect on the hydrogen mixing ratio in the troposphere, at certain levels of consumption, might be indicative of hypothetical Titan lifeforms. Anomalous depletions of acetylene and ethane, as well as hydrogen at the surface, would be indicative of one such non terrestrial lifeform .. (ie: one that is apparently envisaged by some, as possibly existing in a Titan context/environment).

 

[Bradskii]

Life is critically dependent on transport of polar molecules within and between cells. I can't see any life processes functioning without a physical inter or intra-cell transport mechanism.

OK...so we need a transport mechanism. Fine. The presence of such a system might indicate metabolism. Which is one of the characteristics we're looking for.

I thought I just did in my last post(?), as follows:

A measurable effect on the hydrogen mixing ratio in the troposphere, at certain levels of consumption, might be indicative of hypothetical Titan lifeforms. Anomalous depletions of acetylene and ethane, as well as hydrogen at the surface, would be indicative of one such non terrestrial lifeform .. (ie: one that is apparently envisaged by some, as possibly existing in a Titan context/environment).

But we're not looking for what might indicate life. We're discussing the characteristics of life. Water or methane or oxygen or depletion of methane and ethane is not a defining characteristic of life. It's an indication that life might exist (notwithstanding that we could find an exoplanet soaked in water with abundant oxygen and lots of methane but with zero life). In which case we could try to find something that had the characteristics as previously discussed. If we do, then we have found life.

 

[SelfSim]

But we're not looking for what might indicate life. We're discussing the characteristics of life. Water or methane or oxygen or depletion of methane and ethane is not a defining characteristic of life. It's an indication that life might exist (notwithstanding that we could find an exoplanet soaked in water with abundant oxygen and lots of methane but with zero life). In which case we could try to find something that had the characteristics as previously discussed. If we do, then we have found life.

The only way we'll know some alien life's characteristics, is by way of measurements and then noticing that those measurements are distinguishably dissimilar from those of the backdrop/environment from which that isolate was sampled. Those measurements then become the basis for what distinguishes life from its environment (and becomes part of its definition in that environment).

'Try{ing} to find something that had the characteristics as previously discussed', is only known to be valid in the case of Earth-life. We don't have a clue as to whether those characteristics exist elsewhere. That is the real problem we're dealing with here. Researching a totally new, non-Earthly environment is not driven by some logical test which assumes the 'likely' existence of Earth-life somewhere else. That is not a scientific approach to the problem of dealing with the virtually unknown .. We ain't rollin' dices when researching a totally new, non-Earth environment, y'know? And that's in spite of how most people here, think science operates .. (I'm not just singling yourself out here ..).

The evidence for what I'm saying here, comes largely from the ambiguous outcomes of the Mars Viking probe life experiments of the 1970's. Those experiments ultimately failed because they approached the problem from that same flawed unscientific way of thinking

 

[Bradskii]

The only way we'll know some alien life's characteristics, is by way of measurements and then noticing that those measurements are distinguishably dissimilar from those of the backdrop/environment from which that isolate was sampled. Those measurements then become the basis for what distinguishes life from its environment (and becomes part of its definition in that environment).

'Try{ing} to find something that had the characteristics as previously discussed', is only known to be valid in the case of Earth-life. We don't have a clue as to whether those characteristics exist elsewhere. That is the real problem we're dealing with here. Researching a totally new, non-Earthly environment is not driven by some logical test which assumes the 'likely' existence of Earth-life somewhere else. That is not a scientific approach to the problem of dealing with the virtually unknown .. We ain't rollin' dices when researching a totally new, non-Earth environment, y'know? And that's in spite of how most people here, think science operates .. (I'm not just singling yourself out here ..).

The evidence for what I'm saying here, comes largely from the ambiguous outcomes of the Mars Viking probe life experiments of the 1970's. Those experiments ultimately failed because they approached the problem from that same flawed unscientific way of thinking

Then you need to give possible alternative defining characteristics. What you've offered so far is possible evidence of life. If there are no alternatives characteristics, then how do we know when we've found life? And as I said, the environment is irrelevant. But proffer any environment you feel helps your case.

 

[SelfSim]

Then you need to give possible alternative defining characteristics. What you've offered so far is possible evidence of life. If there are no alternatives characteristics, then how do we know when we've found life? And as I said, the environment is irrelevant. But proffer any environment you feel helps your case.

The environment some sample of sample of interest is isolated from, is 100% relevant .. its the baseline for comparison. We for example, are products of our environment .. if you don't accept this, then where do you think our life came from?
(As you argue your point there, you will be up against the mountains of biological evidence including evolution back to LUCA and the evidence of the standard genetic code).

Just because one cannot state a 'possible defining characteristic' which might satisfy your emotional demands, doesn't erase the real problem we're all confronted with when it comes to exo-life and the possibility of testing another instance of Abiogenesis elsewhere.

We cannot know, what we don't know yet .. for goodness sake!

 

[Bradskii]

The environment some sample of sample of interest is isolated from, is 100% relevant .. its the baseline for comparison. We for example, are products of our environment .. if you don't accept this, then where do you think our life came from?
(As you argue your point there, you will be up against the mountains of biological evidence including evolution back to LUCA and the evidence of the standard genetic code).

Just because one cannot state a 'possible defining characteristic' which might satisfy your emotional demands, doesn't erase the real problem we're all confronted with when it comes to exo-life and the possibility of testing another instance of Abiogenesis elsewhere.

We cannot know, what we don't know yet .. for goodness sake!

My emotional demands?

Anyway, it looks like we have to go with the definitions we have until such time as some others somehow emerge. Let me know if you can come up with any in the meantime.

 

[Ophiolite]

The evidence for what I'm saying here, comes largely from the ambiguous outcomes of the Mars Viking probe life experiments of the 1970's. Those experiments ultimately failed because they approached the problem from that same flawed unscientific way of thinking

A handful of people think it possible the failure was in the rejection of the positive results from two of the the three tests and unjustified confidence in the data from the GCMS that failed to detect organic matter. I'm one of those people. Another decade should tell us who is right.

 

[FrumiousBandersnatch]

.. and those characteristics change depending on the physical context (the environment) and on the behaviours of the specimen within that context. Their preconceptions (including the definition of life) of 'how life must be', (in your scenario there), could quite easily be completely amiss in a really non-earth-like context.
No matter how much they talk it up, they don't know what they're looking for until 'a specimen of interest' shows up in some radically different non-earth environment. In the case of Titan, the arm-wavers have conjured up a scientifically meaningless lifeform called a 'methanogen' (because it will have to based on the methane). However the term 'methanogen' only has meaning in an Earth-life context. We have anaerobic methanogens here on Earth .. but their base chemistry is still related to all other Earth-life .. which will be nothing like Titan's. The term is being abused for the sake of stirring up interest in alien life.

What I'm saying here is that the definition of life is totally context dependent. We will have to restart the process of redefining it in the context of an alien landscape and our preconceived definition/notions and tests for it, will also have to be restarted from scratch in that new context.

NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”. But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more.

 

[SelfSim]

A handful of people think it possible the failure was in the rejection of the positive results from two of the the three tests and unjustified confidence in the data from the GCMS that failed to detect organic matter. I'm one of those people. Another decade should tell us who is right.

So Curiosity's GCMS-CG is pretty well a state of the art instrument. It detected organics (chlorobenzene) at the Cumberland mudstone in Gale crater and some other reasonable (in mass) molecules. The controversy over Levin's experiments still continues however, (with still no consensus on detection methods). MSL/SAM has made no further announcements about more complex organics detection since, (AFAIK).

Regardless, clearly no similar, specific, metabolism-based life detection experiments have been sent since. Its been almost 50 years now since Levin's experiments. So why do you think that is?

 

[SelfSim]

NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”.

.. and yet Darwian evolution is not possible under the low temperatures and physically absent liquid water conditions on Titan's surface (and methane lakes).

Yet one particular NASA Ames Planetary scientists publishes papers on 'the possibility' of Titan based methanogenic 'lifeforms'? Why is that?

But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more.

Yes .. a different definition to suit the particular context/environment under study .. Highlights what I've been saying about the importance of thoroughly categorising the natural environment as a first step .. which may/may not lead to concluding/diagnosing 'life' within that specific environment/context.

Life's definition is far from being established as a universal 'given' .. yet everyone throws around the term as though it is!?

 

[SelfSim]

NASA's astrobiology section defines it as “... a self-sustaining chemical system capable of Darwinian evolution”. But there are more general definitions - Erwin Schrodinger said, "Life is something that goes on doing something much longer than you would expect it to", which is a bit too general and subjective for my taste; philosopher Paul Churchland says life is, "Any semi-closed physical system that exploits the internal order it already possesses, and the energy flux passing through it, in such a way to maintain and/or increase its internal order"; Wikipedia gives some more.

This one showed up recently .. which I tend to think of as being a rather well considered and well modelled attempt which might lead to better analysis techniques of remotely sourced mass spectrographic data. Well worth the read, (IMHO):
Identifying molecules as biosignatures with assembly theory and mass spectrometry:

The search for alien life is hard because we do not know what signatures are unique to life. We show why complex molecules found in high abundance are universal biosignatures and demonstrate the first intrinsic experimentally tractable measure of molecular complexity, called the molecular assembly index (MA). To do this we calculate the complexity of several million molecules and validate that their complexity can be experimentally determined by mass spectrometry. This approach allows us to identify molecular biosignatures from a set of diverse samples from around the world, outer space, and the laboratory, demonstrating it is possible to build a life detection experiment based on MA that could be deployed to extraterrestrial locations, and used as a complexity scale to quantify constraints needed to direct prebiotically plausible processes in the laboratory. Such an approach is vital for finding life elsewhere in the universe or creating de-novo life in the lab.

 

[Astrid]

.. and yet Darwian evolution is not possible under the low temperatures and physically absent liquid water conditions on Titan's surface (and methane lakes).

Yet one particular NASA Ames Planetary scientists publishes papers on 'the possibility' of Titan based methanogenic 'lifeforms'? Why is that?
Yes .. a different definition to suit the particular context/environment under study .. Highlights what I've been saying about the importance of thoroughly categorising the natural environment as a first step .. which may/may not lead to concluding/diagnosing 'life' within that specific environment/context.

Life's definition is far from being established as a universal 'given' .. yet everyone throws around the term as though it is!?

By what is it determined that Darwinian evolution isn't possible
there.

 

[Ponderous Curmudgeon]

By what uis it determined that Darwinian evolution isn't possible
there.

2LoT, come on the argument has been used before.

 

[Astrid]

2LoT, come on the argument has been used before.

Well evolution itself is impossible so this is like double jeopardy