Origins of the First Living Cell and Evolution

Discussions on topics related to biochemistry and molecular biology, functional genomics, etc.

Re: Origins of the First Living Cell and Evolution

Postby Forest_Dump on April 11th, 2017, 10:12 am 

Braininvat wrote:If God can sit in a laboratory and stitch together proteins and protein-synthesizing nanomachines and then plant them in ponds on the young Earth, then you have definitely postulated a metaphysical theory that God is, itself, a physical being that interacts with other physical matter. And using such a postulate to fill explanatory gaps in the process of abiogenesis would seem outside the realm of biochemistry. So, either we get back to probabilistic analysis of spontaneous protein synthesis and replication, based on actual science, or we move the thread.


That was my insertion, of course, which as simply intended to close off a minor point from near the beginning of this. In these kinds of critiques, personally I'm not sure how often it is really possible to seal off science, etc., from exterior belief systems be they religious, economic, political, etc. As we see here, neither "science" nor the broader public live or act in a vacuum.
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Re: Origins of the First Living Cell and Evolution

Postby scientificphilosophe on April 13th, 2017, 8:43 am 

Eclogite » March 31st, 2017, 2:44 pm
Most and probably all of the subsequent points you make in your OP are predicated on the truth of your statement: there is no credible theory of the origin of the first living cell. We need, therefore, to deal with that statement first. What is it that you find incredible out these hypotheses?

Stuart Kauffman's Autocatalytic Sets

Christian de Duve's pathway from thiosesters to RNA to protocells

Cairn-Smith's Clay Templates


Eclogite
I realise that I haven’t responded to your suggested sources – apologies.

In brief I have now checked them out and discovered that Kauuffman and de Duve have only made credible proposals about how the first single-celled organisms developed into multi-cell organisms. Those proposals are interesting but are unproven, and do not address my core point – the origin of the first cell.

I have already mentioned that the outline idea of Cairn-Smith about crystals on the edges of muddy pools have not been shown to work with amino acids or even the nucleotide components of RNA. They do not even begin to address the questions of assembling proteins or the sequence of codes inherent in the only reproductive mechanism that we have.
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Re: Origins of the First Living Cell and Evolution

Postby scientificphilosophe on April 13th, 2017, 9:16 am 

vivian maxine » April 10th, 2017, 8:32 pm
Forest is right. Oxygen (safe oxygen) was a late-comer.

"Oxygen Revolution, 1800Myr. Although animals need oxygen to survive, primitive life began in the absence of free oxygen, and when oxygen built up in the sea-water, it was deadly poison for organisms unequipped to deal with it."


Hi Vivian
The point which Forest seemed to be making was that the only reason why amino acids and nucleotides haven't been shown to be active with any of the suggested mechanisms is because of the presence of free oxygen in our current environment. By implication he was saying that if free oxygen could be removed then such things would be possible - and that hasn't been demonstrated in the lab to my knowledge.

We know that different rocks which appear in the earth's crust are believed to come from two planetary bodies that collided some 4.5 billion years ago. As the water is here, it is likely that one of those bodies held most of the water/oxygen when the other had virtually none. This, I thought, was one of the basic arguments for the different types of rock and the environments that they were formed in.

It is entirely possible that free oxygen could be present somewhere in the planet even in the earliest days - possibly even in large quantities - but that doesn't mean it was everywhere. Tectonic activity could easily melt rocks and mix them with organic material later.

Having said that, I agree that life probably did originally form in an environment without free oxygen, even if this was murky fluids devoid of free oxygen - but that doesn't detract from the core point. None of the proposed environments seem to support the generation/manipulation of either amino acids or nucleotides.

Indeed, I believe that the only way in which nucleotides can be produced in the lab is through re-cyling or the use of ribosomes. There is no known manufacturing process outside the living cell.
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Re: Origins of the First Living Cell and Evolution

Postby Eclogite on April 13th, 2017, 9:43 am 

scientificphilosophe » Thu Apr 13, 2017 1:16 pm wrote:We know that different rocks which appear in the earth's crust are believed to come from two planetary bodies that collided some 4.5 billion years ago. As the water is here, it is likely that one of those bodies held most of the water/oxygen when the other had virtually none. This, I thought, was one of the basic arguments for the different types of rock and the environments that they were formed in.
It is, perhaps, off-topic, but I am not sure where you got these ideas from. They are incorrect, or at best a badly mangled interpretation of the currently understood situation.

The rocks present in the Earth's crust do not come from either Theia (the Mars sized protoplanet collider) or the proto-Earth. The energy of the collision insured the Earth was molten and without a crust. Perhaps you meant that the material now present in the Earth's crust came from the two protoplanets. That is correct, but is quite different in its implications from what you actually said.

Thinking on the nature of the collisions and the character of the two bodies continues to evolve, but as to the best of my understanding there has been no serious suggestion that the water was concentrated in one or other. Indeed, the consensus view at present appears to be that both Theia and the proto-Earth formed in roughly the same portion of the proto-planetary disc and consequently have similar compositions, including water.

The variety of rocks to be found in the crust are a consequence of post-collision developments, including development of the crust, formation of oceans and atmosphere, inception of plate tectonics, etc. It has nothing to do with differences or similarities of the two protoplanets.

I don't think, either way, this impacts on your thesis or questions, but I felt it was a serious enough misunderstanding to merit correction.
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Re: Origins of the First Living Cell and Evolution

Postby SciameriKen on April 13th, 2017, 9:50 am 

scientificphilosophe » Thu Mar 30, 2017 2:47 pm wrote:If the process of evolution cannot explain the origin of the first cell then you are back into the realms of God so it is an important consideration for everyone - whether you have religious leanings or not. It is not my problem per se.


Greetings SP - I am not sure if this is your position or if you are merely representing the lay person - but why is there a need to invoke the "realms of god" if evolution cannot explain the origins? Sure to do so answers the question where did life come from - but that is it - where do we go from there? If we search for life on other planets will we look for signs that God was there? :D
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Re: Origins of the First Living Cell and Evolution

Postby scientificphilosophe on April 13th, 2017, 10:00 am 

Eclogite » April 13th, 2017, 2:43 pm

The rocks present in the Earth's crust do not come from either Theia (the Mars sized protoplanet collider) or the proto-Earth. The energy of the collision insured the Earth was molten and without a crust. Perhaps you meant that the material now present in the Earth's crust came from the two protoplanets. That is correct, but is quite different in its implications from what you actually said.


Hi Eclogite
I am happy for the point to be clarified in terms of the way in which my words are read, but I believe I was making the correct point.

We have only theorised about the different planetary bodies because of the presence of two different types of rock in the crust. That they are different means that they haven't mixed.
I don't disagree that the surface was molten - but they didn't mix so they were true to their sources - if the theory is correct.

As oxygen was thought to become 'free' after the solidification of the rocks, the different types of source rock, (some of which I believe could be formed in an environment with oxygen), does seem to point to one planet being without oxygen/water, and the other having it.
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Re: Origins of the First Living Cell and Evolution

Postby Forest_Dump on April 13th, 2017, 10:22 am 

scientificphilosophe wrote:We have only theorised about the different planetary bodies because of the presence of two different types of rock in the crust. That they are different means that they haven't mixed.


I am curious about what the two different types are. Do you mean felsic vs. mafic? Or those that formed in an oxygen free environment vs. those that formed in an atmosphere with free oxygen? If the latter dichotomy, then we would have to take into account time of when the rocks formed as both kinds are forming today. Rocks forming at the surface, for example, are forming in an atmosphere with free oxygen while rocks forming deep down from overall cooling of the earth are still forming in an oxygen free environment but can then be exposed from various causes.
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Re: Origins of the First Living Cell and Evolution

Postby scientificphilosophe on April 13th, 2017, 10:30 am 

SciameriKen » April 13th, 2017, 2:50 pm

Greetings SP - I am not sure if this is your position or if you are merely representing the lay person - but why is there a need to invoke the "realms of god" if evolution cannot explain the origins? Sure to do so answers the question where did life come from - but that is it - where do we go from there? If we search for life on other planets will we look for signs that God was there? :D


Greetings to you too SciameriKen.
Good ID name bye-the way - assuming it reflects your real first name!

I briefly raised the point about God in response to the personalisation of a previous post which sought to make the issue 'my problem'. It isn't.

Having said that, as I made clear in a later response, we can all be challenged by people with religious beliefs and it is useful to know how to answer such points.

There are many grades of religious belief, and also many religions.
I am not concerned with that. I am interested in what can be reasonably demonstrated.

Science can determine facts, but these still have to be interpreted. We have to explain all facts because they never change - only our interpretations change. Equally, science has to work with philosophy because it is the disciplines of philosophy which help to structure our speculations about the unknown.... but the theorising always has to match the facts.

It is a fact that the Theory of Evolution doesn't demonstrably work before the first cell.
That will ultimately lead us to questions about spontaneity, randomness and the abilities of existence to set a direction, or even to design outcomes. Whether we talk about hidden properties of matter at the deeper levels of existence; other types of stuff; or indeed, God - there are certain logical steps/factors that have to be overcome and these generally point to certain capabilities. Whether you attribute them to God or something else is a personal choice... but the necessary capabilities seem to be required.

In my opinion the search for other life is not bound to the questions posed by the dilemmas of origin, but the issues of the 'origin of life' may help to reveal more about ourselves and the nature of the Universe we occupy.

The emergence of Life is a second point of apparently fundamental change. If so, that seems to require a spontaneous, random, or external influence.

If living things demonstrate a level of control, spontaneity, consciousness etc that cannot be explained by physical matter alone then something else may be involved. If it is something like another 'force' then we might use it. I suspect that we may have less success in trying to 'bottle God'. ):
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Re: Origins of the First Living Cell and Evolution

Postby Eclogite on April 13th, 2017, 10:42 am 

scientificphilosophe » Thu Apr 13, 2017 2:00 pm wrote:Hi Eclogite
I am happy for the point to be clarified in terms of the way in which my words are read, but I believe I was making the correct point.

Unfortunately you have a fundamental misunderstanding, but I am happy to work with you to resolve it.

scientificphilosophe » Thu Apr 13, 2017 2:00 pm wrote:We have only theorised about the different planetary bodies because of the presence of two different types of rock in the crust. That they are different means that they haven't mixed.
This is completely incorrect. Can you tell me where you picked up this notion. And, to repeat Forest's question, what two types are you referring to?

There is no evidence - and I cannot state this too strongly - of two different types of rocks thought to have originated on different protoplanets. This is absolute. If you believe you have evidence to the contrary please post it.

The closest I can get to your perception is that by looking at isotope ratios in meteorites, moon rocks and the Earth, we can make certain deductions as to the original composition of Theia and the proto-Earth. This is totally different (much more subtle and elegant and complex and difficult) than there being two remnant rock types of the Earth.

scientificphilosophe » Thu Apr 13, 2017 2:00 pm wrote:I don't disagree that the surface was molten - but they didn't mix so they were true to their sources - if the theory is correct.
I take the risk of being repetitive. There is no such theory. I would be delighted to be proven wrong, for it would open up worlds of possibilities. I expect to be disappointed.


scientificphilosophe » Thu Apr 13, 2017 2:00 pm wrote:As oxygen was thought to become 'free' after the solidification of the rocks, the different types of source rock, (some of which I believe could be formed in an environment with oxygen), does seem to point to one planet being without oxygen/water, and the other having it.
This makes no sense to me at all. You are aware, are you not, that oxygen is the most abundant element in most rocks?
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Re: Origins of the First Living Cell and Evolution

Postby vivian maxine on April 13th, 2017, 11:33 am 

Having reached the bottom of this thread, I now forget who mentioned rocks that form at the surface and rocks that form deep underground. Are talking about volcanic rocks and sedimentary rocks?
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Re: Origins of the First Living Cell and Evolution

Postby scientificphilosophe on April 20th, 2017, 6:46 pm 

Eclogite » April 13th, 2017, 3:42 pm

There is no evidence - and I cannot state this too strongly - of two different types of rocks thought to have originated on different protoplanets. This is absolute. If you believe you have evidence to the contrary please post it.



Hi Eclogite

Thanks for taking the trouble to write this, and I am happy to learn if people seek to argue their case.

In truth this was a foolish venture of mine into an area that isn't my main strength, but I did it to make a point to Forest, which still stands. I will return to this later.

There have been many hypotheses that postulated about different forms of rocks here on earth - admittedly largely based on different oxygen isotopes - but from one apparently incorrect article I saw, this extended to fundamentally different chemical compositions.

In 2014 a German research team claimed in support of this 'two rock type' hypothesis, that chemical analysis of moon rock has shown that it had a fundamentally different isotope profile. However a newer article I have just discovered makes reference to this and now disputes those findings.

http://newsroom.ucla.edu/releases/moon- ... planetMoon was produced by a head-on collision between Earth and a forming planet

If you look it up it claims that the rocks on Earth and the Moon basically have identical isotope proportions... more specifically it says that the UCLA team could find no differences.

While I have no preference on who to believe it does show you that other theories do exist, and that it is conceivable that material/rock might form without oxygen.


The underlying point I was trying to make is that you can't make assumptions about the earliest conditions on Earth or the potential for regularly generating amino acids and nucleotides in the same conditions.
This has never been demonstrated in the lab let alone in the real world.
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Re: Origins of the First Living Cell and Evolution

Postby Forest_Dump on April 20th, 2017, 8:16 pm 

Whichever ever of the two contrasting papers is correct, it is moot for this discussion. Regardless of whether there were two isotope signatures or one or twn, there is no question that there was oxygen present but it was not free oxygen in the atmosphere as O2 - ot was bound up with other atoms such as carbon dioxide.
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Re: Origins of the First Living Cell and Evolution

Postby vivian maxine on April 21st, 2017, 11:37 am 

scientificphilosophe, I don't know how much this will contribute. Just thought I'd mention it. New Scientist Collections, volume three, issue 5, has an article about how life came to be on Earth. "What If We Came From Space?". #7 on page 22.

The point is made that life appeared on Earth far too fast to have simply slowly developed here. It has to have come from elsewhere. It goes on to contend that "the galaxy is teeming with life, and our biosphere is just part of a vast, interconnected cosmic ecosystem". From there it introduces something called "Panspermia", making four points: sky-high bugs (evidence on a balloon experiment in 2012), alien fossils, lifelike light from space and red rain. Red rain? Is anyone thinking "Pern"?

So, make of it what you will/can. I never heard of Panspermia. And I am not sure there is any value in these ideas. Just a contribution to your original question of where life started.
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