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Evolution, if true, puts life everywhere and every way.

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#1 Pess

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Posted 01 March 2020 - 09:32 AM

I've often posted here that evolution, if true, only requires a persistent niche, an energy source and something that can serve as 'food' for building material.

 

This article discusses the first 'animal' discovered that does not rely on aerobic respiration to generate energy (ATP molecules).

 

 https://www.msn.com/...gen/ar-BB10t20T

 

Evolution doesn't require the 'easy route', it just requires a route that works.

 

What I really struggle with in terms of living material developing out of simpler compounds is the issue of chirality.  All proteins are either left or right 'handed'.  When you make them in a lab you usually end up with an equal number of each termed isomers of each other.

 

The trouble is life favors only one isomer for some proteins and the other for other proteins.  100% of the time (so far discovered).

 

True evolution, as far as we know, should have utilized both isomers along the way.

 

Creationists like to point out that this is a deep flaw in the evolutionary theory and thus favor a creator origin for life.  I don't go that far but I can only think of a couple possible reasons for this unique molecular finding in proteins in living systems:

 

1. All life arose from a single metamorphosis of a collection of chemicals from a precursor vacuole into something that could replicate itself and, thus, all life evolved from this initial single solitary highly unlikely event that didn't repeat over the entire globe.  

 

2. Life, of some sort, arrived on Earth via panspermia and took hold and no original life arose on Earth itself.

 

Any other ideas out there?

 

Pesse ( I'm verklempt", "Talk amongst yourselves!) Mist

 

 

 

 

 

 

 

 

 

 



#2 bobzeq25

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Posted 01 March 2020 - 09:49 AM

I am not troubled by the fact that life uses different isomers.  Many biochemical reactions require complicated things to fit together in a precise "lock and key" fashion.  It's not at all surprising that a certain isomer would work, and its optical mirror twin, won't.

 

As far as whether picking at evolution is a way to further the idea of a creator, as opposed to life being a random accident of physics, I also have a position.  It's not a good argument to say that just because we haven't worked out all the details of evolution, unexplainable miracles are the answer.

 

I think the question of whether a creator was involved, or just randomness, is far above the pay grade of the human race, and likely to remain so.  <smile>

 

What science tells us is that, if there was a creator they started off 14 billion years ago with a bang.  A big bang.  And that evolution (which certainly exists) was part of the plan, a tool to go from simpler life forms to more complex ones.

 

That's all for now, I have to go to church.  I'm serious, mine is full of people who can harmonize science and religion.


Edited by bobzeq25, 01 March 2020 - 10:04 AM.

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#3 Astrojensen

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Posted 01 March 2020 - 09:53 AM

 

True evolution, as far as we know, should have utilized both isomers along the way.

I think the keywords here are: As far as we know. 

 

The explanation as to why one isomer or the other is the only one used might be extremely simple, we just haven't found it yet. Such has been the case with A LOT of things in nature. 

 

 

Clear skies!
Thomas, Denmark


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#4 Lukes1040

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Posted 01 March 2020 - 10:13 AM

[quote name="Pess" post="10015255" timestamp="1583073175

What I really struggle with in terms of living material developing out of simpler compounds is the issue of chirality. All proteins are either left or right 'handed'. When you make them in a lab you usually end up with an equal number of each termed isomers of each other.

The trouble is life favors only one isomer for some proteins and the other for other proteins. 100% of the time (so far discovered).

True evolution, as far as we know, should have utilized both isomers along the way.

Creationists like to point out that this is a deep flaw in the evolutionary theory and thus favor a creator origin for life. I don't go that far but I can only think of a couple possible reasons for this unique molecular finding in proteins in living systems:

1. All life arose from a single metamorphosis of a collection of chemicals from a precursor vacuole into something that could replicate itself and, thus, all life evolved from this initial single solitary highly unlikely event that didn't repeat over the entire globe.

2. Life, of some sort, arrived on Earth via panspermia and took hold and no original life arose on Earth itself.

Any other ideas out there?

Pesse ( I'm verklempt", "Talk amongst yourselves!) Mist[/quote]

Evolution does not try to describe how the first living organism came to be. These two are typically lumped together, but are quite different theories. Evolution by natural selection is how populations change over time, and is backed up by lots of data. How the first life came to be, panspermia, abiogenesis, created, what have you, is still uncertain.
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#5 Pess

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Posted 01 March 2020 - 10:36 AM

I am not troubled by the fact that life uses different isomers.  Many biochemical reactions require complicated things to fit together in a precise "lock and key" fashion.  It's not at all surprising that a certain isomer would work, and its optical mirror twin, won't.

 

 

 

Yes, 'some' should work one way and 'some' should work the other way.

 

But they shouldn't 'all' work exactly the same way...exactly 100% of the time. Wouldn't you agree?

 

...at least based on what we know.

 

I am not posting this in any sort of religious argument. I just mentioned it as an aside that creationists lean on it heavily.  That just confirms the weight of the question and necessity to figure out the answer from known laws of the universe.  

 

However, in my mind this is a key missing ingredient in evolution. If molecular evolution is as current theory suggests, I can think of a mechanism to account for it. And dismissing it as (not) a bothersome question misses the key point.

 

I equate the answer to this question on the same level as a GUT theory linking gravity with the other fundamental forces.

 

My personal take is that evolution just requires some basic energy, niche and building material and really has no other limits.  So where are organisms utilizing the other 'lock & key' proteins?  

 

If you take ismers of proteins from living systems, they'll happily engage in the same enzymatic re4actions in a test tube that their cousins do in living cells.  Very odd. 

 

Pesse (Maybe it's just me) Mist


Edited by Pess, 01 March 2020 - 10:40 AM.


#6 Astrola72

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Posted 01 March 2020 - 11:11 AM

While I agree with Lukes1040 that the theory of evolution (of species) does not address the evolution of life itself and certainly not the evolution of biochemicals, I do know that experimental evidence exists of a (probably entropic) advantage in the evolution of large biomolecules from enantiopure mixtures of smaller compounds over racemic (enantiomerically mixed) ones. While this would not explain a preference for handedness it would explain the existence of a singular handedness in particular cases.


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#7 bobzeq25

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Posted 01 March 2020 - 01:34 PM

1.  Yes, 'some' should work one way and 'some' should work the other way.

 

But they shouldn't 'all' work exactly the same way...exactly 100% of the time. Wouldn't you agree?

 

2.  So where are organisms utilizing the other 'lock & key' proteins

1.  No, not at all.  In this context, even though they are mirror images, you're essentially talking about two different chemicals.  While key a may fit lock b, there's no reason to think mirror image key a prime will, even though it has a similar (but not identical) structure.

 

2.  In all the biochemical reactions you are troubled by.  They are pretty universal, not specific to humans.

 

Still not troubled.  Same atoms, similar structure, but different chemicals.
 



#8 brentwood

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Posted 01 March 2020 - 02:48 PM

I don't understand a lot being said here but I still don't why we have not yet created life yet. We were doing experiments back in the 50s when amino acids were being created in a jar. We don't seem to have progressed much since then. 

A few years ago I asked the same question to an exobiologist at McMasters and she looked at me as though I was something that was stuck to her shoe! I must have sounded like a creationist! Didn't really get an answer either. 



#9 DaveC2042

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Posted 01 March 2020 - 03:20 PM

I'm not an expert at this at all, but would simply observe that the fact science cannot yet explain something, does not mean there isn't a scientific explanation for it.

Also, the existence of a current gap in our scientific understanding of something does not mean you are free to fill the gap with whatever you feel like, and expect it to be taken seriously.

The real power of science is encapsulated in the phrase "I don't know". It is the start of all good research.
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#10 ColoHank

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Posted 01 March 2020 - 03:44 PM

This is more information than I can process.  I'm still trying to wrap my head around the notion that lightning and thunder aren't caused by Thor striking his anvil.


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#11 BGazing

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Posted 01 March 2020 - 04:05 PM

I think the keywords here are: As far as we know. 

 

The explanation as to why one isomer or the other is the only one used might be extremely simple, we just haven't found it yet. Such has been the case with A LOT of things in nature. 

 

 

Clear skies!
Thomas, Denmark

Matter-antimatter reloaded...



#12 SillySMS

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Posted 01 March 2020 - 11:24 PM

I don't understand a lot being said here but I still don't why we have not yet created life yet. We were doing experiments back in the 50s when amino acids were being created in a jar. We don't seem to have progressed much since then. 

A few years ago I asked the same question to an exobiologist at McMasters and she looked at me as though I was something that was stuck to her shoe! I must have sounded like a creationist! Didn't really get an answer either. 

Why haven't we produced a supernova in the lab? Because it's extremely difficult! Also the supernova would destroy Earth. 

 

Even simple life is an extraordinarily complicated arrangement. It was compared to a 747 spontaneously building itself out of scrap in a scrapyard. Likely the biggest reason there is life on Earth is that there were large areas with just the right conditions for hundreds of millions of years. Even low probability events become near certainties if you try them often enough. 

 

In the lab, you have a handful of flasks with an effectively negligible fraction of the volume and time of the early Earth. Not enough junkyards for a 747 to spontaneously appear. On top of that, it could be easily contaminated by extant Earth life with vastly more efficient biochemical processes. One E. coli in your flask, and the next day, you have a flask of E. coli.


Edited by SillySMS, 01 March 2020 - 11:24 PM.


#13 DaveC2042

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Posted 01 March 2020 - 11:44 PM

Why haven't we produced a supernova in the lab? Because it's extremely difficult! Also the supernova would destroy Earth. 

 

Even simple life is an extraordinarily complicated arrangement. It was compared to a 747 spontaneously building itself out of scrap in a scrapyard. Likely the biggest reason there is life on Earth is that there were large areas with just the right conditions for hundreds of millions of years. Even low probability events become near certainties if you try them often enough. 

 

In the lab, you have a handful of flasks with an effectively negligible fraction of the volume and time of the early Earth. Not enough junkyards for a 747 to spontaneously appear. On top of that, it could be easily contaminated by extant Earth life with vastly more efficient biochemical processes. One E. coli in your flask, and the next day, you have a flask of E. coli.

One point often not given much attention is that it is the stuff we see in even a very simple cell today almost certainly arrived long after life initially started.

 

We look at DNA, or even just RNA and think, this is impossibly complicated and could never have arisen by chance.  And we are right.  It developed over the top of something else that was there before it, which it initially needed.  The problem we have now, is that once DNA and the modern cell had developed, they didn't need it anymore, and outcompeted it to extinction or discarded it as useless. And now, 4 billion years later, we have almost nothing to tell us what it was that has disappeared.  And without knowing what that precursor looked like, we are really up against it understanding how DNA developed.

 

And this takeover process could have happened more than once, obscuring the initial chance event even further.

 

Working out the origin of life is probably a pretty good candidate for the most difficult scientific question we have to answer.


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#14 Jarad

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Posted 02 March 2020 - 07:50 AM

The current hypothesis is that some of the early self-replicating molecules were chiral. Because they self-replicate, they gradually turned a racemic mixture of precursor materials into one that was almost 100% chiral. It was probably a coin flip which chirality showed up first, but once one showed up and started copying itself the rest followed. The basic principle of evolution (imperfect self-replication and natural selection) works to explain chirality as well as anything else - you just need that first chiral self-replicating molecule and go from there.

 

Jarad


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#15 bobzeq25

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Posted 02 March 2020 - 10:08 AM

One point often not given much attention is that it is the stuff we see in even a very simple cell today almost certainly arrived long after life initially started.

 

We look at DNA, or even just RNA and think, this is impossibly complicated and could never have arisen by chance.  And we are right.  It developed over the top of something else that was there before it, which it initially needed.  The problem we have now, is that once DNA and the modern cell had developed, they didn't need it anymore, and outcompeted it to extinction or discarded it as useless. And now, 4 billion years later, we have almost nothing to tell us what it was that has disappeared.  And without knowing what that precursor looked like, we are really up against it understanding how DNA developed.

 

And this takeover process could have happened more than once, obscuring the initial chance event even further.

 

Working out the origin of life is probably a pretty good candidate for the most difficult scientific question we have to answer.

The origin of the universe is harder.  Arguably, whether there's more than one.

 

"Wine from water is not so small.  But an even better magic trick, is that anything is here at all."  - Peter Mayer

 

 



#16 llanitedave

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Posted 02 March 2020 - 11:52 AM

The current hypothesis is that some of the early self-replicating molecules were chiral. Because they self-replicate, they gradually turned a racemic mixture of precursor materials into one that was almost 100% chiral. It was probably a coin flip which chirality showed up first, but once one showed up and started copying itself the rest followed. The basic principle of evolution (imperfect self-replication and natural selection) works to explain chirality as well as anything else - you just need that first chiral self-replicating molecule and go from there.

 

Jarad

The difficulty here, I think, is that the mixture can't work if it's only a little bit racemic.   Once chiral chains begin to form, they can be truncated by the presence of a single monomer with the wrong chirality.  Something had to segregate the different monomers so as to prevent contamination.

 

There's some evidence that polarized radiation can influence the chirality of amino acids, but sugars need to be chiral as well, and in the opposite sense as the amino acids.

 

So it's all very complex, and I don't have any idea of what the workaround is at this point.



#17 BillP

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Posted 06 March 2020 - 03:34 PM

One point often not given much attention is that it is the stuff we see in even a very simple cell today almost certainly arrived long after life initially started.

Apparently very true.  The ongoings inside the single cell we find today is incredibly complex and not something that could ever be considered the starting point - That being the case though, it also might be the case that all that led up to the complexity we see in cells today is preserved no where and we will never be able to discover exactly how abiogenesis occurred here (if it even did occur here).  So quite possibly the question might be completely unanswerable and beyond the ability to ever know.



#18 BillP

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Posted 06 March 2020 - 10:37 PM

What I really struggle with in terms of living material developing out of simpler compounds is the issue of chirality.  All proteins are either left or right 'handed'.  When you make them in a lab you usually end up with an equal number of each termed isomers of each other.

 

The trouble is life favors only one isomer for some proteins and the other for other proteins.  100% of the time (so far discovered).

 

True evolution, as far as we know, should have utilized both isomers along the way.

 

You should read this.  https://www.quantama...-life-20141126/
 


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#19 llanitedave

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Posted 07 March 2020 - 12:00 PM

Apparently very true.  The ongoings inside the single cell we find today is incredibly complex and not something that could ever be considered the starting point - That being the case though, it also might be the case that all that led up to the complexity we see in cells today is preserved no where and we will never be able to discover exactly how abiogenesis occurred here (if it even did occur here).  So quite possibly the question might be completely unanswerable and beyond the ability to ever know.

There's a very good chance of that.  I think the best we can hope to do is discover plausible pathways of how it could have happened.  We may then be able to make predictions of how it can happen elsewhere.



#20 llanitedave

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Posted 07 March 2020 - 12:10 PM

You should read this.  https://www.quantama...-life-20141126/
 

That's a fascinating article.  It implies evolution and natural selection were operating quite well even before life itself -- life is the result of evolution, not just it's beneficiary.



#21 BillP

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Posted 07 March 2020 - 12:36 PM

That's a fascinating article.  It implies evolution and natural selection were operating quite well even before life itself -- life is the result of evolution, not just it's beneficiary.

That is a good point as it would seem to imply that the the very obtuse natural biological forces of evolution and selection played their role in presumably "pre-life" stages as well.  I would not find it surprising though as I don't really view evolution and selection as something that is set at a fine enough level of detail to be determinable as would be say a law of physics.  Instead I view them as more or less a common sense movement of biology.  So what they contend I personally assess as the same as saying when one walks thru a dark room without a light they tend to stumble more than when they have a light.  Not some detailed predictive theory but more just simple common sense.  I don't think we yet have what I would call a real theory of evolution along with its multiple influencing mechanisms, natural selection being just one very obvious one.  We are still a long way off.  Our better understanding of DNA though will help build a real theoretical understanding some day I hope.  But we still have a long way to go to fully understand DNA as well.


Edited by BillP, 07 March 2020 - 12:43 PM.


#22 Jarad

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Posted 10 March 2020 - 07:59 AM

The article is a much more elegant description of what I was trying to say - once you have a mechanism that selectively incorporates one chirality in self-replication, you will rapidly convert a racemic mixture into all of that type.

 

Jarad



#23 llanitedave

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Posted 10 March 2020 - 09:10 AM

The article is a much more elegant description of what I was trying to say - once you have a mechanism that selectively incorporates one chirality in self-replication, you will rapidly convert a racemic mixture into all of that type.

 

Jarad

It's still not out of the woods early on.  Even when you have a process that naturally selects for one enantiomer of the mixture, it doesn't convert from one to the other.  It just picks one and ignores the other.  You end up with not a racemic mixture, but two different chiral populations.  One is concentrated in the proto-life molecules, and one is the leftover dregs which make up the remaining environmental background.  In other words, the environment is now contaminated and impoverished in potential resources.

 

That leads to -- wait for it -- competition for resources!

 

Selection is intensified, and evolution is accelerated.



#24 scottk

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Posted 14 March 2020 - 04:20 PM

Perhaps "life" with it's chirality and the seemingly endless forms it takes are two different things.

 

(I think "Endless Forms" is the name of a book I haven't read yet.)



#25 CygnuS

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Posted 14 March 2020 - 10:28 PM

I'm getting off on a bit of a tangent here so please ignore me and continue your conversation if you can't enlighten me.

Whenever I see the drawing of several frames of a monkey evolving into a walking man I wonder why it stopped at the monkey. Why not go back farther and show the rat (or whatever it was) in several frames becoming a monkey?...and then continue to go back to whatever single cell thing that started it all. I get that it would be very lengthy but that's never stopped science before. Is the problem that there would be so many speculative gaps nobody wants to monkey (pun intended) with it? Or has it been done?




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