Evolution and abiogenesis

[jimbob]

Here's one:
Dollo's law of irreversibility^WP

Thanks Marplots, I hadn't come across that but would say that it's an example of the case described in my first two paragraphs.

It doesn't seem to be the sort of predictability that SelfSim is claiming.

 

[marplots]

Thanks Marplots, I hadn't come across that but would say that it's an example of the case described in my first two paragraphs.

It doesn't seem to be the sort of predictability that SelfSim is claiming.

Yeah, I'm probably losing the thread here. Most of the stuff I can think of is predictions about what can't be predicted.

 

[RecoveringYuppy]

For example the mammalian retina is not going to loose its blind spot by having its light receptors move in front of the nerves as the intermediate stages would be far less beneficial than the status quo and thus would be selected against, even though the final configuration would be superior.

How do you know that? What are you presuming the intermediate state to be? How do you know there even is an intermediate state?

 

[Emily's Cat]

Did you happen to ask Darwin where he thought natural selection first began?

Isn't it a given there had to be a beginning?

Depends on how you think about Evolution.

Disclaimer: I am not a biologist, all my knowledge is based on a combination of pop-sci, interwebs discussions with smart people, a smattering of science fiction, and good old-fashioned mind-brain reasoning. Thus, I'm probably wrong on quite a few details. But that's not going to stop me from sharing my perspective, because I think I've got a good idea about this

On Evolution:

Evolution is a process. We usually think of it in terms of a process of living things, but I think the heart of the process applies to anything that exists within a changing environment. When we're talking about living things, evolution is about how those things change over time, how a species adapts and passes on heritable characteristics. But we could just as easily change the frame and talk about stability within an environment, we can talk about likelihood to persist in a given form against competing forces. In that light, molecules are an evolutionary step from particles - they are more stable, they re more likely to persist in most environments, they're less likely to be changed by external forces. Similarly, complex molecules that respond to their environment are more likely to persist in that form than those that don't respond. Complex molecules that can react, take in and use other elements, and create copies of themselves are more likely to persist in that form than those that just get bombarded by photons and eventually fall apart. The process is the same, it's just a matter of whether you're talking about living things or non-living things. That's my take on it anyway.

On Abiogenesis:

Abiogenesis is to Evolution what Solar Formation is to the Development of the Universe. That's a pretty awkward analogy, I know. Basically, Abiogenesis is a specific point in a process: the point at which non-life becomes life. Just like a large mass floating in a disk of crud crosses a critical point and becomes a star. On one side of that point in time it's a blob of stuff. On the other side of that point in time, it's a photon-emitting powerhouse. And understanding abiogenesis is pretty much the same as understanding how exactly a blob turns into a star. The challenge here is that we've been able to observe proto-starts, and brand-new-baby stars, and old dying stars, and a bunch of stages in between... but we haven't yet been able to observe the almost-but-not-quite life and the just-barely-alive. I'm figuring we will at some point, then it won't be as much of a mystery, because we'll be able to understand what happens.

Beyond Abiogenesis and Evolution:

Lurking underneath all the creation arguments, there seems to be another issue (at least to me). It falls into that same camp that free-will vs determinism falls in. That's the discussion of machine or being. Program or Sentience or Sapience. Are we, as sapient beings, actually in control of ourselves, or are we responding in a very complicated fashion to very basic sensory inputs? If our brains effectively run because of a bunch of on/off switches in the form of electrical impulses... does that mean that a machine might be capable of sentience? Of sapience? If we some day create sapient machines, what does that imply about us? Does that strengthen the argument that we could be created beings?

*************************************

That's my take on it, in layman's terms, from the mostly uneducated on the topic side of the house. Please feel free to correct my errors

 

[jimbob]

Yeah, I'm probably losing the thread here. Most of the stuff I can think of is predictions about what can't be predicted.

That's a more concise way of putting it.

How do you know that? What are you presuming the intermediate state to be? How do you know there even is an intermediate state?

Thinking about it, that might be a slightly bad example. I had been thinking that the retina is now optimised with its nerves in front of the rods and cones. The general point was that local optima are not necessarily the best solution but the selective pressure in the vicinity would still be towards the local optimum rather than the overall optimum.

 

[SelfSim]

What sort of predictions are you talking about?

Evolution as it pertains to Earth-life biology, is a scientific Theory, (perhaps arguably, even a 'law'). There are also many predictions of how it might be falsified inside Earth's biosphere, which have been well-documented. The extrapolation of this theory to Universality, or its maybe, having 'Universal principles' is, at best, a hypothesis under test when we explore other 'worlds'.

The pathway(s) of events that led to biology on Earth are recognised as being influenced by random and deterministic factors. These two competing factors can combine in totally 'unexpected' ways in an 'alien' environment. (Ie: 'unexpected' when compared with predictions based solely from Earth's biological evolution basis). 'Self-replication' in an alien environment may not necessarily have the same implications, going forward, in that environment. We already know that diversity of compounds, chemistry and physical environments, looks to be very much part of 'the norms' in planetary theory. Our own version of life has its own sensitivities. Some argue (evidence based) that life is balanced ('tuned') on the edge of chaotic behaviors, and is highly sensitive to rapid environmental changes beyond the 'norms' established by Earth's steady-state (but changing) physical environment. Diversity when considered alongside deterministic and random influences on Evolutionary pathways, compromises the predictability, (ie: broadens the 'error bars'), of hypothesised universal Evolution principles.

Invoking hypothesised 'Universal Evolutionary principles' in a thought experiment conducted in an alien environment, also calls upon considerations of these compromised predictability factors and can only really be ultimately settled by discoveries on planetary bodies.

Autocatalytic sets, currently being researched from the 'origins of life (OOL), perspective as being potentially 'pre-biotic' componentary, sometimes produce chaotic behaviors. This means certain features, by-products and behaviours, may not necessaily persist over predicatable timeframes or; they might or; they might, and then stop, and maybe even then appear to reverse. To me, this phenomenon is worthy of attention. Evolution's predictions applied to the net impact of these behaviors seems to recognise only the three possible outcomes(?), as you mention: (i) transition to life's more clearly distinguished functions: metabolism, homeostasis, etc, via competitive pressure and natural selection, (ii) consumption by presumed co-existing descendents or (iii) extinction of the replication function. All are supportable by evidence drawn from Earth-life's historical record but this record is surely, not necessarily, universally shared in all planetary environments(?) So all this considered, why should we accept that Evolution's hypothesised universal predictions, should be shared by all planetary environments?

 

[Skeptic Ginger]

The point about prions was that they evolve. And that's what the link I posted provided evidence of. The point was not that they reproduce independent of other life forms. Prions reproduce by changing the protein they contact in a cascade reaction.

The molecules that are hypothesized to be the first replicators were the rRNA molecules I mentioned and provided citations on.

RNA That Replicates Itself Indefinitely Developed For First Time

Now, a pair of Scripps Research Institute scientists has taken a significant step toward answering that question. The scientists have synthesized for the first time RNA enzymes that can replicate themselves without the help of any proteins or other cellular components, and the process proceeds indefinitely.

The work was recently published in the journal Science. [in 2009]

IOW on the other side of the line people are drawing in the continuum of evolution.

 

[marplots]

The molecules that are hypothesized to be the first replicators were the rRNA molecules I mentioned and provided citations on.

RNA That Replicates Itself Indefinitely Developed For First Time

Ruh-roh. Ice-nine.

 

[Skeptic Ginger]

Ruh-roh. Ice-nine.

Ice-nine?

 

[Tanalia]

Ice-nine?

Ice-nine is a fictional form of ice that exists under normal conditions and "replicates" by crystallizing any water it contacts.

Not to be confused with Ice IX which is real but exists only under exotic conditions. It does not have the fictional replication ability; nor do any of the other ice phases.

 

[SelfSim]

The point about prions was that they evolve. And that's what the link I posted provided evidence of. The point was not that they reproduce independent of other life forms. Prions reproduce by changing the protein they contact in a cascade reaction.

Ok .. thanks.

The molecules that are hypothesized to be the first replicators were the rRNA molecules I mentioned and provided citations on.

RNA That Replicates Itself Indefinitely Developed For First Time

IOW on the other side of the line people are drawing in the continuum of evolution.

RNA enzymes are still very complex.

In this case, they were specifically engineered to perform efficient replication:

The goal was to take one of the RNA enzymes already developed in the lab that could perform the basic chemistry of replication, and improve it to the point that it could drive efficient, perpetual self-replication.

then it says

"This is the only case outside biology where molecular information has been immortalized," says Joyce.

I believe ribosomes have also been engineered (by Ventner etal?). Perhaps this came later than this study(?)

So, says Lincoln, "What we have is non-living ..

Technically speaking: 'yes'. But it was engineered from one of life's large, basic, informatically rich, complex building block molecules.

The group is pursuing potential applications of their discovery in the field of molecular diagnostics,
...
But the main value of the work, according to Joyce, is at the basic research level. "What we've found could be relevant to how life begins, at that key moment when Darwinian evolution starts." He is quick to point out that, while the self-replicating RNA enzyme systems share certain characteristics of life, they are not themselves a form of life.

As I said (and they more or less concur with at the end of the article): 'engineered'.

My point now is that 'molecular engineering' is only done under human control. In the real testing grounds for the hypothesised 'universal principles of Evolution Theory', (meaning exo-planetary bodies and exo-environments), there are no humans!

Therefore, this is not evidence of anything in particular, as far as supporting the hypothesised 'universality of Evolutionary principles' beyond Earth's biosphere.

IOW on the other side of the line people are drawing in the continuum of evolution.

(Its like the EU folk citing engineered desktop plasma-balls in support of their enthusiastic 'ideas'. In this case here, however, we have another engineered product (or model) .. But so what?)

 

[truethat]

FTFY. Might I gently reiterate:

...

Yes, laws and universals, as opposed to particulars. (I think. Mr Cryptic is tough to decipher; must be translating from Franglish.)

Curious why you edited it to another "instance" of abiogenesis when my meaning was another FORM of abiogenesis.

How can you know there is only one form of abiogenesis?

 

[jimbob]

Evolution as it pertains to Earth-life biology, is a scientific Theory, (perhaps arguably, even a 'law'). There are also many predictions of how it might be falsified inside Earth's biosphere, which have been well-documented. The extrapolation of this theory to Universality, or its maybe, having 'Universal principles' is, at best, a hypothesis under test when we explore other 'worlds'.

The pathway(s) of events that led to biology on Earth are recognised as being influenced by random and deterministic factors. These two competing factors can combine in totally 'unexpected' ways in an 'alien' environment. (Ie: 'unexpected' when compared with predictions based solely from Earth's biological evolution basis). 'Self-replication' in an alien environment may not necessarily have the same implications, going forward, in that environment. We already know that diversity of compounds, chemistry and physical environments, looks to be very much part of 'the norms' in planetary theory. Our own version of life has its own sensitivities. Some argue (evidence based) that life is balanced ('tuned') on the edge of chaotic behaviors, and is highly sensitive to rapid environmental changes beyond the 'norms' established by Earth's steady-state (but changing) physical environment. Diversity when considered alongside deterministic and random influences on Evolutionary pathways, compromises the predictability, (ie: broadens the 'error bars'), of hypothesised universal Evolution principles.

Invoking hypothesised 'Universal Evolutionary principles' in a thought experiment conducted in an alien environment, also calls upon considerations of these compromised predictability factors and can only really be ultimately settled by discoveries on planetary bodies.

Autocatalytic sets, currently being researched from the 'origins of life (OOL), perspective as being potentially 'pre-biotic' componentary, sometimes produce chaotic behaviors. This means certain features, by-products and behaviours, may not necessaily persist over predicatable timeframes or; they might or; they might, and then stop, and maybe even then appear to reverse. To me, this phenomenon is worthy of attention. Evolution's predictions applied to the net impact of these behaviors seems to recognise only the three possible outcomes(?), as you mention: (i) transition to life's more clearly distinguished functions: metabolism, homeostasis, etc, via competitive pressure and natural selection, (ii) consumption by presumed co-existing descendents or (iii) extinction of the replication function. All are supportable by evidence drawn from Earth-life's historical record but this record is surely, not necessarily, universally shared in all planetary environments(?) So all this considered, why should we accept that Evolution's hypothesised universal predictions, should be shared by all planetary environments?

I don't understand the highlighted part - what other options are there that could be stable? I'll grant you the possibility that such groups of imperfectly self-replicating molecules could continue to evolve without ever developing any of the other functions of life except for self-replication, but I think that would be unlikely (in fact, as self-replication requires energy, I'd say that there would have to be an analogue of respiration occurring during that process anyway).


As for your whole post, very fine, but if you have imperfect self-replication within a system with finite resources, then natural selection is a logical consequence. It doesn't matter what the system is, as long as the self-replication is imperfect, and there is some constraint on the resources.

The only way round that is to play with the definitions, and that isn't a helpful way round it.

 

[SelfSim]

I don't understand the highlighted part - what other options are there that could be stable? I'll grant you the possibility that such groups of imperfectly self-replicating molecules could continue to evolve without ever developing any of the other functions of life except for self-replication, but I think that would be unlikely (in fact, as self-replication requires energy, I'd say that there would have to be an analogue of respiration occurring during that process anyway).

Ok, so can a self-replicating chemical system capable of chemical transformations in its environment, be considered 'life'? Because if self-replicating chemical compounds are not 'life', then replication by itself, is not sufficient as a defining characteristic of 'life'. So ... similarly, the ability to undergo Darwinian evolution, (heritable changes in a population), is also not a sufficient basis for defining 'life' considering things like, for eg, minerals that are capable of reproducing errors in their crystal structure. (Which would be, sort of, the equivalent of evolution .. with the exception of selection of 'more functionally fit' variants).

So the only alternative for producing diversity would have to be someplace where environmental conditions continuously create different life forms, or similar life forms with random and frequent errors in the synthesis of chemistries used as perhaps as the equivalents of replication or metabolism. (These errors would be equivalent to mutations and could lead to traits that give some selective advantage in an existing community, or in exploiting new habitats). That random (unpredictable) process, could then lead to 'life' forms which undergo a form of 'evolution' without a master information macromolecule, (eg: DNA or RNA). Equivalent 'evolution' into more complex structures would be difficult, but maybe some type of 'symbiosis' or joining with other 'units' (ie: cells) might then overcome this.

I guess what I've done here is to 'engineer' something different, starting with self-replication, to fit, (yet again), into Evolution's processes. This demonstrates precisely, what happens in the attempt of conducting mind-experiments, like this one, (which I'm personally willing to do on some occasions). However, it is not an appropriate way for establishing the universality of hypothesised principles! That takes exploration and new discoveries, not findable from an Earth-centric life derived theory. The only other alternative, as you say below, is to redefine what we mean by 'life', but I don't see anything wrong with doing that, particularly if that's what it takes, in the light of some unimaginable non-Earth based discovery. After all, that's how science works in the real universe, (as opposed to mind experiments), and how Evolution Theory and life definitions, were developed in the first place!

As for your whole post, very fine, but if you have imperfect self-replication within a system with finite resources, then natural selection is a logical consequence. It doesn't matter what the system is, as long as the self-replication is imperfect, and there is some constraint on the resources.

The only way round that is to play with the definitions, and that isn't a helpful way round it.

See the above scenario description .. (oh and I guess I did, unashamedly, play around with the definitions).
I'm not sure about the absolute need for resource constraints(?) They might be just topped up continuously in the habitat somehow(?)

 

[Hlafordlaes]

Curious why you edited it to another "instance" of abiogenesis when my meaning was another FORM of abiogenesis.

How can you know there is only one form of abiogenesis?

What I wish to convey is that if some universal process were to be identified, its particular workings in any given environment would be subject to the same sensitivities to starting conditions as any other process. This makes any particular case, or instance, in which the universal operates subject to variations along arbitrary parameters.

If geology and gravity and so on operate along universal rules, we still get each and every mountain, each instance, in the form of a unique expression of the class /mountain/. Same for snowflakes and fingerprints. Earth abiogenesis, under this view, would operate along some universals, but be affected by, say, the specific chemical and energy environment, making Earth's instance of abiogenesis unique.

 

[SelfSim]

What I wish to convey is that if some universal process were to be identified, its particular workings in any given environment would be subject to the same sensitivities to starting conditions as any other process. This makes any particular case, or instance, in which the universal operates subject to variations along arbitrary parameters.

Re: the underlined bit: 'Parameter values' is yet another interpretation I've encountered, also.

If geology and gravity and so on operate along universal rules, we still get each and every mountain, each instance, in the form of a unique expression of the class /mountain/. Same for snowflakes and fingerprints. Earth abiogenesis, under this view, would operate along some universals, but be affected by, say, the specific chemical and energy environment, making Earth's instance of abiogenesis unique.

Its interesting to note that, (perhaps), most would agree with what you said above, right up until the last 4 words. The last 4 words seem to vary from one extreme to the other (which is a sure sign that beliefs are at play). One 'extreme' for instance, would be 'uniqueness', (as you mention). Another would be 'ubiquitous'!

 

[jimbob]

Ok, so can a self-replicating chemical system capable of chemical transformations in its environment, be considered 'life'? Because if self-replicating chemical compounds are not 'life', then replication by itself, is not sufficient as a defining characteristic of 'life'. So ... similarly, the ability to undergo Darwinian evolution, (heritable changes in a population), is also not a sufficient basis for defining 'life' considering things like, for eg, minerals that are capable of reproducing errors in their crystal structure. (Which would be, sort of, the equivalent of evolution .. with the exception of selection of 'more functionally fit' variants).

So the only alternative for producing diversity would have to be someplace where environmental conditions continuously create different life forms, or similar life forms with random and frequent errors in the synthesis of chemistries used as perhaps as the equivalents of replication or metabolism. (These errors would be equivalent to mutations and could lead to traits that give some selective advantage in an existing community, or in exploiting new habitats). That random (unpredictable) process, could then lead to 'life' forms which undergo a form of 'evolution' without a master information macromolecule, (eg: DNA or RNA). Equivalent 'evolution' into more complex structures would be difficult, but maybe some type of 'symbiosis' or joining with other 'units' (ie: cells) might then overcome this.

I guess what I've done here is to 'engineer' something different, starting with self-replication, to fit, (yet again), into Evolution's processes. This demonstrates precisely, what happens in the attempt of conducting mind-experiments, like this one, (which I'm personally willing to do on some occasions). However, it is not an appropriate way for establishing the universality of hypothesised principles! That takes exploration and new discoveries, not findable from an Earth-centric life derived theory. The only other alternative, as you say below, is to redefine what we mean by 'life', but I don't see anything wrong with doing that, particularly if that's what it takes, in the light of some unimaginable non-Earth based discovery. After all, that's how science works in the real universe, (as opposed to mind experiments), and how Evolution Theory and life definitions, were developed in the first place!
See the above scenario description .. (oh and I guess I did, unashamedly, play around with the definitions).
I'm not sure about the absolute need for resource constraints(?) They might be just topped up continuously in the habitat somehow(?)

The thing is that it dosen't seem that useful or novel.

We already have a perfectly cromulent set of features to identify life, namely living organisms perform the following functions

• Nutrition
• Respiration
• Excretion
• Growth
• Reproduction
• Sensing
• Movement

Any chemical-based life would have to do the first five of these, and proto-life would have to have analogues to perform equivalent functions for it to work as proto-life. The remaining two would arise from evolution pretty soon, and possibly are also necessary.

 

[Skeptic Ginger]

Ok .. thanks.
RNA enzymes are still very complex.

In this case, they were specifically engineered to perform efficient replication:
then it says

I believe ribosomes have also been engineered (by Ventner etal?). Perhaps this came later than this study(?)

Technically speaking: 'yes'. But it was engineered from one of life's large, basic, informatically rich, complex building block molecules.

As I said (and they more or less concur with at the end of the article): 'engineered'.

My point now is that 'molecular engineering' is only done under human control. In the real testing grounds for the hypothesised 'universal principles of Evolution Theory', (meaning exo-planetary bodies and exo-environments), there are no humans!

Therefore, this is not evidence of anything in particular, as far as supporting the hypothesised 'universality of Evolutionary principles' beyond Earth's biosphere.

(Its like the EU folk citing engineered desktop plasma-balls in support of their enthusiastic 'ideas'. In this case here, however, we have another engineered product (or model) .. But so what?)

If I'm reading this right, your whole argument is nothing more than that self replicating rRNA molecules were experimentally made in the lab, ergo à la the Ken Ham philosophy, it doesn't count.

 

[SelfSim]

If I'm reading this right, your whole argument is nothing more than that self replicating rRNA molecules were experimentally made in the lab, ergo à la the Ken Ham philosophy, it doesn't count.

I don't care in the slightest about Ken Ham, or about what he believes in, nor am I a Creationist ... Your implication here is a complete red herring.

In science, predictions made from models require testing in the environment for which they apply, and in this case, that environment demands more than just a thought experiment. It hasn't happened yet beyond Earth, and if you think it has, then show us your data.

 

[Hlafordlaes]

Re: the underlined bit: 'Parameter values' is yet another interpretation I've encountered, also.



Its interesting to note that, (perhaps), most would agree with what you said above, right up until the last 4 words. The last 4 words seem to vary from one extreme to the other (which is a sure sign that beliefs are at play). One 'extreme' for instance, would be 'uniqueness', (as you mention). Another would be 'ubiquitous'!

But the twain are not mutually exclusive, no? Universals would imply ubiquitous life wherever the right conditions pertained, during such time life is possible at that location, and life at any one particular would be unique, owing to the local specifics in its genesis. (Hate to use that last term 'nakedly,' but whatever.)

Depending on how restrictive or permissive the rules thought of as universal are, the range of possible variations is more or less limited. If highly restrictive, Earth abiogenesis would then be one case of the more rare, yet more mutually similar, cases in which the rule produces a positive outcome, affecting the search of life.