Gaia Hypothesis

[Agent Smith]

Gaia Hypothesis, in short that the earth is in some kind of self-balancing system. Proposed by late James Lovelock and promoted by Lynn Margulis in the 1970s.  

This hypothesis gained some notoriety because of novelty, but lacked scientific evidence; in fact some scientists have claimed that in most ecosystems, imbalance is the norm.

 

I offer below 2 chemical reactions for review by members:

 

1. Carbon dioxide + Water -> Sunlight -> Glucose + Oxygen [Green Plants]

2. Oxygen + Glucose -> Energy + Carbon dioxide + Water [Plants + Animals]

These are converse reactions in that one is the reversal of the other.

From the chemistry that I know, these 2 reactions are subject to the laws of chemical reactions, a few of which I recall are:   1

1. Increase the reactants and the reaction will speed up

2. Remove the products and the reaction will speed up 

3. Product accumulation means the reaction will slow down

4. Product accumulation and the reaction might reverse

 

Aren't these the hallmarks of homeostasis, the essence of self-regulation? So do these 2 chemical reactions support the Gaia Hypothesis?

 

 

[exchemist]

21 minutes ago, Agent Smith said:

Gaia Hypothesis, in short that the earth is in some kind of self-balancing system. Proposed by late James Lovelock and promoted by Lynn Margulis in the 1970s.  

This hypothesis gained some notoriety because of novelty, but lacked scientific evidence; in fact some scientists have claimed that in most ecosystems, imbalance is the norm.

 

I offer below 2 chemical reactions for review by members:

 

1. Carbon dioxide + Water -> Sunlight -> Glucose + Oxygen [Green Plants]

2. Oxygen + Glucose -> Energy + Carbon dioxide + Water [Plants + Animals]

These are converse reactions in that one is the reversal of the other.

From the chemistry that I know, these 2 reactions are subject to the laws of chemical reactions, a few of which I recall are:   1

1. Increase the reactants and the reaction will speed up

2. Remove the products and the reaction will speed up 

3. Product accumulation means the reaction will slow down

4. Product accumulation and the reaction might reverse

 

Aren't these the hallmarks of homeostasis, the essence of self-regulation? So do these 2 chemical reactions support the Gaia Hypothesis?

 

 

They are, overall (though not at all in the steps by which they are carried out), one reaction scheme: a redox reaction, which can be driven "uphill"  (reduction) by the energy in sunlight and "downhill" (oxidation) by thermodynamic "gravity", as it were. Just about any chemical reaction can, in principle and rather trivially, be driven in either direction, so the mere fact of this is not in itself evidence of balance. 

My understanding is that homeostasis refers to a stable biological state that resists being changed, as a result of some regulatory feedback. There is no such regulatory feedback implied by the reversibility of this reaction. However if you  were to expand the scope of the question to look at the Earth's carbon cycle, there is a kind of balance, with carbon sources and sinks more or less in equilibrium: https://en.wikipedia.org/wiki/Carbon_cycle    I'm not sure it is correct to call that homeostasis though, as many of the components involved are not biological. 

 

[Agent Smith]

38 minutes ago, exchemist said:

They are, overall (though not at all in the steps by which they are carried out), one reaction scheme: a redox reaction, which can be driven "uphill"  (reduction) by the energy in sunlight and "downhill" (oxidation) by thermodynamic "gravity", as it were. Just about any chemical reaction can, in principle and rather trivially, be driven in either direction, so the mere fact of this is not in itself evidence of balance. 

My understanding is that homeostasis refers to a stable biological state that resists being changed, as a result of some regulatory feedback. There is no such regulatory feedback implied by the reversibility of this reaction. However if you  were to expand the scope of the question to look at the Earth's carbon cycle, there is a kind of balance, with carbon sources and sinks more or less in equilibrium: https://en.wikipedia.org/wiki/Carbon_cycle    I'm not sure it is correct to call that homeostasis though, as many of the components involved are not biological. 

 

Arigato for your response.

The negative feedback loop you're looking for would be the pushback from accumulating products. For photosynthesis, as oxygen accumulates in the atmosphere, it would slow down photosynthesis and speed up respiration and vice versa if carbon dioxide accumulated in the atmosphere. This is homeostasis or self-regulation ... cogito. 

Reduction means  removing protons/adding electrons, oui? Oxidation is adding protons/losing electrons? It's been so long, I'm a bit rusty 😄.

In the chemical reaction for photosynthesis, carbon in carbon dioxide gets hydrogenated to glucose. Is this also reduction, adding hydrogen?

[studiot]

1 hour ago, Agent Smith said:

These are converse reactions in that one is the reversal of the other.

Not exactly, no.

The second reaction does not produce sunlight.

 

2 hours ago, Agent Smith said:

Aren't these the hallmarks of homeostasis, the essence of self-regulation? So do these 2 chemical reactions support the Gaia Hypothesis?

 

Again not exactly, no.

 

In fact the degradation to a lower form of energy supports normal thermodynamic theory as well as evolution and other types of change.

[exchemist]

6 minutes ago, Agent Smith said:

Arigato for your response.

The negative feedback loop you're looking for would be the pushback from accumulating products. For photosynthesis, as oxygen accumulates in the atmosphere, it would slow down photosynthesis and speed up respiration and vice versa if carbon dioxide accumulated in the atmosphere. This is homeostasis or self-regulation ... cogito. 

Reduction means  removing protons/adding electrons, oui? Oxidation is adding protons/losing electrons? It's been so long, I'm a bit rusty 😄.

In the chemical reaction for photosynthesis, carbon in carbon dioxide gets hydrogenated to glucose. Is this also reduction, adding hydrogen?

Yes. but these are not the factors that lead to near-equilibrium in the carbon cycle, as there are so many other sources and sinks of carbon at work. 

[Agent Smith]

6 minutes ago, exchemist said:

Yes. but these are not the factors that lead to near-equilibrium in the carbon cycle, as there are so many other sources and sinks of carbon at work. 

Initially, I thought The Gaia Hypothesis was restricted to the biosphere. Turns out it includes the inorganic component of the earth as well; so marine carbon sinks, if that's what you're referring to, are also part of the overall "equilibrium". The earth as a whole is what the hypothesis considers as being in some kind of self-sustaining equilibrium. You disagree then. What's the current status of the hypothesis among ecologists/biologists? Sorry, scientific journals are not on my reading list. 

16 minutes ago, studiot said:

Not exactly, no.

The second reaction does not produce sunlight.

 

 

Again not exactly, no.

 

In fact the degradation to a lower form of energy supports normal thermodynamic theory as well as evolution and other types of change.

😁

[studiot]

26 minutes ago, Agent Smith said:

😁

Incidentally, Wikipedia on Gaia is a little short of a complete history.

 

Like many ideas, Gaia was floating around many centres of learning. Lovelock just formalised it, but the idea was incorporated for instance into Conan Doyle's fictional character Professor Challenger.

[exchemist]

1 hour ago, Agent Smith said:

Initially, I thought The Gaia Hypothesis was restricted to the biosphere. Turns out it includes the inorganic component of the earth as well; so marine carbon sinks, if that's what you're referring to, are also part of the overall "equilibrium". The earth as a whole is what the hypothesis considers as being in some kind of self-sustaining equilibrium. You disagree then. What's the current status of the hypothesis among ecologists/biologists? Sorry, scientific journals are not on my reading list. 

😁

No. What I said is while the carbon cycle is in near-equilibrium, that is not really "homeostasis", because that term applies specifically to biological systems with regulatory feedback. In this case I am not sure there is any regulatory feedback. We just have an equilibrium, reached at a particular level. If this were altered by increasing or reducing sources or sinks, the equilibrium would settle at a different point. I do not think there is any process to ensure the current level would be maintained. 

Edited July 11 by exchemist

[studiot]

If you can get to BBC iplayer there is a most revealing set of four programmes, released in 2023 containing the most up to date picture of the story of the Earth and life on it.

 

In particular the billions of years that passed whilst the atmousphere was too hazy for the correct wavelengths for photosynthesis to get through so the only life was not plant or animal.

Also the peculiar sequence of events that occurred for the steps from a barren planet to the present very fragile balance and just how fragile that balance is.

 

I thoroughly recommend watching these.

 

https://www.bbc.co.uk/iplayer/episodes/p0fpwhhm/earth

[dimreepr]

1 hour ago, Agent Smith said:

Initially, I thought The Gaia Hypothesis was restricted to the biosphere. Turns out it includes the inorganic component of the earth as well; so marine carbon sinks, if that's what you're referring to, are also part of the overall "equilibrium". The earth as a whole is what the hypothesis considers as being in some kind of self-sustaining equilibrium. You disagree then. What's the current status of the hypothesis among ecologists/biologists? Sorry, scientific journals are not on my reading list. 

The gaia hypothesis is just another word for god, which is just another word for 'we don't know yet'.

What exactly are you asking?

The world will spin on, despite what you do or think; such is the word of Dave... 😉

[Agent Smith]

34 minutes ago, exchemist said:

No. What I said is while the carbon cycle is in near-equilibrium, that is not really "homeostasis", because that term applies specifically to biological systems with regulatory feedback. In this case I am not sure there is any regulatory feedback. We just have an equilibrium, reached at a particular level. If this were altered by increasing or reducing sources or sinks, the equilibrium would settle at a different point. I do not think there is any process to ensure the current level would be maintained. 

That is correct methinks.

 

4 minutes ago, studiot said:

If you can get to BBC iplayer there is a most revealing set of four programmes, released in 2023 containing the most up to date picture of the story of the Earth and life on it.

 

In particular the billions of years that passed whilst the atmousphere was too hazy for the correct wavelengths for photosynthesis to get through so the only life was not plant or animal.

Also the peculiar sequence of events that occurred for the steps from a barren planet to the present very fragile balance and just how fragile that balance is.

 

I thoroughly recommend watching these.

 

https://www.bbc.co.uk/iplayer/episodes/p0fpwhhm/earth

That'll be most helpful, gracias.

 

3 minutes ago, dimreepr said:

The gaia hypothesis is just another word for god, which is just another word for 'we don't know yet'.

What exactly are you asking?

The world will spin on, despite what you do or think; such is the word of Dave... 😉

Interesting thought! 

Perhaps, the feedback loop doesn't allow the levels of the reactants and products to rise to levels that would reset the thermostat 😊. How exactly this is achieved is a mystery to me. In human body temperature regulation, heat up and cool down physiological processes like shivering/sweating don't result in the hypothalamic thermostat being reset to a new temperature. Do you know? 🤔

[dimreepr]

31 minutes ago, Agent Smith said:

Perhaps, the feedback loop doesn't allow the levels of the reactants and products to rise to levels that would reset the thermostat 😊. How exactly this is achieved is a mystery to me. In human body temperature regulation, heat up and cool down physiological processes like shivering/sweating don't result in the hypothalamic thermostat being reset to a new temperature. Do you know? 🤔

It's not a feedback loop, it's more a filter bubble; you hear what you want to hear... 😉

[sethoflagos]

5 hours ago, Agent Smith said:

... The earth as a whole is what the hypothesis considers as being in some kind of self-sustaining equilibrium. You disagree then. What's the current status of the hypothesis among ecologists/biologists? Sorry, scientific journals are not on my reading list...

😁

There are many potential states of relative long-term global stability embedded as islands within a sea of relative instability:

During the Cryogenian epoch ('Iceball Earth') the planet was near fully ice covered for hundreds of millions of years whereas it was pretty well ice free for most of the Mesozoic. Hopefully we're a very long way from a tipping point towards a Venus-like climate, but that state would be remarkably stable.

Much depends on the relative movements of the continental masses and, in very recent times, human activity. Both are pretty random phenomena.

[Agent Smith]

2 hours ago, dimreepr said:

It's not a feedback loop, it's more a filter bubble; you hear what you want to hear... 😉

What's a "filter bubble"? A good remark there.

Just now, sethoflagos said:

There are many potential states of relative long-term global stability embedded as islands within a sea of relative instability:

During the Cryogenian epoch ('Iceball Earth') the planet was near fully ice covered for hundreds of millions of years whereas it was pretty well ice free for most of the Mesozoic. Hopefully we're a very long way from a tipping point towards a Venus-like climate, but that state would be remarkably stable.

Much depends on the relative movements of the continental masses and, in very recent times, human activity. Both are pretty random phenomena.

Are you in any way acquainted with the Gaia hypothesis? What mechanism sustains the purported equilibrium? @exchemist made a valid criticism - the equilibrium point in chemical systems are labile.

5 hours ago, Agent Smith said:

Reduction means  removing protons/adding electrons, oui? Oxidation is adding protons/losing electrons? It's been so long, I'm a bit rusty 😄.

In the chemical reaction for photosynthesis, carbon in carbon dioxide gets hydrogenated to glucose. Is this also reduction, adding hydrogen?

Anyone willing to confirm/disconfirm these beliefs of mine? 👋

[sethoflagos]

6 minutes ago, Agent Smith said:

Are you in any way acquainted with the Gaia hypothesis? 

Somewhat. I find it quite 'Little England-ish'. Rather like Lord of the Rings, it has a grain of optimistic truth here and there.

17 minutes ago, Agent Smith said:

What mechanism sustains the purported equilibrium? @exchemist made a valid criticism - the equilibrium point in chemical systems are labile.

@exchemist is correct.

Processes may feature negative feedback promoting stability, positive feedback (eg Agent Smith-like autocatalysis) promoting instability, or quite often a combination of the two.

A stable global state is dominated by negative feedback loops at it's heart. A large enough disturbance my drive the system towards the boundary where positive feedback loops are more influential. Ultimately, the latter take over and drive the system towards a different equilibrium state. One perhaps where biochemistry can no longer occur rendering all consideration of photosynthesis etc. moot.

Post scriptum.

I meant to mention Le Chatalier's principle. It colours much of my thoughts on this regarding the local primacy of negative feedback.

 

[StringJunky]

6 hours ago, exchemist said:

No. What I said is while the carbon cycle is in near-equilibrium, that is not really "homeostasis", because that term applies specifically to biological systems with regulatory feedback. In this case I am not sure there is any regulatory feedback. We just have an equilibrium, reached at a particular level. If this were altered by increasing or reducing sources or sinks, the equilibrium would settle at a different point. I do not think there is any process to ensure the current level would be maintained. 

What about about all the living systems, directly or indirectly modulating the environment according to their needs? Amongst all the various competitions for resources there can be an overarching homeostasis that allows a certain range of organisms to exist simultaneously. within the parameters of that prevailing environment and maintain it. There are also endosymbiotic and ectosymbiotic relationships that between them can modulate their immediate environment.

Then you have microscopic organisms and plant life recycling carbon dioxide and other materials whose effects are environmentally global in their effects, so you have hierarchies of organisms all doing their job of maintaining an Earth-sized environment that sustains them together. That's  homeostasis in my book. If people want to call that overarching process 'Gaia' that's fine with me. I know what they mean.

Edited July 11 by StringJunky

[exchemist]

29 minutes ago, StringJunky said:

What about about all the living systems, directly or indirectly modulating the environment according to their needs? Amongst all the various competitions for resources there can be an overarching homeostasis that allows a certain range of organisms to exist simultaneously. within the parameters of that prevailing environment and maintain it. There are also endosymbiotic and ectosymbiotic relationships that between them can modulate their immediate environment.

Then you have microscopic organisms and plant life recycling carbon dioxide and other materials whose effects are environmentally global in their effects, so you have hierarchies of organisms all doing their job of maintaining an Earth-sized environment that sustains them together. That's  homeostasis in my book. If people want to call that overarching process 'Gaia' that's fine with me. I know what they mean.

I was talking about the carbon cycle specifically, as that seemed the planetary equilibrium most closely connected to the OP question. You seem to be addressing a different point - unless I have misunderstood.

[StringJunky]

10 minutes ago, exchemist said:

I was talking about the carbon cycle specifically, as that seemed the planetary equilibrium most closely connected to the OP question. You seem to be addressing a different point - unless I have misunderstood.

It's quite possible that I'm off the mark. The reason I put my post up was because I thought, maybe wrongly, the focus on  purely chemical processes was far too fundamental/low level to be talking about Gaia-type processes in the same breathe.

Edited July 11 by StringJunky
Edited

[exchemist]

1 minute ago, StringJunky said:

It's quite possible that I'm off the mark. The reason I put my post up was because I thought, maybe wrongly, the focus on  purely chemical processes was far too fundamental/low level to be talking about Gaia-type processes in the same breathe.

OK I see. No, my comments were to express scepticism that the carbon cycle, especially the CO2 content of the air, was subject to homeostatic control just because plants grow faster with higher CO2 content etc. There are so many other elements: absorption of CO2 by the oceans, emission by volcanoes, the release of CO2 from plants back into the atmosphere when plants die, apart, that is, from those that get immured by geological processes, and so on and so forth. I don't believe it is self-correcting - and indeed the climate change experience strongly indicates it is not.

[Agent Smith]

11 hours ago, sethoflagos said:

Somewhat. I find it quite 'Little England-ish'. Rather like Lord of the Rings, it has a grain of optimistic truth here and there.

@exchemist is correct.

Processes may feature negative feedback promoting stability, positive feedback (eg Agent Smith-like autocatalysis) promoting instability, or quite often a combination of the two.

A stable global state is dominated by negative feedback loops at it's heart. A large enough disturbance my drive the system towards the boundary where positive feedback loops are more influential. Ultimately, the latter take over and drive the system towards a different equilibrium state. One perhaps where biochemistry can no longer occur rendering all consideration of photosynthesis etc. moot.

Post scriptum.

I meant to mention Le Chatalier's principle. It colours much of my thoughts on this regarding the local primacy of negative feedback.

 

Gracias for bringing up Le Chatelier's principle; Cogito the point in re natural equilibrium I was making is precisely this principle. @exchemist is right, the set point will change i.e. if the initial equilibrium point was maintained at levels of constituents A, the subsequent equilibrium would've moved away from A. However this would require an external source for the constituents of a chemical reaction. Since the earth is, as far as I can see, a closed system in that respect, there's a good chance that the equilibrium point is constant i.e. the Gaia hypothesis could be true. However, according to paleoclimatologists there was time when the earth had very high levels of oxygen; the evidence being gigantism as can be seen in the fossil records of insects and dinos. 

10 hours ago, StringJunky said:

What about about all the living systems, directly or indirectly modulating the environment according to their needs? Amongst all the various competitions for resources there can be an overarching homeostasis that allows a certain range of organisms to exist simultaneously. within the parameters of that prevailing environment and maintain it. There are also endosymbiotic and ectosymbiotic relationships that between them can modulate their immediate environment.

Then you have microscopic organisms and plant life recycling carbon dioxide and other materials whose effects are environmentally global in their effects, so you have hierarchies of organisms all doing their job of maintaining an Earth-sized environment that sustains them together. That's  homeostasis in my book. If people want to call that overarching process 'Gaia' that's fine with me. I know what they mean.

I suppose you're on the right track there insofar as the Gaia hypothesis is concerned. Unknown to me initially, Gaia is the whole, the whole enchilada, encompasses both living and nonliving dimensions. 

 

9 hours ago, exchemist said:

OK I see. No, my comments were to express scepticism that the carbon cycle, especially the CO2 content of the air, was subject to homeostatic control just because plants grow faster with higher CO2 content etc. There are so many other elements: absorption of CO2 by the oceans, emission by volcanoes, the release of CO2 from plants back into the atmosphere when plants die, apart, that is, from those that get immured by geological processes, and so on and so forth. I don't believe it is self-correcting - and indeed the climate change experience strongly indicates it is not.

The Gaia hypothesis isn't restricted to the biosphere and also includes the nonliving aspects of earth, such as volcanism, ocean sinks, etc. However I have yet to figure out how the set point of our earth's thermostat (equilibrium point), so to speak, remains constant, instead of rising and falling with changes in the levels of the reactants and products. Isn't the earth a closed system when it comes to that? With a beaker of chemicals the only way I can alter the level of the components is with an external source; that can't be done with the earth (cycles are the way things are done on earth). 

 

[exchemist]

2 hours ago, Agent Smith said:

Gracias for bringing up Le Chatelier's principle; Cogito the point in re natural equilibrium I was making is precisely this principle. @exchemist is right, the set point will change i.e. if the initial equilibrium point was maintained at levels of constituents A, the subsequent equilibrium would've moved away from A. However this would require an external source for the constituents of a chemical reaction. Since the earth is, as far as I can see, a closed system in that respect, there's a good chance that the equilibrium point is constant i.e. the Gaia hypothesis could be true. However, according to paleoclimatologists there was time when the earth had very high levels of oxygen; the evidence being gigantism as can be seen in the fossil records of insects and dinos. 

I suppose you're on the right track there insofar as the Gaia hypothesis is concerned. Unknown to me initially, Gaia is the whole, the whole enchilada, encompasses both living and nonliving dimensions. 

 

The Gaia hypothesis isn't restricted to the biosphere and also includes the nonliving aspects of earth, such as volcanism, ocean sinks, etc. However I have yet to figure out how the set point of our earth's thermostat (equilibrium point), so to speak, remains constant, instead of rising and falling with changes in the levels of the reactants and products. Isn't the earth a closed system when it comes to that? With a beaker of chemicals the only way I can alter the level of the components is with an external source; that can't be done with the earth (cycles are the way things are done on earth). 

 

This is the point I find contentious about the Gaia hypothesis. There are so many inorganic processes which, so far as I can see, do not have any regulatory feedback mechanism, that I question the self-regulation hypothesis. I suspect it is something of a romantic myth. It seems to me we have an equilibrium point, set by the various levels of substances and the rates of the processes, but that any change to those will in general not result in a correction back to the same equilibrium level as before. The rise in CO2 concentration in the atmosphere is a case in point.  

With a chemical equilibrium, the concentrations of reactants and products are linked, so that if you change one of them, or change the temperature, a new, different set of equilibrium concentrations of all of them will result. There is nothing that restores the levels to be the same as before the change was made.  Whereas with biological homeostasis, there are processes that actively restore the levels to what they were before, in response to a perturbation.  

 

[Agent Smith]

Just now, exchemist said:

This is the point I find contentious about the Gaia hypothesis. There are so many inorganic processes which, so far as I can see, do not have any regulatory feedback mechanism, that I question the self-regulation hypothesis. I suspect it is something of a romantic myth. It seems to me we have an equilibrium point, set by the various levels of substances and the rates of the processes, but that any change to those will in general not result in a correction back to the same equilibrium level as before. The rise in CO2 concentration in the atmosphere is a case in point.  

With a chemical equilibrium, the concentrations of reactants and products are linked, so that if you change one of them, or change the temperature, a new, different set of equilibrium concentrations of all of them will result. There is nothing that restores the levels to be the same as before the change was made.  Whereas with biological homeostasis, there are processes that actively restore the levels to what they were before, in response to a perturbation.  

 

Si, that's what threw me off, but what about the fact that the earth is a closed system? We're not adding stuff to the system, we're only reallocating it. However, as you said carbon dioxide levels are rising, but that's only over the past century or so, no? What maintained carbon dioxide levels before the oil-gas-coal era? I guess, in a way, the biosphere was in some kind of semi-isolation from the inorganic carbon cycle. It wasn't built to withstand the "pressure" humans are exerting on it, assuming the atmosphere is regulated by living organisms. 

[joigus]

1 minute ago, Agent Smith said:

the earth is a closed system?

Far from it.

[Agent Smith]

Just now, joigus said:

Far from it.

A pseudo-closed system then, oui? I don't know how to explain that though.

[joigus]

14 minutes ago, Agent Smith said:

A pseudo-closed system then, oui? I don't know how to explain that though.

Not even pseudo. The Sun is a big factor, and drives many reactions, keeping all those cycles going, as stated before in the thread. Otherwise all those cycles would grind to a halt in geological time, probably.