Thermodynamics
gives evolution/OOL direction!
In
this post I’m going to assume that the academic establishment’s understanding
of evolution/OOL holds up; that is, I’m assuming that by a series of trial and
error incremental changes one organic structure changes into another with a slightly
different configuration and that this incremental process explains the transformation
of matter from its elementary state to highly complex self-perpetuating
configurations. This, as we have seen in the previous part, requires the mathematical
existence of a class of self-perpetuating configurations that are arranged in
configuration space to form a fully connected set, stretching from the “low
reaches” of elementary matter to complex multicellular organisms. This
connectedness allows self-perpetuating structures to effectively “migrate”
across configuration space by diffusion.
The
caveat here, as I mentioned in the last part of this series, is that it is by
no means clear that this connectedness is the case: In particular, self-perpetuating structures
are very likely to constitute such an extremely small fraction of the class of
all possible configurations that it feels intuitively unlikely there is enough
of them to populate configuration space with a connected set sufficiently dense
to facilitate evolution/OOL (although I have no proof of this and I don’t think
anyone else has; that’s why I continue worry the subject!). However, for the
purpose of this post I am taking on board the establishment’s assumption that
incremental evolution/OOL has happened in this way and seeing where it takes
us.
Well,
one place where it takes us is the conclusion that evolution/OOL, fairly
obviously, does have an asymmetrical directionality, just as do other
thermodynamic processes: That is, given certain initial conditions these
processes have an asymmetrical curve of change over time. For example, if we
take an elementary thermodynamic change like gas diffusion, then down at the
low level each particle knows no direction – all degrees of freedom are equally
preferred. However at the higher
macroscopic level, depending on initial conditions, the system asymmetrically
moves toward thermodynamic equilibrium as its particles populate the available
states. Lijkewise, evolution/OOL works as a kind of morphological disequilibrium: If we
start from a state of elementary matter (solids, liquids, gases) the result is diffusion
across configuration space toward organic structures. This diffusion motion across configuration
space is described in part 2 of this series*
It
is ironic that evolution/OOL is an outcome of the second law of
thermodynamics. The apparent intuitive
contradiction between the second law and evolution/OOL is not actually the case
because the second law only quantifies the overall entropy changes in a (closed)
system as it moves toward a higher statistical weight. Because the second law
places a constraint only on the overall system then increases in
order in subsystems do not violate the second law. (See for example:
Evolution/OOL,
as the academic establishment conceives it, has, then, directionality in the
thermodynamic sense. Actually this result is fairly intuitively obvious from computational
considerations: If evolution/OOL has
happened then starting from matter in its
elementary states (i.e, solids, liquids and gases) then it is obvious that
to reach the so-called “higher organisms” matter must pass through stages of organised forms that can only occur
in a particular sequence in time. E.g. organic
molecular precursors precede cells, cells precede multicellular organisms; that is, it is logically impossible for multicellular organisms to proceed
the organic components of which they are made. Of course it is quite possible, given the diffusional
nature of evolution/OOL, that individual cases can go “backwards or forwards” on
this sequence, but the sequence itself cannot be disrupted, thus imposing a
direction on the diffusion driven morphological changes in matter. There is, therefore, a general drift (if not individual drift) from
an initial condition of being in an elementary state (i.e, solids, liquids and
gases) toward more morphologically differentiated structures.
The
above point is also fairly obvious from more general computational considerations:
Not all problems are equally computationally complex. All other computational resources being equal, such as speed, memory, processor count etc, then clearly some
outcomes will take longer to compute than others. Computational complexity itself
imposes complexity sequencing or at least complexity banding on sets of outcomes.
But
getting some people to see this relatively elementary lesson is difficult
because it cuts across the intellectual interests of the polarised parties in the
North American debate. If you look at this old
post by Larry Moran you will see what I mean. He is very unwilling
to admit that from a starting point of elementary matter evolution/OOL has
anything that smacks of “progress”; in fact the whole idea that there may be
some kind of computational complexity banding amongst configurations gives him the
jitters. He has been so influenced by the implicit overriding nihilism of his atheism that
a cosmos showing a progressive development in complexity just looks too
spooky to him; the notion that some organisms are more “complex” than others
probably unnerves him because it could be the thin end of the theist wedge
about life having purpose. Also, see the discussion I had with one of Larry Moran’s
atheist commenters in the comments section of the same blog post. This atheist
showed that he was very unwilling to accept an elementary thermodynamic lesson.
I have actually recreated this discussion in the comments section of this post
(coming soon).
There
is nothing intellectually untoward with this concept of evolutionary/OOL
direction; it is simply a thermodynamic outcome of the academic establishment’s
requirements. But as I have already suggested, the above considerations
actually cut across the expectations of both sides of the polarised North
American debate between atheists and theists. Nihilistically inclined atheists are
confounded by the directionality of our universe and many in the creationist/IDist
lobby still cling onto the idea that the second law of thermodynamics contradicts
evolution. Moreover, both sides are inclined to parody evolution as a directionless,
unguided, “chance” , something-for-nothing process; at least that is something they can both agree on! But then that is something they are both wrong
about!
An idyllic initial creation according to the Jehovah's Witnesses! This picture trades on the thermodynamic naivety that as far as morphology is concerned the only way is down. Interesting to note that there are no dinosaurs in this picture; I have never seen dinosaurs appearing in JW depictions of the pre-fall world!
(From http://www.jw.org/en/publications/books/bible-stories/part-1-creation-to-the-flood/)
Footnote:
Clearly
there aren't enough organisms to approximate a real gas-like diffusion. However,
the diffusion we are thinking of here can be thought of as the abstract flow of mathematical probability.
Below I reproduce the discussion I had with Chris Nedin in the comments section of this post on "Sandwalk"
ReplyDelete“Advanced species and less advanced species”??? I see no problem with this terminology. Larry, you might like to explain to this member of the public why I have got this so badly wrong. This is my take on it:
ReplyDeleteIf the evolution of biological structures is abstracted as a series of assembly steps arrived at via stochastic paths (entailing the traversal of at least some blind alleys), then it seems clear to me that some structures require more steps in their construction than others.
This is fairly obvious (to me at least) when a stage of evolution depends on organic precursors or biological antecedents being in place, thus implying that there are variations in the number of construction steps required by different biological structures. For example, when a structure has a nested “components of components” organization then the number of construction steps will increase as nesting level increases. Moreover, some structures would appear to present a much ‘harder problem’ for evolution than others: e.g. Meta problems like evolving ‘evolvability’ or evolving heuristics capable of creating heuristics. (That latter ‘problem’ might have been ‘solved’ in humans).
Frankly I don’t see why Prof Stern’s references to ‘more advanced’ and ‘less advanced’ species warrants the rather strong comment that he shouldn’t be publishing papers about evolution. My lay interpretation of Stern is that on the basis of the foregoing considerations ‘advancement’ refers to the natural sequencing of species defined in terms of construction steps. My perception is that the ‘ladder of life’, if based on construction steps, is a theoretically robust concept. However, as with cladistic ‘hierarchies’or ‘trees’, in spite of this robustness of concept, it may be difficult to practically place species in their correct topological relations.
The above, of course, doesn’t necessarily give license to valued judgments about ‘superiority’ of structure, but it is very difficult to discuss the subject in neutral language as naturally enough human language is laden with the noise of association and values: hence terms above like: ‘hierarchies’, ‘trees’, ‘ladder of life’ ‘more advanced’, ‘harder problem’, ‘solved’ etc
.
Fred Hoyle was frank, I believe, about his ‘perfect cosmological principle’ being motivated by the atheism of his youth. He sought to impose on the universe a perfect symmetry in time and space. To him big bang was anathema because it posited a very special event on the universe, an event giving it an asymmetry in time, a center, a place of deep mystery and significance. Much better to dilute that significance over an infinite and homogeneous universe, thus having the effect of suppressing questions about its nature and helping to deny theists a foothold with an glaring ‘gap’ in science. However, with the advent of multiverse versions of big-bang Hoyle’s super-copernicanism is back on the agenda.
Be that is it may, attempts to impose an analogous symmetry on the complexity space of biological structures are doomed to failure. In complexity space everywhere does not look the same. Also, there is a time asymmetry in evolution; the process doesn’t start with complex structures – complex structures are going to appear later rather than sooner. The principle of mediocrity can’t be applied to biological structures. Scientifically speaking organisms might be all equal – but some are more equal than others. In any case I’m feeling particularly equal at the moment as I sure I’ve got this one right!
But if I have got it wrong, Larry you have only got yourself to blame. I’ve been reading your blog for several few weeks now and clearly I still haven’t understood this evolution business! Call yourself an educator? Perhaps I ought to complain to the Her Majesty!! Sir Larry? No chance! You’ve got some explaining to do!
Timothy V Reeves wrote:
ReplyDelete“Advanced species and less advanced species”??? I see no problem with this terminology. Larry, you might like to explain to this member of the public why I have got this so badly wrong. This is my take on it:
If the evolution of biological structures is abstracted as a series of assembly steps arrived at via stochastic paths (entailing the traversal of at least some blind alleys), then it seems clear to me that some structures require more steps in their construction than others.
You appear to be saying that more complex pathways are more evolved than less complex pathways. If my reading is correct then there are two problems. One is that this assumes there is some directionality to evolution, that it is striving for complexity. The other is that the position fails to take into account instances were evolution results in a reduction of components to produce the same structure. I.e. according to the view you appear to be suggesting, an organism that evolved a more efficient pathway to produce a structure, leading to less steps in the development process, would result in devolution, or a retrograde step back towards a less advanced species.
In other words the most convoluted, tortuous, complex process is more advanced than a simpler process that achieves the same result using fewer steps. There are many complex (i.e. many component) processes in biology, but many are needlessly complex - a biochemist could devise a simpler process, using less steps, to produce the same outcome. These processes are not complex because there is an advantage to them being complex, or that evolution is striving for complex solutions, but because evolution can only work by co-opting the processes and components available to it.
In manufacturing, the more 'advanced' process is one which uses the least number of steps to produce the desired result.
You appear to be equating evolution with complexity. This is problematic because we have no good definition of what constitutes "complex". While intuitively we mammals appear to be more 'complex' than single celled organisms, are mammals more 'complex' than any other vertebrates?
Frankly I don’t see why Prof Stern’s references to ‘more advanced’ and ‘less advanced’ species warrants the rather strong comment that he shouldn’t be publishing papers about evolution.
Larry was commenting on the language used in the press release associated with the paper, not on the language used in the paper itself.
Timothy V Reeves wrote:
ReplyDeleteMy lay interpretation of Stern is that on the basis of the foregoing considerations ‘advancement’ refers to the natural sequencing of species defined in terms of construction steps. My perception is that the ‘ladder of life’, if based on construction steps, is a theoretically robust concept.
Species and groups of species do not 'advance'. As a group they evolve, expand into new areas of morphospace, contract from other areas. The 'natural sequence' or lineage is the result of the somewhat random evolutionary 'walk' that started at from A and ended at form D. The sequence A-B-C-D did not occur from a striving for complexity. We could not say at form A that D would be the result, nor that it would be achieved via B-C. In fact the true sequence would be more like A-P-H-V-D. And D does not necessarily have to be more complex than A.
There is no "ladder of life". It's not just an incorrect analogy, it’s a bad one. It is incorrect because it does not remotely reflect the actual situation. And it's bad because it entrenches the very value judgements you clam it doesn't -
The above, of course, doesn’t necessarily give license to valued judgments about ‘superiority’ of structure, but it is very difficult to discuss the subject in neutral language as naturally enough human language is laden with the noise of association and values: hence terms above like: ‘hierarchies’, ‘trees’, ‘ladder of life’ ‘more advanced’, ‘harder problem’, ‘solved’ etc
Hence terms like "upward", "above", "advanced" "higher", 'lower", "below", "downwards". It also perpetuates judgements about purpose and direction in evolution.
Scientifically speaking organisms might be all equal – but some are more equal than others. In any case I’m feeling particularly equal at the moment as I sure I’ve got this one right!
This is the problem. What do you mean by "more equal"? More numerous? Can live in more environments? Can reproduce more rapidly? Can exists in the absence of light? In all of these, bacteria have it all over vertebrates. Clearly 'complexity' doesn't help us there.
Arguments about ladders and complexity usually have more to do with entrenching the view that humans are special, or more equal, than they do of accurately reflecting evolution.
But if I have got it wrong, Larry you have only got yourself to blame. I’ve been reading your blog for several few weeks now and clearly I still haven’t understood this evolution business! Call yourself an educator? Perhaps I ought to complain to the Her Majesty!! Sir Larry? No chance! You’ve got some explaining to do!
It's a bit harsh to say that after 'several few weeks' of reading a blog entitled "Strolling with a Sceptical Biochemist", it's the author's fault for any misunderstanding of evolution you may have?
Thanks for the reply Chris. Quoting myself:
ReplyDeleteIt seems clear to me that some structures REQUIRE more steps in their construction than others.
Sorry, but I realize that this statement doesn’t make the emphasis clear: I’m talking about the minimum path by which a stochastic process could be expected to arrive at a structure: hence the word ‘require’. Actually, if a process did arrive at a structure by the absolutely minimum path it is unlikely to be stochastic because such processes do not work at maximum efficiency as construction algorithms. Hence more relevant is the expectation value of the number of construction steps given the random walk nature of the process. This expectation value would be a mathematical property intrinsic to the structure itself and would not necessarily be equal to the length of the actual route by which the structure was arrived at; but I expect a correlation between the magnitude of this mathematical quantity and the actual number of construction steps
One point you have put your finger and which I should have taken cognizance of is the distinction between function and structure. A structure’s complexity might, as you suggest, be over kill given the function it serves. Hence, we really need to talk about ‘function structure’ rather ‘than actual structure’.
Although I’m not an expert in the subject of computation (actually I’m not an expert at anything apart from being augmentative) I think I grasp the subject well enough to apply it to evolution. For some biological structures the expectation number of construction steps is going to be greater than for other structures, just as some computations are necessarily longer than others. I think this is fairly obviously for nested structures like organisms that are communities of cells; in this case the construction entails both cell construction and the construction of a cell community.
So, in short I believe we can lay biological structures out on a scale of construction complexity. (emotively ‘The ladder of life’!) This construction complexity lurks in the biological background just as do cladograms, although in both cases it may be practically difficult to correctly relate organisms in these respective spaces. In any case I think it is intuitively clear that bacteria requires less construction steps than say an animal like a cat. In that sense a cat is ‘more equal’ than bacteria – it is very probably going to appear much later in the evolutionary processes than bacteria because of a construction step disparity. As I said, evolution is asymmetrical in time, just as is big bang theory. The universe is thermodynamically and dynamically in disequilibrium. It is also in morphological disequlibrium - we believe slots in morphospace have been slowly populated over the course of evolution, and there was a time when they were not populated on Earth.
In the light of the above considerations I still can’t see what is wrong with Prof Stern using the terms ‘less advanced’ and ‘more advanced’ (which the report quoted by Larry claims he used), if those terms are meant in the technical sense I am groping toward above.
I like your the term ‘morphospace’; in my imagination I picture the metaphor of a ‘cloud’ of probability probing that space and ‘finding’ the ‘quasi-equilibrium’ states of survival solutions. Is this process directed? Yes and no. ‘No’ because, given our physical regime, standard ‘balanced’ statistics applies to the dynamics of the probability ‘cloud’; that is, there is (I guess) no special weighting on the construction paths consistent with the physical regime. ‘Yes’, because evolution is sensitive to the exact details of the physical regime – the latter must effectively cut down the size of morphospace to a sufficiently small size for the probabilistic probings of evolution to work in realistic time. Moreover, certain physical regimes don’t work at all, like for example if the universes were just composed of electrons. So our physical regime is special – special enough to make evolution work like a computer suitably programmed to run genetic algorithms.
ReplyDeleteThis now leads us into multiverse theory: multiverse theory attempts to reinstate ‘mediocrity’ by merging the apparently special conditions of our physical regime into an enormous background of randomness. Our physical regime is then no longer special but is seen as statistically expected given a sufficiently large multiverse. Hence my comments about Hoyle. (Interestingly Hoyle turned to a kind of eccentric ‘scientific’ theism later in life)
Some things scare theists and some things scare atheists. Many theists are scared by evolution – it cuts across their theology. But many atheists are scared by ‘special conditions’ because it is a barrier behind which theists may claim God is hiding. Hence atheists seek to neutralize the question begging effect of special conditions with a generalized principle of mediocrity (or super-copernicanism).
I am myself a theist. I try hard not to allow myself to become emotionally uptight about either the theist of atheist options and I continue to probe them both, but for a variety of reasons I won’t bore you with here, theism now has the ascendancy in my mind.
Don’t take all that stuff I said about ‘Sir Larry’ , ‘Her Majesty’, and Larry being a bad educator too seriously!! It’s just a wind up! I have a very abstracted view of evolution, so abstracted that really I need to get up to speed on the details. Hence I read Larry’s very educational blog in order to do this. As for his grumpy atheism, I like it: it’s like having hot mustard in a ham sandwich! I love a bit of contention!
Timothy V Reeves said...
ReplyDeleteSo, in short I believe we can lay biological structures out on a scale of construction complexity. (emotively ‘The ladder of life’!) This construction complexity lurks in the biological background just as do cladograms, although in both cases it may be practically difficult to correctly relate organisms in these respective spaces. In any case I think it is intuitively clear that bacteria requires less construction steps than say an animal like a cat. In that sense a cat is ‘more equal’ than bacteria – it is very probably going to appear much later in the evolutionary processes than bacteria because of a construction step disparity.
The issue is that you are equating 'complexity' with 'advanced' and, by inference, that more complex organisms are somehow 'better', 'more evolved', 'more equal, than less advanced forms. The problem is that the term "advanced" has inescapable connotations of 'better', 'moving forward', 'moving up', and other positive inferences compared with 'less advanced'. These connotations cannot be divorced for the term and so inevitably lead to reinforcement of the ladder, or tree, or directional, or 'more complex is best' view of evolution.
More importantly, apart from the fact that your definition of 'advanced' is somewhat circular, 'advanced forms are complex forms that are more complex than less complex forms', what information does the term 'advanced forms' give us? The answer is, not much.
Advanced forms are more complex than less advanced forms. So what? Is this significant in evolutionary terms? The answer is no.
Your average bacterium might say, "you keep your advanced, convoluted, and extraordinarily resource intensive, constructional complexity, and we'll keep our less complex, less advanced constructional complexity, and we'll just continue to be the most successful group in the history of life on Earth.
Which of the following statements seems more accurate to you?:
Manufacturer1: My process results in exactly the same outcome as my competitor, but my process contains more steps, is therefore more complex, and so more advanced.
Manufacturer2: My process results in exactly the same outcome as my competitor, but my process contains less steps, is therefore less complex, and so more advanced.
Organisms are all looking to produce the same outcome in evolution terms. Some organisms attempt it through more complex pathways than others, but that doesn't make them more advanced. Why not say that, given the same outcome, the organism that achieves it in the most simple way is the most advanced?
Timothy V Reeves said:
ReplyDeleteI like your the term ‘morphospace’; in my imagination I picture the metaphor of a ‘cloud’ of probability probing that space and ‘finding’ the ‘quasi-equilibrium’ states of survival solutions. Is this process directed? Yes and no. ‘No’ because, given our physical regime, standard ‘balanced’ statistics applies to the dynamics of the probability ‘cloud’; that is, there is (I guess) no special weighting on the construction paths consistent with the physical regime. ‘Yes’, because evolution is sensitive to the exact details of the physical regime – the latter must effectively cut down the size of morphospace to a sufficiently small size for the probabilistic probings of evolution to work in realistic time.
I didn't invent the term, it's been in use for a while now. But morphospace is a much better way of visualising evolution than a ladder or tree.
Imagine a cube filled with water. This represents the maximum extent of morphospace. Now, black ink is injected into the cube. The black ink represents the region(s) of morphospace occupied by organisms. The movement of the ink during and after injection is a much better description of evolution than a ladder or tree. There is no directionality, no forwards or upwards (and consequently no backwards and downwards). Groups are free to expand and contract along any axis x, y, or z.
Just because one set of coordinates within the ink corresponds to greater complexity, does not make that area 'better' or more advanced, in terms of evolution, than any other coordinates.
Also there is no process of direction as we would normally understand the term. Groups entering regions of morphospace may find that this blocks their access to certain other areas of morphospace. There are constraints, but no directions to a definite end result (turning left on axis x does not mean that you will inevitably become a reptile – there is no card that says "go to reptilia, go directly to reptilia, do not pass mammalia, do not collect fur!)
I’ll accept that I should drop all these provocative terms like ‘ladder of life’, ‘more equal’, ‘advanced’, which as you suggested are over laden with connotations of ‘better’. Your average human being might well reply to your average bacterium with this:
ReplyDelete“Stuff all this business about being the most successful group in the history of life; you’re so boring! All you do is multiply and you all look the same. You live to reproduce and reproduce to live. In any case what does ‘most successful group’ mean? Rapidity of reproduction? ability to colonize the greatest number of environmental niches? robustness? Greatest biomass? Rapidity of evolution? Genus Longevity? You’re just playing the numbers game, just more of the same; you know nothing about quality of existence - feelings, thoughts, reason, creativity, language, love, etc etc.”
This argument is really only rightly taken up in a philosophy publication, and in any case such publications are going to be biased, because most of them have been written by humans for humans. I have yet to locate any philosophical publications written by bacteria for bacteria.
However what the above argument does tell us is that evolutionary outcomes are qualitatively very diverse. Moreover, value laden terms apart they are also quantitatively very diverse and there is a hard mathematical parameter that allows us get one handle on this diversity: namely, the minimum number of construction steps required to generate a structure, a quantity which is a function of structure. Your metaphor of the manufacturer raises a valid issue, but in setting the ‘outcome’ as a constant, rather than a variable, it misses the question of what effect varying the outcome has on the number of steps needed to generate it. The ‘outcome’ will have a structure, and therefore we can ask the question about the minimum number of construction steps required to generate that outcome. This minimum number of construction steps will be a mathematical quantity intrinsic to the outcome itself, and will vary from outcome to outcome. In the case of manufacturer 1 he might be generating the outcome inefficiently, but what we do know is that the manufacturer 2 will NOT be generating the outcome in less steps than the mathematically determined minimum value for that outcome.
It is clear to me that outcomes in evolution are not the same (although in scientific papers we, of course, should resist evaluating those outcomes and stick to description). Some ‘outcomes’ are intrinsically more complex than others in the sense that they demand a greater minimum number of construction steps True, this mathematical quantity is a relatively gross concept and misses a lot about complexity we may be interested in, but nevertheless it is very informative.
You comment as follows:
ReplyDelete.
Advanced forms are more complex than less advanced forms. So what? Is this significant in evolutionary terms? The answer is no.
The answer is, I believe, yes and no: No because there need be no morphotropic directionality in the ‘random walk’ process of evolution and ‘yes’ because of the following:
Although your morphospace cube captures some of the features of evolutionary diffusion it suggests it has a homogenous ‘ everywhere looks the same’ quality. That this is not true can be intuitively appreciated if we ask this question: At what point should we introduce the liquid? At the point that represents a cat? At the point representing a bacterium with a ‘engineered’ looking flagellum? At the point representing a prototype replicator? At a point representing a prebiotic precursor? The whole point of evolution is that it attempts to explain a fundamental asymmetry in nature: that is, if we introduce the fluid at the ‘simpler’ points, in time complex outcomes develop. Those more complex outcomes will have a higher minimum number of construction steps and so are less probable and will most likely appear sooner rather than later. Above all, structures with a high number of construction steps number will not appear instantaneously ‘IDiot-wise’ from who knows where. The diffusing fluid may not be morphotropic, but the process of evolution has direction, an arrow of time, just as does big bang theory. As I said before, the universe is morphologically in disequilibrium as it is dynamically and thermodynamically.
It’s easy to glibly talk about evolution: lots of assumptions have to be made about the speed of diffusion and the physical regime which has to cut out lots of avenues for an indifferently diffusing fluid if it is to eventually arrive at cats and dogs and their masters in realistic times. We are assuming that these are tuned to allow evolution to have the efficacy to reach complex organized structures in a mere 10^9 years.
BTW: What’s your view on theism? As I said, I am a theist myself.
Your metaphor of the manufacturer raises a valid issue, but in setting the ‘outcome’ as a constant, rather than a variable, it misses the question of what effect varying the outcome has on the number of steps needed to generate it.
ReplyDeleteBut in terms of evolution there is only one outcome - successful representation in the next generation. Fail that and it's the end of the line, game over. Everything that doesn't directly lead to that outcome is window dressing.
Don't get me wrong, I am not denigrating the achievements of humans. Being able to extract meaning from daubing pigment on chapel ceilings in Rome is amazing, but then so to is Staphylococcus aureus. In an environment that would have either eradicated Homo sapiens, or at least bombed them back to the stone age, Staphylococcus aureus has survived and is now thriving.
There are many pathways to successful representation in the next generation, some are simple, some are complex. Can we extract meaningful information regarding evolution from a quantitative measure of complexity? Maybe we can, but certainly not an indication of successful representation in the next generation.
A bacteria may respond to your response thus:
"you can keep your quality of existence - feelings, thoughts, reason, creativity, language, love, etc, as they are irrelevant distractions to the only outcome in town, and we'll still be here when you are a ghostly outlier on a contracting axis of evolution."
So I would rewrite your paragraph here:
ReplyDeleteIt is clear to me that outcomes in evolution are not the same (although in scientific papers we, of course, should resist evaluating those outcomes and stick to description). Some ‘outcomes’ are intrinsically more complex than others in the sense that they demand a greater minimum number of construction steps True, this mathematical quantity is a relatively gross concept and misses a lot about complexity we may be interested in, but nevertheless it is very informative. as:
"It is clear to me that while the outcome in evolution is the same, the pathways to achieving that outcome are not the same (although in scientific papers we, of course, should resist evaluating those pathways and stick to description). Some ‘pathways’ are intrinsically more complex than others in the sense that they demand a greater minimum number of construction steps. True, this mathematical quantity is a relatively gross concept and misses a lot about complexity we may be interested in, but nevertheless it is very informative."
Although your morphospace cube captures some of the features of evolutionary diffusion it suggests it has a homogenous ‘everywhere looks the same’ quality. That this is not true can be intuitively appreciated if we ask this question: At what point should we introduce the liquid?
The morphospace analogy is not perfect, but it is better than the usual tree approach. In fact, one of its strengths is precisely the point you raise. At what point should we introduce the liquid? The answer is - it doesn't matter. It could be in the middle towards the top, the bottom or the sides. Evolution expands outwards from the starting point. With trees or ladders you are forced to start at the bottom and then upward is the only direction open to you. With the morphospace example, unless you start ridiculously close to a corner evolution is free to expand in three dimensions. It doesn't matter if you start in the centre (0,0,0 using cube-centred coordinates) or anywhere else (0,246,10987604539).
It’s easy to glibly talk about evolution: lots of assumptions have to be made about the speed of diffusion and the physical regime which has to cut out lots of avenues for an indifferently diffusing fluid if it is to eventually arrive at cats and dogs and their masters in realistic times. We are assuming that these are tuned to allow evolution to have the efficacy to reach complex organized structures in a mere 10^9 years.
I would argue that there is no tuning involved. Conditions on Earth allow life to exist. If we were to look at the situation 1 billion years ago, would we remark upon the efficacy of evolution to produce complexity? Nope. There would be very little. However, in the past billion years there have been no fundamental changes in speed of diffusion and the physical regime and yet complexity has evolved. It is conceivable that is we were to run the Gouldian tape again over the history of life on earth that, in some cases no complexity would evolve at all, or that it may take much longer.
However, given the conditions on Earth, and the mechanisms of evolution, my gut feeling is that some form of complexity would evolve, but whether that outcome has been tuned into the system, and whether it would result in organisms that daub paint on chapel ceilings in Rome and domesticate carnivorous mammals, is another question entirely . . . :-)
BTW: What’s your view on theism? As I said, I am a theist myself.
I'm an atheist
OK Chris, let’s see if we can take this a bit further.
ReplyDeleteI can’t argue that an aptitude for quasi-eternal self-perpetuation (via replication) isn’t critical, but we just can’t ignore the degree of complexity that a genus maintains by successfully pitching it into the next round of replication. True, complexity is a vague notion, but we have a sufficient qualitative grasp of it, and in these days of computational theory some semblance of a quantitative grasp, to understand that an organism which is clearly perpetuating a much larger burden of complexity than bacteria, is doing something far more significant than the latter. In the self-perpetuation stakes what and how much is being perpetuated is at least as an important an issue as the perpetuation powers of bacteria measured simplistically and quantitatively in terms of longevity of genus and niche occupation. Let’s face it, ‘organisation’ as a physical phenomenon is at least, if not more interesting than energy, temperature, pressure, gravitation etc.
As you say the ‘higher’ organisms (‘higher’ in terms of complexity) may not be as robust as a ‘simple’ staphylococcus aureus (which I had to look up), but then look at what the ‘higher’ organisms are perpetuating – a whole new ball game in terms of organization – something far from trivial. That organization has one very fascinating character – it is self-referencing – if an organism is highly complex, it must have the necessary complexity to carry and perpetuate that complexity; in other words it is complex because it is complex! What we then have is a non-linear feedback effect, (perhaps the sort of thing that Sir Paul Nurse was talking about). This concept is likely to knock the socks off anyone who is stuck with a linear conception of organization. Don’t be distracted by the indifference of the ‘diffusing fluid’ – self-sustaining organisation has fascinating intrinsic properties no matter how it is arrived at.
On the introduction of the fluid: Yes, accepted, an organism could conceivably de-evolve because the fluid is not morphotropic (would flightless birds fit into this category?) However, we have to say this: there is a basic asymmetry in evolution demanded by the conjunction of the starting conditions, the mathematical properties of stepwise construction and an ‘isotropically diffusing fluid’.
In fact I thought that this asymmetry is where the explanatory power of evolution resides. It explains why an Achaean Earth had very little going for it complexity-wise and why we now see complex organisms. I think that Steven Jay Gould captures this well in his graph showing numbers of organisms against complexity. The ‘fluid’ of evolution diffuses and away from the wall of minimum complexity, just as gases released from volcanic eruptions of a primeval planet diffuse to reach a maximum height. True, some gas molecules, in their random meanderings, will move downwards, but there is a bulk upwards migration of probability populating the levels available, given the physical constraints that ‘tune’ the probabilities. (I have to be careful and say that it is the probability that ‘migrates’ because it is possible that the probabilities don’t come up trumps and nothing actually evolves). In terms of evolution the phrase that captures the analogous movement in morphospace is ‘The cosmos is in morphological disequilibrium’. But now we hit another potential non-linearity; the organisms ‘stumbled’ upon, might be so subtle that they start to warp and bias the flow of the diffusing fluid. For me this disequilibrium and non-linearity is the trigger for conjectures about theism, but I won’t go into that.
ReplyDeleteAnd this brings us on to ‘tuning’. This, I believe, is a conclusion that cannot be avoided. A gas of ‘model’ electrons will evolve nothing: the physical regime has to have the ability to reach and lock in self-sustaining organization should it come about. A tin of paper clips sitting on a table will do nothing. Now open the tin and open up each paper clip, then close the tin and shake it up: in a short while you end up with networks of paper clips. Clearly the physical regime impinges upon the reachability and fixability of a self-sustaining complexity. You, might as an atheist, however, object to the word ‘tuning’ as it hints at somebody out there tinkering around with the physical system. Nevertheless, mathematical facts suggest that not every physical system has the probability to evolve anything. From your angle the efficacy of our physical regime to ‘compute’ organisms is simply a brute fact, just as for me theism is a brute fact – well actually let me concede a ‘brute conjecture’.
We (and apes, cats, dogs) are special - more special than bacteria. Why? Because they cut across that bland ‘more of the same’ type mathematics. They represent discontinuities and asymmetries. And discontinuities and the heterogeneity of asymmetry interest us because we are complex creatures and complex self-sustaining creatures are curious and alert to discontinuities and changes in their environment. Homogeneity is boring and lacks significance; discontinuities are interesting and stimulating. Science is human because the focus our science on is based on valued judgments about what we should study. Accordingly human science identities a discontinuity between self-sustaining high organisation and homogenous matter as something of great interest and value. I suggest that one of the underlying motivating factors behind multiverse theory is that it attempts to remove the mysterious discontinuities inherent in our cosmos by blending them into a bland ‘more of the same’ type background. This is why Hoyle so hated big bang, but the irony was that in time he discovered a weird kind of theism!
.. to understand that an organism which is clearly perpetuating a much larger burden of complexity than bacteria, is doing something far more significant than the latter.
ReplyDeleteIs it? What is the "significance" of complexity in evolution?
Complexity is not a 'goal' of evolution, it is a mechanism to achieve the 'goal' of evolution. We can celebrate complexity and the fact that such complex mechanisms are the by-product of a natural process, but by the same token we should also celebrate 'simplicity' because that also delivers on the 'goal'.
In the self-perpetuation stakes what and how much is being perpetuated is at least as an important an issue as the perpetuation powers of bacteria measured simplistically and quantitatively in terms of longevity of genus and niche occupation. Let’s face it, ‘organisation’ as a physical phenomenon is at least, if not more interesting than energy, temperature, pressure, gravitation etc.
Complexity of form does not translate to complexity of the genetic information passed on. Many 'simpler' organisms have far larger genomes than humans (for example). Nor is there any evidence that humans have significantly more genes to pass on than less complex forms. Clearly it is not how much is being perpetuated that is important, but what is done with it subsequently. Indeed may of the key genes associated with developing complexity are homologous to genes in insects and other "simpler' forms. So if what is being passed on does not correlate with complexity, how much is being perpetuated is not important.
I agree, organisation is important, it is interesting, and is worthy of study. But let's not assume that it has greater stature in evolution. It's more important to us, let's not make the mistake of therefore assuming that it is more important to evolution.
"On the introduction of the fluid: Yes, accepted, an organism could conceivably de-evolve because the fluid is not morphotropic (would flightless birds fit into this category?)"
This is the problem inherent in the directional view of evolution. Organisms do not "de-evolve" But, using the directionality view, any evolution that appears to repeat ancestral conditions is viewed as a retreat, a backward step. However, the ratites (the group of flightless birds such as emus) have not de-evolved but have entered an area of morphospace in which they are superficially like their ancestors. In fact their development could almost be considered more complex because they start in the same way as flying birds but changes are then made that override the normal development, or shut down 'normal' development before it has run its full course. Note they have not 'lost' the ability to develop into flying birds, but that process has been interupted.
ReplyDeleteThe ‘fluid’ of evolution diffuses and away from the wall of minimum complexity, just as gases released from volcanic eruptions of a primeval planet diffuse to reach a maximum height.
You continue to use directional metaphors. There is no "wall of minimum complexity" and there is no movement "away" The point of 'minimum complexity' is somewhere in morphospace away from any confining walls. Movement is outward not up. Also you appear to be equating evolution with complexity.
Evolution has resulted in complexity, but most evolution has not produced complexity. The vast majority of evolution has not resulted in complexity. The directional view of evolution tends to emphasis complexity as the main result of evolution. It isn't. Modern bacteria have undergone the same amount of evolution from their ancestors in the last 500 million years as we have from our first chordate ancestors. We have focussed on the increase in complexity because its result contains us, and that has influenced our view of evolution – that complexity is more important, that complexity is the main result of evolution, that complexity is the only result of evolution, that evolution can be measured as the rise of complexity, etc. The result is that, evolution that has not resulted in complexity, has been ignored, or waved away as not being as important. The tree of life metaphor is a classic example of this. It represent evolution solely as the rise of complexity, whereas, that rise represents only a small part of evolution. In the morphospace metaphor, the rise of complexity represent only a small area of morphospace, only a small fraction of the amount of evolution activity that has, and is, taking place.
By the way, as this thread has now cycled off the front page of Larry's blog, I suspect no one else is reading these exchanges. So if you want to move on, that's fine.
Fine, let's call it a day on that one Chris. Thanks for giving the issue some serious consideration.
ReplyDelete