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Author Topic:   Evolution and complexity
Saviourmachine
Member (Idle past 3554 days)
Posts: 113
From: Holland
Joined: 01-16-2004


Message 61 of 119 (85884)
02-12-2004 5:43 PM
Reply to: Message 60 by Trixie
02-12-2004 5:00 PM


Can you explain me how these bacteria with a 2CS are trying to encode the antisense strand also?
There is a lot of stuff about antisense regulation, and I found also an example of a protein encoded on the antisense strand of nuclear DNA in eukaryotes:
NCBI
I didn't find the answer, but I didn't have enough time. Maybe you already know..
I assume we stop about the 2CS matter to not stray off from topic. Thanks for your input.

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 62 of 119 (85917)
02-12-2004 8:32 PM
Reply to: Message 23 by Saviourmachine
01-31-2004 9:47 AM


Re: Relation complexity and information
It seems at least the Kolmogorov-Chaitin information theory tells that, where complexity is related to the length of the shortest program it would take to output a specific string.
Maybe you don't see biological systems as complex too, why is that?
Kolmogorov complexity is, as best as I can tell, not the same as information and not proportional to information.
You need to decide what measure of complexity you are going to use. In your other examples (types 1,2,3 and 4) you use information.
This whole area is quantitative. You can't make any progress without being precise.
yes, I agree that biological systems are some kind of "complex".
[This message has been edited by NosyNed, 02-12-2004]

This message is a reply to:
 Message 23 by Saviourmachine, posted 01-31-2004 9:47 AM Saviourmachine has replied

Replies to this message:
 Message 63 by Saviourmachine, posted 02-13-2004 8:19 PM NosyNed has replied

  
Saviourmachine
Member (Idle past 3554 days)
Posts: 113
From: Holland
Joined: 01-16-2004


Message 63 of 119 (86182)
02-13-2004 8:19 PM
Reply to: Message 62 by NosyNed
02-12-2004 8:32 PM


Kolmogorov complexity
NosyNed writes:
Kolmogorov complexity is, as best as I can tell, not the same as information and not proportional to information.
Uhm, you're right, when I said this I didn't meant Kolmogorov complexity. I thought of complexity as 'density of information', the less code is needed for the same information, the complexer it is. And in that way it's kind of proportional.
If we go back to Kolmogorov complexity, I've to re-think about the information types I defined, because I think now that you're right in proposing that they are not proportional. Anyway the information types I consider as very useful in 'information' matters, so I am not going to delete these posts.
I've to think out a case where information increases and Kolmogorov complexity decreases. I think that's not that difficult. And a case where information density is increasing and Kolmogorov complexity decreases! Actually, you should...
NosyNed writes:
This whole area is quantitative. You can't make any progress without being precise.
That's not true, friction does delay a train, it's not accelerating it. We can make progress without knowing numbers exactly.
Anyway, if I do not prove mine point, I didn't prove that evolution can or cannot count for complexity. So, what matters? I believe it cannot, you believe it can. This discussion is just for trying to get to a point where you can deside on rational grounds. I'm trying to provide a framework for that. I compare it to building a house together. So, everybody welcome! Please think about how 'information' or 'complexity' should be defined in a way you like, maybe it's a cornerstone for getting to the solution. I had to say this...

This message is a reply to:
 Message 62 by NosyNed, posted 02-12-2004 8:32 PM NosyNed has replied

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 Message 64 by NosyNed, posted 02-13-2004 8:33 PM Saviourmachine has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 64 of 119 (86183)
02-13-2004 8:33 PM
Reply to: Message 63 by Saviourmachine
02-13-2004 8:19 PM


Re: Kolmogorov complexity
Anyway, if I do not prove mine point, I didn't prove that evolution can or cannot count for complexity. So, what matters? I believe it cannot, you believe it can. This discussion is just for trying to get to a point where you can deside on rational grounds. I'm trying to provide a framework for that.
Well, I think that is a very good thing to do.
However, neither of us has to "believe" anything.
First we need a clear definition of complexity then we have to see if we can demonstrate that evolutionary processes can or cannot account for changes in it.
As far as I can tell any definition you have given so far is accountable for with darwiniam processes.

This message is a reply to:
 Message 63 by Saviourmachine, posted 02-13-2004 8:19 PM Saviourmachine has replied

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 Message 65 by Saviourmachine, posted 02-16-2004 3:37 PM NosyNed has replied

  
Saviourmachine
Member (Idle past 3554 days)
Posts: 113
From: Holland
Joined: 01-16-2004


Message 65 of 119 (86709)
02-16-2004 3:37 PM
Reply to: Message 64 by NosyNed
02-13-2004 8:33 PM


Question remains
NosyNed writes:
As far as I can tell any definition you have given so far is accountable for with darwiniam processes.
I'm glad to hear that, because I really tried not to offend anyone, evolutionist nor creationist.
NosyNed writes:
First we need a clear definition of complexity then we have to see if we can demonstrate that evolutionary processes can or cannot account for changes in it.
Complexity as 'density of information', what do you think about that?
I think Kolmogorov isn't that propriate, because a cell doesn't have many decoding techniques. Nature doesn't want to design the most efficient program, but the best adapted dataset (although the dual system of Trixie shows that there is evolution in the decoding program too, sometimes).
An easy to read webpage states this:
For example, Kuppers found an elegant way to reconcile the paradox of increasing information. Life is biological information, and the origin of life is the origin of biological information. Information has different aspects: syntactic (as in information theory), semantic (function and meaning of information for an organism's survival), and pragmatic (following Von Weiszacker, "information is only that which produces information"). Since evolution depends on the semantic aspect of information, there is no contradiction with the second law of Thermodynamics, which only deals with the structural aspect of matter (i.e., the syntactic aspect of information). The origin of syntactic information relates to the prebiotic synthesis of biological macromolecules. The origin of semantic information relates to the self-organization of macromolecules.
Do you know studies that handle different levels of information?
Here I found an other easy to read article.

This message is a reply to:
 Message 64 by NosyNed, posted 02-13-2004 8:33 PM NosyNed has replied

Replies to this message:
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Percy
Member
Posts: 22391
From: New Hampshire
Joined: 12-23-2000
Member Rating: 5.2


Message 66 of 119 (86712)
02-16-2004 3:56 PM
Reply to: Message 65 by Saviourmachine
02-16-2004 3:37 PM


Re: Question remains
Saviormachine writes:
Complexity as 'density of information', what do you think about that?
The more complex the encoding, whether for reasons of error tolerance or security, the less dense the information.
--Percy

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NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 67 of 119 (86723)
02-16-2004 5:00 PM
Reply to: Message 65 by Saviourmachine
02-16-2004 3:37 PM


Re: Question remains
Complexity as 'density of information', what do you think about that?
How do i calculate the "density"? This just introduces a term that isn't defined either. It seems to me, at first glance, that a completely random pattern would have the maximum density.
As I noted elsewhere, the problem of defining complexity so that it fit with intuitive ideas of what it should be and doesn't reach a max on a random pattern is hard, or so it seems.
Until I see a useful definition I don't know how to proceed.

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 Message 65 by Saviourmachine, posted 02-16-2004 3:37 PM Saviourmachine has not replied

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 Message 68 by FliesOnly, posted 02-17-2004 10:27 AM NosyNed has replied

  
FliesOnly
Member (Idle past 4144 days)
Posts: 797
From: Michigan
Joined: 12-01-2003


Message 68 of 119 (86960)
02-17-2004 10:27 AM
Reply to: Message 67 by NosyNed
02-16-2004 5:00 PM


Re: Question remains
NosyNed:
It seems that we have taken what I thought to be a relatively simple concept and transformed it into a complex monster (pun intended). Let me attempt to simplify it once again. If what we’re trying to do is determine if evolution has a drive towards complexity, then we do need to restrict our definition to something both measurable and applicable to living organisms. I think that some of the attempts to define complexity on this thread have gone a bit beyond that. A while back I mentioned organs and organs systems as a measure of complexity. Let me put it another way. Can complexity be meaningful if we define it as the number of differentiated cells within an organism? I’m not talking about the total quantity of cells, but rather the number of different types of specialized cells within the organism. This would of course lead us back to tissues and organs, and organ systems (at least for animals).
One-celled organisms would be the most simple, while mammals would certainly be one of the more complex. But then what happens when we have two organisms that have equal numbers of specialized cells (comparing a chimp to a human for example)? If asked: Are we really more complex than a chimp? my answer would be: It doesn’t matter. But if people do want to answer this question, then between closely related organisms, we can look in more detail at these systems.
I think it’s important to remember what we’re trying to do here, which is to determine if evolution is biased towards more complex organisms. Is a lion more complex than a bear? Who cares. Is a lion more complex than a starfish? Yes, if we look at the specialization of cells within each species. Is a rotifer more complex than a gastrotrich? Again, who cares. But a rotifer would be more complex than a sponge. However, the more important question is if evolution drives towards these more complex organisms or are they merely an artifact of the left hand wall? My understanding of the evidence is that they are merely an artifact and not the result of an inherent drive.
So I guess what I’m asking is if it is reasonable to use the specialization of cells within an organism as a measure of relative complexity?

This message is a reply to:
 Message 67 by NosyNed, posted 02-16-2004 5:00 PM NosyNed has replied

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 Message 69 by NosyNed, posted 02-17-2004 11:14 AM FliesOnly has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 69 of 119 (86976)
02-17-2004 11:14 AM
Reply to: Message 68 by FliesOnly
02-17-2004 10:27 AM


Re: Question remains
It seems that we have taken what I thought to be a relatively simple concept and transformed it into a complex monster (pun intended).
Unfortunately I haven't been able to find anything on the web that goes into complexity the way I want. I have read a bit of material on it. The problem, as I see it from that reading, is that it is not all that simple. It isn't easy to find a good, quantitative definition of complexity that also feels right intuitively.
So I guess what I’m asking is if it is reasonable to use the specialization of cells within an organism as a measure of relative complexity?
That is a pretty good idea, I think. It is something that brings it down to a, maybe, measureable, thing.
However, the measureing may be hard. It is not immediately obvious to me that a dog is more complex than a housefly. By this measure they may well be the same.
We do know that we would like a definition to give us some complexity at least because of our brains which we would like to define as complex. However, does our brain consist of 1, 3 or dozens of diferentiated types of cells. (It sure seems to be more than 1). Is the number more than the number in a dog, snake, fish or cockroach? That I don't know.
Your idea works if you step back far enough to have a kind of big picture view of things. But that still won't be enough to tell us whether there has been any increase in complexity for the last, say, 100 million years (or maybe even the last 300 Myr).

This message is a reply to:
 Message 68 by FliesOnly, posted 02-17-2004 10:27 AM FliesOnly has replied

Replies to this message:
 Message 70 by FliesOnly, posted 02-17-2004 12:04 PM NosyNed has replied

  
FliesOnly
Member (Idle past 4144 days)
Posts: 797
From: Michigan
Joined: 12-01-2003


Message 70 of 119 (86985)
02-17-2004 12:04 PM
Reply to: Message 69 by NosyNed
02-17-2004 11:14 AM


Re: Question remains
NosyNed:
Thanks for the quick response. I do think you jumped the gun a bit on this first example however.
NosyNed writes:
However, the measureing may be hard. It is not immediately obvious to me that a dog is more complex than a housefly. By this measure they may well be the same.
My idea would answer this one quite simply. Looking at the differentiation of cells we see the development of cardiac muscle in the dog and the connective tissue of bone as well. So by my measurements, even a cursory glance at these organisms tells us that the dog is more complex.
These are a bit more complicated but I'm actually glad you brought them up:
NosyNed writes:
We do know that we would like a definition to give us some complexity at least because of our brains which we would like to define as complex. However, does our brain consist of 1, 3 or dozens of diferentiated types of cells. (It sure seems to be more than 1). Is the number more than the number in a dog, snake, fish or cockroach? That I don't know.
The cocroach falls into the same category as my earlier fly explanation. However, the snake and fish need a bit more explaining. Let's start with the snake because it is the more closely related to us of the two. Well, as I said, the more closely related two organisms are, the more detail we need to examine. An important note here is to understand that we need to look at measurable qualities so we must look at characteristics that are expressed. Snakes (with a few rare exceptions I believe) have only one lung, no fore or hind limbs, and, again with exception of couple bones found in pythons and boas, no pectoral or pelvic girdles. So snakes would be less complex that humnas. (As a matter of fact, I think snakes would make an excellent example of an organism that evolved from a more complex ancestor ( a legged reptile) into a less complex form). As for the fish, we need look no further than the vertebral column itself. All the vertebrae in a given fish are essentially identical cylindrical "tubes", where-as in humans we have cervical, thoracic, and lumbar vertebrae, plus the sacrum and coccyx, each with many processes and grooves and holes included.
I do agree that using the brain as a measure of complexity could present some problems, but I have my suspicions that if we look at the neurophysiology of a dogs brain compared to ours, we would see some differences. Remember, just because something may be difficult to do (after all, nobody said science was easy) doesn't mean we shouldn't attempt it.
I guess if my plan is destined to fail, this might be one area that would help it on its way:
NosyNed writes:
Your idea works if you step back far enough to have a kind of big picture view of things. But that still won't be enough to tell us whether there has been any increase in complexity for the last, say, 100 million years (or maybe even the last 300 Myr).
Hmmm. Help! Actually, it's lunch time for me and I am starving so maybe after I get some food in me I can think about this a little bit more. But hey, if there's anyone else out there with any suggestions...feel free to pipe right in.

This message is a reply to:
 Message 69 by NosyNed, posted 02-17-2004 11:14 AM NosyNed has replied

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 Message 71 by NosyNed, posted 02-17-2004 2:37 PM FliesOnly has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 71 of 119 (87039)
02-17-2004 2:37 PM
Reply to: Message 70 by FliesOnly
02-17-2004 12:04 PM


Not so fast
So by my measurements, even a cursory glance at these organisms tells us that the dog is more complex.
But a housefly has chitin which a dog does not have. This is why a "cursory glance" just doesn't cut it. I do not know which is more complex by your 'diferentiated cell types' idea. At my cursory glance I would expect to see a housefly and a dog being very close in complexity.
"by my measurements" --- what measurements? All you have so far is a 'cursory glance'.
Snakes (with a few rare exceptions I believe) have only one lung, no fore or hind limbs, and, again with exception of couple bones found in pythons and boas, no pectoral or pelvic girdles. So snakes would be less complex that humnas
Nope. Your own measure is of number of different kinds of differentiated cells. Boas have bones, you didn't say it mattered how many. This is slipping back to the bigger is more complex argument that you, or someone, started with. Snakes have lungs, we do too. Snakes have heat detecting pits, we don't. So far they are equal to us.
All the vertebrae in a given fish are essentially identical cylindrical "tubes", where-as in humans we have cervical, thoracic, and lumbar vertebrae, plus the sacrum and coccyx, each with many processes and grooves and holes included.
What does the shape of the bones have to do with complexity based on the definition we have, for the moment, agreed to explore. You are making up new things as you go along.
Help.
My suggestion would be to do some research into what work exists on the definition of complexity first. Then see if there is any on 'biological complexity'. I know there is some general work done but don't know where.
The other choice would be to fall back on 'information'. However, I think that this is clearly inadequate. Random 'information' isn't what we want to talk about.
You could perhaps also try to explain where you want to get too.
If it is to discuss the nature of changes that can be produced by evolutionary processes then we can see that any definition you are likly to come up with will be producable by those processes. We see living things as one test of this and we can simulate the processes with computers and see changes that will probably match whatever you come up with.
You seem to think this is simple. I'm sure know expert but what I think I do know is that there is a whole lot to know and understand. It is not simple. To try to make it simple will be a futile exercise.

This message is a reply to:
 Message 70 by FliesOnly, posted 02-17-2004 12:04 PM FliesOnly has replied

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 Message 72 by FliesOnly, posted 02-18-2004 10:04 AM NosyNed has replied

  
FliesOnly
Member (Idle past 4144 days)
Posts: 797
From: Michigan
Joined: 12-01-2003


Message 72 of 119 (87228)
02-18-2004 10:04 AM
Reply to: Message 71 by NosyNed
02-17-2004 2:37 PM


Re: Not so fast
NosyNed:
Hello again. Sorry I didn't respond sooner but you caught me just as I was headed out the door. Plus, I wanted to think a bit about what you had written. I alway enjoy reading your responses and in this one, you brought up some very good points. Let me take another stab at it.
NosyNed writes:
But a housefly has chitin which a dog does not have. This is why a "cursory glance" just doesn't cut it. I do not know which is more complex by your 'diferentiated cell types' idea. At my cursory glance I would expect to see a housefly and a dog being very close in complexity.
"by my measurements" --- what measurements? All you have so far is a 'cursory glance'.
My (initial) measurement is differentiated cell types, and I picked out two just off the top of my head (cardiac muscle and bone) Yes, a fly has chitin. And a dog has: the capability to regulate body temperature internally, three distinct muscle types, two basic types of bone, four different types of teeth (with enamel, and dentin, and cementum), a pancreas, a liver, a well developed immune system, keratin, a four chambered heart, a closed circulatory system (with the associated arteries, arterioles, capillaries, venules, and veins), ureters, a urethra, a blabber, paired kidneys, nine types of epithelium, eleven connective tissues, and a multi-layered epidermis (with its many associated accessory structures), just to name a few things. And each of these is a result of differentiation. I know, flies have some unique structure as well, but (and I can’t say with complete certainty because I am not a dipteran anatomical physiologist) I’d be willing to bet that a mammal has many more specialized cells. But you know what NosyNed, it doesn’t matter. I’m not trying to claim that a dog is more complex than a fly. I’m saying that we can determine which is more complex by looking at differentiation because it is measurable. If it turns out that the fly has many more types of specialized cells...then so be it. Three cheers for the complex fly
NosyNed writes:
Nope. Your own measure is of number of different kinds of differentiated cells. Boas have bones, you didn't say it mattered how many. This is slipping back to the bigger is more complex argument that you, or someone, started with. Snakes have lungs, we do too. Snakes have heat detecting pits, we don't. So far they are equal to us.
I wasn’t really clear when I talked about the loss of limbs in snakes and the shape of fish vertebrae. When I said we need to look at more detail when dealing with organisms that are more and more closely related (and therefore more likely to share numerous types of differentiated cells) I went the route of Dan McShea from the University of Michigan and looked at morphology because as he points out, these things can be precisely measured and tested. I guess I wasn’t clear on thatsorry. Also, I don’t care how many bones there are. I looked at the types of bones. If we simply looked at how many, then we would also have to consider that a snake has many more ribs and vertebrae than does a dog. Total kindsnot total quantity. Again, I’m sorry for not being more clear about this, but I usually write too much as it is. I was trying to be concise and instead came off as appearing to go in many different directions.
With that in mindwhen you lack limbs and their associated girdles, that’s quite a bit of stuff you no longer have to worry about developing. Bones, muscles, ligaments, tendons, and blood vessels, just to name a few. And if we accept morphology as one measure of complexity, then, with all other things being equal, a tubular body plan is less complex than a quadraped body plan. A one lung system would be less complex than a two lung system. So this is not a bigger is more complex argument (and no, that was not started by me). It is an argument that looks at kinds of things. I never said bigger was more complex, but when considering complexity (at least in biological terms) certainly you would agree that the more parts involved, the more complex. Not necessarily better or more efficient, but more complex.
NosyNed writes:
What does the shape of the bones have to do with complexity based on the definition we have, for the moment, agreed to explore. You are making up new things as you go along.
I am not making things up as I go along. I said that as we begin to look at more closely related organisms we would have to compare them in greater detail. I realize (as I look back at what I had written) that I didn't specifically state that I was going to use morphological characters as the basis for these comparisons, but I thought it was self evident...sorry. If they share a lot of differentiated cell types, then what’s left? Well, we should look at the results of this differentiationand one way to do that would be to look at morphology. When a vertebral column consists of cylinders, all of the same basic size and shape, why should we not consider this less complex than a vertebral column consisting of different types of vertebrae that have transverse and spinal processes, transverse foreman, and various articulation surfaces (as well as other morphological differences)?
But let’s step back for a second, and again ask ourselves what it is we are trying to do. We’re trying to determine if evolutionary processes have an inherent drive towards complexity. So we have to decide on what we consider to be complex and what we consider to be simple. These have to be measurable characteristics and therefore they have to be outwardly expresses by the organism. In Gould’s book Full House we get a nice quote by McShea that says: The point is to rescue the study of biological complexity from a swamp of impressionistic evaluations, biased samples, and theoretical speculations, and try to place it on more solid empirical ground. (McShea, D.W. 1996. Metazoan complexity and evolution: is there a trend? Evolution, in press). He chooses morphology as a tool to do this (for reasons I stated earlier.)
NosyNed writes:
You seem to think this is simple. I'm sure know expert but what I think I do know is that there is a whole lot to know and understand. It is not simple. To try to make it simple will be a futile exercise.
You’re correctme saying that I wanted to try to "make it simple" was not the best choice of words. But I didn’t mean simple as in easy. I meant simple as in something we can see and measure. Determining the number of differentiated cell types found in an organism may not be simple to do, but it can almost certainly be done. Using morphology as a measure of complexity may not be easy, but again it can be done (and importantly, it can be done repeatedly with the same percision).
So let me sum it all up. I think that by initially using differentiation, we can "quickly" separate simple from complex. Then, as organisms get more and more difficult to sort out in this manner, we can look at morphology as another tool to separate the less complex from the more complex. At the same time, keeping in mind that we are only trying to answer this question: Does evolutoiun show a tendency towards complexity? Comparisons between extremely distant related organisms (or very early organisms with more recent organisms) do not really help much in answering that question.

This message is a reply to:
 Message 71 by NosyNed, posted 02-17-2004 2:37 PM NosyNed has replied

Replies to this message:
 Message 73 by NosyNed, posted 02-18-2004 11:27 AM FliesOnly has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 73 of 119 (87244)
02-18-2004 11:27 AM
Reply to: Message 72 by FliesOnly
02-18-2004 10:04 AM


Re: Not so fast
And a dog has...
And a fly can fly! Where is this getting us. I don't even know how to count "cell types". You are mixing in things like 4 chambered heart etc.
I agree that a dog appears to be, intuitively, more complex than a fly. But that doesn't get us anywhere until we have a lot more precision in what complexity is measured by and real measurements of it.
A one lung system would be less complex than a two lung system.
Again, at first glance, that seems an intuitively reasonable position but I don't think it is by any means a given. You are counting organs now not differentiated cell types. Let's have just one definition.
(McShea, D.W. 1996. Metazoan complexity and evolution: is there a trend? Evolution, in press). He chooses morphology as a tool to do this (for reasons I stated earlier.)
Could you explain morphology in more detail please?
So let me sum it all up. I think that by initially using differentiation, we can "quickly" separate simple from complex.
Yes, but it is just a rough and ready, intuitive thing. Now the hard slog has to happen where someone gets down and does the numbers. Of course, right off the bat someone has to tell me how to tell when two cells are differentiated and when they are not. My guess would be that there will be places where that isn't perfectly clear either (maybe not though, I dunno).
[This message has been edited by NosyNed, 02-18-2004]

This message is a reply to:
 Message 72 by FliesOnly, posted 02-18-2004 10:04 AM FliesOnly has replied

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 Message 74 by FliesOnly, posted 02-18-2004 4:10 PM NosyNed has replied

  
FliesOnly
Member (Idle past 4144 days)
Posts: 797
From: Michigan
Joined: 12-01-2003


Message 74 of 119 (87294)
02-18-2004 4:10 PM
Reply to: Message 73 by NosyNed
02-18-2004 11:27 AM


Re: Not so fast
How can we look at complexity? How about this (Personally, I like this one): The complexity of a system is generally acknowledged to be some function of the number of different parts it has, and of the irregularity of their arrangement. Thus, heterogeneous, messy, or irregularly configured systems are complex, such as organisms, automobiles, compost heaps, and junkyards. Order is the opposite of complexity. Ordered systems are homogenous, redundant, or regular, like picket fences and brick walls. (McShea, D.W. 1993. Evolutionary change in the morphological complexity of the mammalian vertebral column. Evolution, 47:730-40. )(as found in Gould’s Full House).
How do we get these parts? We get them via differentiation, which is (as I’m sure you know) the specialization of cells within a multi-cellular organism. Now, if we couple this idea with the morphological study of the structure of these parts, then I think we can compare the relative complexities of two or more organisms.
NosyNed writes:
And a fly can fly! Where is this getting us.
Flight in and of itself does not equal complexity. How does a fly fly? Again, I’m not an expert with dipterans, but I think it's something along the lines of using indirect flight muscles attached to the inner chitinous wall of the thorax. Wing beats come about as a result of distortion of the thorax as the muscle contracts and then relaxes. Is that complex? Well I guess it depends on what you’re comparing it to. For example, if we look at the number of parts involved just with flight, then I think avian flight would be more complex than insect flight. Of course, I don't know for sure that this is indeed the case, but I will say this: If we use the above expanation of complexity (number of parts), and if necessary couple it with a look at their morphology, then we can figure it out.
NosyNed writes:
You are mixing in things like 4 chambered heart etc.
Ok, I mentioned the 4-chambered heart because it has specialized cells. But I also stated that morphology could be used as a measure of complexity. Would you not agree that the 4-chambered mammalian heart is more complex than the tube heart of a typical insect? If we can’t even agree on this, then what’s the point?
But let me say it againI don’t care if a dog is more complex than a fly. It doesn’t matter which is more complex. What matters is that we can determine which is more complex if we look at the number of partswhich came about via differentiation. Will it be easy to determine this? I don’t know...in some cases probably "yes"...in others, probably "no". Could we determine this? I see no reason why we could not.

This message is a reply to:
 Message 73 by NosyNed, posted 02-18-2004 11:27 AM NosyNed has replied

Replies to this message:
 Message 75 by NosyNed, posted 02-18-2004 4:18 PM FliesOnly has replied

  
NosyNed
Member
Posts: 8996
From: Canada
Joined: 04-04-2003


Message 75 of 119 (87295)
02-18-2004 4:18 PM
Reply to: Message 74 by FliesOnly
02-18-2004 4:10 PM


Re: Not so fast
Would you not agree that the 4-chambered mammalian heart is more complex than the tube heart of a typical insect?
Yes, I would. But so what? My intuition may say the same as yours. You didn't tell me clearly what morphology was but I guess it would say the same thing.
So far the definition you want is something that we would agree is intuitively "more complex". But I thought we were trying to answer a question like "Is a horse more complex than a triceratops?" We want to do that to see if we can say if 'complexity' has increased or not over time. So far you've given me clues as to how I might decide if a dog is more complex than a fly (but not for sure). That isn't all that helpful.
[qs]How can we look at complexity? How about this (Personally, I like this one): The complexity of a system is generally acknowledged to be some function of the number of different parts it has, and of the irregularity of their arrangement. Thus, heterogeneous, messy, or irregularly configured systems are complex, such as organisms, automobiles, compost heaps, and junkyards. Order is the opposite of complexity. Ordered systems are homogenous, redundant, or regular, like picket fences and brick walls. (McShea, D.W. 1993. Evolutionary change in the morphological complexity of the mammalian vertebral column. Evolution, 47:730-40. )(as found in Gould’s Full House).

This message is a reply to:
 Message 74 by FliesOnly, posted 02-18-2004 4:10 PM FliesOnly has replied

Replies to this message:
 Message 76 by FliesOnly, posted 02-19-2004 2:27 PM NosyNed has replied

  
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