Evolution and complexity

Hello Again:In reply to my question about the complexity of the mammalian heart compared to the insect heart you wrote: What more do you want me to tell you about morphology? It’s the study of structure. I think the problem comes in when we try to relate morphology with complexity. In that sense then, I look at morphology in terms of its heterogeneity. Although you may intuitively think a mammalian heart is more complex than an insect heart, I say that it is unquestionably more complex, because of its more complex structure. I guess that in a nutshell, I ascribe to the view that when we talk about an organisms biological complexity we are, at least in part, talking about it’s morphological complexity. Does this help clear things up a bit?But I think the bigger question is not whether one part of an organism is more complex then its counterpart in or on another organism, but rather, how many parts does one organism have when compared to another? Can we use parts as a measure of complexity? I agree with others that say yes. The more parts, the more complex. How do we measure parts? We can look at functions (after all, function always reflects structure). Since most parts will not have overlapping functions, the variance in the number of functions for each part will be low. So the number of functions will positively correlate with the number of parts (McShae D.W. 2000. Functional Complexity in Organisms: Parts as proxies. Biology and Physiology. 15(5):641-668). Sorry, but I don’t agree with this statement? I don’t think my definition is based on intuition (actually, it’s not mine per-say, it’s just something I agree with and am apparently doing a poor job of relaying to this site). As I have said before, it’s based on the differentiation of cells that ultimately lead to how morphological characteristics are expressed. How is that intuitive? We can count the parts, and if we still need more detail (or, as in the case of the fossil record where all we really have are the bones) then we can measure many morphological characters. How is that "intuitive"? Yes, that's what we're trying to do (hey, we agree on something (lol )....and I would look for the answer by looking at the morphology of the two organisms. Specifically (in this case at least), their skeletal morphology. I do not know what other type of measure you could realistically use when looking at the fossil record. I don't think that this particular comparison has been made, but other skeletal comarisons have been done and based on that evidence we can say that it does not seem to show a trend towards complexity (see Thomas, R.D.K. 1993. The skeletal Space: A finite set or Organic Designs. Evolution.47(2): 341-360. for more info if you want).So now I ask: How else would you answer a question dealing with complexity between a horse and a triceratops, other than by looking at the fossil record? And if you use the fossil record, what else could you use besides the morphological characteristics of the bones? I haven’t given you just clues on how to get to the answer of: Which is more complex, a dog or a fly?I’ve given you a map and the route on how to get there. Just because I have not driven the route does not mean it is impassable.
To be honest NosyNed, I don’t really have the time, or the tools, or the expertise to drive the route. I have read a few papers and couple of books on the subject of biological complexity and just happen to agree with those findings that say there appears to be no evolutionary drive towards complexity. I guess I’m just doing a lousy job of trying to convey what I have learned. Sorry.Maybe I should just ask you this question instead. Do you believe there is an evolutionary drive towards complexity?
I have stated that do I not beleive that such a trend exists and have tried to explain why I feel this way. I'm curious as to how you would answer the question. My guess would be that you feel it is currently an unanswerable question...is that correct?

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Maybe I should just ask you this question instead. Do you believe there is an evolutionary drive towards complexity?

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Sorry if I am jumping in, but this is a good question. I would say that in general, there is a general trend towards complexity. I think this has to do more with specialization, with complexity being a byproduct of specialization. Will there always be a trend towards complexity? No, but as a general trend, yes. Chlamydias and Rhickettsias seem to go in the opposite trend, these are bacteria that are less complicated and require a host. So there are trends in the opposite direction as well. However, specialization allows more effecient sequestering of resources (fancy words for better fitness) and this will usually cause what we would consider complexity. So perhaps, instead of measuring complexity, maybe we should measure specialization? Just a thought?

Hi Loudmouth:I'm flailing around like a chicken with its head cut off, trying to explain "complexity" and now you jump in with "specialization" as someting new to try and measure and explain! Thanks... lol.As for your thoughts on there being a general trend towards complexity, would you equate that with an inherant drive? I guess I'm asking because I'm not sure what you mean by "a general trend" (and I must admit, that I have used the term myself. But then, of course, I also knew what I meant by it )? My feeling (as I have so eloquently explained in my prevous posts...ha...lol...sorry NosyNed) is that as many organisms evolve "towards" simplicity as evolve "towards" complexity...that there is no directional bias either way.

Can you explain that further? Why would adaption/specialization occur by adding complexity and not by loosing it? (I still think that loosing redundant 'functions' goes faster than gaining new) You can consider coupling between organisms as complex also. The computer organisms of Ray share 'genetic material' with hosts. I would consider that shared material as someway belonging to these organisms.I was a little bit tired of NosyNed. He's an excellent nay-sayer. But maybe he's right. And we will 'never' find a good definition of complexity or information. If you look at complexity as 'complex to understand' you've to model a neural network of the size of our brain. That will take a pretty long time. The same if you see 'information' as 'surprising'.
Personally I still think that these things are something absolute. Just like ideas as 'to do good is better than to do bad'. It's a circular reasoning, but for me 'a truth as a cow' (Dutch saying meaning 'a horse is a horse, of course'). If you predict snow in the summer I would consider it as highly informative, but if you're a charlatan I won't... Information has something to do with reality too.

1. Doesn't it mean that you think that loosing 'complexity' is as likely as gaining? Or doesn't?
2. Why do you not assume some kind of bias?

Yes, loosing complexity is a likely as a gain in complexity. Why should I? What is there about evlutionary theory that would imply that a bias (one way or the other) will occur?

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Can you explain that further? Why would adaption/specialization occur by adding complexity and not by loosing it? (I still think that loosing redundant 'functions' goes faster than gaining new)

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I was thinking of specific examples when I put this forth, it was just more of a thought than anything else.Examples:1. Open sea hunters vs. ambush hunters: We could equate this to the complex camoflage patterns on fish that sit on the bottom of the ocean. This usually involves complex appendages and sometimes the adaption of one of those appendages as a lure. One example are the bioluminescent lanterns of deep sea anglers, or the worm like lure of the alligator turtle.2. Lemurs on Madagascar: This isolated island houses several specialized lemur species. One of those species is an insectivore that feasts on grubs in trees. It has developed acute hearing to sense grubs moving in the tree, one long claw to dig into small holes in a tree, and a "double jointed" elbow to facilitate better articulation within the hole. This species is obviously related to the land/tree dwelling lemurs on the island but it has more complexity due to specialization.I could probably think of a few more, but again this was just more of a thought experiment than anything else. It goes back to the theory of variation and limited resources, or even generalists vs. specialists. When resources are limited you have two choices, either get better at harvesting that resource (specialist) or expand your resources (generalist).

Yes and no. (to continue to be a bit obtuse )I am of the opinion that, as Gould has said, that there is no 'drive' at all. However, given a wide variety of empty environmental niches the evolutionary process will fill them and this may produce an overall increase in complexity (however, you define it).There is still room to argue. I rather like the arguement that Gould put forward in "Full House". If I choose what I count in some ways then, from a numbers point of view, there hasn't been any really big increase in complexity.That is, on average, the complexity of individual living things on earth is still around that of a bacteria. This would be calculated by taking a measure of the complexity of each organism and adding them all up and deviding by the total number of creatures.My conjecture is this: If a bacteria has a defined complexity of 1.00 then the average complexity of all life currently on earth is about 1.000000001. That is, other than a bias towards ourselves, life is not more complex than it was a couple of billion years ago.That is an approximate paraphrase of Gould's suggestion in "Full House", I think.Another thing to measure is the maximumly complex single organism. This is another extreme. In that case, the complexity (based on a bacteria at 1.00) is probably over 1,000,000. However, whether or not that has changed all that much recently is less clear.It is possible that a triceratops has a complexity of 898,456 and a horse of 897,923 and we have a complexity of, say, 1,234,582 and a chimp of 1,233,921. In which case even by this extreme measure complexity isn't increasing all that fast over the last few 100 million years.Just as in a Drunkard's walk random processes can appear to be moving in a direction. Specifically when there is a bound on one side. It is not at all impossible that the trend in complexity over the next 1,000,000 years ( a short term thing) will be downward. If we are complex (as given above) then our extinction will reduce the maximal complexity a bit. In addition, the reduction in number of species occuring now must decrease the average complexity by a smidge too.

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When you're at the bottom of the barrel, there's no place to go but up.

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I agree in your statement in principle but even the most simple single celled living oragnisms at the bottom of the barrel seem to be light years above the complexity of dirt. I am puzzled as to what's holding the barrel including the bottom of it so high off the ground?

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I agree in your statement in principle but even the most simple single celled living oragnisms at the bottom of the barrel seem to be light years above the complexity of dirt. I am puzzled as to what's holding the barrel including the bottom of it so high off the ground?

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Who say's that the current bottom of the barrel has always been the bottom of the barrel. Bacteria may only be the simplest "complex" lifeforms, but there may have been simpler lifeforms that simply could not compete. Cellularity may have been a watershed moment that did away with non-cellular life because of the level of effeciency that cellularity affords.

Loosing as likely as gaining...A mutation that
- adds code that prevents the forming of a tail
- destroys code that forms a tail
is likely probable?You're stating there is no bias. If I should state that the bias is negative I've to prove that, so do you.

That is a separate topic. We are discussing whether the evolution of life has a tendancy to increases (or any change for that matter) in complexity. The origin of life may or may not be considered to be a quantum leap in complexity. It is after that has occured that we are interested in here.

The example is at too high level. What mutation would cause the addition of a tail?There are single base pair changes (insertion or deletion or substitution mutations). If such a change results in any decrease then the oposite would be an increase.Why would any on of those single base pair changes be more or less likely than any other?

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That is a separate topic.

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Noooooo, that's not a seperate topic. It's a reply to a compelling statement that Crashfrog raises in his post that got me thinking about THIS topic.To go from single celled life to complex life according to an evolutionary model is mapable, at least hypothetically. But does the known universe have the ability to go from one phenomenom of the 4 forces, to another phenomenon of life? That is definitly going from less to more complex in a greater magnitude then from single celled to multi-celled.

Life is just a kind of self-sustaining chemistry. I would hardly put in on the level of a fundamental force, seeing as how it's an emergent state of them.