Evolution and complexity

It's nice to think about 'complexity niches', but I agree, it's hard to think nature has such things. However, you can think of 'size niches', often you can move over a bigger distance, reach higher leaves, and so on when you're bigger. And a bigger size often requires a more complex organism.Ordinarily, I relate complexity with robustness (reversed proportional). If I think of size in stead of complexity it makes the issue a little bit easier for me.Problem: If you define some kind of niches, the top ones are only able to evolve further. They are most often able to fill a niche of another kind when they find it, isn't it? And will (d)evolve in this before unknown area. So, if the reptile-ancestors conquer the world, the mammals-ancestors wouldn't get a chance. Maybe a catastophe will explain some things, but wouldn't the old species not evolve faster then some new mutants? Or do kinds lose some elasticity by evolving?

Welcome here SaviorMachine.I do have to say that I find your post rather rambling. It does? You'd have to define complexity to me to convince me. And "often" is a bit of a waffle here isn't it? How often is that?The last paragraph I just don't follow. Sorry

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Common sense isn't

Thanks! It was what I was thinking intuitively, for the reasons I explained. Bigger organisms can cover greater distances, reach higher leaves, have predator advantage, overcome natural barriers more easily (why do you think birds are so succesful?), and so on. I do not want to define complexity or information, I never found a good definition. Nobody did give me one, neither. Do you want to give me one?It's only based on the idea that size not can be extended without adaption. A little example: the large neck of the giraffe has consequences for the blood circulation. I think it requires more often a more complex organism in stead of a less complex organism. You can overwhelm me with counterexamples if you want. Problem, summarized: What's the chance that new mutants will overcome old species (even if there occurs some catastrophe)?[This message has been edited by Saviourmachine, 01-31-2004]

Portuguese Man-of-Wars (Men-of-war?) grow to huge sizes, and being jellyfish-like (if not true jellyfish), nobody would accuse them of great complexity.The largest known organism is a single soil fungus that, as I recall, covers some several square miles. If the environment changes in such a way that the new mutants are adapted to it and the old species is not, then the odds are %100.[This message has been edited by crashfrog, 01-31-2004]

Please excuse the 2 cents from me with no scientific background, but a question popped up to me, so I'm asking it.If it's a principle of some sort that life tends to fill all the niches available to it, then isn't there a certain tendency toward complexity. Yes, microbes outnumber us significantly, and if mitochondria is a "species," as Lyn Margulis suggests, then very simple life really outnumbers us, but there are niches for complex life that bacteria and other single-celled forms of life will never be able to fill. So there would be a "tendency" towards complex life, just because there are niches they can fill, right?

Okay, maybe there aren't things as 'size niches' neither. It was an attempt to search for an alternative for 'complexity niches'. It's almost answered by MarkAustin, maybe it's out of context, but it has some parallels. What kind of environment changes do you think of?

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I was playing devil's advocate, because I'm not convinced about the working of the evolution mechanism in biological sense. I would rather say that there is some decrease in complexity from a range of ancestors until current life. But I don't want to say much about that before an evolutionist will define 'information' and 'complexity' for me.I want to give it a try first:Definition of information
I'm thinking of information in terms of
1. the amount of genetic variety in a population
2. the amount of genetic material in an individual / a population
3. the amount of genetically-regulated abilities
4. the amount of variety in the natural environmentI see natural selection as that thing that transfers information type nr. 4 to information type 1, 2 and 3. There are three ways to do this:
A. add new information of type 1, 2 or 3
B. change old information of type 1, 2 or 3
C. delete old information of type 1, 2 or 3
(everything with the result of synchronizing information of type 4 with the other types)If you accept the evolution theory (from unicellular life to current life) you're stating that A and B will occur more often then C.That's not likely for me, I will give you an example: I would expect type 1C on the grounds that the mutations have a more or less randomly nature. Why do you expect type 1A or 1B?
(I know that this happens sometimes by the way, but I don't see why this should happen, and neither why this generally should happen)[This message has been edited by Saviourmachine, 01-31-2004]

I guess I really don't see the relevance of information to biology. But that's just me, I guess. So I'm not really going to be the person you want to discuss information with...

I think information is related to complexity. 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?[This message has been edited by Saviourmachine, 01-31-2004]

correct me if i am wrong, please.let's all just remember one thing...no matter how "complex" something is, if it doesn't live long enough to reproduce or outcompete other organisms that occupy or are trying to occupy their specific niche, then its "complexity" doesn't mean squat. why are we just concentrating on information? that is only a third of the picture!an organism's "information" is stored in its genotype (genetic code, DNA, genes, chromosomes, whatever). how that genotype is expressed is the phenotype. identical twins have the same genotype, but their phenotypes can be drastically different. then you have to look at the fitness of the organism's phenotype in its environment.so, "information" means nothing if it confers no advantage or is expressed in the wrong environment.one more thing, it might be wise for all of us to try not to anthropomorphize our arguments. sure, we see complexity in the things we make, but that doesn't mean that the "complexity" we see in nature is the result of a creator.

So, the point is this? That's why I defined 4 types of information (take a look at number 4).I defined natural selection as the process that transfers 'information' about the environment to the organism/specie. How would you define natural selection?Let's try to find an analogy. Speed? Moving organisms have some speed. A quantity has a lowerlimit and an upperlimit. Somewhere on earth you will find the fastest animal, somewhere the slowest. They've to be there, although nature doesn't explicit select for a particular side. Actually, nature does select a little bit for a higher speed, I think. Maybe blood temperature is a better quantity. Correct me, if you find some flaws.Complexity is only a side-effect, just as blood temperature. If nature doesn't have a mechanism what favours complexity, why is there such a range in current life? You do not have to accept that there is a creator, but you've to admit that 'natures nature' is very creative. To keep it simple: I do not understand, why you think that declaring complexity as a side-effect will explain (high) complexity in current life.

Since this thread has complexity in the title I would think that complexity would be defined. So far it has been defined synonmously with information. I think we might find that to be unsatisfactory.Can you define the term you are using and diferentiate it from information?Given one level of complexity of life then making random changes to it offers a wider range of choices in the population. I presume that this results in an increase in complexity in your mind. Is that correct? This complexity is in the overall population of course.If we have two organisms of identical complexity and they both have offspring that are not identical to the parent is it not likely that some of the offspring will have a different level of complexity? If not why not?If these kind of changes in complexity keep occuring then the total complexity of population could well be higher and also of individuals.Is there something wrong with this? Since I don't know what you mean by complexity I can't tell for sure.

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Common sense isn't

Definition of complexity
It’s even more difficult to find a definition for complexity then for information. So, I prefer a definition in relation to information: complexity on a certain level is proportional to the amount of information on that certain level. I defined 4 types/levels of information. An increase of information on level 2 will lead to an increase of complexity on level 2. It says nothing about information/complexity on other levels.
I want to illustrate this with an example: Adding a regulator gene (level 2) will lead to increase of information of type 2. If it is switching off some ability, it’s decreasing information of type 3 and the complexity on level 3 is decreasing.Maybe there are situations were adding information on a certain level will lead to a decrease of complexity on that very same level. In that case, I’ve to include a possibility for fluctuations in the definition, but I think that the definition generally holds.

is complexity that important, saviourmachine? is an increase in information on any of your levels a prerequisite for evolutionary change to occur over time? natural selection is a process in which the fitness of an organism/population is determined by its/their interaction with the environment. or, if you would rather hear it coopted from the conclusion of On the Orgin of Species:

quote:

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IF there are organisms that reproduce, and
IF offspring inherit traits from their progenitor(s), and
IF there is variability of traits, and
IF the environment cannot support all members of a growing population,
THEN those members of the population with less-adaptive traits (determined by the environment) will die out, and
THEN those members with more-adaptive traits (determined by the environment) will thrive

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look at it this way--the environment is not intentionally choosing for anything, complex or otherwise. the organisms rise or fall or remain constant under their current environmental conditions. if the conditions change, such as, say, africa drying out and savannas replacing jungle there, then the organisms/populations that better adapt will nudge out the organisms in that niche that don't adapt so well. however, that adaptation doesn't have to lead to an increase in complexity.some dinosaurs could be considered more complex (just look at some of their sizes and the mechanisms they had to inherit to attain and remain that size), than many organims alive today that fill the same niches those dinosaurs once occupied. i still don't see why complexity is such an issue. maybe it is just our way of trying to keep the hierachy of organisms, with us at the top of course, alive.

Yes, complexity is that important! First question; yes. It's necessary for declaring the observed difference in complexity over time. Second question; no. Increase or decrease, it doesn't matter, if it changes it's okay, that's evolutionary change. But it counts for an increased level of complexity over time. You can call that evolution on the big scale. It's the observed hierarchy in the layers. Yes, that's where I'm afraid of. Adaptation doesn't have to lead to an increase, but maybe it's worse, why should it generally lead to an increase at all? (it does maybe only in some extraordinary cases as in the case of the 'nylon' bacteria) Of course, we do. But in generally over time everything became more complex (from unicellular life to mammals/birds).It seems natural selection is indirectly prefering adding of code/abilities above deleting them. Why isn't adaption by deletion just as probable as adaption by addition/insertion? An explanation of the example of the human tail would help, I think (see above).[This message has been edited by Saviourmachine, 02-05-2004]

I'm not sure you can make this statment so easily. For one thing do we know that a microbe today is necessarily more complex, however you define it than a microbe 2 billion years ago?Is a bird more complex than a theropod dinosaur?I would expect that the average complexity of all life on the planet hasn't changed much at all in some 100's of millions of years. It may be that, depending on how you calculate complexity it hasn't done more than nudge up a percent or less in the last couple of billion (on average, remember).

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Common sense isn't