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Universal Symbiosis 
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Post Universal Symbiosis
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...Being a colony of colonies of colonies seems to be a successful recipe for life.

I want to return to the genes' eye view and push the idea of universal symbiosis--'living together'--to its ultimate conclusion. Margulis is rightly seen as a high priestess of symbiosis. As I said earlier, I would go even further, and regard all 'normal' nuclear genes as symbiotic in the same kind of way as mitochondrial genes. But where Margulis and Lovelock invoke the poetry of cooperation and amity as the primary in the union, I want to do the opposite and regard it as a secondary consequence. At the genetic level all is selfish, but the selfish ends of genes are served by cooperation at many levels.



From the chapter: The Selfish Cooperator, p 231.

Judging from this it would seem that Dawkins holds the belief that evolution is directional and 'progresses' (indirectly) toward the tendency of collaboration. And not only that, but there seems to be an implicit affirmation of the idea of increasing complexity especially in terms of colonial approbation and integration.

I know that in the past, there has been some disagreement amongst ourselves as to whether or not there is a direction of evolution and whether or not the idea of increasing complexity is sound. Am I interpreting Dawkin's correctly on these matters and if so, what do you all think about.




Mon May 19, 2003 1:04 pm
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Post Re: Progress?
By remarkable luck, Dawkins was good enough to write an entire essay on the topic:
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To evolution: is it progressive? Gould's definition of progress is a human-chauvinistic one which makes it all too easy to deny progress in evolution. I shall show that if we use a less anthropocentric, more biologically sensible, more 'adaptionist' definition, evolution turns out to be clearly and importantly progressive in the short to medium term. In another sense it is probably progressive in the long term to.

Gould's definition of progress, calculated to deliver a negative answer to the question whether evolution is progressive, is

a tendency of life to increase in anatomical complexity, or neurological elaboration, or size and flexibility of behavioral repertoire, and any criterion obviously concocted (if we would only be honest and introspective enough about our motives) to pace Homo sapiens atop a supposed heap.

My alternative, 'adaptionist' definition of progress is

a tendency for lineages to improve cumulatively their adaptive fit to their particular way of life, by increasing the numbers of features which combine together in adaptive complexes.

. . .

By this definition, adaptive evolution is not just incidentally progressive, it is deeply, dyed-in-the-wool, indispensably progressive. It is fundamentally necessary that it should be progressive if Darwinian natural selection is to perform the explanatory role in our world view that we require of it, and that it alone can perform. Here's why.

Creationists love Sir Fred Hoyle's vivid metaphor for his own misunderstanding of natural selection. It is as if a hurricane, blowing through a junkyard, had the good fortune to assemble a Boeing 747. Hoyle's point is about statistical improbability. Our answer, yours and mine and Stephen Gould's, is that natural selection is cumulative. There is a ratchet, such that small gains are saved. The hurricane doesn't spontaneously assemble the airliner in one go. Small improvements are added bit by bit. To change the metaphor, however daunting the sheer cliffs that the adaptive mountain first presents, graded ramps can be found the other side and the peak eventually scaled. Adaptive evolution must be gradual and cumulative, not because the evidence supports it (though it does) but because nothing except gradual accumulation could, in principle, do the job of solving the 747 riddle. Even divine creation wouldn't help. Quite the contrary, since any entity complicated and intelligent enough to perform the creative role would itself be the ultimate 747. And for exactly the same reason the evolution of complex, many-parted adaptations must be progressive. Later descendants will have accumulated a larger number of components towards the adaptive combination than earlier ancestors.
Richard Dawkins, "Human Chauvinism and Evolutionary Progress"



Mon May 19, 2003 9:00 pm
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Post Re: Progress?
What sometimes gets me confused is the misassociation of teleological progress with the immediate and indifferent progress of cumulation Dawkins seems to refer to. When we speak of evolution is terms of progression, the natural but misleading reaction for me is to ask 'progress towards what', as if evolution has some ultimate or teleological ends. Clearly that is a poor way to look at what is a systemmatic and indiscriminative process, but I think it is a mental pitfall that is easily fallen into, especially if ornamented in anthropocentric language.

What is not clear to me, however, is why evolution necessarily progresses toward increasing adaptive complexity. It seems that Dawkins definition applies only to the adaptive complexity of local lineages and not to the average complexity of lineages as a whole. It seems to me that there are instances where the mechanism of evolution could best be served via a reduction of complexity.




Tue May 20, 2003 2:49 pm


Post Re: Progress?
The simple answer to the question of why evolution seems to progress in the direction of increased complexity is that there is nowhere else to go. If you start with a very simple organism, even if the direction of evolution is 100% random, the lineages it engenders will tend on average to be more complex (if they deviate from the original form, they can only go in one direction.) In the case of a more complex form, the "scattering" will occur in both directions: towards more complex systems and possibly also towards simpler systems, if they are adaptive. The simpler forms are nothing to write home about, since they are no more complex than the lineage's ancestors, and are probably comparable to existing forms. The more complex forms, however, are "paving new ground". Normally this sort of scattering would "average out", except that in this case you can't "go below zero" (i.e. there is a certain lower limit to complexity.) Because of this there will be increasing complexity in biological systems. It is not necessary for there to be a consistent adaptive pressure towards more complex forms for these forms to progressively appear, only that they are adaptive some of the time. Even in the situation where simpler forms are more adaptive in 95% of situations, the progression of biological complexity is inevitable.




Tue May 20, 2003 5:31 pm


Post Re: Progress?
What do you think about the argument that biological complexity is impeded by a principle of diminishing returns? What I mean is, suppose a simple organism is sufficiently adapted to a particular set of environments. I'm not a biologist so I'm afraid a lucid example will not be forthcoming. Now suppose that this organism adapts by means of increasing its complexity to excel within a particular subset of its previous environment. In other words, its complexity is translated into specificity allowing it to occupy and dominate a niche-environment. Further development complexity along these lines paints an organism into a specific corner and eventually imposes a 'soft' limit upon its adaptive capacity. It could be argued in response to this argument, that complexity gravitates not only toward the niche category, but also toward the generic. Organisms whose complexity allows them to survive within a range of environments are more equiped to propagate themselves than organisms confined to narrowly defined environments. Yet it would seem that even in this category, the more complex an organism becomes, the more dependent it is (i.e. inflexible) upon its antecedent adaptations and the less responsive it is to increased complexity. What this suggests to me is that while evolution may always be driven toward increasing complexity, that complexity is nebulously bounded, both in terms of generic and specific adaptivity, by a principle of diminishing returns. If this is the case, is it still appropriate to call evolution progressive?

Edited by: Timothy Schoonover at: 5/20/03 6:21:05 pm



Tue May 20, 2003 6:20 pm
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Post Re: Progress?
This is exactly why Dawkins talks about "adaptive fit" instead of complexity. Becoming simpler is actually the norm for parasites; and the bacteria have done remarkably well without much increase in complexity in the last, oh, three billion years or so. Moles who live underground loose their eyes because eyes have a cost with no benefit for them. Parasites that live in another animal loose their integument because it simply gets in the way. Mockingbirds have lost the ability to build nests.

But in each of these cases, you will notice that the change is adaptive. Parasites become less complex because it benefits them; birds' wings have become more complex because it helps them fly better. Each is progress in the adaptive sense without invoking teleology.

I think Louis is right that the "drunkard's walk" gets replicators started on the path to greater complexity, but adaptation keeps us going.




Wed May 21, 2003 4:52 pm
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Post Re: Progress?
I'm still kind of struggling with these concepts. Are you saying that by progression Dawkins means a continuous tailoring of the organism towards a relatively greater adaptivity which may or may not involve increased biological complexity? It just seems to me that the more biologically complex an organism is, the less likely an increase in complexity will result in a better adaptive fit. If adaption is the impetus, as complexity increases, wouldn't the impetus gradually decrease and eventually reverse?

Hehe, it's amatuer hour in the forums today. Please bear with me.




Wed May 21, 2003 6:24 pm
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Post Re: Progress?
Complexity isn't beneficial if it doesn't bring about adaptivity. Sometimes you need to lose something to become better able to survive. Look at the tape worm. It's basically a meter or more of skin and ganglia and reproductive organs. No digestive system is needed, because it lives in a hosts intestine, which is full of already-digested material, and it only has to absorb nutrients through it's thin skin. All it really needs to do is reproduce, have its eggs carried out with the hosts feces, and repeat the cycle of parasitism.

There's a plant (can't remember the name, unfortunately), that's adapted to it's environment by becoming more like an ancient plant called chara, which lacks a good deal of "modern" plant systems, but it survives.

Edited by: Jeremy1952 at: 5/22/03 5:51:25 am



Wed May 21, 2003 10:26 pm
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Post Re: Progress?
Timothy
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If adaption is the impetus, as complexity increases, wouldn't the impetus gradually decrease and eventually reverse?
What prevents adaptation from coasting to a halt is known as the "Red Queen Effect", or arms races. When you say "environment" my first inclination is to think of the air and water, to which we do become optimally adapted; and adaptations for, say, retrieving oxygen from the water or air are remarkably stable for millions of years. But for an organism or a gene, its environment is mostly made up of other organisms and other genes. When a random mutation in the wildebeest allows it to run a little faster, the environment of lions has changed.

Say the mutation in the wildebeest made the muscle cells in its legs grow a little faster. Wildebeest with this allele run faster and so lions catch their slower brethren, until the herd is predominated by the new version. So far obvious, yes? But what about the environment of red blood cell producing genes in wildebeest? Their environment has changed, too. Before the muscle mutation, a variation in the direction of more blood cells may have been harmful, but now the animal has a use for them; its new muscles need more oxygen, and so higher red blood cell count gets selected.

Lions' "response" is not necessarily greater speed. They could get smarter, to compensate; they could get more cooperative. Or they could go extinct. Or find a different herbivore to eat.

The thing about the red queen is, she never stops. (in Alice in Wonderland, the Red Queen explained a race where everyone had to run as fast as they could, just to stay in the same place). The term has been adopted in biology because predators and prey, parasites and hosts, sexual competitors, and even plant cohorts (trees get tall to compete with other trees) are adapting to each other as fast as they can, just to stay even with the competition.




Thu May 22, 2003 5:50 am
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Post Collaboration?
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'As I said earlier, I would go even further, and regard all 'normal' nuclear genes as symbiotic in the same kind of way as mitochondrial genes'
There are some recent papers that suggest that certain evolutionary changes in the genome are due to retrovirus infection (or symbiosis within the nucleus). Apparently there are 8 species of Rock Wallaby in Queensland that differ due to retrovirus action. I couldn't find a direct link, only a reference to this in:
www.comp.nus.edu.sg/~cs62.../02.bw.pdf
It has even been suggested that the nucleus within Eukaryotic cells could have formed initially from a symbiotic virus.

Is this kind of symbiosis considered 'collaboration' or 'selfish infection'? It would certainly lead to increased complexity, as you are effectively adding the genotypes together. I would speculate that this process is more often succesful than any process that tried to reduce the complexity of a genome. If there is no upper limit to genome complexity, then where is the pressure to reduce it? 95%+ of our DNA is so called 'junk' DNA.. remnants of unwanted (viral?) proteins & enzymes. Possibly these are 'stored in case they are ever needed again', but I prefer the explanation that as they are randomly interspersed throughout the genome, it would be extremely difficult to remove the junk without damage, & probably harmful to the animal as it would reduce the rate of genome mixing that occurs during sex. Thus we have selfish gene reasons for increased genetic complexity, that also benefit to collaborate whole.

Question: Is a tapeworm genetically simpler than an earthworm? Or does it have the genes for a digestive system but never expresses them (they're part of the 'junk')?

You can't judge a genome by its organism... :lol




Fri May 23, 2003 10:31 am
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Post Re: Collaboration?
Interesting questions, Dom. Birds have very much less "junk" than the rest of us... the hypothesis is, that weight is so critical to bird survival that there is actually selective pressure against non-coding DNA.




Fri May 23, 2003 2:27 pm
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