Evolution and complexity

Crashfrog has hit it on the nose. Humans tend to overlook the microscopic life on earth when considering "life on earth." We tend to look at cuddly and cute macroscopic species, such as mammals. For comparison, there is probably more bacteria in your colon than there are humans in the world. Nematodes (roundworms) species outnumber mammal species by a magnitude of at least 10. The same could be said for arthropods.Subjectively and qualitatively, life could be considered to be increasing in complexity as an overall trend. Of course there are exceptions to this rule, such as obligate intracellular parasites, namely chlamydia. These bacteria like organisms require a host in order to multiply, they have lost the ability to do this on there own. I consider this a loss of complexity, but it is a very subjective judgement. Until complexity can be measured quantitatively, we will be stuck with subjective judgements and general trends. I wonder what the units would be (eg, evolution caused an increase of 23 complexicons in E. coli, )

Sorry for the double post.

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Can the universe as a whole be also under the control of an evolutionary mechanism of some sort, in which biological evolution may be integrated?

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This is an interesting question in that basic chemistry and physics govern both processes. However, the scale on which these things happen is quite different (eg, mutation of a gene compared to supernovae). But it isn't the scale that separates the two but rather natural selection. I can't think of an example where matter or the massing of matter is affected by a selection process (Eta may correct me on this). The closest thing that I can come up with is the creation of heavier elements in supernovae which then results in more "complex" arrangments of bodies, be they solar systems or space dust.So the only way I see of integrating both types of evolution (universe vs life) is in looking at how things are passed on to the next "generation". That is, supernovae pass on heavier elements to the next generation of celestial bodies in a similar way that DNA is passed on to subsequent generations. However, celestial bodies are not changing so that they better fit their environments but rather trying to balance themselves within physical laws.In the long run, I can't see a way to infer a common mechanism between the evolution of the universe and the evolution of species. I don't see biological evolution as a subset of universal evolution, but I can see them as being independent of each other.

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More importantly, why did life first emerge?

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It might be as simple as "why did the rock fall to the ground when I let go of it?" If certain conditions are met life may just be a simple effect of chemistry just as a falling rock is a consequence of gravity.The origin of life, however, is still very speculative (the Big Bang probably has better models at this point). In my opinion, huge amounts of progress could be made in this arena if life were found on another planet/moon/asteroid. It would be interesting to see if other life forms use different strategies for self-replication which could then give us clues as to the mechanisms and reactions that can lead to life. This is why scientists have high hopes for upcoming missions to Europa (a moon of Jupiter). If Europa does have liquid water and as a consequence it has life this could be one of the biggest discoveries of the last century, if not last millenia. I'm sure there are a few scientists who have wet dreams about Europa, hopefully they can make those dreams a reality.

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That is, the string A x A x A x A x A x A x A x A x A x A x A could be expressed algorithmically as A10, whereas the string A x B x C x D x E x F x G x H x I x J x K" cannot be compressed in the same manner.

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Actually, couldn't you compress "A x B x C x D x E x F x G x H x I x J x K" into K! (factorial)? Just a minor point, but I do get the gist of what you were talking about.

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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?

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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).

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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.

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If you agree with me that there are to types of adaptions, normal adaptions (driven by selection) and complexity adding adaptions (due to this passive drive towards complexity) then it's maybe possible to calculate the speed of both.

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Why couldn't both be driven by natural selection? Although, complexity could possibly be increased by neutral mutations. However, at some point this increase will most likely be selected for or against.

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Until now I saw that the observed speed of mutations is much higher than should be expected looking to the fossil record.

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Could you give an example? One example that from the top of my head, the proposed divergence between chimps and humans was measured independently of DNA differences. However, the two measures (fossil record and DNA differences) match up with human mutation rates. Is there another example that shows incapatible mutation rates?