Evolution - Has Increased Complexity Been Observed?

[ParanoiA]

Surprisingly, I can't find an answer to this question. My search skills are horrid, I admit, but I can't quite find anything on Talkorigins and Google searches keep bringing up other forums that I'm not familiar with.

 

I'd rather just ask you fellas...

 

In discussing the complexity of the Eye, it was said that while we have observed microevolution, we have never observed something becoming more complex or sophisticated.

 

Subtending that remark came the follow up that viruses never become anything more, and yadda yadda - after all this time we evolved into the most impressive life form, yet viruses are still...viruses.

 

Would someone mind pointing me in the right direction where I could read a bit about it?

 

I know we've observed evolution and even speciation with micro-organisms, so I find it hard to believe that none of our observations suggested an increase in complexity. And I have no idea where to go with the follow up...

[Sisyphus]

I don't really know the answer to that, but I am prompted to ask how complexity is being defined. What would count as "more complex?" A parrot is more complex than an amoeba, presumably, but according to what quantifiable criteria? (A potentially easy one - size of genome - is problematic, since an amoeba's genome is actually dozens to hundreds of times larger.) More pertinently, how would it be defined on the smallest scales, i.e. in the timeframes of direct observation? You wouldn't expect viruses to necessarily evolve into something else in that timeframe (and possibly not at all - evolution tends towards more success at passing on genes, not more "complexity," and viruses are damn good at that, which is why not only are there still viruses but there are more than ever).

 

So anyway, we're stuck with "complexity" in a subjective sense, which makes it difficult to judge incrementally. And we're stuck with an extremely short timeframe for direct observation, which means we're limited to mostly incremental changes, and mostly in organisms that have the capacity to evolve very quickly and have very short generations, like microorganisms. That said, I did find this at talkorigins that is sort of pertinent:

 

Prediction 5.2: Morphological change

 

Cladistic classification' date=' and thus, phylogenetic reconstruction, is largely based on the various distinguishing morphological characteristics of species. Macroevolution requires that organisms' morphologies have changed throughout evolutionary history; thus, we should observe morphological change and variation in modern populations.

 

Confirmation:

 

There have been numerous observations of morphological change in populations of organisms (Endler 1986). Examples are the change in color of some organ, such as the yellow body or brown eyes of Drosophila, coat color in mice (Barsh 1996), scale color in fish (Houde 1988), and plumage pattern in birds (Morton 1990). Almost every imaginable heritable variation in size, length, width, or number of some physical aspect of animals has been recorded (Johnston and Selander 1973; Futuyma 1998, p. 247-262). This last fact is extremely important for common descent, since the major morphological differences between many species (e.g. species of amphibians, reptiles, mammals, and birds) are simple alterations in size of certain aspects of their respective parahomologous structures.

 

Prediction 5.3: Functional change

 

One of the major differences between organisms is their capacity for various functions. The ability to occupy one niche over another is invariably due to differing functions. Thus, functional change must be extremely important for macroscopic macroevolutionary change.

 

Confirmation:

 

Many organisms have been observed to acquire various new functions which they did not have previously (Endler 1986). Bacteria have acquired resistance to viruses (Luria and Delbruck 1943) and to antibiotics (Lederberg and Lederberg 1952). Bacteria have also evolved the ability to synthesize new amino acids and DNA bases (Futuyma 1998, p. 274). Unicellular organisms have evolved the ability to use nylon and pentachlorophenol (which are both unnatural manmade chemicals) as their sole carbon sources (Okada et al. 1983; Orser and Lange 1994). The acquisition of this latter ability entailed the evolution of an entirely novel multienzyme metabolic pathway (Lee et al. 1998). Bacteria have evolved to grow at previously unviable temperatures (Bennett et al. 1992). In E. coli, we have seen the evolution (by artificial selection) of an entirely novel metabolic system including the ability to metabolize a new carbon source, the regulation of this ability by new regulatory genes, and the evolution of the ability to transport this new carbon source across the cell membrane (Hall 1982).

 

Such evolutionary acquisition of new function is also common in metazoans. We have observed insects become resistant to insecticides (Ffrench-Constant et al. 2000), animals and plants acquire disease resistance (Carpenter and O'Brien 1995; Richter and Ronald 2000), crustaceans evolve new defenses to predators (Hairston 1990), amphibians evolve tolerance to habitat acidification (Andren et al. 1989), and mammals acquire immunity to poisons (Bishop 1981). Recent beneficial mutations are also known in humans, such as the famous apolipoprotein AI Milano mutation that confers lowered risk to cardiovascular disease in its carriers. [/quote']

 

Things like new metabolic systems in bacteria seems like something that could be subjectively called an increase in complexity. And though it might not be that dramatic, it's probably the most you would expect to see directly, given observational limitations.

 

AND OF COURSE, all of this is limited to direct observation. The fossil record, obviously, paints a much broader picture.

[StringJunky]

Have you already read this?

 

http://en.wikipedia.org/wiki/Evolution_of_complexity

[ParanoiA]

I don't really know the answer to that' date=' but I am prompted to ask how complexity is being defined. What would count as "more complex?" A parrot is more complex than an amoeba, presumably, but according to what quantifiable criteria? (A potentially easy one - size of genome - is problematic, since an amoeba's genome is actually dozens to hundreds of times larger.) More pertinently, how would it be defined on the smallest scales, i.e. in the timeframes of direct observation? You wouldn't expect viruses to necessarily evolve into something else in that timeframe (and possibly not at all - evolution tends towards more success at passing on genes, not more "complexity," and viruses are damn good at that, which is why not only are there still viruses but there are more than ever).

 

So anyway, we're stuck with "complexity" in a subjective sense, which makes it difficult to judge incrementally. And we're stuck with an extremely short timeframe for direct observation, which means we're limited to mostly incremental changes, and mostly in organisms that have the capacity to evolve very quickly and have very short generations, like microorganisms.[/quote']

 

Yeah, I realized that once I found this page on talkorgins.org about "adding information". They question the premise similarly. I think, ultimately, the "Eye" is being questioned. I wish I understood enough about biology to translate that into what kind of "complexity", or added information, that would then suggest. Such as "increased genetic material" or "novel genetic material" or "novel genetically-regulated abilities".

 

When you walk through the proposed steps of how the eye evolved, and if we assume this is an increase in complexity, then what would those fractional steps in-between be? Increased genetic material? Novel genetic material?

 

In other words when we go from a "photosensitive cell" to "aggregates of pigment cells without a nerve" - would we call that "Increased genetic material?" Or is "increased information" even relevant?

 

I'm really out of my element, but it sure is interesting.

 

Things like new metabolic systems in bacteria seems like something that could be subjectively called an increase in complexity. And though it might not be that dramatic, it's probably the most you would expect to see directly, given observational limitations.

 

I think that's a good demonstration though. If we've observed it, then I think it qualifies. I would never expect much beyond that. In fact, I was surprised we've observed speciation.

 

Thanks for the piece on Morphological Change. I do find it hard to understand, lots of terminology I'm not familiar with, but it will keep me occupied for a while.

 

Have you already read this?

 

http://en.wikipedia.org/wiki/Evolution_of_complexity

 

No I haven't and that looks terrific. Thanks.

[Mr Skeptic]

How about tetrachromats. In humans, some people have a mutation that makes them colorblind. The genes for two of our colors for cone cells go on the X chromosome. However, women have two X chromosomes so they can end up with 4 different colors for cone cells. This is in fact related to the same thing that would make a man colorblind. The point of this example is that you could call the same thing both a nasty mutation that reduces function, or a new capability to see in an extra color, depending on the circumstances.

 

Incidentally, if some programmer were to put the code for 2 out of 3 colors in the same place and the code for the third color elsewhere, I would probably smack them.