evolution - in the details

Discussion of everything related to the Theory of Evolution.

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damien james
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Post by damien james » Wed Sep 06, 2006 1:18 am

Actually, James is ok to criticize because hybriddevil's is a intelligent design argument (irreducibly complex) that has been used to in media many times lately. Not only with reference to organs but also:

Does anyone remember the bacteria flagellum argument that was put to rest many time over?

Or the blood clotting cascade?

Or the venus flytrap?

Some things are always assumed in this argument in order to assign it credibility.

Like comparing biological processes to man made objects like mousetrap (or computers in hybriddevil's example).

Also assuming that complex biological system will not work if one thing is missing, which is almost always untrue.

And totally disregarding that present incarnation of biological system had no prior use unrelated to present function (like weesper pointed out).

I suggest that hybriddevil study evolutionary biology further and these question will be answered.
The hand of God may well be all around us, but it is not, nor can it be, the task of science to dust for fingerprints.

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NOT intelligent design

Post by hybriddevil » Mon Sep 25, 2006 6:33 pm

Damien - My questions do NOT stem from an intelligent design perspective ... by supposing this you assign me a set of beliefs, questions, reasonings that I do not ascribe to.

You have a problem with intelligent design - take your rant somewhere else. Add to this discussion in a constructive way or post on a different thread. This is not an attack on evolution. This is an honest questioning of the science behind it. If that makes you uncomfortable then leave, but for christ's sake, cut the pedantic crap.

I graduated valedictorian of my high school class and received collegiate honors. I do very well for myself in the business community. I'm no idiot.

You want to know why these questions keep coming up? Because you're not giving any good answers. Yes, I will keep bringing up organs - because I want people to talk about scenarios. That's why I brought up a venomous snake. Guide me through the process. Make me see it. If you don't know the answer - then say so! We can pick a different scenario. At least at that point we're all being honest.

I cannot stress enough what an important discussion I believe this is - evolution is widely accepted as the explanation for life as we know it. That's no small statement. When you impart key information to a child, you are providing them a lense through which to see the world. Before any parent does that, it is their duty to question their own sources.

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Post by AstusAleator » Tue Sep 26, 2006 7:03 pm

Hybrid, your questions do sound very much like the ID argument, but they're valid questions.
One thing I noticed in your initial post is that you're likening organs or "systems" to hardware and software in computers.
This is a false analogy, as computers are specifically engineered for specific functions. Engineers simply mimic biology in their "creations". This analogy is a classic straw man, very akin to the watchmaker analogy.
What did the parasitic Candiru fish say when it finally found a host? - - "Urethra!!"

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Post by hybriddevil » Tue Sep 26, 2006 11:31 pm

Excuse my frustration, but too often I feel like these discussions focus on semantics rather than tackling the issue.

My questions do not stem from ID or any other supposed theory - I'm trying to reverse engineer evolution in my mind, especially with regards to systems.

Here's another example - many sea-faring birds inflate airsacks through-out their skeleton when diving into the water to cushion them from the pressures of impact. Prior to having these structures these birds could not have hunted for their food in the manner we currently see. The impact would destroy their internal organs. So we have the organs themselves, musculature, nervous system control, and behavior. Once again, it looks like a specialized system.

It doesn't need to be that scenario - people, feel free to post links to one with plenty of supporting research.

As I've said before - I'm not asking for a play by play; just thoughts, possibilities, etc.

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Post by lyricen » Thu Sep 28, 2006 4:48 pm

The second set of wings on all flies (Diptera) have been reduced to little nubs known as halteres; these function as gyroscopes, allowing flies to perform their astounding aeronautical feats.

How and why did these halteres arise?

Drosophila melanogaster, the fruit fly, has been used extensively in genetic studies (starting with Morgan at the turn of last century). Neat things have been done to fruit flies, including turning an antenna into a leg; turning black eyes red; and, if you can believe it, doing a bit of reverse engineering and turning a haltere back into a hind wing.

A protein called Ultrabithorax (Ubx) controls the expression or suppression of genes that direct the formation of a wing; this is how many wing modifications have arisen in insects, including the haltere.

So the haltere is a modified wing. Where did the wing come from? Snodgrass proposed a theory that wings arose from paranotal lobes on the thorax; these lobes have been found in fossil insects, as well as extant insects (silverfish have paranotal lobes and use them to control their descent when they fall from high places); also, paranotal lobes are precursers to wings in developing winged insects.

Another theory (Kukalova-Peck) is that wings arose from gills that are used by aquatic immature insects, such as the mayfly naiad.

Once modified as the a precursor to wings, whether from paranotal lobes or from gills, two theories hold on how these turned into functional wings. One, water insects used the wing precursers to glide across bodies of water (some species of mayflies are known to do this today); or, insects climbed up plants and when they jumped off, they used the wing precursors to glide.

Where did the paranotal lobes or the gills come from?

From the modification of the segments that make up the insect body.....they are masters of modification. But alas, I am going to cease with this digging for now.

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Post by lyricen » Thu Sep 28, 2006 4:56 pm

As an aside, if a fly loses one of its halteres, it can only fly in circles. This has been demonstrated time and time again in entomology 101 classes.

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Post by weesper » Sun Oct 22, 2006 6:49 pm

This is still a great thread and once again I applaud hybriddevil for asking questions w/ a background in business (man if I only I could understand the stock markets when I read the newspapers, but I'm just a dumb/biologist MD; to each his own).

Just maybe hybriddevil keeps bringing up these examples because they are what the public is spoonfed by the media on the wonders of life. To my disappoint ment this is always where every series stops without digging deeper and trying to understand evolution beyond 'survival of the fittest' - see my original contribution, most often it is the moments that appear to defy these laws that are the most interesting and we have valid answers yet they are almost never explained to the public. But once again, Stephen Jay Gould's stories are a great place to start for interested layman.

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Post by narrowstaircase » Sat Oct 28, 2006 11:39 am

im only a first year science student. this is just what i think.

hybriddevil wrote: My questions are always of a specific nature...Why do I never hear anything about how complete systems evolved?

This is the same reason science doesn't really know that much about systems in the first place. understanding systems is whole view oriented. not specific, reductionist.

hybriddevil wrote:An organ, for example, is a system - it is a complete hardware device with all the necessary components with which to function. A form of "software" must also be present within an organism to regulate proper use of that organ and integrate it into an organisms infrastructure.

an organ is a system, it is also one part of a larger system, and so on. it is under the same constraints of any other piece of a system. it can change as long as the change does not affect the system in an adverse way. in this way small changes can be investigated over millions of years to eventuate in a system that is perfectly integrated. you have to remember that good and bad changes are investigated. obviously only good changes survive and contribute to the developement of the system. i dont know what you mean by 'software'. if it is DNA we have to remember that the 'software' (DNA) developes with the organism. the 'software' isn't static.

hybriddevil wrote: Now, say there's an increase in genetic materials out there through all the usual pathways (mutation, speciation, etc.) and you've got all the pieces you need. Let's use a snake - did the organism compile all the necessary genes to create lets say it's venom glands and then boom ... there it is? I mean that whole deal is a system - you need the venom gland, the right musculature, the hollow fangs, etc., etc., etc.

the perspective is flawed from the outset. there aren't pieces. or at least they arent static. the pieces developed thereby changing the organism. you cant collect completed genes or organs to compile a 'finished' organism.

hybriddevil wrote:On top of that, let's say that you get a snake now that has this complete package - what are the odds that this combination will be bred out of the species within a few generations?

that depends on how well the newly changed/evolved/developed organism fits into its ecosystem. if it fits well the change stays. if it doesnt the organism is eliminated. this brings up questions of purpose. to what end is a change 'good' or 'bad'? survival for the 'piece', equilibrium for the system?

hybriddevil wrote:On the PBS special on evolution there was an example used of a fish that has a special protein which protects its blood from being frozen. Ok, well, we know that evolution is not a "need" based process so if the water suddenly got really cold these fish aren't going to spontaneously evolve this defense. At the same time we've seen animals move out of areas where the environment moves towards an extreme. Having your blood freeze is pretty extreme. Now, can anyone follow this through to a conclusion? How did they get there?

small variances already exist in the genetic makeup of any species. through natural selection only the fish with the special protein in the blood that resisted freezing survived. thereby giving rise to a whole species with that trait. it didnt even have to start out with a black and white freeze or no freeze situation. the protein could have originally been in some other form that allowed the fish to inhabit only colder waters than its original environment. the benefits of this are new areas to feed and reproduce, away from the crowded/dangerous area it inhabited before. the developement of this gene and protein allowed it to spread to even further extremes away from competition.

hybriddevil wrote:In all these cases I'm not looking for THE answer but at least approach the question in some detail that gives me a better understanding of how biologists think these creatures evolved.

i think its important to remember that systems exist on all levels. lower and higher than the organ. if you are happy with the idea of evolution of whole organisms, then it is only a slight stretch of the imagination to see this process happening on all levels.

hybriddevil wrote:One last note - the reaction I've received upon asking these questions from a lot of scientists is often a frustrated/defensive one ... which is not very helpful. You want to teach my kids that this is the way the world works - that this is what life is about. Those are very important messages so either pony up and tackle the issues or stop whining about the criticisms.

These questions are infact mechanistic or reductionist oriented in my opinion which makes me wonder why scientists would become uncomfortable with them.

I think this is due to the subject. system developement requires you to change your perspective to whole-view/teleological. these perspectives might lead to questions of meaning. maybe thats why you have been met with those unhelpful reactions.

*edit spelling

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