Irreducible Complexity.

[CoxRox]

Leo, you're quite right, it was Adrian that mentioned the 'upside down' problem. I provided two links for the retina being inside out. Both are not long and one was from Cambridge University. Did you have a chance to read them? They seem to explain very clearly why this is so.

Leo you said: 'This is actually more a case supporting the notion that intuitively things do look designed.'- I had a feeling you would say that.

All things considered regarding the eye, I shout from the roof tops 'it is a marvellous seeing machine' as beautiful to look upon as the planet earth seen from outer space which allows me to see very well, all the wondrous things around me.

I am happy to take each 'design flaw', one at a time.

Design 'flaw' 2: this explains the esophagus/trachea problem

'One of the examples of "bad design" proposed..... is the human esophagus. At the bottom of the throat, the trachea (the passage that leads to the lungs) enter the esophagus. When you swallow food or water, a structure called the epiglottis closes to cover your trachea so that these materials do not go into your lungs. The system does not work perfectly every time, as we have all experienced when choking on food or water that "goes down the wrong way." In some instances, this choking can be life threatening. Olshansky et al. suggest that a better design would be to have two separate tubes - one leading from the nose directly into the lungs and the second leading from the mouth directly to the stomach.

There are several problems with this "better" design. First, to have two tubes in the neck would require extra space and extra systems (with the associated additional energy costs) to maintain two structures. More importantly, it would be very difficult to breathe when you get a sinus infection. Congestion in the nose would be life threatening, since it would prevent or severely restrict breathing, since the nose would be the only way that air could enter the lungs. There would also be the problem of getting rid of liquid that accidentally enters the lungs. It would have to be pushed all the way up to the nose and expelled there (make sure you carry lots of tissue with you!). Under the current system, it need only go to the top of the trachea and the down the esophagus to the stomach. The two tube design would also restrict the amount of physical activity that humans could do. When we run, we take in air through our mouths, since the larger opening allows for a more rapid respiration rate. The only way to allow for a large respiration rate with one tube to the nose would be to greatly increase the size and openings in our nose. Not only would this look ugly, but the larger openings would present problems. Things could enter into such large openings and have direct access to your lungs (How would you like to inhale a fly into your lungs?). Larger nasal passages would also reduce the temperature of the air, since it could not be heated as effectively (important for cold climates). Another major problem would be speech and language. We need to use our mouths and tongue in order to produce speech. Air running over vocal cords, in the absence of a tongue, lips and teeth, would only be able to produce a very limited number of sounds (it might not affect Rambo, but the rest of us would have a difficult time communicating). Try it some time (hold your mouth open and don't move your tongue as you attempt to communicate). Of course the evolutionist might propose additional structures in the nose (like a tongue, lips and teeth-like structures).

So, here is what the evolutionists are proposing for a superior breathing apparatus. Our trachea would continue up to our nose, requiring our necks to be at least 1 inch wider. We would have huge noses with nose lips and a tongue protruding out. Of course, our faces would have to be much longer to accommodate the additional structures. Now, we would really be ugly! On second thought, it might be interesting trying to kiss with two sets of lips - nah, constantly expelling liquid out our nose would make it kind of gross. Aren't you glad you weren't designed by an evolutionist!'

http://www.godandscience.org/evolution/d...nebad.html

Forgive the quite big cut n paste. So....what do you think......?

[leo-rcc]

So why is it other animals that do have their airways and food intake separate have none of the issues described above?

[CoxRox]

Which animals are these? Were you convinced by the retina articles?

[leo-rcc]

Snakes for instance, they even put their breathing tube out during eating.

[lukec]

CoxRox, I can't help but feel that your quote is taken from somewhere which takes Humans as the pinnacle species- who is trying to come up with a better design for "Human" and failing. It is written as though the only possible configuration is a nose and a mouth- and if you want to "speak" you had better have some lips for it. Now why should this be the case? The piece ridicules the idea of a large nose, for example, as ugly. Now, this is very clearly not open-minded thinking. Would you mate with an elephant seal? No, because you are not an elephant seal. But one assumes that elephant seals find each other quite attractive, and perhaps their large, "ugly" (in human terms) nose is just a beautiful organ.

The article also talks about problems with large openings in the nose- but why would this pe a problem? It's as though there is no way to protect the lungs, for example (hair, cilia, etc), and also for some reason assumes that the only place to put the hole is in the nose. Why not coming on in the neck? Or anything really there's many possiblities.

As for speech, perhaps this Human2 wouldn't be able to create the same words as we do, but this does not mean they could not communicate. It is thinking that only a human that looks like us would do that leads to this kind of thinking, but it doesn't really make any sense.

[CoxRox]

Leo, have you any examples that are like humans? Mammals for instance? I say this and I'm completely speculating now so forgive me if it's a load of tosh I'm about to say, but a snake operates in a different type of 'world' to us. It's construction is hugely different to ours. It slides around etc, so the dynamics for all it's bodily functions are probably quite different. Just my 'intuitive' thoughts on that.

Lukec- many of your points are valid. I like big noses. If we leave aside the aesthetics part of the argument, then I still think there are relevant points in the article that explain why we don't have two tubes.

[lukec]

Lukec- many of your points are valid. I like big noses. If we leave aside the aesthetics part of the argument, then I still think there are relevant points in the article that explain why we don't have two tubes.

My point about aesthetics was merely to demonstrate that although we are one way, does not mean we could be another way. This applies to anatomy; for example, in the pharynx, just below the jaw, we do have two tubes. Why would the neck have to be an extra inch thick then? I don't know.

So, I think I'm missing the points that explain why we couldn't have two tubes- if you could maybe list/summarize? Appreciate it!

[leo-rcc]

Snakes have lungs, snakes breath air, they just don't have a diaphragm (so no hick-ups) and no larynx. Their mode of transportation or circulatory system is not the subject at hand, but the respiratory system is, so how they move or look is not relevant in this case. So my question stands, why is it other animals that do have their airways and food intake separate have none of the issues described above? Why couldn't it have been done any other way?

As for mammals, most if not all have a Larynx, since mammals have common ancestry, the trait of having a Larynx is passed down from generation to generation.

Evolutionary opportunism results in suboptimal functions and structures. In gradually evolving a new function, organisms must make do with what they already have. Thus, functions are likely to be performed by structures that would have been arranged differently (e.g. more efficiently) if the final function were known from the outset. "Suboptimality" does not mean that a structure functions poorly. It simply means that a structure with a more efficient design (usually with less superfluous complexity), could perform the same final function equally well. Suboptimal structures and functions should have a gradualistic, historical evolutionary explanation, based on the opportunistic recruitment of ancestral structures, if this history is known from other evidence (e.g. if this history is phylogenetically determined by closely related organisms or fossil history).

The mammalian gastrointestinal tract crosses the respiratory system. Functionally, this is suboptimal; it would be beneficial if we could breathe and swallow simultaneously. Unfortunately, we cannot, and this is why we are susceptible to death by choking. However, there is a good historical evolutionary reason for this arrangement. The Osteolepiformes (Devonian lungfish), from which mammals evolved, swallowed air to breathe. Only later did the ancestors of mammals recruit the olfactory nares of fish for the function of breathing on land. It so happens that the nares (originally used only for smelling) are on the opposite side of the esophagus from the lungs (Futuyma 1998, p. 5). Mammals and therefore indeed humans have inherited this original design, even though it now causes problems.

Ref:
29+ Evidences for Macroevolution Part 3: Opportunism and Evolutionary Constraint by Douglas Theobald.
Futuyma, D. (1998) Evolutionary Biology. Third edition. Sunderland, MA, Sinauer Associates ISBN 0878931899, 9780878931897.

[CoxRox]

Leo, I'm just checking some stuff on your last response. What did you think of the information regarding the retina?

[leo-rcc]

Catherine, I though I'd already answered that, anyhow basically it is the same objection as with the esophagus and all other objections we can post, even though it works, that doesn't mean it is a well thought out design and certainly not a design I would attribute to a master designer as ID supports it has to be.