“Design Flaws” in the Human Breathing System

Something I read today that reminded me of the importance of seeing the big picture, and how seeming “improvements” in one area can have drastic implications in the overall picture.

Joseph Burdo, Assistant Professor of Biology at Boston College, wrote a comment entitled “Design Flaws” in response to a Wired magazine article on “10 Worst Evolutionary Designs.” Professor Burdo wrote:r7_croup

“[Y]ou forgot about one of the best arguments against the "theory" of intelligent design: the shared opening to the esophagus and trachea in humans (and many other mammals). Hundreds of choking deaths occur in the US every year due to food obstructions in the trachea. Doesn't seem too intelligent to purposefully design such a hazard.”

If you’ve ever had food or water go down the wrong way then you’ve experienced this “bad design” first hand. This argument was also listed in a 2001 Scientific American article called “If Humans were Built to Last” by S. Jay Olshansky, Bruce Carnes, and Robert Butler. The authors suggested that a better design would feature independent tubes for breathing and eating.

But though it seems so obvious that a dual tube system would eliminate the possibility of choking, and seems like a much better design, consider some of the implications of this change. Have you ever had a bad cold, so bad that your nose became completely plugged up and the only way you could breathe was through your mouth? With our current shared opening between mouth, nose, and trachea, nasal congestion is an uncomfortable but minor nuisance. But if the nose was the only means of getting air to the lungs, then nasal congestion would potentially be a fatal condition! Instead of a few hundred people dying of choking each year, you would be looking at possibly millions of people dying from asphyxiation due to the common cold or allergy symptoms.

Richard Deem from the Evidence for God from Science website offers some more implications of the alternative design for the human trachea and esophagus system:

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!

Even in a well designed and engineered system, it may seem as if you can improve one specific aspect of the system by changing a certain part, but what you quickly discover is that even minor changes lead to consequences that actually degrade the functioning of the system as a whole. In considering “bad designs” in nature, it’s critical to remember that living organisms do not function as a set of independent parts, but as cohesive and finely tuned wholes. Most arguments of “bad design” in nature fail to appreciate this intertwining cohesiveness.

Human throat image obtained from the Mayo Foundation for Medical Education and Research (https://www.bcbsri.com/BCBSRIWeb/images/mayo_popup/Yourthroat.jsp)

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  1. Anonymous said...

    This article completely misses the point. The problem is not that both tubes have two openings (mouth and nose), but that the esophagus lies above the trachea in the throat, allowing food & liquid to fall into the trachea where they cross. An intelligent design would have the esophagus below the trachea (i.e. at the front of the neck) so gravity would help keep us from choking. You can trace our "wrong" arrangement all the way back to the amphibians and fish from which we evolved. Evolution cannot fix this as it is topologically constrained. But a putative intelligent designer could.

  2. Kendalf said...

    Hello Anon. Thank you for your comment.

    Since this article is a response to the claim that the shared opening to the esophagus and trachea is a flawed design and that a "better" design would have independent tubes for breathing and eating, it seems that if anyone has missed the point it is Professor Burdo and the authors of the "If Humans were Built to Last" article.

    Second, it is very easy to say that putting the esophagus below the trachea would solve the choking problem, but can you actually demonstrate that this is more than just fanciful speculation? It seems that many of these "design flaw" arguments depend on such hand-waving and speculation as "proof" that a particular design is flawed and that a real intelligent designer would do it this way. See this post on the design of the eye for another common example of this flawed argument.

    Third, if you look at diagrams (example one and example two) of the trachea and esophagus, one is not really "above" or "below" the other. When a person is vertical, both tubes are pretty much parallel, and when a person swallows, the more direct route is down the esophagus, while the trachea is the more diverted passageway. It certainly does not seem obvious that gravity would be any help if the two tubes were switched, as you suggested.

    Also, there are some good reasons why the esophagus is deeper inside the throat than the trachea. For one, the act of swallowing requires the coordinated workings of a number of muscles; thus switching the location of the esophagus would require a significant reworking of the musculature of our necks, with unpredictable consequences. The point being that again, what seems like such a simple "fix" can have drastic and undesirable consequences, which was the whole point of this article.

  3. Anonymous said...

    Hi Ken, thanks for your quick reply.

    OK, I admit I didn't read the article you critique, which seems a little silly if it proposes completely separate breathing & eating tubes. As you point out, there are advantages to having multiple openings and also the ability to widen the intake as needed but keep it small most of the time.

    Thanks for the diagrams. In both diagrams it seems quite obvious to me that it is risky to have the trachea wide open at the back of the mouth almost all the time. The only thing stopping us from choking to death (or at least coughing like crazy) every time we swallow is the epiglottis flipping down to cover the tracheal opening. That's a neat mechanism, but it has to be extremely reliable. I estimate that we swallow several million times in a lifetime (mostly saliva every minute or so), so a failure rate of just one in a million could lead to premature death by choking. It is an active safety system which needs to work very well because there is no plan B. It would be far more fail-safe to have passive safety designed in, perhaps with an active system on top for extra safety (so that a failure of the active system would not be life-threatening). The only time we are not at risk of something falling down our trachea is when it is covered, but this also stops us from breathing so it must be left open, and at risk, most of the time. It would be much safer to have no connection between the mouth and trachea most of the time, and only connect them on the rare occasions it is needed.

    Now, I'm not omniscient so perhaps I'm missing something here, but if I were given this design brief:

    1. Get food and liquid into the stomach

    2. Get air into the lungs through small openings which can be enlarged if needed on relatively rare occasions

    3. Do not under any circumstances let solids or liquids into the lungs

    I would:

    a. have the esophagus at the front of the neck, directly connected to the back of the mouth without having to leap over the trachea

    b. have the trachea behind the esophagus and connected to the back of the sinuses

    c. for safety, have no connection between the trachea and mouth under normal circumstances, but have a flap (perhaps like the soft palate) which could open to connect the two as needed for occasional heavy breathing, vocalisation, clearing mucus from the sinuses, etc. - and obviously not when eating or drinking. And have this connection high up at the back of the mouth so that gravity would assist in preventing choking.

    True, there may be unforseen problems with this related to musculature etc, but I don't think these would be beyond the problem-solving capacity of a God claimed to be powerful & intelligent enough to create the entire universe from nothing.


  4. Kendalf said...

    Hi Andrew,
    Thank you for your additional commentary on this article. Sorry to keep you waiting. I've moved our exchange to an actual blog post as I wanted others to follow the discussion, plus the comment box wasn't offering enough room to address some of the interesting issues that you raised. I hope that we can continue this exchange at the new post linked below:

    Revisiting “Design Flaws” in the Human Breathing System

  5. Anonymous said...

    Something that has bothered me about the "Design Flaws in Human Breathing" argument is it overlooks an obvious Ray Comfort-like explanation. Since I was a kid, I presume I've either been told or thought myself the esophagus and trachea work in cooperation. Primarily, the mucous produced in the sinuses then swallowed adds to that lining the esophagus. The extra coat bolsters protection against stomach acid escaping the esophageal sphincter. That mucous people hock up and spit out is there to discourage ulcers and cancer. If anything, that sphincter is the design flaw and evolution addresses the problem.

  6. Anonymous said...

    The question that brought me here is which should be in front of the other. Wouldn't it be better if the esophagus were in front of the trachea? My concern is the in the event of illness where the stomach decides to expel the contents, the poor sap is usually leaning forward to get it out of the mouth, and with the present situation that means a greater chance of inhalation of the stomach contents before it gets to the mouth (and I don't see the stomach having enough power to expel the contents UP out of the mouth when the person is laying on their back... but... Yes, as a father, I have experienced "Projectile vomiting" in my kids!).

  7. Anonymous said...

    Pardon me whilst I sorta answer my own comment from yesterday. I am presently in a bout with a virus of some sort and I can see that I might drown if I lay on my back to sleep and the Trachea were on the opposite side. By being on top (while I lay on my back), the mucus that is constantly swept up the trachea, can just drop into the esophageal area and get swallowed. But this begs the question of whether the arrangement is the same for animals that sleep on their stomachs, dogs, cats, horses, deer, etc.?

  8. Anonymous said...

    hahaha. fail. if there is an intelligent designer. he would solve the problems you suggested. simply a special pipe and opening to the mouth, or to the side. or through chest to help with extra breathing in case of a cold. does an intelligent designer needs to infect us with cold anyway? intelligent desigists always stick with this BS. if you have god capable of everything, you should stop finding reasons in nature for his flaws. as he is supposed not to be constrained by nature rules.

  9. Al Goma said...

    In response to # (8) above: "simply a special pipe and opening to the mouth, or to the side. or through chest to help with extra breathing in case of cold."
    Yeah a special pipe. A special pipe would be fitting for a special kind of Evolutionism whorshipper such as you. Good luck keeping it clean, closed, and free of germs; it is far more likely that this half-baked idea of yours would be the reason one would become ill to begin with.

    Also, you stated "if there is an intelligent designer. he would. . ."
    Now just who in the hell do you think you are to state what the hypothetical designer would do?

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