The Pharynx (Throat)

If you look closely at the figure above you’ll see that the pharynx (throat) is the common entry for both the respiratory and gastrointestinal tracts. So, whatever is ingested can potentially go down the airway and cause obstruction which can result in death by choking. Below are three critiques on, and some recommendations for, this alleged “bad design”.    

The Critics Speak

“Humans have a dangerous tendency to choke on food...the passage that air follows to get into the lungs actually crosses the path that food allows to get to the stomach. This would be an example of really stupid (or perversely sadistic) design if a god had actually designed it that way. But this is not the result of anyone’s conscious “design”. This choking problem simply reflects our own past evolutionary history.” (The Science of Evolution and the Myth of Creationism: Ardea Skybreak: Insight Press: 2006)

“The biggest danger in the human throat’s design is choking. If we had separate openings for air and food, this would never happen. Swallowing is a good example of the limits of Darwinian evolution. The human throat is simply too complex for a random mutation—the basic mechanism of evolution—to undo its fundamental defects. We have to resign ourselves to the absurdity of taking in air and food through the same pipe.”(Human Errors: Nathan H. Lents; Houghton Mifflin Harcourt: 2018)

“A better designed system would keep the tubes for air and food separate to avoid unnecessary fatalities. If we were designed why did the Designer do this job so badly? Or is it that the Creator likes other animals better? There are creatures in which the air passages and food passages are entirely separate. The whale’s respiratory system is completely separate from its digestive system. This means that a whale, unlike a human, can’t choke on its food by inhaling it. If the Creator could do that for the whales, I don’t know why he couldn’t do it for us?”(The Not-So-Intelligent Designer: Abby Hafer; Cascade Books: 2015)

Filling in the Gaps

Besides the structures noted in the figure above, there are over forty different muscles innervated by six different nerves involved in the preparation for, and act of, swallowing. After food in the mouth has been formed into a small ball (bolus), the tongue voluntarily moves it to the pharynx which automatically triggers the involuntary swallow reflex.

Sensory data from the bolus entering the pharynx is sent to the swallow center in the brainstem. It immediately turns off respiration so air is not breathed in (to prevent choking). It also starts a series of precisely ordered, well-coordinated muscle contractions that result in the bolus being moved downward, bypassing the airway and entering the esophagus. All of this takes place in about a second, usually without incident, a thousand times a day.

Referring back to the figure above, here is what happens. As swallowing begins, several different muscles immediately contract to move the bolus into the pharynx while moving the back part of the palate and the upper pharynx closer together to close off the path to the nose. At this point, if you happen to laugh, in exerting upward pressure before this region can be closed, some of what you are trying to swallow may sneak up there and come out of your nose. 

Now comes the tricky part. The bolus has just been prevented from going north into the nose and muscular contraction is hurtling it south towards the airway and the esophagus. There are three separate actions that now take place to protect the airway. First, muscles contract to allow the larynx, which is the gateway to the lungs, to close at various levels. Second, as noted by feeling the front of the neck while swallowing, other muscles move the larynx not only up, but also forward to hide it under the floor of the mouth and the base of the tongue while being protected by the epiglottis. This action combined with other muscular activity results in the third event, the upper esophagus opening up to allow the bolus to enter it. The animation, "Swallowing Reflex, Phases and Overview of Neural Control" demonstrates the beauty of these safe swallowing actions (a picture/video is worth a thousand words!).

To get this done right the swallow center has to quickly tell each of the nerves to send their messages to the right muscles at the right time for swallowing to take place without choking. Also, as the bolus moves from the pharynx to the esophagus there is only so much time available for the coordinated motor activity to move the structures of the upper respiratory system out of the way.  In other words, the messages from the pharynx to the swallow center in the brainstem and back to the muscles, along with their reaction time, must be fast enough to prevent choking.

Finally, one must keep in mind that, in addition to the swallowing reflex, the neuromuscular system also provides a gag reflex to prevent foreign matter from going down the throat into the airway and a cough reflex to propel foreign matter out of the airway if it somehow does. These two reflexes are dependent on sensors present in the respiratory system detecting foreign matter that send electrical signals through interconnecting neurons which results in automatic precisely ordered, well coordinated muscle contractions that try to protect the airway.  

So, besides the different structures surrounding and including the pharynx there’s a lot more to swallowing safely than what’s mentioned by these three critics. Here are three questions to which they don’t even allude, never mind try to answer, which should give the reader pause.
                                                                                                 

    1. In what order and from where did the new genetic information come that specifies the size, shape and position of the pharynx, each of its nearby structures and the forty or more muscles involved in swallowing and what is the real probability that such a system could have come about by undirected forces while remaining functional in intermediate organisms each step along the way? 

    2. In what order and from where did the genetic information come to make the swallow center in the brainstem and its ability to bring about safe swallowing through the precisely ordered, well-coordinated contraction of over forty different muscles and what is the real probability that such a system could have come about by undirected forces while remaining functional in intermediate organisms each step along the way?  

    3. In what order and from where did the genetic information come to bring about the gag and cough reflexes and given their dependence on the presence of the head and neck structures and neuromuscular coordination needed for swallowing, what is the real probability that such a system could have come about by undirected forces while remaining functional in intermediate organisms each step along the way?

So, are you willing to accept the undirected forces of natural selection acting on random variation as the definitive answer to the above questions?  The “smoke and mirrors” of neo-Darwinism which doesn’t even try to account for how each of the parts needed for swallowing came together and happened to have the right size and shape, be in the right position, with the right specifications, doing the right things fast enough and at the right times, for survival?

It’s important to realize that natural selection acting on random variation (genetic mutation) means exactly what it says. Over time, life required a gazillion bits of new genetic information (not natural selection) to bring about new structures with new functions. All natural selection did was preserve the life that was up and running properly and able to survive due to these gazillion undirected genetic mutations. But keep in mind, natural selection cuts both ways.

Based on what we know about how life actually works neo-Darwinism may explain the survival of the fittest but not the arrival of the fittest. That’s because, when it comes to survival, logic tells us that the same power that natural selection had to preserve human life when its swallowing mechanism worked right would have also prevented it from surviving if any one of the parts mentioned above were either missing, defective, misplaced or not working well or fast enough.

The known engineering principles needed to bring about the safe swallowing that resulted in human survival means that, in principle, not only does Darwin’s theory of gradualism fail, but so do all the other neo-Darwinian attempts to replace it. What do you think?

Comments

The first critic mentions that “humans have this dangerous tendency to choke on food”. This is true, but as noted above, we tend to swallow about a thousand times a day without incident. The incidence of death by choking is 1.6 per 100,000 which is similar for drowning but is only one-tenth of what it is for falling. So far, I haven’t seen any “bad design” arguments about the human ability to swim. And despite the complaints about some human joints not being adapted well enough for bipedal life, it would seem myopic to complain that since falling is a common cause of death, humanity would be better off as quadrupeds. She then calls this “really stupid” and “perversely sadistic” design and then claims that it didn’t take place by conscious effort, but provides no evidence of how it could have really come about except by the magic of “evolution”.  

The second critic certainly seems confused as he says that the human throat is designed but the danger of choking could be alleviated if there had been separate openings for air and food. This is certainly true but the reason for why things are the way they are will be dealt with below. He then states that the human throat is indeed too complex for a random mutation to undo its fundamental defects. He quite rightly sees that one simple change in genetics would not be able to correct the situation. But nowhere does he even mention what would have been needed for it to develop into being “simply too complex” in the first place, except the claim of “Darwinian evolution” which lacks any details. Maybe he could start by answering the three questions posed above?  Like the first critic, he tells us about “the absurdity of having to take in air and food through the same pipe.” Maybe he’d rather have been a whale? (see below)

The third critic like the second seems to be confused because in saying that “a better designed system would keep the tubes for air and food separate to avoid unnecessary fatalities” she’s  admitting that it was “designed” albeit badly. What she means by “unnecessary fatalities” is hard to know but given the very low incidence of choking deaths I assume she’d be against driving or riding in a car, walking on the street or climbing a ladder never mind being a first responder or a member of the armed forces. It’s great that whales can’t choke on food, but after all, they do mostly eat it whole and so the diameter of their esophagus is much larger than ours. But in rhetorically asking “Why the Creator couldn’t do it for us?” she seems to forget that, on top of this choking issue, there are a lot of other major differences between us and given our limited intellect we  may not know all of the physical parameters and biological limitations involved. 

Laufmann’s Triple Filter

Not understanding the objectives of the designer
It’s clear that the pharynx affords us the dual abilities to breathe in air and safely swallow food and water. However, according to these critics, since humans are at risk of choking to death, this renders the origin of the pharynx by design as invalid and points instead to the magic of “evolution”, the details of which are totally absent. To get a better picture of what’s at stake it’s important to point out here a third function (objective) that the pharynx affords us, the nature of which distinguishes us from all living beings; the ability for speech and language.

Dr. Stuart Burgess, https://www.liberty.edu/engineering/faculty/stuart-burgess/ a distinguished and celebrated British professor of mechanical engineering, who was involved in the European Space Agency’s spacecraft design, says that the vocal tract, consisting of the trachea (windpipe), larynx (vocal cords), pharynx (throat), mouth and nasal passages are “supremely well designed to produce intricate speech”. Human speech involves the use of about one hundred different muscles directed by the brain through about six different nerves. In particular the teeth, the lips and the tongue play a major role, the latter two according to Dr. Burgess being “uniquely agile” for this complicated task. However, in order for all of this to work right the human pharynx has to be deeper and longer than it is for other animals. As Dr. Burgess points out, this allows the tongue “a wide range of positions to produce a wide range of vowel sounds”. So, it is our longer pharynx, which not only helps give us the ability for speech and language but also puts us at higher risk for choking to death compared to other animals.

Two of the above critics (and others elsewhere) make the suggestion that a “better design” would be for humanity to have two separate openings for bringing in air and food and water. Most of them neglect to mention that this would preclude speech and language as we know it. And then, what would have been the use of having developed the multiple areas in the brain that work together for speech and language?  It’s hard to know if they’re just joking. After all, without mentioning this third and very important objective (speech and language) it would be hard to make a determination about “bad design” or not, wouldn’t it? Let’s take a closer look..  

Not accounting for the functional requirements, constraints and trade-offs

What must be obvious to the casual observer is that the same structures (lips, teeth, tongue, associated muscles and nerves) needed for human speech are also needed for preparing and moving what is to be swallowed to the pharynx. As critics suggest, having two separate openings for bringing in air and swallowing would prevent choking, but would that preclude speech as well?  One answer is that both functions could be preserved if all of the parts needed could be duplicated. Also, the nasal passages would most likely have to be much larger to allow for the intake of enough oxygen during survival mode activity. All of this would necessarily change the entire anatomy of the head and neck.

Given that we only need one set of parts within the confines of a much smaller head and neck (compared to a whale) which allows for the triple function of the pharynx, even though it can rarely cause choking, doesn`t demonstrate “stupid design” but actually “elegant invention”. That’s what Dr. Douglas Axe, a molecular biologist and fellow of the Discovery Institute says. https://evolutionnews.org/2021/04/douglas-axe-stupid-design-or-elegant-invention/

Each of the triple objectives for the pharynx are associated with functional requirements (breathe in enough air, swallow enough food and water, good enough speech and language). And each of them must be done within certain physical constraints (all the necessary parts must be contained within specific anatomical limits). In this case, the trade-off for the triple function afforded us by the pharynx is the exceedingly rare possibility of choking to death. Let’s take a closer look.

Failure to acknowledge user abuse and degradation over time

One common reason for choking to death is “user abuse”. This can happen when a healthy adult takes in too large a piece of food and/or doesn’t chew it well enough or a child takes in a foreign body, like a small toy, into the mouth. These objects can get stuck in the airway which can quickly lead to respiratory failure and death. Children represent about 3% of the 1.6 per 100,000 annual choking deaths and healthy adults about 41%.  

Another common cause of swallowing problems which can lead to choking is neuromuscular injury or degeneration related to aging and/or disease. As noted above, safe swallowing requires the precisely ordered, well coordinated contraction of many different muscles under the direction of many different nerves controlled by the brainstem. So, any condition that compromises nerve or muscle function (stroke, Parkinson's disease, Multiple Sclerosis) can lead to difficulties in swallowing which puts the person at risk for aspirating food into their lungs and even choking to death.  This represents about 56% of the 1.6 per 100,000 annual deaths by choking.

Common sense tells us that no matter how well an engineer designs a product it’s always at risk of being misused and, due to invariable wear and tear, its functional capacity lessening over time.

Conclusion

Most people swallow a thousand times a day without incident while breathing in enough air, swallowing enough food and water and being capable of speech and language. The proof is borne out by the longstanding existence of humanity. Therefore, the exceedingly rare possibility of choking to death as evidence for “bad design” in the human body is not only misguided but, based on engineering principles, totally absurd. What do you think?

 

Also see Dr. Glicksman's Series on

"Beyond Irreducible Complexity"

"Exercise Your Wonder"

"On Being Alive"


Howard Glicksman M. D. graduated from the University of Toronto in 1978. He practiced primary care medicine for almost 25 yrs in Oakville, Ontario and Spring Hill, Florida. He now practices palliative medicine for a Hospice organization in his community. He has a special interest in how the ethos of our culture has been influenced by modern science’s understanding and promotion of what it means to be a human being.

Comments and questions are welcome.

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