March 17, 2022 | Jerry Bergman

Another Claim of Poor Design Refuted

We can close our eyes and mouth, so why can’t
we close our ears? There are good reasons.

 

 

by Jerry Bergman, PhD

The claim of poor design is one of the most widely used attempts to disprove creationism as support for evolutionism. The argument is, if we humans were created by an all-knowing God, why would we have so many design flaws? Purported examples include the backward retina, defective knees, a back designed to walk on all fours as our ape ancestors did, and a poorly designed left recurrent laryngeal nerve. As one evolutionist explained,

The recurrent laryngeal nerve is an often cited example of “unintelligent design” in biology… The recurrent laryngeal nerve (RLN) has become a touchstone in evolutionary biology, as an example of suboptimal morphology caused by a developmental constraint.[1]

The basic claim is the laryngeal nerve, rather than going to the larynx by the direct route called the nonrecurrent route, shown in green in the illustration, takes the longer route called recurrent. In this route the laryngeal nerve hooks around the aortic arch, and gets longer as the body lengthens during early development. The recurrent laryngeal nerve, shown in orange, appears to be far longer than required for function. Since I published the major problems with this claim in Chapter 9 of my Poor Design book, more research has found some very good medical reasons for its existing design:

Nonrecurrent laryngeal nerves are rare in humans, and never occur bilaterally. A nonrecurrent laryngeal nerve is present on the right side in less than 1% of humans, and is associated with abnormal arterial supply to the right forelimb. If the major artery to the right forelimb develops directly from the dorsal aorta distal to the left subclavian artery, there is no remnant fourth aortic arch (normally the right subclavian artery) to pull the nerve down into the chest, and the nerve can take a direct path from the brainstem to the larynx, although the nerve is still recurrent on the left side in these individuals. A nonrecurrent laryngeal nerve on the left is extremely rare (0.04%) and is always associated with situs inversus [where the arrangement of the internal organs is a mirror image of normal anatomy]… The course of the recurrent laryngeal nerve appears to be an unchanging aspect of tetrapod embryology, being as developmentally fixed as the presence of a heart and paired vessels to the head.[2]

All the other claimed examples of poor design have likewise been decidedly refuted.[3]

The recurrent laryngeal nerve.

He Who Has an Ear, Let Him Hear

One of the newest poor-design claims is that our ears are not properly protected from dust, pollution, water, insects, and other outside insults compared to other animals. As University of Bergen evolutionary biologist Jarl Giske explains,

The human body has undergone a long evolution to the way it is today.

Eyelids protect our eyes and if we close our mouths, we prevent debris from entering. Our ears, on the other hand, stay open. They can’t close like the ears of seals, rhinos and otters, for example. Why? Wouldn’t it be nice to be able to close our ears, for example when we are underwater or when we’re surrounded by a lot of noise?…. Isn’t it a little stupid that we can’t close our ears though? What about protecting them against dirt and dust?[4]

Professor Giske explains how the “proper” design evolved in seals:

Seals have gone from living on land to living in water again. And so they needed to be able to close their ears. Seals don’t have outer ears like us that hang and dangle, instead they have a flap that allows them to close their ears. When they dive, they can close their eyes, mouth, nose and ears.[5]

Giske gives the following evolutionary explanation for this poor design in humans: “The short answer is that it’s been a real long time since we started our development in water. About 380 million years ago, our ancestors stopped being fish and they came ashore” so, he concludes, natural selection has never evolved the ear protection that seals have evolved.[6]

Many Animals Have Systems to Protect their Ears

Actually, many animals have well-designed mechanisms to protect their ears. For example, roosters have built-in ear plugs. Roosters crow so loudly that the sound level they produce is close to 100 decibels, similar to standing 15 meters from a jet plane taking off. A single crow sound very close to your ear is over 140 decibels. Sound this loud can cause damage to the hair cells, and thus hearing, in about a second.

Will We Evolve Ear Protection like Some Animals?

To the question of whether humans are evolving ear covers, Giske answers ‘probably not’ because, he speculates,

human ears have not evolved to close. And that will not be happening anytime soon either. We can still have children even if our hearing gets worse. A lot of animal species have better hearing, better eyesight and are faster than us. Our specialization is that we’ve learned to use tools and make aids for ourselves. For example, we can use ear protection or earplugs if the surrounding noise is too loud, such as on a construction site. In other words, we won’t be seeing any ear evolution to protect us from modern noise.[7]

To understand how roosters could crow so loudly without developing hearing loss, researchers used micro-CT scans of rooster (the male) ears to reconstruct the geometry of their ear canals when their beaks are open, thus crowing, and also closed, thus not crowing. They learned that when a rooster opens its beak to crow, parts of the ear canal closes up and a thin skin covers half of the eardrum. When they completely opened their beaks to produce a loud crow, their external auditory canals were completely closed. In short, roosters have built in earplugs activated when necessary.[8] The researchers also found the hens, the female chickens, do not crow and therefore have no need of this protection. This system display’s clear evidence of intelligent design. To be consistent, therefore, evolutionists should agree that there are many good reasons for the existing design of the human ear.

We Already Have an Ear Protection System

We actually can prevent most debris (dust, pollution, and even water) from entering our ears by a “lid,” namely the eardrum (properly called the tympanic membrane). This “lid” protects the ear and, at the same time, keeps water, insects and dust from entering the inner ear while, at the same time, it does not impede hearing ability. The design, therefore, achieves the best of both worlds. We can close our mouth and eyes, but do not need to close our ears to achieve the same protection due to the tympanic membrane.

Volume Control

Loud noise can damage the human ear, and one of the chief means of reducing the sound level is some type of covering like floppy ears, as is common in some dogs. Fortunately, we have a better system that rapidly responds to loud noises. This sound control consists of the smallest skeletal muscles in the body. They stiffen the ear ossicles to reduce the loudness entering the inner ear.[9] These muscles reflexively contract about a tenth of a second after one or both ears are hit with loud sounds.[10] Though this feature is helpful to an enormous degree, not being instantaneous (no system is),  loud noises like gunshots may, eventually over time, cause damage without additional ear protection.

The system, however, also enhances sound discrimination. For example, these ossicle-stiffening middle-ear muscles disproportionally muffle the higher frequency sounds which improves the hearing in the more important range for humans, such as the ability to hear other people talking. This system is clearly superior to “closing” the ears as we close our mouth or eyes.

The Outer Ear

One way to close the outer ear is to design a flap to cover it like some animals have (e.g., dogs). The problem is that the main function of the outer ear, called the pinna, is to collect sound within specific frequency ranges and a range of loudness levels that vary from a friend’s whispering “in your ear” to normal room conversations.[11]

The pinna. Notice the specific design which strengthens the sounds humans want to hear and reduces other sounds such as background noise. (Wiki Commons)

The pinna does not amplify sound, but functions as a funnel, collecting and concentrating certain sound frequencies, and directing them into the ear canal. When directed by the pinna, sound also goes through a filtering process in which vibrations in the frequency range of normal human speech are enhanced, and other sounds, called background noise, are reduced.  Ears have a designed functional geography to achieve this filtering process that involves the rim design

called the helix, after a fancied resemblance to a coil, and it curves in over the pinna like a breaking wave. A second ridge abuts it halfway down: the antihelix. The antihelix swings up into a little plane and down into the lobe.  While most of the ear is cartilage, the lobe is soft and fatty, just right for hanging [an] ornament. The hollow near the ear canal is the concha, from the Latin for “shell.”[12]

McNeill added that the small nub of flesh beside the ear, called the tragus,

protects the ear canal. The name, Greek for “he goat,” stems from the hair on its inward side.  It suggested a goat’s beard to Rufus of Ephesus, a contemporary of Pliny and the first medical lexicographer, the man who christened the tragus as well as the helix and lobe.[13]

Ward et al. noted that the auditory canal is also designed to effectively collect sound in the important 3 kHz region.[14]  The head, the pinna, and the ear canal all work as a unit to maximize sound transmission in the two-to-four kHz region by 10 to 15 decibels. The researchers concluded that

Amazing Factsbecause of the exact dimensions of the convolutions of the pinna, certain sound frequencies are amplified, others attenuated, so that each individual’s pinna puts its distinctive imprint on the acoustic wave progressing into the auditory canal.  This information is used in the recognition and localization of sounds.[15]

Both the pinna shape and the ear muscle variations produce what is called a distinctive imprint on hearing. This “distinctive imprint” allows humans not only to discriminate sounds because we hear differences, but also helps to produce unique sounds. The human sound system allows us to achieve the variety so necessary for voice specialization in a large, complex modern society.

Sound Direction

The external ears are very functional in another way: they can help us determine the direction of a sound. We can effectively locate sound due to the fact that we have two ears, which creates an auditory parallax: “Sound waves strike one ear slightly before the other, and the brain notes the difference.”[16] The filtering process also adds directional information to the sound. Specifically, the pinna helps to locate sound because its

ridges and clefts bounce a few sound waves into the ear later than the rest, in a pattern that depends on their source. The brain then decodes it. Scientists have filled subjects’ pinnas with wax, and found they perceive sound as coming from inside the skull, as with headphones.[17]

Summary

Closing the ear canal in ways suggested by those who speculate that it would be helpful for the ear to be protected by a means similar to how we close our eyes and mouth would be very impractical. The system we have is actually far better than closing our eyes or mouth because it also regulates sound to improve our hearing. The tympanic membrane effectively keeps out dust, water, and insects without interfering with hearing. It is a good design.

References

[1] Wedel, M., A monument of inefficiency: The presumed course of the recurrent laryngeal nerve in sauropod dinosaurs, BioOne, Acta Palaeontologica Polonica 57(2):251-256, 2011. See also  Toniato, A., et al., Identification of the nonrecurrent laryngeal nerve during thyroid surgery: 20-year experience, World Journal of Surgery 28(7):659–661, 2004, and Sanders et al., Nonrecurrent inferior laryngeal nerves and their association with a recurrent branch, American Journal of Surgery 146(4):501–503, 1983.

[2] Bergman, J., Poor Design: An Invalid Argument Against Intelligent Design, Bartlett Publishing, Tulsa, OK, 2019.

[3] Bergman, 2019.

[4] Schou, I., We can close our eyes and mouth. Why can’t we close our ears? Science in Norway, https://sciencenorway.no/evolution-the-human-body/we-can-close-our-eyes-and-mouth-why-cant-we-close-our-ears/1990711, 10 March 2022, emphasis added.

[5] Quoted in Schou, 2022.

[6] Quoted in Schou, 2022.

[7] Quoted in Schou, 2022.

[8] Claes, Raf, et al., Do high sound pressure levels of crowing in roosters necessitate passive mechanisms for protection against self-vocalization? Zoology 126:65-70, 2018.

[9] Borg, E., and A. Counter, The middle-ear muscles, Scientific American 261(2):74-81, August 1989.

[10] Borg and Counter, 1989, p. 74.

[11] Berger, E.H., L.H. Royster, J.D. Royster, D.P. Driscoll, and M. Layne (editors), The Noise Manual, Fifth Edition, American Industrial Hygiene Association, Fairfax, VA, 2000.

[12] McNeill, D.,The Face, Little, Brown and Company, Boston, MA, pp. 63–64, 1998.

[13] McNeill, 1998, pp. 63–64.

[14] Ward, W.D., L. Royster, and J. Royster, Anatomy and Physiology of the Ear: Normal and Damaged Hearing, Chapter 4, pp. 101–122, 2000.

[15] Ward et al., 2000, p. 102.

[16] McNeill, 1998, p. 63.

[17] McNeill, 1998, p. 63.


Dr. Jerry Bergman has taught biology, genetics, chemistry, biochemistry, anthropology, geology, and microbiology for over 40 years at several colleges and universities including Bowling Green State University, Medical College of Ohio where he was a research associate in experimental pathology, and The University of Toledo. He is a graduate of the Medical College of Ohio, Wayne State University in Detroit, the University of Toledo, and Bowling Green State University. He has over 1,300 publications in 12 languages and 40 books and monographs. His books and textbooks that include chapters that he authored are in over 1,500 college libraries in 27 countries. So far over 80,000 copies of the 40 books and monographs that he has authored or co-authored are in print. For more articles by Dr Bergman, see his Author Profile.

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