A funny complaint about the recurrent laryngeal nerve !

The funniest complain I've ever heard by some Darwinists and atheists is that RLN is too long, It must be badly designed !!

Analysis:


1- Failure of Natural Selection ?!

[For the sake of argument] A totally nonsensical and relictual misdesign would be a severe contradiction in their own neo-Darwinian (or synthetic evolutionary) world view. Biologist and Nobel laureate Francois Jacob described this view on the genetic level as follows:
 "The genetic message, the programme of the present-day organism ... resembles a text without an author, that a proof-reader has been correcting for more than two billion years, continually improving, refining and completing it, gradually eliminating all imperfections."
The result in the Giraffe?
Jerry Coyne:
 "One of nature’s  worst designs is shown by the recurrent laryngeal nerve of mammals."
the question arises: why did natural selection not get rid of this "worst design" and improve it during the millions of generations and mutations from fish to the giraffe onwards?

2- Maldesign = No design ?

[For the sake of argument] why "imperfect design" should refute design. we complained before about the breakdowns and flaws I've had with computers, but obviously computers are designed. In fact, every piece of technology that has ever had a flaw shows that imperfect designs are still designed!

3- Homology (similarities) is NOT and evidence for common ancestry, Why ?

4- Prefer direct nerve to the larynx ?

Actually, Some innervations to the larynx go directly to the larynx, including the sensory internal laryngeal nerve and the motor external laryngeal nerve. Other nerves, the left and right superior laryngeal nerves, branch off close to the larynx to provide this structure with direct innervation.
 A hint is provided from the fact that the two nerves regulate different vocal responses. Paralysis of the superior laryngeal nerve (the non-circuitous nerve) causes difficulty in increasing voice loudness, producing a high pitch, vocal fatigue, and an inability to sing because the vocal cords lack their normal tone and cannot sufficiently lengthen. In contrast, paralysis of the recurrent nerve results in a weak voice that sounds like Mickey Mouse.

In one patient, a traumatic rupture of the aortic arch in a car accident required an aortic graft that left him with a severed left RLN. Although his voice was slightly feeble, his articulation was unaffected. He speaks perfectly well, but cannot project his voice because the laryngeal muscles have multiple innervations and the set as a unit controls its function.



5- Long course = Bad design ?

The optic nerves do not take the shortest route to the occipital lobe of the brain (the lobe near the back of the head), but rather cross over at the optic chiasm (where the two tracts cross over in the form of an "X") for reasons now known to be based on good design. The nerves from the right side of the brain go to the left side of the body (except for the right and left frontal branches of a facial nerve, which are supplied by both sides of the brain) also for good reasons.

 “Human-designed machines and structures are full of such things as circuitous wiring and plumbing, but that hardly means that they are not the products of intelligent design.

6- You were an embryo !

 Human-designed devices, such as radios and computers, do not need to function until their assembly is complete. By contrast, living organisms must function to a high degree in order to thrive during every developmental stage from a single-cell zygote to adult. The embryo as a whole must be a fully functioning system in its specific environment during every second of its entire development. For this reason, adult anatomy can be understood only in the light of development. The embryo develops from a single cell in a certain order. Embryo needs a functioning simple heart early on; this later descends to its position in the chest, dragging the nerve bundle with it.


The recurrent laryngeal nerve, move downward as development proceeds. The movement occurs because the neck's formation and the body's elongation during fetal development force the heart to descend from the cervical (neck) location down into the thoracic (chest) cavity.
As a result, various arteries and other structures must be elongated as organs are moved in a way that allows them to remain functional throughout this entire developmental phase. 

6-Importance for ductus arteriosus:

However, just to refer to one possible substantial function of the Nervus laryngeus recurrens sinister during embryogenesis: "The vagus nerve in the stage 16 embryo is very large in relation to the aortic arch system. The recurrent laryngeal nerve has a greater proportion of connective tissue than other nerves, making it more resistant to stretch. It has been suggested that tension applied by the left recurrent laryngeal nerve as it wraps around the ductus arteriosus could provide a means of support that would permit the ductus to develop as a muscular artery, rather than an elastic artery" - Gray's Anatomy, 39th edition 2005, p. 1053.




7-  This is the vagus !


"In mammals, this nerve avoids the direct route between brain and throat and instead descends into the chest, loops around the aorta near the heart, then returns to the larynx. That makes it seven times longer than it needs to be.(Prothero, D. 2008. Evolution: What the Fossils Say and Why It Matters. New York: Columbia University Press, 37-38.)

Images and statements like those above are often used to make you imagine that RLN origin is from the brain, However, It actually originates from The vagus nerve below far away from the brain !!


The vagus nerve (the longest of the cranial nerves) travels from the neck down toward the heart, and then the recurrent laryngeal nerve branches off from the vagus just below the aorta (the largest artery in the body, originating from the left ventricle of the heart and extending down the abdomen). The RLN travels upward to serve several organs, some near where it branches off of the vagus nerve, and then travels back up to the larynx


8- Any other purpose ?

If we find some rational function or a reasonable purpose for a design, then the "imperfect" or "inferior" design objection falls apart.
The larynx  only its main destination. In reality, the nerve also has a role in supplying parts of the heart, windpipe muscles and mucous membranes, and the esophagus, which could explain its route.
The fact that the left RLN also gives off some fibers to the cardiac plexus is highly indicative of developmental constraints because the nerve must serve both the larynx (in the neck) and the heart (in the chest).The well-known textbook Gray’s Anatomy states:

    “As the recurrent nerve hooks around the subclavian artery or aorta, it gives off several cardiac filaments to the deep part of the cardiac plexus. As it ascends in the neck it gives off branches, more numerous on the left than on the right side, to the mucous membrane and muscular coat of the esophagus; branches to the mucous membrane and muscular fibers of the trachea; and some pharyngeal filaments to the Constrictor pharyngis inferior.”
Other textbooks explain its importance:
Maintenant que nous connaissons les gros vaisseaux artériels issus de la base du coeur, nous allons pouvoir décrire les nerfs cardiaques.Disons auparavant que leur disposition est infiniment variable, très malaisée à suivre vu leurs fréquentes anastomoses, et que nous ne pouvons en indiquer ici que le type moyen
le plus connu chez l’animal est le « nerf dépresseur de Cyon », né par deux racines, l’une du nerf laryngé supérieur, l’autre du nerf vague. Chez l’homme, ce nerf a été rarement vu isolé ; mais ses fibres existent et doivent passer par les anastomoses que les nerfs cardiaques contractent avec le laryngé supérieur
Le nerf cardiaque cervical moyen naît du nerf laryngé récurrent
http://books.google.co.ma/books?id=7V5JAAAAYAAJ&printsec=frontcover&hl=fr#v=onepage&q&f=false
Darwinian explanations (as is also true for many other so-called rudimentary routes and organs) are not only often in contradiction to their own premises but also tend to stop looking for (and thus hinder scientific research concerning) further important morphological and physiological functions yet to be discovered. 



9- Non-recurrent inferior laryngeal nerve (NIRLN) is a congenital anomaly !

The non-recurrent inferior laryngeal nerve (NIRLN) is a rare congenital anomaly (0.5–0.6% on the right side, extremely rare on the left side (0.004%)), which increases the risk of damage to the nerve during surgery. The right NRILN is associated with a right subclavian artery arising directly from the aortic arch. The left NRILN is associated with situs inversus.
http://casereports.bmj.com/content/2009/bcr.10.2008.1107.full

It  can have catastrophic consequences for the persons so affected: problems in deglutition (difficulties in swallowing) and respiratory difficulties (troubles in breathing) (see Rammerstorfer 2004; moreover
“dysphagia  (if the  pharyngeal and oesophageal branches  of nonrecurrent or recurrent inferior laryngeal nerve are injured)” – Yang et al, 2009: http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=5868576).

Bergman, J. 2010. Recurrent Laryngeal Nerve Is Not Evidence of Poor Design.
Sarfati , J. 2010.Recurrent Laryngeal Nerve
http://www.weloennig.de/LaryngealNerve.pdf
 http://www.eltwhed.com

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