Comment by JohnBerea | Hacker News Reader

Comment by JohnBerea | Hacker News Reader

Parent Full thread

On the recurrent laryngeal nerve in mammals: A direct route to the larynx already exists through the superior laryngeal nerve. A second path provides redundancy if one is damaged (e.g. by disease or developmental defect)

The nerve innervates the deep cardiac plexus at the bottom, and the esophagus and trachea on its way to the larynx. So the path needs to be run anyway, leaving little advantage to another route.

Gray's Anatomy (the book, not the tv show) says during development the recurrent laryngeal nerve provides "a means of support that would permit the ductus to develop as a muscular artery" which it can do because it "has a greater proportion of connective tissue than other nerves, making it more resistant to stretch." Having a single cell build itself into a giraffe (or human) requires scaffolding along the way, and having the scaffolding that is also reused as a functionally redundant component of its own is better design than if it were not.

The inverted vertebrate retina is needed to allow additional cooling through blood flow. This article goes into additional tradeoffs in the design: http://www.quarkphysics.ca/scripsi/vision-of-octopi-and-the-...

So more or less you are hitting all the points from this bit: https://rationalwiki.org/wiki/Laryngeal_nerve#But_it_is_desi...

so I'll answer from there myself:

Make no mistake, as an explanation this achieves as much as saying "because the Flying Spaghetti Monster wanted a laugh". It does leave a few curiosities about the supposed intelligence of the designer, however, which are unanswered by this non-explanation. It effectively makes the larynx an afterthought in the design process; as if it was only a by-product of the nerve's existence rather than an aim, despite communication and language being so important to humans. But the designer, given omnipotent powers to yield creatures as She sees fit, doesn't think to merely alter the branching points of the nerves instead? This is a very counter-intuitive approach design at the very least.

The article you quoted says "there seems to be no apparent benefit to an extensive routing of the nerve supplying the larynx," but it doesn't mention or address the three reasons I cited above.

> On the recurrent laryngeal nerve in mammals: A direct route to the larynx already exists through the superior laryngeal nerve. A second path provides redundancy if one is damaged (e.g. by disease or developmental defect) > The nerve innervates the deep cardiac plexus at the bottom, and the esophagus and trachea on its way to the larynx. So the path needs to be run anyway, leaving little advantage to another route.

So the main route between NY and Philly will loop through Chicago. We will build a secondary direct route between NY and philly, but it'll only allow access to certain suburbs not the entire city [1].

This route will connect NY and Chicago on its way there, and NY and philly on the way back. I certainly don't see any advantage to any other route. not even if I were omnipotent and omniscient could I do that.

>during development the recurrent [....] own is better design than if it were not.

During the building of the NY-Philly-throughChicago route, we will be bringing life and jobs to the local communities, so this is of course GOOD DESIGN.

ps.

[1] According to wiki https://en.wikipedia.org/wiki/Superior_laryngeal_nerve "All intrinsic laryngeal muscles except the cricothyroids are innervated by the recurrent laryngeal nerve." so I don't know what you're talking about in (1)

If you need to make deliveries along the whole path from NY to Chicago to Philly, the path makes sense. If the road is necessary to anchor Chicago and keep it from floating away during the development of the United States, that's another reason, although our analogy is becoming strained lol.

If you are missing either of the superior or recurrent laryngeal nerve, you can still speak, although not as well as if you have both. Doctors use this hoarseness as a diagnostic for various chest issues.

United Airlines Flight 232 also illustrates the importance of running redundant cables through different paths. One piece of shrapnel pierced all three hydraulic systems on board, and nearly half the passengers were killed.

>If you need to make deliveries along the whole path from NY to Chicago to Philly, the path makes sense.

Come on man seriously? No, what makes sense if you are designing this is to make one direct connection between Ny-Philly and another NY-chicago.

Reply on news.ycombinator.com