The stupidest nerve in the human body

there appears to be a bit of a theme emerging in that I always seem to be on nights when I make these videos but as the parent of two young children at home I've actually been volunteering to do on-call shifts at one of London's busiest hospitals it's the only way I get any rest but time is short so I'll get straight to the point here's the human body isn't it amazing no it's idiotic your idiotic specifically miss nerf not this note that one's fine not this nerve that one's amazing this nerve there are a current laryngeal nerve it's Battier then a backwards retina let me tell you why I don't know in the next calls coming in so I've chosen a topic that I could do off-the-cuff because it's a favorite with evolutionary biologists in a previous video we saw how evolution has clumsily left remnants in your DNA but you don't even need a microscope to be able to spot pointless leftovers in the human body yes I know you don't use a microscope to look at genes it was like a metaphor here is the tongue here is the pharynx open it up and here is the larynx here is a nerve that allows you to speak the evidence for a designer is incredibly weak part of the larynx is innovated by the superior laryngeal nerve which comes off the Vegas and goes to the larynx in a fairly straightforward common-sense route but the other part of the larynx is supplied by the recurrent laryngeal nerve on the left look at the route it takes goes all the way down into the chest loops under the arch of the aorta and then back to the larynx on the right side it goes underneath the right subclavian in both cases it takes a far longer route than is necessary to borrow an engineering technical term here I believe this could be described as wack so was this a one-off cock-up with humans definitely not every tetrapod has the exact same moronic setup including NBA camels also known as giraffes whose recurrent laryngeal gives a whole new meaning to the expression King the long way round so how did we end up with this fresh nonsense well to answer that we need to go back way back back to when our brains were kind of on our back because at this point in our history we looked like some kind of fish our primitive ancestor who may or may not have tasted fantastic with matter and chips didn't have a larynx but they did have the precursor that an organ that would evolve into the larynx namely the gills this is the international symbol for gills in case you didn't know a set of aortic arches or blood vessels spanned across the gills and connected up to the heart from their tiny brain a nerve also went in the most direct route to the heart which passed the gills but as life became more complex over the subsequent millions of years body shapes changed animals started having necks moving their brains further away from the heart instead of plotting a new route to the larynx the recurrent laryngeal was stuck behind the embryonic vessel that would become our aorta cart taking this manic loop instead of a much shorter direct route I always thought there was something fishy about you and now I know I was right when you were one month old one month from conception that is you kind of looks a bit like a primitive fish just like a fish you had a set of aortic arches instead of a single a water cart that baby has you also had no neck but you did have nerves including a recurrent laryngeal nerve which started its life taking a fairly sensible route before it was yanked down but with the heart into the chest as you developed from a little blob into a baby taken to its extreme this deviation achieves frankly comical levels Mathew Adele wrote a fantastic paper poking fun at a tendency to trot out that giraffe as an example with it's two and a half meter neck it's got a recurrent laryngeal of about 5 meters in length that's nothing where else says in comparison to the sauropod whose dimensions truly were next-level the largest sauropods had about 14 meters between their brain and their heart and as we know that sauropods all had oranges we can conclude that their recurrent laryngeal nerves must have been about 28 meters in length and the vast majority of that was just an accident of evolution for a final bonus factoid remember that nerves are made up of extremely long cells that run their entire length so the axons that nerve fibers in the recurrent laryngeal nerve were a sauropod would be about the same length as the cells in a blue whale's dorsal root ganglion making them possibly the longest cells in the history of the world VidCon last week we were told to put a subscribe message in our videos so but we were told maybe we could offer incentives to our subscribers now I don't have a patreon but if I did the top tier it would be rewarded with a one-hour video of me wearing my special super indoor radiation-proof non sunglasses which are literally made with LED they're very heavy and they protect my eyes from x-ray so I don't get cataracts and also helped me being Superman in a staring competition [Music]

Channel: Medlife Crisis

Views: 745,553

Rating: 4.8617506 out of 5

Keywords: Evolution, Science, Biology, Anatomy, Medicine, Neurology, Darwin, Nerves

Id: wzIXF6zy7hg

Length: 5min 33sec (333 seconds)

Published: Thu Feb 28 2019

Reddit Comments

[u/duncan619]

“There needs to be a subreddit called Look what I found & wanted to share”

Isn’t that all of reddit?

[u/sophiesour]

I am a big fan of this guy! He is amazing!

[u/MedlifeCrisis]

Hey! It's me, the dumb guy from the dumb video! A boss in one of my old hospitals just messaged me to say I'm on reddit, crazy. Thank you for sharing the video and glad you enjoyed it! Happy to answer any questions people might have :)

​

[u/bleak_gypsum]

Has evolution ever adjusted such topological features? I would expect it to be impossible for any gradual genetic changes to change the topology of any physical structures, but I'd be interested to hear of any counterexamples.

[u/Joinourclub]

Oh man. I’ve not seen this guy before. I think I’m a little bit in love.

[u/K1ller90]

This video also popped up in my recommended and can I say, this mans humour, my favourite line: “And to borrow a term from professional engineering, WACK”

[u/FooolsGOlld]

I liked his little rhyme scheme at 1:11

[u/Redivivus]

Today I Learned

[u/arizonapedia]

The NBA camel sind it for me and I immediately subscribed.