Humans Have an Actual Superpower…

This video is made possible by our supporters over on patreon find the link in the description below right now i am forcefully and precisely exhaling air out of my vocal tract it's zipping by my vocal cords bouncing around in my throat rolling off my tongue as it exits my mouth and you assuming you speak and understand english are comprehending it .

That's absolutely incredible and in today's video we're going to use the cadavers to look at the human vocal tract we're going to see exactly what makes it so unique in the animal kingdom that i'm willing to go as far as to call it a legitimate human superpower it's going to be a fun one let's do this .

speech is such an incredibly complex process that we're going to need an entirely separate video to address the neurological side of things in today's video i want to focus on the vocal tract anatomy and what makes it so unique in humans that we're the only creatures on the entire planet to have it structured .

The way that we do i also want to mention that if you're interested in what i'm talking about today you might want to check out this book right here the evolution of the human head by daniel lieberman he's a harvard professor paleoanthropologist and does a fantastic job in this book of condensing .

And consolidating 60-plus years of the published research and literature into a somewhat approachable format it's a dense book not gonna lie but if you're interested in the whys the hows of just the human body especially the human head this is a fantastic read i will leave a link to the book in the description below if you're interested in that and .

Plenty of his other books which are all phenomenal let's start off by discussing the lungs because this is obviously where speaking is going to have to begin because when you're speaking you are actually speaking exhaled air if you want you can try and speak as you're breathing in i'll do it right now how are you doing .

Right like it's completely ridiculous and impractical to try and speak as you are breathing in so what happens is you are breathing out so let's take a look at this lung real quick and this is a right lung and first off just so you know this is a healthy lung this black you're seeing here these are blood vessels this is a really good looking .

Lung this is exactly what we'd want to see although it is missing an entire lobe but that's a different story for another day but this is the right lung and i want you to know that inside of this what you're this tissue you're looking at is a series of hollow tubes and i'm going to kind of pull this up .

Here and you can see kind of rest that this this long tube right here this is called the trachea and then that's going to transition into what's called the larynx and this is going to be a very important player later on in our discussion but these respiratory tubes are going to come down and then they're just going to .

Start branching and they branch many many many times and completely permeate and fill up this lung so there's a bunch of hollow tubes surrounded and embedded inside of an elastic-based connective tissue a lot of elastin protein fibers are going to be in here and the reason why that's important .

Is because elastin recoils you can literally think of it like a rubber band right if you stretch the rubber band and release it it's going to recoil well when you're breathing normally like right now i assume you're breathing normally well what's happening is most of that recoil is passive like you breathe in .

And then you kind of just let go and the lungs just kind of snap back and that's the vast majority of that exhalation however when you're speaking that has to be different because if you did that and you and you're speaking all of the air would just come out at once so it's like how are you doing .

Hey hi my name is justin right that's a very ineffective way to communicate so what you need to be able to do is more slowly exhale as you're speaking and you're also going to want to make it consistently loud but let's just go right here real quick real quick is that i have a chest plate here that has a .

Bunch of muscles attached because in order to combat the the natural passiveness of the lungs and their desire to just release the air you're going to need to inhale slightly so what you'll notice is we have a rib cage up top and then we also have the abdominal muscles down below well in between the ribs there are muscles .

Called the intercostals and then the muscle down here that you can probably see is the rectus abdominis well what's going to happen is you're going to get these muscles that will start to contract when you are speaking to actually cause some slight inhalation and as you do that it combats the exhalation and you .

Create like this rigidity that allows for consistency when speaking so you can do this right now like if you need to pause the video that's fine once you start feeling around your chest and your abdomen and then just start talking and you're going to feel some tightness start to occur that's simply just for consistency .

Purposes but what's going to happen is you're just going to start go back let's go back to the lung here all right so you're going to the lungs are going to start to recoil but then the muscles are going to contract which is going to try and pull the lungs back out slightly and as you're speaking though you still have to release all .

That air and the air is going to then come out the trachea and then go to the larynx now i can flip this over and you can see the inside of the trachea here hopefully i can get this pretty well on camera you can see the inside of the trachea as it leads to this amazing cross section of the larynx or your voice box which is .

Going to be right here so the air is coming up and then this is the next real important part of the story is going to be your larynx or voice box so what i'm going to do is i'm going to quickly just grab another cadaver dissection and we can in better detail discuss it all right so what you're looking at here is going to be an anterior view of pretty .

Much what we were just looking at with a few other things attached so if you look down here there's going to be two branching tubes this is part of the bronchial tree so the lungs would be on either side and then what's happening is they're merging together to form this long trachea that's that windpipe we saw earlier .

And then it's going to come up and you meet the thyroid gland now that that's what this is right here the thyroid gland is part of the endocrine system so it's not really involved in respiration but just above it this is going to be the most important player is this whole structure right here and kind of just slowly turn it around .

This is the larynx or the voice box now i want to briefly go over some of the anatomy here so right in front this car this is a piece of cartilage called hyaline cartilage but its name is the thyroid cartilage so you have the thyroid gland and then the thyroid cartilage thyroid means shield and this .

Is just going to act as a shield for the vocal cords which are going to be deeper down but this does not run all the way around it ends about right here on the sides but it's a pretty broad and massive piece of cartilage and this prominence here can get elongated in males due to .

Testosterone and we would call that the adam's apple although both males and females have the thyroid cartilage then underneath it there is another piece of cartilage which is going to be more difficult to see but i'm kind of palpating it with my fingers called the cricoid cartilage the cricoid is in fact going to run all the way around um so .

It's it's a circular piece of cartilage then up top here you can probably have already noticed there's this flap if i turn it to the side you can see it can come down this is what is known as the epiglottis the epiglottis and it's called epiglottis because it's on top of the glottis which is going to be in here .

All right so this is an elastic cartilage while the cricoid and the thyroid were hyaline cartilage and this is it's just there to block the airway and what you'll notice is if i open it up you can see that opening going down into here maybe it might be best with the probe this opening right there that is .

Going down into the trachea so that's the airway this opening behind it is going towards this uh this is the digestive tract so this is going to be the esophagus so we're looking at the end of the throat as it's transitioning into the respiratory and digestive systems but looking in there .

You can see that there is a gap that gap is actually called the rhima glottidus and that is just going to be the gap between the two vocal cords and we're going to be able to see the vocal cords in a slightly in a different direction a little bit better in a second but that is where air is going to be traveling .

Through so think about that remember right as you're exhaling and then the muscles are contracting it's it's regulating how much air and the pressure that it's coming up the trachea into the larynx and through that rhimoglotidus that that gap inside of the larynx so let's go ahead .

And look back here at this cross section because then we can see a little bit more of what's going on so to kind of let you understand exactly what we're seeing again this is that epiglottis right so this is that flap that we were just looking at .

Here you can see sorry see this with the probe this is going to be that thyroid cartilage and then you see this little tiny piece of cartilage here and then this big piece of cartilage in the back both of these are the cricoid cartilage it's smaller .

In the anterior or the front and larger or taller in the posterior aspect now this next part might be very difficult to see but if you look closely there is another cartilage right here called the arytenoid cartilage and these there's actually two of them but you're only looking at one .

And what happens is this is really important because again if you look really closely you'll see this really thin white line right here that thin white line is connecting the aritanoid cartilage to the thyroid cartilage that thin white line is called the vocal ligament or what most people would call the vocal .

Cord and then on either side and attaching to the vocal ligament is a bunch of connective tissue epithelial tissue muscular tissue that we kind of combine all of it together to call the vocal folds so you have the vocal ligaments and the which are inside of the vocal folds now .

What happens is you have two of those on either side right and what will happen is they are going to be able to open and close like this when you're breathing in and out like it's just adjusting how much is going through but what's really amazing is that when you are speaking .

They are going to become taut they become really tight and that's due to muscles pulling on the arytenoid cartilages and then as air is passing through that rhimoglobus if we go back to this right here so as air is passing through that rhimoglotidis now that that opening is really large right now because obviously .

This is a cadaver dissection and the muscle is all relaxed but imagine that being very taut right almost like a pulling a rubber band really tight and then as air is passing through it it's actually going to start vibrating it's going to start vibrating it'll move a little bit in either direction and going up and down .

And this is what the larynx is for right it's the larynx or your voice box is for controlling pitch and loudness so i apologize for what i'm about to do but pitch is going to be things like that was terrible i apologize but i tried to keep that as consistently loud as possible but i also could have gone and what i did is i changed pitch and .

Increased how loud it was to make it louder you're just going to actually send more air through and more forcefully so the voice box is there to control the pitch right your tone and then how loud it is so think about this right as you're speaking and right now i'm trying to put inflections in my tone and i might i .

Might whisper right all of that is going to be controlled through here and again we're not even we're not even taking into account the mind and how it's going down there this is just incredible at all the different muscles that are going back and forth adjusting as you are speaking or i am speaking to you right now it is absolutely incredible to think .

Of all the tiny adjustments that are happening as you are speaking of all the things that we've discussed so far they haven't been unique to human beings you're gonna find lungs a trachea a larynx in mammals all across the world as well as human beings but from here on out this is where things start to get very unique so in .

Order to understand this you are looking at a human head that has been cut in the mid-sagittal plane so right down the middle this allows you to see a lot of really interesting anatomy but our focus is going to be right here because this is going to be that vocal tract so you understand exactly what you're looking at .

This down here is going to be the trachea as it's transitioning into the larynx and this is a vocal ligament or a vocal cord so this structure here is going to be the larynx then what you're now seeing is what's called the pharynx the pharynx is actually pretty big it comes all the way up into .

Here but just to make things easiest we're just going to call this the pharynx even though this is specifically the oropharynx but this is just your throat then what you would get into is the oral cavity or what most people would refer to as the mouth and you can see the tongue is absolutely massive and .

Takes up the vast majority of that space so what we're talking about here is all of this space from the pharynx all the way out the mouth to the lips this is what's known as the supralaryngeal vocal tract because it's on top of the larynx so supra laryngeal vocal tract but no one wants to say all of that so we just shorten it .

To svt for short but there's different components to the svt so if we come back here we have a vertical svt and a horizontal svt and it's specifically measured from the top of the vocal folds the vertical one that is goes from the .

Top of the vocal folds up to this piece of tissue here which is called the soft palate and so that distance from here to here is your vertical svt then going from the back of the pharynx to the lips this is your horizontal svt now here's where things get fascinating because when we're talking about this being different in humans what .

We're really talking about is a difference in face and head shape so whether you're a horse you're a cow you're a mouse you're a chimpanzee or a human you're gonna have different structured cranium and that's going to affect the way that the acoustic properties of speech right so let's go ahead and .

Pretend like we're discussing like our closest cousin to chimpanzee a chimpanzee does not have a flat face like a human they're going to have a longer snout what that means is they're going to have a longer oral cavity or a longer horizontal svt .

But what also happens in a chimpanzee is their larynx doesn't rest as low down as it does in humans their entire larynx comes up and what that means is they have a shorter vertical svt also to take note of the tongue in a chimpanzee is going to be .

Flat that's going to play a very important role but so the now think about this if when humans started to evolve a flatter face what could have happened and likely happen is the tongue got pushed back and that made it rounded right so as the tongue got pushed back and rounded this is going to be so important to in order .

To articulate different sounds it also started to push back into the throat you don't see the tongue going down lower into the pharynx like this in a chimpanzee at the same time with humans our larynx drops over the first three months of life the larynx is going to drop significantly and then it's going .

To continue to drop until you're about six years old but before it drops if you actually look at a neonate so a newborn what will happen is it's crazy the epiglottis here the larynx is so high up the epiglottis actually connects with the nasal the the goes into the nasopharynx it connects with the uvula or the soft palate so you actually have .

A completely blocked off system here but as the larynx drops then it opens it up and that's this is a different topic for a different day but that actually creates a choking liability that exists in humans that you actually wouldn't see in other mammals because if you like say like if you have a larynx that is high up this .

Is the same with chimpanzees this is the same with many mammals when their larynx is higher up they actually have this whole airway closed because the epiglottis is in contact with that soft palate so it's kind of interesting so what i'm trying to get at here and i'm getting kind of wordy .

Is that the larynx is lower in humans meaning we have a longer vertical svt than most mammals plus a lot of other mammals their ac their uh sv their vertical spt is more of like an oblique svt it kind of comes at an angle but in humans we have a shorter horizontal svt so when you actually do .

It measure this in human beings our vertical svt and our horizontal svt are actually more or less the same length creating this l shape and that has very interesting consequences on the acoustic properties without getting too nitty gritty into it it allows for humans to make more sounds .

Were like if we're to get into the linguistics of it it would get kind of nitty-gritty but they're called phonemes just understand that humans are able to make more sounds a more diverse amount of sounds plus when you add in the rounded tongue as opposed to a flat tongue that also allows us to articulate .

And make different kinds of sounds like like we can do some really cool things with the tongue that other mammals can't do this is where you get the uniqueness of the human spt and our ability to speak it all comes down to having a flat face which pushed your tongue back which made it curved and then you have that .

Vertical l-shaped svt and horizontal svt all of that together creates the uniqueness of the human vocal tract i want you to take a step back and just think about this what has speech done for the human species with speech we have been able to create music or at least sing to the .

Music that we create we've been able to not only just talk with one another we've been able to communicate diverse ideas we come up with philosophy we come up with culture we're able to communicate very specific things we could point to a bush of berries and say that bush is poisonous i saw it kill ted as opposed to having to just .

Communicate with each other through a series of grunts or bodily gestures it's not as though communication only happens through speaking right we all know this right animals communicate with each other all the time i mean come on humans have even created american sign language right there's a difference between language and .

Languages specifically like speaking those languages and communicating through tones and frequencies as opposed to gestures right what's fascinating is that we as humans have created many different languages different dialects and it's allowed for our brains to just be able to evolve in some very interesting .

Fascinating ways so for this reason the sheer diversity of sounds that we are able to produce which no other animal on this planet can even though they still can communicate it's for those reasons that i believe it to be a legitimate human superpower thanks for watching everyone but real quick i just wanted to mention that making .

Videos like this one is possible due to the support from our patrons over on patreon jonathan and i love making these videos but i'm not gonna lie to you there is a considerable amount of time effort and energy that goes into making each one although i will say hopefully we have been making improvements that you have noticed such as camera quality .

Sound quality hopefully that one's been a pretty big struggle we even painted the walls here in the lab to just make things actually more visually appealing but these are small goals and we have much more lofty and big goals that we're looking to accomplish but we need your help to pull those off think like kids books ebooks .

Textbooks online courses there are plenty more that we have in mind but like i said we need your help to pull it off so if you're interested in becoming part of the ioha crew you'll find a link in the description below to our patreon page feel free to click it explore it see if that's something that is going to be valuable to you and if it is we'd .

Love to have you because then you can know that your support will help teach millions more across the globe about their bodies but anyways thanks for watching again and i will see you in the next video you .

Support us here! ____ Humans Have an Actual Superpower… ____ In this video, Justin from the Institute of Human Anatomy discusses the unique anatomy of the human vocal tract, and why it’s made such an impact on what it means to be human ____ Daniel Lieberman Books ____ Cool Stuff Merchandise Codex Anatomicus Coupon Code for 20% OFF: IOHA20 mUvmethod Coupon Code for 30% OFF: IOHASPLITS30 ____ Video Timeline 00:00 – 00:39 Intro 00:40 – 01:32 The Best Book Ever 01:33 – 05:40 Breathing and Speaking 05:41 – 08:55 Outside of the Voice Box 08:56 – 10:26 Vocal Cords and Friends 10:27 – 12:35 How the Vocal Cords Work 12:36 – 14:45 The Supralaryngeal Vocal Tract 14:46 – 18:05 Humans Compared to Chimps 18:06 – 19:01 Flat and Round 19:02 – 20:33 Why Speech Is a Superpower 20:34 – 22:00 Want to Help Us Out? ____ Audio Credit: ____ #Speech #Linguistics #VocalCords