I’ll bet her hand tells the best jokes

You may not know this but…

we are in possession of ancient technology. I’m talking about Men in Black, Star trek phaser-level technology. Forget about your smartphone or the connectivity of your Wi-Fi to your oh so shiny tablet (yeah..your tablet is boring). We have ears! Do you understand how remarkable the phenomenon of hearing is?! Mammalian ears are a curiously sophisticated adaptation. They’ve crossed species borders and traveled the millennia just to stay virtually the same. As far as mammals are concerned, version 1.0 is still the best thing out there and those cute little ears of our furry ancestors have been around since the dinosaurs. Archaeologists in China discovered the fossil of a 195 million year old mouse-like mammal (Hadrocodium) with a fully developed inner ear, not unlike what we have today. That’s the physiological equivalent of finding King Tut’s blue-ray collection.

Do we hear with our ears or with our brains?

Sound Waves and Philosophy

Sound is a physical property. Sound happens because people and animals and objects interact with the physical environment and the resulting energy of those interactions is transferred into sound waves that travel through air, water, asphalt or whatever. What we “hear,” on the other hand, is what our brains say we hear. Our brain translates that physical phenomenon into an experience and our brain instantly labels that experience as familiar or unfamiliar, safe or dangerous, pleasing or Nickelback.

Ear Anatomy

The pinna, that floppy, fleshy, flap of skin and cartilage on the outside of our heads is a total cover girl. It’s the most recognizable part of the ear and it helps to funnel a small portion of the infinite variety of sound waves whizzing pass our heads every second of the day. However, to learn the secret to the riddle of sound we need to look beyond the pinna, down the icky, wax filled canal (external auditory meatus) into the middle and inner ear where the tiny bones and membranes play percussion for our central nervous system.

The path of sound…

Tempanic > malleus > incus > stapes > oval window > vestibules > cochlea > Brain!

Once sound waves slinky down our ear canal they reach the tempanic membrane (ear drum) and that’s where the magic really happens. Waiting just behind the tympanic membrane is a highly specialized set of tiny bones (ossicles) that move in sync with each vibration.

At this point we have this nifty domino effect happening where vibrations move from one tiny bone to the next. That’s right, I said “vibrations.” Sound is energy and it behaves the way all energy does, never destroyed just moving from one form to another.

Anyway, vibrations move from the tympanic and then pass the baton to the malleus, along to the incus, and then to the tiniest bone of all, the stapes.

Here’s where it changes up a little. Those 3 bones I mentioned occupy this air filled space (tympanic cavity), kind of like a hallway in your head and at the end of that hallway is a door (or rather a window), the oval window. This window is a part of the next compartment of the ear. When that vibration reaches the stapes it basically knocks on that window, handing off the remaining sound energy to the inner ear.

Keep in mind that this is all happening at the speed of sound. Sound waves gallop along at a healthy pace of 1,126ft/sec through the air. Just imagine jumping 13 train cars in a fraction of a sec. Of course, your ear canal is only about an inch long so this all happens MIGHTY quick.

The inner ear is like another dimension. There are fluid filled vessels and a chamber at the end shaped like a snail shell with hairy receptor cells transmitting signals to the brain. I mean What?! It sounds like the hallucination of a band groupie at a Pink Floyd concert, but it’s real.

So what happens?

The stapes knocks on the oval window, transferring the sound vibration to fluid contained behind the window that will move along tubular ventricles.

So in case you got lost, sound moved down the pinna, through the canal, to the tympanic, shaking hands with the malleus, incus, and stapes hanging out in the hallway of the tympanic cavity where the stapes bangs on the oval window to stir up some nasty fluid on the other side.

This fluid (endolymph) now surging with sound energy, will transmit vibrations within the coiled vestibules where they connect with a spiraled chamber called the cochlea.

OK…here it is..

Tucked inside the cochlea is a layer of epithelial receptor cells that make up the Organ of Corti. As the energy charged fluid passes over the tiny hairs of these cells an electrochemical signal (neural transmitter) is released. Neural transmitters are basically like biochemical text messages, but instead of going through Verizon or Sprint this message travels down a bundle of nerves called the spiral ganglion where the temporal lobe of your brain is waiting to…well..”hear” it.

Stay curious, stay classy, and never stop learning my friends 🙂

9 out of 10 Beagles prefer French roast

I have to be honest with you my friends, after many hours of extensive research (2 whole hours) I just can’t wrap my head around this topic. I’ve flipped through page after page of neurophysiology, human anatomy & physiology, and re-runs of Bill Nye the Science Guy. All the while this topic mocks me from across the room, laughing and pointing at me while I stand vulnerable with my intellectual fly open. Yes my friends, the question of why we yawn is quite the physiological puzzler. So allow me to share what I’ve learned so far.

PANDICULATION! (get your minds out of the gutter…I was here first)

Pandiculation refers to the act of yawning and stretching at the same time. It’s that moment we’ve all witnessed when a dog first wakes from his nap. They’ll stretch out onto their paws in that awkward straddle that always reminds me of yoga on stilts. They then open their jaws impossibly wide and yawn. We may not be as cute as our fury friends when we do this but all the tell tale signs are there. Also, have you ever noticed how unsatisfying a yawn without stretching is? In fact, it is suggested that this is one of the main advantages of this activity. What other involuntary responses to stress, fatigue, and boredom do you know of that simultaneously stretch your jaw, tongue, throat, and eardrums aside from dry heaving?

So what does yawning do for us?

Here’s where the theories rear their ugly, wishy-washy heads. As you know, it has always been my mission to give you the facts – raw, unfiltered, with no artificial fillers or sweeteners, but surprisingly, there are more theories on this subject than Rihanna has hairstyles. So here are my top 3 favorite explanations:

Theory #1 – Increased CO2

This charming little theory has been circulating like an urban legend for eons. It suggests that yawning is triggered by a shift in the concentration of CO2 in the blood. Remember that breathing is a kind of constant exchange of oxygen for CO2 and it is just as vital to rid the body of the CO2 generated during the daily metabolism of our cells as it is to take in oxygen. So the idea that the sudden and deep inhalation of air taken in during a yawn is the body’s way of self-regulating for these shifts makes perfect sense to me.

Upon experimental investigation with test subjects however, increasing oxygen and reducing CO2 seemed to have no measurable effect on the incidences of yawning. Sorry CO2, you can take away our polar caps but not our right to yawn.

Theory #2 – Brain Temperature

This theory suggests that yawning is a means of cooling off the brain. As a fan of Sci-fi I dig this explanation because I like to imagine the brain overheating like a high-tech super computer developed in a secret government lab. So in order to keep our test tube, android bodies from nuclear meltdown we have to yawn occasionally.

So it’s not more oxygen that our yawns are bringing in but cooler air to lower our body temperature. When you think about it, the hypothalamus of the brain regulates body temperature anyway. Yawning could just be a sign that our internal thermostat is kicking in. Since body temperature fluctuates with our sleep cycles, it is believed that cooling off the brain heightens alertness and mental efficiency. In fact Alertness ties in beautifully with our third and final explanation….

Theory #3 – Alertness

This is my favorite (my blog defies science and thus picks favorites). This theory argues that yawning is an activity evolved to promote not only alertness but a kind of group vigilance.

fun fact – I yawned approximately 17 times in the process of editing this article.

From the moment we wake our inner clock is ticking, counting down the hours until sleep. As the light changes throughout the day, adenosine (neuron inhibiting, smooth talker that gets your central nervous system into bed) accumulates in our cells like sand at the bottom of an hour glass. Your awareness to stimuli, reaction time, and perception of subtle changes in the environment becomes muffled and muddy. Staying vigilant is crucial in a prehistoric wilderness of dire wolves and sabertoothes that think of homo sapiens as walking, P.F. Chang appetizers (I like the spring rolls).

So there you are, standing guard by the cave with your hairy arms and caveman abs. Having just chowed down on grilled mastodon your eyes start to droop. Your respiration shallows and your body temperature fluctuates, but just then, you hear bushes rattle in the distance. The sudden sound makes your shoulders jump (known as a hypnic jerk), jolting you back into consciousness. You smell the distinct musk of a predator dangerously close by. Reaching for your flint tipped spear you start to…yawn? The other members of your tribe also reach for their weapons. Women gather up the little ones and they too begin to yawn (a phenomenon of contagious yawning observed primarily among relatives and close friends rather than strangers). The yawning stretches the jaw, tongue, eardrums, and throat. Arterial blood flow is increased, allowing the brain to cool, prompting arousal just in time to perceive the threat of wolves approaching…or so the theory goes.

Stay curious, stay classy, and never stop learning my friends 🙂