Why Are They Called Theropods?

Every night, before he goes to bed, my wife and I read a book to my son.  Last night, he picked out one of the books he got from the library.  I don’t recall the title, but it was full of cartoon dinosaurs accompanied by facts about them.  A lot of those facts were things I’ve learned in a lifetime of obsession with the “terrible lizards”, and a good number of them are things he’s learned from Dinosaur Train and from other books we’ve read.  But that really isn’t the point of the evening ritual.  If he learns something, that’s great.  For me, though, it’s the opportunity to read to him.

“What’s a theropod?” my son asks.

“It’s a type of dinosaur,” I say, realizing that I’ve forgotten what a theropod is or what the other type of dinosaur is.

“Why is it called a theropod?” he continues.

“I don’t know,” I tell him.

“Can you find out?”

Of course I can.

Dinosaurs!

Let’s start off with the basics.  You may have heard that dinosaurs aren’t reptiles.  This is not strictly true, as Dinosauria is a clade of the class Reptilia – a class that in modern times includes turtles, crocodilians, snakes, amphisbaenians (aka worm lizards), lizards, and tuatara.  Dinosauria contains two Orders, Ornithischia (primarily herbivorous dinosaurs with a hip structure similar to birds) and Saurischia (primarily carnivorous dinosaurs with a hip structure similar to lizards), although it appears that many contemporary paleontologists classify Ornithischia and Saurischia as clades rather than orders.

Clades?

A clade can be thought of as a branch on the tree of life.

tree-of-life_2000

More specifically, a clade consists of a single ancestor species and all the species that evolved from it.  In broad strokes, all life is a clade because everything traces back to a single organism.

Theropods?

“Theropod” derives from Greek, and means “wild beast foot”, and was coined in 1881 by O. C. Marsh as a suborder to hold Allosaurus.  They are ancestrally bipedal, ancestrally carnivorous dinosaurs – “ancestrally”, because some species of theropods evolved omnivorous or herbivorous diets, or quadrupedal gaits, or both.  Depending on the “age” of the species and the specific lineage they may have had scales or feathers or both.  The order includes many of the famous, “sexy” dinosaurs, such as the Tyrannosaurus Rex, the “four-winged” Microraptor, and chickens.

Chickens?

Yes, chickens.  See, one clade within Theropoda was Averostra (“bird snouts”), and Averostra had a couple of clades survive the Cretaceous–Paleogene extinction event:  Ceratosauria and Orionides.  Within Orionides was the clade Maniraptoriformes, which was the parent clade for Avialae, which was the parent clade for Aves – modern birds.  So, yes, birds are “lizard-hipped” dinosaurs.  Go figure.

dinosaurs

What Are Vocal Cords?

“Dad?” my son asks. “Why does Darth Vader sound funny?”

We’re sitting on the couch when he asks the question. I’m reading, and he’s playing with his Legos, and the question doesn’t come from as far out of left field as it might seem. The majority of his Legos are Star Wars themed, after all. “Because the people who made the movie wanted him to sound scary,” I say.

“No,” he huffs. “I mean, in the movie!”

“Oh,” I say. “Well, his vocal cords got hurt when he fought Obi Wan.”

“Vocal chords?” he asks, sounding baffled. “What are vocal chords?”

What Indeed?

I don’t know, to be honest. Oh, sure, I know they’re the things in your throat that vibrate when you talk, and that they’re the things that actually let you speak. But I have no idea beyond that. The name always made me imagine a set of fleshy guitar strings stretched across my throat – when I thought about it at all – but I’m fairly confident that this isn’t correct. So, let’s look into the answer. Literally.

Vocal Cords

Those are vocal cords – also known as vocal folds – in action. Medscape describes them as “mucous membrane infoldings that stretch horizontally across the middle laryngeal cavity. They are attached anteriorly at the angle on the interior surface of the thyroid cartilage and project posteriorly to the arytenoid cartilages on either side.” They’re found within the larynx, at the top of the trachea, and open when inhaling and close when swallowing. They also close to help vibrate and modulate air expelled from the lungs to enable us to produce sounds (like, for instance, speech).

illu_larynx

Technically, there are two sets of vocal cords. The “true vocal cords” (or vocal folds) and the “false vocal cords” (or vestibular folds). These vestibular folds primarily serve to protect the more delicate vocal folds, but may also be “used in the production of deep tones and screaming or throat singing”. So, if you happen to enjoy black metal or Tuvan or Mongolian throat singing, you have heard and appreciated the false vocal cords.

On average, adults have larger vocal cords than children and men have larger vocal cords than women. This is why, again on average, adults have deeper voices than children and men have deeper voices than women. Larger vocal cords vibreate more slowly and with a longer frequency, creating lower sounds. Women are also more likely to have vocal folds that appear to be a pearly white, while men are more likely to have pinkish vocal cords.

Human are not born with fully developed vocal folds. Infants lack a vocal ligament, which allows the muscles of the larynx to easily control the vocal folds. “The vocal ligament begins to appear at about 4 years of age. The formation of the 3 defined lamina propria layers occurs between the ages of 6 and 12 and are fully mature at the end of adolescence.”

Care to tie this back to Star Wars?

Of course I would, because that’s what spawned this question. Clearly, the vocal cords can be damaged – acid reflux and smoking can thicken them, and significant use can stiffen them. Stiff vocal cords don’t vibrate as well, reducing vocal range and making speech difficult. Surgeons can repair this stiffness by replacing the vocal cords with synthetic materials. Specifically, a variation of polyethylene glycol called PEG30, which mimics the flexibility of human vocal cords and moves in a very similar manner to the natural tissues that compose them. So, instead of having a raspy mechanical voice, Darth Vader could have been given an amazing singing voice.

Not that the Dark Lord of the Sith doesn’t rock out anyway.

There’s Creepy Stuff In My Ears!

Not too long ago, we had to clean my son’s ears out. When I was a child, this involved q-tips. There have been all kinds of advances since then, though, and now we use drops that get flushed out with warm water.

My son hated it. Not because it hurt, mind. But he had to lay down for a full minute per ear, with a washcloth on his ear, and he was bored. Then, after we rinsed out the ear, he looked at what came out. “There’s creepy stuff in my ear!” he said.

“That’s just ear wax,” I told him.

“What’s ear wax?”

Uhm…

Seriously? Last week wasn’t enough for you?

Look. Ear wax is a fact of life. I have it, you have it, famous actors and supermodels have it. Everyone has it. But, how many of us know what it actually is or what it is for? I sure don’t. And I promised my son I’d answer his questions. So, we’re going to start with glands.

Glands

Your skin has glands, which are organs that synthesize some substance and then release that substance for use by the body. Chief among them are the sebaceous glands, found everywhere on your skin except for the hands and the soles of the feet. These sebaceous glands secrete an oily or waxy substance called sebum, which lubricates and waterproofs your skin. Sebum is also slightly acidic, and helps serve as a barrier to viruses and bacteria.

howdowehear

Along with sebaceous glands, the outer third of your ear contains ceruminous glands. These glands produce cerumen, which helps you hear by keeping your eardrum pliable. It also helps keep the external auditory canal clean, and serves as another barrier to bacteria and foreign particles.

Earwax

Earwax is a mixture of sebum and cerumen and all the things block and trap: dirt, bacteria, shed hair and skin cells, and so on. People of African and European origin are likely to have wetter cerumen (and wetter, dark brown earwax), while Asians and Native Americans will have dryer cerumen (and dryer, grey or yellow earwax).

Normally, earwax helps to clean the ear canal by a process of “epithelial migration”. Cells in the ear canal are pushed outwards by the growth of new cells, and earwax – being sticky – clings to the cerumen and sebum produced by the glands and moves with the cells. Eventually it is pushed to the outside of the ear and out, taking dead skin cells and dirt and bacteria with it.

Excess Earwax and Blockages

According to the Mayo Clinic, excess earwax is caused by the ear secreting excess ebum and cerumen. Or, in other words, excess earwax is caused by excess earwax. Go figure. If you have excess earwax, it can be softened with a few drops of mineral oil or hydrogen peroxide, and then – after softening for a day or so – rinsed out (gently) with warm water. They recommend that you never attempt to dig it out, as that can push the wax deeper and block the ear canal or even damage the eardrum. If you can’t clean it out yourself, you should see a doctor.

Why Do We Get Boogers?

It’s winter, and the temperature has been really strange. Up and down, up and down. One day I can walk around outside, thinking my light jacket is too much coat. Two days later, it’s snowing. It’s been that kind of season, and I think that’s why my son has the sniffles. He’s not sick, per se, but he’s sniffling and sneezing and his nose is running. So recently, he goes and grabs a tissue and wipes his nose. “Dad,” he asks, “why do we get boogers?”

Well, I did say I’d answer his questions…

the-nose

What is a booger?

Let’s be honest here. You know what a booger is. You were a kid once, even if you haven’t been around any recently. Still, let’s do this right. Merriam-Webster gives two different definitions for the word “booger“:

  1. Bogeyman
  2. a piece of dried nasal mucus.

Clearly, in the contex of my son’s question, we’re talking about the second definition. I’ve never told him about the “bogeyman”, and I don’t think any of his friends have told him about that character. He’s six, and he’s feeling scared of the dark, so I think it would have come up if he had. So, let’s focus on the dried nasal mucus. The Online Etymology Dictionary gives the following explanation for the word

“nasal mucus,” by 1890s; earlier bugger. Also boogie.

So, yeah. No Greek or Latin or Proto-Indo-European here.

What is mucus?

Going back to Merriam-Webster, mucus is defined as “a viscid slippery secretion that is usually rich in mucins and is produced by mucous membranes which it moistens and protects”. It’s a fairly common fluid produced by the human body – heck, by nearly every animal, not just us humans. The respiratory system produces mucus in the nose, the airways (i.e. your sinuses and throat), and the lungs, as a way of trapping foreign particles. What foreign particles, you ask? Dirt. Dust. Bacteria. Pollen. Allergens. You name it, your mucus traps it. And the more your respiratory system needs to trap, the more mucus it produces. That’s why you generate more mucus (and then cough) when you get exposed to allergens or you get sick. Your body is trying to trap more of the foreign particles and expel them before they can cause you more problems.

Your respiratory system isn’t the only place that makes use of mucus, however. Your digestive system uses it for the whole length – from the esophagus into the stomach and the intestines and into the colon – as a way of lubricating your food in its journey through your body. It also shows up in the reproductive system, functioning as a lubricant and a means of transporting sperm and eggs through the body. Your eyes generate mucus as well, lubricating and protecting sensitive cells and keeping them moist.

So. How does mucous become boogers?

Bear in mind that mucus isn’t just water. It’s full of proteins and antibodies (because it isn’t just a passive defense) and electrolytes, not to mention all the dust and dirt and bacteria and such that it has trapped. As the water in the mucus evaporates or gets absorbed by the body, these solids get left behind, sticking and clumping together until – if not disturbed – they form masses of noticeable size.

I can’t believe I’m going to ask this, but… why the nose? Why not eye boogers?

Actually, those can happen. Eye crust, also known as rheum, is essentially eye boogers.

Great. Anything else?

Yeah. You know how your mom said you shouldn’t pick your nose and eat it?

Do I want to know this?

Hey, you’re the one still reading.

It turns out that there’s a hypothesis that boogers have a sugary taste that is meant to entice you to eat them. Because the act of doing so helps introduce weakened pathogens from the environment to your immune system, building up your defenses. This is rather controversial (not to mention nauseating), and it has not been tested. A number of scientists als point out that you swallow mucus all the time, just by living. This still serves to introduce the pathogens to your body. So don’t take this as a license to go to town on your nose, please.

I wasn’t planning to. Also, I hate you so very, very much right now.

Look, the human body is endlessly fascinating. Even the bits that we find culturally repugnant. Besides, you’re the one reading the article about boogers. What did you expect?