WOMAN: What do Game of Thrones, The Hobbit, and Harry Potter have in common?

Big, fire-breathing dragons.

You might know these beasts from fairy tales.

But those stories only tell a fraction of the dragon's history.

And I'm here to tell you that dragons are real... sort of.

[MUSIC PLAYING] I'm Dr. Emily Zarka and this is Monstrum.

We like dragons because-- let's be honest-- they look cool.

Many of us have pets.

And the dragon is the ultimate fantasy-- something beautiful yet ferocious, both loyal and capable of protecting us.

But unlike other popular monsters, the dragon is, above all, animalistic, often possessing no human attribute other than intelligence.

Dragons have been a part of human culture for thousands of years, with good reason.

Throughout time, countless countries and cultures have integrated stories of large serpentine creatures into their oral storytelling, art, and literature.

But why?

The reptilian nature of the dragon can most probably be accounted for by some human encounter with an astounding creature, such as a large aquatic animal floating just below the surface.

The discovery of inexplicable natural phenomenon led our imaginations to fill in the gaps.

An abnormally large snake, even an aggressive Komodo dragon, became a legendary monster.

Marco Polo famously claimed to encounter huge serpents with two legs and sharp teeth while traveling in China, writing, quote, "The jaws are wide enough to swallow a man.

"The teeth are large and sharp.

"And their whole appearance is so formidable "that neither man nor any kind of animal can approach them without terror."

Now, it is generally believed that these dragons were in fact just crocodiles.

And before paleontology existed, skeletal remains of some giant reptile were not always recognizable as the bones belonging to long-dead animals.

Dragon myths are, in part, a response to these discoveries.

Like other monsters, there is a great history to these creatures.

Each dragon's appearance and purpose finds shape in the culture of its creation.

Every dragon is unique to the land and its people.

This is why there is no one type of dragon.

Not all dragons breathe fire.

Some don't even have wings or feet.

This is a dragon.

But so is this.

Even these guys could all be considered dragons.

But what accounts for these differences in dragon appearance?

While there are examples of dragons all across the globe-- from the benevolent, shape-shifting dragons of China to the feathered Mesoamerican dragon god Quetzalcoatl-- for now, let's just focus on those most common in modern fantasy literature: the classical dragon, and one of my personal favorites, the wyvern.

The wyvern is a dragon frequently associated with the United Kingdom.

It's distinct from other types of dragons because its reptilian body possesses wings but only two legs.

George R.R.

Martin adopted the wyvern style of dragon.

Khaleesi's reptilian children have very long necks and tails, large wings, and only hind legs.

Martin considered biology alongside myth when crafting Drogon and his siblings, arguing that, living or dead, from bat to pterodactyl, quote, "no beast in nature has four legs and wings."

Well, tell that to the creators of the classical dragon.

Recognizable by their four legs and powerful wings, this form of dragon is the most commonly seen today-- like that movie where Sean Connery played a funny-looking CG dragon.

Remember that one?

No?

Probably for the best.

The prehistoric order of marine reptiles, Plesiosaurus, are large, long-necked creatures with four long flippers, or, as I like to call them, water wings.

Plesiosaurus fossils easily could have been mistaken for the two wings and two legs of the wyvern or even the four legs of the classical dragon.

Even today, we find more evidence that previous cultures encountered reptilian fossils.

In 2015, an ancient fossil was discovered that appeared serpentine and has four legs.

I told you dragons were real.

J.R.R.

Tolkien had his own taxonomic system for dragons.

He classifies the creatures by their capacity to breathe fire and how they move around.

His writings depict dragons with and without wings, with legs and without, and only some capable of breathing fire.

His most famous dragon, the clever, treasure-guarding, wicked worm Smaug checks off multiple boxes in Tolkien's taxonomy.

Like many authors today, Tolkien combines different dragon myths to create the most terrifying beast imaginable.

With larger audiences in mind, the modern dragon needs to appeal to people of different cultures and backgrounds.

J.K. Rowling models this in Harry Potter.

Some of the dragons in that universe have two legs-- most famously, the Norwegian Ridgeback and the Hungarian Horntail breeds, whose lizard-like bodies and large wings resemble a wyvern.

However, other dragons in the series, like the Common Welsh Green, have four legs.

It could be no coincidence that such a dragon appears on the national flag of Wales, a country close to where Rowling grew up.

Fire-breathing dragons are the most popular dragon we see today.

But where did this attribute come from?

The development of fire-breathing dragons could have been a result of the geological features of northern Europe-- specifically, the presence of natural gas vents.

A wayward lightning strike or dropped torch by a miner could have provided the spark that sent a tongue of flame or wave of noxious gas to the surface.

Not having a way to explain this natural phenomenon, we filled in the gaps with a supernatural explanation-- the fire-breathing dragon.

This may also partially explain why dragons are associated with guarding treasure, often below ground or in dark caves.

Miners would have been likely trying to deter thieves with scary stories of a monstrous creature protecting their own fortunes.

The visual of the dragon as a fire-breathing creature also appears as early as the 10th century, when the gates of hell were depicted as the flaming mouth of a demonic beast.

What does all this mean?

What can we make from thousands of years of stories and images of dragons across the globe?

Can these tales teach us anything?

The dragon represents a human appreciation and respect of the power of nature.

They remind us to tread carefully across rivers, to avoid dark caverns, and to humble us in the presence of beasts stronger than ourselves.

The dragon is legendary.

It doesn't really matter so much whether or not it existed.

What does matter is that, in an age when nature was mostly unexplained, dragons were a way to make sense of a world that seemed much more mysterious.

The Great American Read is a new series on PBS about our love of reading.

The show leads up to a vote on America's favorite novel.

And you, dear viewers, are the ones who get to choose the winner.

Head a PBS.org/GreatAmericanRead to vote on your favorite book.

[MUSIC PLAYING]