HBO

A freshly hatched dragon perches on the shoulder of Daenerys in "Game of Thrones."

This the Year of the Dragon, and not just because of the Chinese calendar: Dragons play big roles in HBO's "Game of Thrones" TV series as well as the upcoming film version of "The Hobbit." Those fire-breathing, leathery-winged reptiles have been gripping the human imagination with their sharp talons for millennia, and it's worth wondering why.

Some folklorists trace the dragon myth back to a variety of sources in ancient China, Rome, Greece and India, and speculate that it had its genesis in the discovery of fossil bones from the strange creatures we now know as dinosaurs:

• Scythian lore described griffins with lionlike bodies and birdlike beaks. In the year 77, Pliny the Elder passed down the Scythian stories of gold-guarding griffins with peculiar ears and wings.
• During his travels in northern India, the first-century Greek philosopher Apollonius of Tyana reported that "no mountain ridge was without" a dragon to its name. The locals said they used magic to lure the dragons out of the earth and pry out the gems embedded in their skulls.
• Chinese accounts of "dragon bones" go back thousands of years — and as recently as 2006, ground-up dinosaur bones were being used in traditional medicine by villagers who believed they came from dragons. (The hard-to-crack dragon eggs depicted in "Game of Thrones" may well trace their lineage back to fossilized dinosaur eggs.)

Classical folklorist Adrienne Mayor, who relates all these tales in her book "The First Fossil Hunters," ascribes the reports to discoveries in fossil-rich regions such as the Altai Mountains in Central Asia, the Gobi Desert in China and Mongolia, or the Siwalik Hills in the Himalayas. Not knowing any better, adventurers interpreted the dinosaur bones as representing the remains of dragons, griffins and other mythical monsters.

The gold hoarding? That may have arisen because gold deposits were found close to the fossil beds along ancient Issedonian trade routes.

And the gems? "I think the Indian lore about special gems prised out of dragon skulls alludes to the crystals that can form on mineralized bones," Mayor wrote. "The detailed observations of the first modern investigator of the Siwalik fossils confirm my theory: large, glittering calcite crystals and tubular selenite crystals are common in the Siwalik fossils."

Hard-wired for dragons?
Anthropologist David Jones went even further in his book "An Instinct for Dragons," published in 2000: He proposed that the fables about winged, poison-spewing, fanged and clawed creatures combined three of the top threats to ancient pre-human primates: raptors like the one that may have preyed on a now-fossilized ape-boy known as the Taung child nearly 2 million years ago; poisonous snakes like the ones that may have driven the evolution of big brains and improved vision in primates millions of years ago; and big cats like the ones our pre-human ancestors had to watch out for in Africa.

"The world-dragon was formed by the nature of our own shadowy progenitors' encounters with the creatures who hunted them over millions of years," Jones wrote. The way he sees it, our brain came to be hard-wired with an instinctive fear of dragons.

Paul Jordan-Smith, a folklorist and storyteller who wrote a fiery critique of Jones' book for the journal Western Folklore, thinks the idea that our ancestors somehow evolved a dragon instinct just doesn't hold up. For one thing, Jones' claim that multiple cultures had the same conception of dragons as dangerous beasts is "demonstrably untrue," he said.

"My take on the mythic image of the dragon is that there is no one 'authentic' image, and no one 'true' meaning," Jordan-Smith told me in an email. "The dragon has been a guardian, a thief, a hoarder (like Smaug, in 'The Hobbit') and a dispenser of wisdom (especially in Chinese tales)."

For another thing, the dragon doesn't show up fully formed in ancient tales.

"It's interesting that dragons do not appear in cave paintings," Jordan-Smith wrote. "What does appear are the beasts that they hunted or that were dangerous. ... Where you do see constructs that aren't literal depictions, they're of humans merged with animals. And when you get civilization, you don't see dragons until much later. ... You don't get dragons until you get stories that have dragons in them."

Who's gripping whom?
But once dragons become part of a culture's mythic milieu, they don't fade away. Perhaps that explains why dragons hang around, in Chinese New Year festivals, in European fairy tales, and in American movies and TV shows. Here's what Jordan-Smith had to say about that:

"A dragon, like most mythic imagery, is 'plastic,' in the sense of being adaptable. It can look like whatever the singer of tales wants it to, can serve whatever purpose needed, and can mean just about anything. And some of the traditional qualities may not be incompatible with one another. A dragon that guards a treasure (or an abducted maiden) may be waiting for the right hero that will liberate it from its responsibility. A dragon that threatens to destroy a village may be a wake-up call to rectify misdeeds. Some dragons are enchanted and must be slain to regain their true form. But not all dragons are meant to be slain.

"And what of the hero? He must be changed somehow by the encounter, or else the game is not worth the candle. But what kind of change? In some cultures, to slay a fearsome beast was tantamount to assimilating its powers. ... In Tolkien's books, the Ring exerts its power so thoroughly that its wearer little by little becomes like Gollum. Perhaps there's a particular kind of danger, much more deadly than merely being killed. And perhaps when the hero slays the dragon, he himself is slain, to be reborn as the human incarnation of the dragon. For good or ill? Ask the storyteller."

Maybe it's not the dragon that has a grip on us. Maybe we're the ones who are hanging onto the dragon — and we don't want to let go.

More about dragons and 'Game of Thrones':

• Origin of Komodo dragons revealed
• Chinese villagers ate dinosaur 'dragon bones'
• Sword science plays a role in 'Game of Thrones'
• All about 'Game of Thrones' on The Clicker

Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter or adding Cosmic Log's Google+ page to your circle. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for other worlds.