With prominent examples including Game of Thrones and the Hobbit films, it's clear dragons are as popular as ever. But why is there this widespread affection for a fictional species that couldn’t possibly exist … or could they?

If you saw a heavily armoured winged reptile the size of a building that started belching boiling flame at you, you’d probably run for it. Or, alternatively, you might base copious amounts of fiction on it, or artwork, or, if you’re like us Welsh folk, you might stick it on your flag. Despite the tremendous danger they would obviously pose to physically inferior life forms (ie everything), dragons are very popular with humans. Yesterday was St George’s day in England, and St George is celebrated for killing a dragon. But he wouldn’t get away with that these days, what with dragons being (ironically) very cool. There hasn’t been such mainstream affection for a non-existent entity since Jesus himself.

That last sentence is a joke, by the way; dragons are definitely real (well, sort of).

But it is unusual how widespread dragons are, spanning numerous cultures and many centuries. People would write “here be dragons” on any uncharted area of a map (expect they didn’t). There is generally a difference between eastern and western dragons, with eastern dragons being the snake-like, benevolent magical kind, and western being titanic, dinosaur-like fire-breathing aggressive monsters. Whereas western dragons were often seen as obstacles and threats (hence the St George slaying), in modern fiction they’re more likely to be used as allies, or weapons at the very least, such as in Game of Thrones, or How To Train Your Dragon if you prefer your formidable reptiles with fewer boobs and less incest.

But what makes these fascinating beasts tick? And why do we like them?

Plausibility

How “realistic” are dragons? Obviously, very big reptiles can and did exist. But something with the dimensions of a dragon that can fly? Unlikely.

As an aside, I’m sticking to western-style dragons here because the eastern ones are more associated with magic, so all bets are off. Plus, something the shape of a snake that could fly? Like that could ever happen.

It should come as no surprise that attempts to scientifically explain dragons have already been made. Flight seems to be the main hurdle; biological flight has numerous limitations due to physics that would prevent something dragon-sized from taking off. More modern depictions of dragons have tried to address this with bigger wing-to-body ratios, but when you’re that size your mass poses a big hurdle.

Saying that, pterosaurs (the biggest known flying animal in history) were four-legged brutes with 10-metre wingspans, so maybe dragons aren’t that much of a stretch? Earth’s atmosphere may have been denser back in their day, but given how much CO 2 we're pumping out, it may get that way again.

But what if the wings are vestigial? Once functional, but no longer, perhaps occupying a more decorative function for attracting mates, or making them seem bigger to deter predators? Although what would prey on dragons is anyone’s guess . But without the restrictions of flight, they would be able to grow as big as they can, so maybe that explains the colossal size?

The fire-breathing has some parallels in nature, albeit on a smaller scale. Another interesting possibility is that reptiles are ectotherms, meaning cold-blooded, so their body temperature is dependent on the external environment. It’s believed this is why the bigger dinosaurs were slow, lumbering beasts with tiny brains; it takes a lot of energy to power something that size, and speed and intelligence would just require too much energy.

The only way a reptile of such proportions could become quick and deadly would be for it to, I don’t know, evolve some sort of internal chemical furnace to heat and accelerate their metabolism! Which is ridiculous; such a thing would be hard to contain, it would need to be regularly vented by releasing large jets of flame from … well, there you go!

Dragons would be smarter as a result of this, which may explain why they hoard gold; what better way to ensure a supply of delicious humans comes right to you than by living near their precious metal? This may also be why they guard princesses; same method, different bait.

Why reptiles?

When you think about it, why should dragons be reptiles? They’re fictional, they could have been anything. Granted, an obvious inspiration for dragons would be dinosaurs, but the dragon myth predates palaeontology (ironically). Discoveries of large, inexplicable bones were often thought to be dragon remains, before dinosaurs as a concept were even figured out. And yet, each individual dragon myth, regardless of origin, has decided they’re reptiles. Why?

Large reptiles such as crocodiles are/were relatively common (in that they existed at all), and stories about these could well have permeated throughout different cultures, resulting in a “reptiles = unknown monster” association. Associations with other creature types wouldn’t be as useful. Insects = weird but small and boneless, fish = water-based, mammals and birds = cute and relatable. So it’s reptiles who get the monster roles.

Another fascinating but difficult-to-test possibility is that this fear/wariness of reptiles is an inherent response that we’ve evolved over millions of years. Similar to how chimps seem genetically predisposed to fear snakes, there could be some tiny corner of our mammal brains that remembers our being small, shrew-like creatures at a time when giant scaly beasts ruled the Earth and made our lives a constant pain-filled battle for survival.

Or it could be just a fluke.

Why are they liked?

Eastern dragons were seemingly always nice and pleasant creatures, but western ones couldn’t be a more obvious threat to human civilisation if they were wearing a Ukip rosette. So why are they so popular now?

Part of it could be that people like danger and risk, and dragons represent this in spades. Also, they’re usually very aesthetically pleasing, all majestic and awe-inspiring. But it could also be like how children love dinosaurs; they provide the potential for danger and excitement, but are totally safe because they don’t exist (“any more”, in the case of dinosaurs). The potential for dangerous thrills without ever actually delivering can be very appealing for people. See also “zombies”.

So there you go. Dragons are cool. It’s a shame they don’t exist. Or maybe they did at some point? Who knows what mysterious forces could have wiped them out ...

Dean Burnett is actually quite weary of the excessive dragon-themed merchandise in his home nation of Wales, especially when it’s used to sell cheese. He’s on Twitter, @garwboy